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Article type: Cover
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Cover1-
Published: September 10, 1981
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Article type: Appendix
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App1-
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Article type: Appendix
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App2-
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Article type: Index
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A1-A10
Published: September 10, 1981
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Article type: Index
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A11-A21
Published: September 10, 1981
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Article type: Appendix
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Published: September 10, 1981
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H. Nishimura, K. Kaku, T. Nakamura, J. Mizutani
Article type: Article
Session ID: 1
Published: September 10, 1981
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In connection with the integral utilization of Eucalyptus plants as a renewable biomass, we are concerned with the exploration of biologically active compounds such as plant growth regulator. We report on the isolation, identification, synthesis and structure-activity relationships of allelopathic substances, which are designated as C inhibitors, from E. citriodora Hook. Fractionation of acetone extract of fresh leaves was guided by toxicity to germinating seeds and seedlings of lettuce and some other weeds. Column chromatography of an active fraction gave C_1 and C_2 inhibitors, so called (±)-p-menthane-3,8-cis-diol and (±)-p-menthane-3,8-trans-diol, respectively. The absolute configuration was confirmed by comparisons with physical data of synthetic chiral compounds and chemical transformation to known natural product. Interestingly, the C inhibitors occur in the plant as racemate, and are absent in ontogenetically juvenile tissue of E. citriodora. The biological activity of cis isomers was much higher than that of trans isomers. Furthermore, (+)synthetic C_1 inhibitor had higher activity rather than the optical antipode. The fact indicates that a receptor site concerning germination of lettuce seeds is also chiral.
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S. Uesato, T. Hashimoto, K. Uobe, Y. Takeda, H. Inouye, H. Taguchi, T. ...
Article type: Article
Session ID: 2
Published: September 10, 1981
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From the aerial part of Hydrangea macrophylla f. macrophylla, new secoiridoid glucosides, hydrangenosides B, C and D have been isolated along with hydrangenoside A which had been encountered in the same plant. On the other hand, hydrangenosides C, D, E, F, G and H of the same series have been isolated from Hydrangea scandens. On the basis of their spectral data and chemical evidence, novel type structures of these new glucosides have been established, which are considered to be formed by an aldol type condensation of secologanin with shikimate-malonate-derived moieties.
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Teruaki Suzuki, Akio Furusaki, Hajime Kikuchi, Chuji Katayama
Article type: Article
Session ID: 3
Published: September 10, 1981
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Cycloeudesmol, C_<15>H_<26>O and strongly antibiotic toward Staphylococcus aureus and Candida albicans, has been isolated from the red alga Chondria oppositiclada Dawson by Fenical and Sims and its structure has been proposed as shown in the formula 1 by the spectral and chemical evidences. Recently, the total syntheses of four possible stereoisomers of 1 have been completed and they were found to be different from the natural cycloeudesmol and it was concluded that the structure (1) of cycloeudesmol, proposed by Fenical and Sims, should be revised. On the other hand, the structure of isocycloeudesmol, C_<15>H_<26>O, isolated from the red alga Laurencia nipponica Yamada, has been proposed as the formula 2 by the spectral and chemical properties. Meanwhile, the cautious comparison of ^1H NMR and IR spectra and the optical rotation came to the conclusion that cycloeudesmol was identical with isocycloeudesmol. Herein we wish to report the absolute stereostructure of cycloeudesmol (isocycloeudesmol) by the X-ray crystallographic study.
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Yoshio Takeda, Tetsuro Fujita, Akira Ueno
Article type: Article
Session ID: 4
Published: September 10, 1981
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During the investigations on the biologically active substances from Labiate plants, we examined the constituents of the leaves of Rabdosia umbrosa (Maxim.) Hara var. leucantha (Murai) Hara f. Kameba (Okuyama et Ohwi) Hara collected in Yamanashi Prefecture and isolated six new diterpenoids, leukamenin A, B, C, D, E and F. The structures of these compounds were elucidated as 1, 2, 3, 4, 5 and 6, respectively, from spectral and chemical evidence.
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M. Ochi, M. Okamura, H. Kotsuki, I. Miura, K. Hirotsu, I. Kubo, T. Kub ...
Article type: Article
Session ID: 5
Published: September 10, 1981
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During a search of the biologically active constituents of members of the genus Rabdosia, we examined the ether extract of the leaves of Rabdosia shikokianus Hara and isolated four new diterpenoids. Three of them were established to be 6,7-seco-ent-kaurenoids, 1, 2, and 3, on the basis of spectroscopic evidence and chemical correlations. The remaining one was found to have 6-epi-ent-gibberellane structure 4 by spectral correlation and an X-ray diffraction method. It can be presumed that 4 is derived biogenetically from rabdosianin A (10) by the oxidation of the hydroxyl group at C-6 and the subsequent benzilic acid rearrangement. Antimicrobial and insect growth inhibitory activities were evaluated.
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Y. Kojima, M. Morita, N. Kato, K. Miwa, I. Tanaka, T. Ashida
Article type: Article
Session ID: 6
Published: September 10, 1981
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Absolute configuration of clerodin 1 and caryoptin 9 which were decided by D.H.R. Barton et al. and G.A. Sim et al. and the authors, respectively, were recently corrected by N. Harada and H. Uda and D. Rogers et al. However, at this time, a new problem arised from the above conclusion, i.e., the results of the ketone Cotton effects of their ketone derivatives were in conflict with the conclusion of X-ray analysis. We calculated the minimized energy of an imaginary compound 16a and 6-keto derivs. 11a and 12a by molecular mechanics (program: MM2), to begin with. The calculated results showed that 16a was stable with a chair conformation about a B ring, but 11a and 12a were stable for the boat conformation (Table 1). Further-more, the result of the calculation revealed that caryoptin derivs. 17a and 18a were also retained the boat form on the B ring as the stable conformer. The facts were confirmed by the X-ray analysis of 18a. Therefore, we concluded that the inversion of the Cotton curve for the ketone derivs. was caused by the conformational change to the boat form on the B ring. Furthermore, in the calculation of the steric energy for 19a, 20a, and 22a, it showed that their B ring prefered the chair form as the stable conformer. However, a stable conformer of 21a took on the boat form for the B ring. For confirmation of it clerodin was derived to 21a and 22a. As we would expect, they showed (+) and (-) Cotton curve, respectively. From the above results, it was concluded that complex and subtle steric interactions caused conformational change at the B ring.
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Minoru Suzuki, Etsuro Kurosawa
Article type: Article
Session ID: 7
Published: September 10, 1981
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In connection with our continuing studies of the constituents of the red alga Laurencia okamurai Yamada, a Japanese species of genus Laurencia, we have examined a specimen collected at Bikuni, Hokkaido. This specimen yielded five nonterpenoid C-15 bromoallenes (A〜E) (Table 1) as the minor components together with laurinterol (1) and debromolaurinterol (2) as the major components. The structure of bromoallene-C, designated as okamurallene, was determined as formula 16 on the basis of the spectral evidence. Furthermore, the structures of bromoallene-E (isookamurallene) and -A (deoxyokamurallene) were deduced as formulas 17 and 18, respectively, by comparison of the spectral data with those of okamurallene (16). These bromoallenes are the first examples of the nonterpenoid C-15 metabolites from the genus Laurencia with a cyclopropane ring, a bromine atom at C-6 and a substituent at C-8. The structures of the remaining two bromoallenes (B and D) are currently being investigated.
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Akio Fukuzawa, Yoshikazu Kumagai, Akio Furusaki, Takeshi Matsumoto, Ta ...
Article type: Article
Session ID: 8
Published: September 10, 1981
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A number of halogenated metabolites with C_<15> vinyl acetylenic or allenic cyclic ether structures and halogenated sesquiterpenes have been isolated from the genus Laurencia. We previously reported structure of two cyclic ethers, laurepinnacin and isolaurepinnacin (1 and 2), isolated from L. pinnata. In continuing studies on components of the alga collected at Motsuta point in early July, we newly isolated three halogenated diterpenes and two sterols, designated as pinna-terpenes A, B, and C, and acetylpinnasterol and pinnasterol, respectively. The present paper describes that the diterpenes and sterols are represented by formulas 3, 4, 5, 6, and 7, respectively, on the basis of the X-ray crystallographic analysis and chemical evidence. The present study indicates that the alga L. pinnata is characterized by the following: (i) the alga does not contain halogenated sesquiterpenes but halogenated diterpenes (3〜5), (ii) the alga includes the marine phytosterols (6 and 7 with moulting hormone activity related structurally to ecdysones, and (iii) the alga contains the C_<15> cyclic ethers (1 and 2), considered to be formed in vivo from a new precursor, (3E,6Z,9Z,12Z)-pentadeca-3,6,9,12-tetraen-1-yne, rather than the potential precursor, laurediol, with (12E)- configuration.
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Y. Uchio, M. Nitta, J. Toyota, M. Nakayama, Y. Nishizono, T. Iwagawa, ...
Article type: Article
Session ID: 9
Published: September 10, 1981
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Twelve cembranoid diterpenes (1-12) have been isolated from three Japanese soft corals, Sinularia mayi, Sarcophyton elegans and Lobophytum hedleyi. The structures were elucidated from spectro-scopic measurements and chemical evidence. Among five compounds (1-5) obtained from S. mayi, the isolation of cembrene (1) has not been reported to date from marine sources. Compound 2 was a new simple cembrene derivative. Compound 3 was confirmed to have the same structure as a synthetic intermediate of cembrene-A (13). Another new compound 5 with trans-fused γ-lactone was a stereoisomer of a co-occurred cembranolide (4) which was also isolated from Lobophytum michaelae from Great Barrier Reef. S. elegans contained five compounds (6-10). The stereo and absolute structure of 6 which have so far been found in S. glaucum from Red Sea was determined through the present work. The structures of compound 7 and 8 were deduced by chemical correlation with 6. Compound 9 was a new polyfunctional cembranoid with ketone, dienoic ester and α,β-unsaturated γ-lactone moieties, whose structure was established by correlation with emblide. Compound 10 was assigned to the prototype type structure of 9 by spectroscopic comparison between 9 and 10, and their derivative 22-25. Two new compounds, 11 and 12, isolated from L. hedleyi, were the first carboxylic acid cembranolides from marine sources.
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T. Kikuchi, S. Kadota, H. Suehara, T. Namba
Article type: Article
Session ID: 10
Published: September 10, 1981
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Sterol components of Nervilia purpurea SCHLECHTER (I-tiam-hong), an Orchidaceous plant, were examined. Repeated silica gel chromatography of the neutral fraction of the etherial extracts gave two sterol fractions. The more polar fraction was further purified by column chramatography on 20% AgNO_3-SiO_2 and preparative TLC using AgNO_3-SiO_2 plates to give a new sterol, nervisterol (7a), and seven known sterols: 24-epi-brassica-sterol (1a), campesterol (6a), ergosterol (8), stigmasterol (2a), 22-dehydro-24-isopropylcholesterol (3a), 24-isopropylcholesterol (4a), and 24-isopropenylcholesterol (5a). Of these, 3a, 4a, and 5a, having unusual hydrocarbon side chains, have recently isolated from marine invertebrates. Our present result provided the first example of isolation of these non-conventional sterols from terrestrial sources. Another sterol fraction (substance MB) was also separated by preparative TLC on 20% AgNO_3-SiO_2 to give two new sterols: cyclo-nervilasterol (9a) and dihydrocyclonervilasterol (12a). Structures of these novel sterols were deduced on the basis of chemical and spectroscopic evidence.
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T. Nakagawa, K. Hayashi, H. Mitsuhashi
Article type: Article
Session ID: 11
Published: September 10, 1981
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Chinese crude drug "Pai-ch'ien", dried root of Cynanchum glaucescens Hand-Mazz has been used as an antitussive and expectorant in china. We report herein that five glycosides: glaucoside-A (5), -B (6), -C (7), -D (8), -E (10) were isolated from this drug by repeated silica gel column chromatography. New aglycones glaucogenin-A (2) and -B (3) possessing novel 13, 14: 14, 15-diseco-pregnane type skeleton were isolated from the hydrolysate of crude glycosides and their structures were characterized by chemical and spectroscopic evidences. The sugar linkages of 5, 6, 7, 8, 10 were deduced as Chart 1 by ^<13>C-NMR, FD-MS and the analyses of the hydrolysates.
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T. Takemoto, S. Arihara, K. Yoshikawa, T. Nakajima, M. Okuhira
Article type: Article
Session ID: 12
Published: September 10, 1981
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From the aerial parts of Gynostemma pentaphyllum Makino(Cucurbitaceae), eight glycosides were isolated, namely gypenoside XXII-XXIX (1-8,respectively). Structure of these saponins were established mainly by means of Carbon-13 nuclear magnetic resonance spectroscopy. Gypenoside XXII: 19,21-Dihydroxy-3-O-[β-glucopyranosyl(1→2)-β-glucopyranosyl]-20ξ-O-[β-xylopyranosyl(1→6)-β-glucopyranosyl]-dammar-24-ene Gypenoside XXIII: 19,20ξ-Dihydroxy-3-O-[β-glucopyranosyl(1→2)-β-glucopyranosyl]-21-O-β-glucopyranosyl-dammar-24-ene Gypenoside XXIV: 19-Oxo-20ξ-hydroxy-3-O-[β-glucopyranosyl(1→2)-β-gluco-pyranosyl]-21-O-β-glucopyranosyl-dammar-24-ene Gypenoside XXV: 19-Oxo-20ξ-hydroxy-3-O-[β-glucopyranosyl(1→2)-α-arabino-pyranosyl]-21-O-β-glucopyranosyl-dammar-24-ene Gypenoside XXVI: 19-Oxo-21-hydroxy-3-O-[β-glucopyranosyl(1→2)-α-arabino-pyranosyl]-20ξ-O-β-glucopyranosyl-dammar-24-ene Gypenoside XXVII: 19,20S-Dihydroxy-3-O-[β-glucopyranosyl(1→2)-β-gluco-pyranosyl]-dammar-24-ene Gypenoside XXVIII: 19-Oxo-20S-hydroxy-3-O-[β-glucopyranosyl(1→2)-α-arabino-pyranosyl]-dammar-24-ene Gypenoside XXIX: 19-Oxo-20S-hydroxy-3-O-[β-glucopyranosyl(1→2)-β-gluco-pyranosyl]-dammar-24-ene
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H. Okabe, Y. Miyahara, T. Yamauchi
Article type: Article
Session ID: 13
Published: September 10, 1981
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An extensive survey for the triterpenoid constituents of Momordica charantia L. has been carried out in this laboratory, and so far, five glycosides (momordicosides A-E) of cucurbit-5-ene derivatives were isolated from the seeds, and their structures were determined. They are unique cucurbitacins being highly oxygenated only in the side chain and having no oxygen function at C_<11>. This study concerns the structure elucidation of two bitter glycosides, momordicosides K and L, and four non-bitter glycosides, momordicosides F_1, F_2, G and I isolated from the fruits. The structure of F_1 was proposed as 3-O-β-D-glucopyranoside of 5,19-epoxy-25-methoxy-5β-cucurbita-6,23-dien-3β-ol on the basis of PMR, CMR and CD spectral data and chemical conversion into a cucurbit-5-ene derivative. G is the corresponding β-D-allopyranoside. F_2 and I are the C_<25>-OH derivatives corresponding to G and F_1, respectively. K and L were determined as 7-O-β-D-glucopyranosides of 19-oxo-25-methoxy-cucurbita-5,23-diene-3β, 7β-diol and its C_<25>-OH derivative, respectively, on the basis of spectral data and chemical correlation with F_1-aglycone. F_1, F_2, G and I are the first cucurbitacins having 5β-cucurbitane nucleus found in nature, and K and L are noted as the new cucurbitacins having C_9-aldehyde and 7-O-β-D-glucopyranosyl groups. Among momordicosides, G and F_2 are the first triterpenoid glycosides having D-allose as a component sugar.
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K. Mizutani, H. Kajita, T. Tashima, O. Tanaka
Article type: Article
Session ID: 14
Published: September 10, 1981
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Recently, Stuart et al. reported that hexopyranosides and their derivatives were readily deuterated at carbon atoms bound to free OH by hot D_2O containing deuterated Raney nickel. For the purpose to the application of this procedure to ^<13>C-NMR spectroscopy of natural glycosides, the further examination of the condition of this reaction and partial epimerization of arabinoside, xyloside and rhamnoside with Raney nickel have been investigated. On prolonged treatment with Raney nickel in D_2O, methyl α-L-arabinopyranoside(2) yielded methyl β-D-xylopyranoside(3) and methyl α-L-lyxopyranoside(5) and 3 gave 2 and β-D-ribopyranoside(6), while methyl α-L-rhamnopyranoside(4) was epimerized slowly rather than 2 and 3, affording methyl 6-deoxy α-L-glucopyranoside(7). Selection of the type of Raney nickel, reaction time and solvents as well as comparison of the rate of C-deuteration of each carbinyl carbon of 2, 3, 4 and methyl β-D-glucopyranoside(8) with deuterated Raney nickel were also studied. By means of this procedure, the previous assignments of the carbon signals of α-1,6-glucan(10)(C-4,-5) and methyl β-cellobio-side(11)(C-3,-5) were revised as shown in the chart. Further, confirmation of the assignments of the carbon signals of β-sophorosyl moiety of ginsenosides-Rf(16) and -Rb_1(12) by this procedure led to the elucidation of the structures of the sugar moieties of new saponins, notoginsenosides-R1(13) and -R2(14)(isolated from San-chi Ginseng) and majonosides-R1(17) and -R2(18)(obtained from rhizomes of Panax japonicus var. major).
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Takenori Kusumi, Hideo Naoki, Conway C. Chang, Margaret Wheeler, Isao ...
Article type: Article
Session ID: 15
Published: September 10, 1981
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The leaf extract of the east African folk medicinal plant Triumfetta rhomboidea (Tiliaceae) was found to exhibit antigermination activity against lettuce seeds. The active principle, named 'triumferol', was isolated, and its structure was determined to be 4-hydroxyisoxazole (1), a simple but hitherto unknown heterocyclic compound. The lettuce seed antigermination activity of triumferol was 100% at 100ppm and 70% at 50ppm. Attempts of synthesizing triumferol by the methods used in the synthesis of 3- or 3,5-substituted-4-hydroxyisoxazoles were fruitless; treatment of 4a, 4b, 5a, 5c, and 5d with hydroxylamine afforded no trace of 1; fulminic acid (6b) did not give the 1,3-dipolar adduct (8b); a Sandmeyer-type reaction of 13 produced nothing but water soluble materials. The synthesis of triumferol was finally achieved through three steps of reactions; conversion of the known acid (19) into the acid chloride (20), a Grignard reaction of 20 with methyl-magnesium iodide to give 17, and treatment of 17 with a mixture of 30% H_2O_2 and conc. H_2SO_4 (1:1.3v/v) to afford 1 in 50% overall yield.
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Tozo Fujii, Masashi Ohba
Article type: Article
Session ID: 16
Published: September 10, 1981
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By comparison of its UV spectra in H_2O at various pH's with those of model compounds 10, 13, 15, 16, and 17, the Ipecac alkaloid O-methylpsychotrine has been shown to have the genuine 3,4-dihydroisoquino-line structure (1), not the exocyclic double bond structure (4), in the free base form as well as the protonated form. The ^1H NMR and ^<13>C NMR spectra of the alkaloid have also confirmed this endocyclic double bond structure in the dihydroisoquinoline part. These results indicate that the position of the double bond for simple 1-alkyl-3,4-di-hydroisoquinolines is endocyclic, and factors to stabilize the exocyclic double bond structure are discussed. 1-tert-Butyl-3,4-dihydro-6,7-dimethoxy-2-methylisoquinolinium iodide (27) has been found to be unstable in H_2O. On heating in H_2O at 90℃ for 10 min, it underwent ring opening to give 24 in good yield. The acid dissociation constants for 1-methyl- (15) and 1-tert-butyl-3,4-dihydro-6,7-dimethoxy-isoquinoline (17) in H_2O at 20℃ were UV spectrometrically determined to be 9.16±0.02 and 8.80±0.02, respectively.
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Takuo Kosuge, Kuniro Tsuji, Koichi Hirai, Kentaro Yamaguchi, Toshihico ...
Article type: Article
Session ID: 17
Published: September 10, 1981
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A new toxin, named Neosurugatoxin, was isolated from the toxic Japanese Ivory Shell and its structure was determined by X-ray crystallographic analysis. The space group of the crystal is orthorhombic P2_12_12_1 with four molecules in a unit cell. The cell dimension are a=21.595(10), b=13.964(7), c=10.659(5)A. A number, of 2476 reflexions were measured on a Philips 4-circle diffractometer using CuKα radiation. The crystal structure was determined by the heavy atom method and refined by the block-diagonal least-squares method. The final R value was 0.051 including hydrogen atoms. The molecular structure and bond lengths are shown in Fig.4. The molecule is a glycoside with a pentacyclic aglycone, which is constructed from two planar parts, 6-bromo-2-oxindole (D,E ring) and a heterocyclic system(B,C ring) including a dioxopyrimidine ring(A ring). The saccharide is O-β-D-xylopyranosyl(1→5)myoinositol. Several structural feature common to both Neosurugatoxin and Surugatoxin are: both have an oxindole, a dioxopyrimidine, myoinositol, and other functional groups. Neosurugatoxin at a concentration of 1×10^<-9>g/ml inhibited the contractile response of isolated guinea pig ileum to 3×10^<-5>g/ml of nicotine and evoked mydriasis in mice at a minimum dose of 3ng/g.
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D. Uemura, K. Ueda, Y. Hirata, H. Naoki, T. Iwashita
Article type: Article
Session ID: 18
Published: September 10, 1981
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The structural elucidation of palytoxin has involved some complicated and difficult problems because it is a non-crystalline, water soluble, unstable and nobel molecule. However, we were ultimately able to elucidate its total structure as shown in Fig. 1 by over-coming these problems. As expected, palytoxin falls under the category of polyketides but not polysaccharides or peptides. So far, palytoxin is one of the most complicated and largest molecules known except for some naturally occuring polymers. The structure of palytoxin, C_<129>H_<223>N_3O_<54>, with some portions of its absolute configuration is reported. Furthermore, the relative con-figuration of each fragment and the proposed structure of neopalytoxin, a minor toxin, are described.
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Tamio Ueno, Kazumasa Hirabayashi, Hiroshi Fukami, Shigeyuki Mayama, To ...
Article type: Article
Session ID: 19
Published: September 10, 1981
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Avenalumins I, II and III were isolated as phytoalexins from oat leaves infected with the crown rust fungi, Pccinia coronata f. sp. avenae. Avenalumins I, II and III were characterized as 2-[2-(4-hydroxyphenyl)ethenyl]-6-hydroxy-4H-3,1-benzoxazin-4-one [VII], 2-[2-(3-methoxy-4-hydroxyphenyl)ethenyl]-6-hydroxy-4H-3,1-benzoxazin-4-one [VIII] and 2-[2-(4-hydroxyphenyl)butadienyl]-6-hydroxy-4H-3,1-benzoxazin-4-one [IX], respectively. These structures were confirmed by total syntheses. Phytopathological experiments suggested that avenalumins play important roles on the resistance of oat to the crown rust disease.
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T. Nomura, T. Fukai, Y. Hano, J. Matsumoto, A. Imashimizu, J. Uzawa, S ...
Article type: Article
Session ID: 20
Published: September 10, 1981
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From the Chinese crude drug "Sang-Bai-Pi" (Japanese name Sohakuhi), the root barks of Morus sp. (Moraceae), five new flavanone derivatives were isolated and named sanggenon A, B, C, D, and E. Their structures were shown to be V, VI, VII, VIII, and IX, respectively. Intravenous injection of VII and VIII (0.5mg/Kg) produced a significant hypotension in rat. Sanggenon B, C, D, and E are regarded biogenetically as Diels-Alder adducts of chalcone derivatives and a sanggenon A derivative. Two Diels-Alder adducts, mulberrofuran C and kuwanon I, were isolated from the root barks of the cultivated mulberry tree (a variety of Morus alba L.) and their structures were shown to be XI and XII, respectively. Mulberrofuran C (XI) to rabbit (1mg/Kg, i.v.) produced a significant hypotension. The long-range selective ^1H decoupling (LSPD) technique was examined to presume the disposition concerning the location of the phenyl and benzoyl moiety on the cyclohexene ring of the model compounds.
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T. Hoshino, U. Matsumoto, N. Harada, T. Goto
Article type: Article
Session ID: 21
Published: September 10, 1981
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Since the work of Willstatter, it has been known that anthocyanins are responsible for a variety of beautiful plant colors. Anthocyanins are generally unstable to form colorless products. Stability and variety of flower coloring have been explained in terms of co-pigmentation with flavones etc and the complexation with metal ions. We report a new concept, the self-association of anthocyanins, for the stabilization and variation of flower color. Naturally occurring anthocyanins associate without any other component in the concentration usually found in the flower petals. The occurrence of the self-association of anthocyanins was evidenced by the following experimental facts; color variation (hypsochromic or bathochromic shift) and appearance of typical exciton coupling circular dichroism with increase of anthocyanin concentration. Hydration rate (k) of quinonoidal bases and hydration constant (K_h) of flavylium ions toward the corresponding colorless pseudobases are also presented as the evidence. Vertical stacking structure is proposed for the self-aggregation of anthocyanins on the basis of PMR shift data due to the ring current effect of anthocyanin nuclei. Thus, origin of the anomalous CD comes from the chiroptical stacking of anthocyanin molecules. Such a stacking structure of cyanin quinonoidal base was also suggested by calculation of the exciton chirality method.
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T. Okuda, T. Yoshida, T. Hatano, M. Kuwahara, M. Ashida, K. Yazaki, T. ...
Article type: Article
Session ID: 22
Published: September 10, 1981
Released on J-STAGE: August 18, 2017
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Chiroptical properties of tannins have been shown to offer a new reliable method for determining their stereostructures without chemical reaction. The Cotton effects at about 285, 265 and 235nm in the CD spectra of ellagitannins have been correlated with the stereostructures as follows: (1) The sign and the amplitude of the Cotton effect at about 235nm is shown to be indicative of the absolute configuration and the number of the HHDP group in a molecule. (2) The Cotton effect at 285nm which is one of the coupled Cotton effects centered at about 275nm resulting from interacting aromatic chromophores, reflects the chirality between the aromatic rings, which is predicted by the exciton chirality rule. (3) Split-type Cotton effects centered at about 220nm are also encountered in dehydroellagitannins which possess the dehydrohexahydroxydiphenoyl (DHHDP) group as well as HHDP and galloyl groups in a molecule. The Cotton effect at 200-210nm is diagnostic for the absolute configuration at the asymmetric center of DHHDP group. The absolute configuration of interflavan linkages of the condensed tannins galloylated at O-3, is determined by the Cotton effects at 200-220nm by applying the aromatic quadrant rule in analogous way as ordinary proanthocyanidins. The stereostructures of several new tannins were determined by applying this chiroptical method.
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H. Itokawa, Y. Oshida, A. Ikuta, Y. Shida, H. Inatomi
Article type: Article
Session ID: 23
Published: September 10, 1981
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Eleven compounds isolated from growth-inhibiting active fraction of male flowers of Cucurbita pepo, were identified as p-hydroxybenzaldehyde (1), anisyl alcohol (2), p-hydroxybenzyl metyl ether (3), p-hydroxybenzyl alcohol (4), veratryl alcohol (5), isovanillyl alcohol (6), p-coumaric acid (7), phloretic acid (8), benzyl-β-D-glucoside (12), 4-methoxybenzyl-β-D-glucoside (13) and 3,4-dimethoxybenzyl-β-D-glucoside (14) and 4,5,6,12,13 and 14 are the first isolation from a natural source. Each compound was assayed about growth-inhibiting activity using lettuce seedlings. Four of them showed the strong activity, but same glycosides did not show the activity. Two new flavonol glycosides were also isolated from the inactive fraction and their structures determined by UV, NMR and Field desorption (FD)-MS as rhamnazin 3-rutinoside (24) and isorhamnetin 3-rutinoside-4'-rhamnoside (26). Isorhamnetin 3-rutinoside (25), eleven fatty acids, fourteen amino acids, two triterpenes, two sterols and these glucosides and two nucleic acids were also isolated. The electron impact (EI)-MS of flavonoid glycoside yield no information about the nature of the glycosidic units, while the FD-MS show the protonated molecular ion and is structurally more informative. However the FD-MS had several faults (technique, reappearance and etc.), so we tried to apply other soft ionizations such as In Beam (IB) EI, Chemical Ionization (CI) and Negative Ion Chemical Ionization (NICI). We now had good results about these spectra of eighteen flavonoid glycosides by the IB-NICI method.
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H. Kinashi, K. Someno, K. Sakaguchi, T. Higashijima, T. Miyazawa
Article type: Article
Session ID: 24
Published: September 10, 1981
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Concanamycins A (1a), B (1b), and C (1c) were found as inhibitors of the proliferation of the mouse splenic lymphocytes stimulated by concanavalin A. For the structure determination of the main component, concanamycin A (1a), several chemical transformations were performed. Treatment of (1a) with 0.03N NaOH in methanol afforded an anhydroagly-cone P1 (2a) and a sugar S1 (3a), and their structures were determined by 270MHz PMR analysis. In order to elucidate the mode of binding of these components, ozonolysis of (1a) was performed. Of the three degradation products, Oz3 (5) proved to be the key compound containing S1 and a fragment of P1. Extensive PMR analysis of (5) and (1a) itself revealed the full structure of (1a). Thus, concanamycin A (1a) is a novel 18-membered macrolide antibiotic consisting of an α,β,γ,δ-unsaturated lactone ring, a long side chain which forms an intramolecular hemiketal ring, and 4-O-carbamyl-2-deoxy-D-rhamnose. The structures of concanamycin B (1b) and C (1c) were also determined by chemical trans-formations and spectroscopic methods.
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H. Nakayama, K. Furihata, H. Seto, N. Otake
Article type: Article
Session ID: 25
Published: September 10, 1981
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Monazomycin 1, C_<72>H_<133>O_<22>N, isolated from Streptomyces mashiuensis belongs to the ionophorous antibiotics. The structure of 1 has been elucidated based on the chemical degradations in combination with biosynthetic means using ^<13>C-labeled precursors. Acid hydrolysis of 1 gave D-mannose. α-Glycosidic linkage with aglycone was determined by comparison of 1 and methyl-mannoside. Ozonolysis of peracetyl-monazomycin 3 followed by NaBH_4 reduction and acetylation gave four compounds I 4, II 5, III 4, and X. Alkaline hydrolysis of X afforded two compounds IV 6, and V 7. The gross structure of monazomycin was determined by 400MHz ^1H-NMR experiments and biosynthetic method as shown in 1. It may be interesting to note that monazomycin is the first natural product having a 48-membered lactone.
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K. Shirahata, T. Iida, N. Hirayama
Article type: Article
Session ID: 26
Published: September 10, 1981
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In the course of our screening for new anticancer antibiotics three compounds, trioxacarcins A, B, and C, were isolated from the culture broth of a new Streptomyces species, Streptomyces ochraceus, which was obtained from a soil sample collected in Sapporo. Trioxacarcins showed anticancer activity against mouse Sarcoma 180 and Leukemia P-388 and also showed antibacterial activity against both Gram-positive and Gram-negative bacteria. Methanolysis of trioxacarcin A(TOC-A)(1) gave a mixture of methylα-trioxacar-cinoside A(Fig. 2), its β anomer, methyl α-trioxacarcinoside B(Fig. 3), its β anomer, and trioxacarcinone A(3) together with compound (2). Deacetyl trioxacar-cinoside A was identified with axenoside, and trioxacarcinoside B was identified with the sugar component of quinocycline B. On the other hand oxidation of tetramethyl derivative(5) of the aglycone(3) gave a crystalline compound(6). X-ray analysis of 6 could revealed its novel structure as depicted in Fig. 5. Finally, the structure of TOC-A was determined on the basis of the findings obtained from detailed PMR and CMR experiments on compounds 1, 2, 3, 4, and 5. The structures of TOC-B and C were also elucidated as shown in Fig. 4.
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Yuichi Hashimoto, Koichi Shudo, Toshihiko Okamoto
Article type: Article
Session ID: 27
Published: September 10, 1981
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Mitomycin C (MMC), the potent antibiotic and clinically useful antitumor agent was catalytically reduced in the presence of calf thymus DNA. The modified DNA (1mol MMC/200-300mol P) was hydrolysed with Nuclease P1 to give three modified nucleotides; MG-1, MG-2, and MA. The modified nucleotides were separated with semi-preparative high performance liquid chromatography. Ultra-violet spectra and nmr spectra of MG-1, MG-2, and MA were obtained. The possible structures of MG-1, MG-2, and MA were deduced from these spectral data, stability in acidic or basic conditions, enzymatic hydrolysis, and investigation of acid hydrolysates.
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M. Suzuki, K. I. Harada, N. Takeda, A. Tatematsu, H. Kambara
Article type: Article
Session ID: 28
Published: September 10, 1981
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Approach for obtaining mass spectra of involatile and thermally unstable natural products has been performed by two strategies. One is a optimization of sample vaporization, which contains rapid sample heating followed by thermal desorption and ionization under CI condition, that is Emitter CIMS. Another is a direct ionization of sample from a surface. Although several techniques have been discussed for this purpose, we adopt Molecular SIMS, which does not essentially require heating of sample for ionization and desorption. Emitter CI mass spectra of kanamycin A, B and C showed unequivocally protonated molecular ions (MH^+) in all the cases. The principal fragmentation pattern and m/z value of the characteristic sequence ions (a-е) are summarized in Fig.3. These ions are formed by the reproducible fragmentation process at the glycosidic bonds. Moreover, the shifting technique using ND_3 as the reagent gas was succesfully employed. Secondary ion mass spectra of kanamycins are presented. MH^+, [M+Na]^+ and [M+Ag]^+ were observed as molecular ion species in all the cases. The co-existing NaCl increased the relative abundance of [M+Na]^+ in the spectra. Furthermore, SI mass spectra of other aminoglycoside antibiotics and oligosaccharides could be succesfully measured.
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Y. Sakagami, M. Yoshida, A. Isogai, A. Suzuki, C. Kitada, M. Fujino
Article type: Article
Session ID: 29
Published: September 10, 1981
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Tremella mesenterica is a basidiomycetous fungi and produces a yeastlike cell. In the homokaryotic phase, each of the compatible mating-type cells (A and a types) propagates by budding. When the A- and a-type cells are mixed, conjugation tube formation occurs. The A- and a type cells produce diffusible hormones that induce conjugation tube formation in cells of opposite type. To clarify the mating process of T. mesenterica from a chemical standpoint, we attempted to determine the structures of this pair of hormones. We first isolated the hormone tremerogen A-10 (1) (Fig. 2), which is produced by the A-type cell and induces conjugation tube formation in the a-type cell. Next, we succeeded in the isolation and structure determination of tremerogen a-13 (2) (Fig. 2), a hormone, produced by the a-type cell, that induces conjugation tube formation in A-type cell. To confirm the structures and to study the structure-activity relations, analogs of tremerogen A-10 and a-13 were synthesized.
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K. Nomoto, H. Yoshioka, T. Takemoto, Y. Mino, T. Ishida, N. Ota, M. In ...
Article type: Article
Session ID: 30
Published: September 10, 1981
Released on J-STAGE: August 18, 2017
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Mugineic acid(1), isolated from the roots of water-cultured barley (Hordeum vulgare L. var. Minorimugi), is the first compound to be shown to play a role in the uptake and transport of iron in higher plants. It is capable of effectively solubilizing Fe(OH)_3 within the pH range 4-9. The potentiometric titration, spectroscopic, electrochemical, and X-ray diffraction studies on the mugineic acid-Fe(III) and -Co(III) complexes clarified that in both complexes the coordination involves the azetidine nitrogen, secondary amine nitrogen, both terminal carboxylate oxygen, hydroxyl oxygen, and intermediate carboxylate oxygen in a nearly octahedral configuration (Fig. 1). The structures of Cu(II) and Zn(II) complexes were also elucidated by X-ray crystallographic and PMR studies. The coordinated copper and zinc atoms adopt the teragonally distorted octahedral geometry (Fig. 1). The Mossbauer and ESR parameters for the mugineic acid-Fe(III) complex are typical of high-spin ferric type. The salient feature of the mugineic acid-Fe(III) complex is high reduction potential(E_<1/2>=-102mV vs. NHE), that is, this Fe(III)-complex is thermodinamically readily reducible by physiologically available reductants such as NAD(P)H. Thus, the present results indicate that the mechanism of iron-uptake and -transport in Graminaceous plant involves the excretion of mugineic acid(1) from the roots, which aids Fe(III)-solubilization and reduction of stable Fe(III)-complex (log K=18.1) to the weakly bound Fe(II)-complex (log K=8.1).
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Y. Okami, T. Ohnuki, M. Takashio, H. Umezawa
Article type: Article
Session ID: 31
Published: September 10, 1981
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Dextransucrase of Streptococcus mutans produces from sucrose insoluble polysaccharides which mediate bacterial adhesion on tooth surface and plays an important role in the initiation of dental caries. Ribocitrin, a novel inhibitor of the dextransucrase was isolated from a cultured broth of Streptomyces sp. Hydrolysis of ribocitrin(I) gave D-ribose and (+)-homocitric acid lactone. The result of hydrolysis, FDMS and ^<13>C NMR indicated that ribocitrin(I) consisted of three D-riboses and one (+)-homocitric acid. Oxidation of ribocitrin(I) with sodium periodate followed by reduction with sodium borohydride and mild hydrolysis afforded compound V of which ^<13>C and ^1H NMR spectra showed the elimination of a terminal D-ribose moiety from ribocitrin. Equimolar amounts of 2,3,5-tri-O-methylribose(II), 3,5-di-O-methylribose(III), and 2,5-di-O-methylribose(IV) were obtained by Hakomori methylation of ribocitrin(I) followed by hydrolysis. Hydrolysis of methylated V gave II and IV but not III. Thus the structure of ribocitrin(I) was elucidated to be 2-(S)-[O-α-D-ribofuranosyl-(1→2)-O-α-D-ribofuranosyl-(1→3)-α-D-ribofuranosyloxy]-1,2,4-butanetri-carboxylic acid agreed with the ^<13>C NMR, ^1H NMR, FDMS and IR spectra of ribocitrin(I). The α-anomeric configuration of three glycoside linkages was determined by the vicinal coupling constants (J=3.5 and 4.0Hz) of the anomeric protones in the ^1H NMR spectrum of ribocitrin(I).
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Y. Matsubara, K. Yokoi, K. Yamaguchi, H. Kumamoto, Y. Iizuka, T. Murak ...
Article type: Article
Session ID: 32
Published: September 10, 1981
Released on J-STAGE: August 18, 2017
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We attempted isolation and structural determination of hypotensive substances on the hot water extraction-solvent extraction-gel filtration-RP-2 column-RP-8 lobar column. A depressive effect of each fraction was examined. Four hypotensive substances, adenosine (1), flavanoid (2), rutinoside (3) and glycopeptide (4) were isolated from hot water extract of lemon peels. When adenosine (1) was isolated from a depressive effect fraction, the blood pressure of SHRSP showed falls of about 45mmHg at 0.5 hour after interavenous administration, and of 25 to 35mmHg at 0.5 hour after intraperioneal cavernous and subcutaneous administration. However, after intragastric administration, the blood pressure of SHRSP didn't show falls. Glycopeptide (4) related to bring down blood pressure (about 72mmHg at 1 hour after interavenous administration) of SHRSP contained abundantly arginine, serine, lysine, glysine, histidine, asparatic acid, and some meiner amino acids. And also some components (hesperidine (5), related compound of cholesterol (6), uracil derivatives (7)-(9) were isolated with these separation.
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H. Takayanagi, H. Ogura
Article type: Article
Session ID: 33
Published: September 10, 1981
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Many additional reaction derivatives of α-santonin (1) such as santonin dichloride (2), 2-chlorosantonin (3), santonin chlorohydrin (4), santonin α-epoxide (5), and santonin isochlorohydrin (6) have been reported. The stereochemical assignments of these known compounds were made by Hendrickson and Bogard. We synthesized several new santonin derivatives such as 4-methoxy-5-chloro santonin (7) and additional chlorination reaction products of the known compounds. During the stereochemical study of the new chlorinated santonin derivatives, we found it necessary to re-investigate structures of the compounds decided by Hendrickson and Bogard. We re-examined the structures of the known compounds mentioned above including new chlorinated santonin derivatives by X-ray crystallographic analyses. We could definitely decide their structures and revised their structure of santonin dichloride (2) to 1α,2β-dichlorosantonin (2') and santonin chlorohydrin (4) to 4α-hydroxy-5β-chlorosantonin (4'). From CD study of these compounds, it became clear that conformation of the compounds in solid are almost the same as in solution.
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K. Tsujimoto, F. Tokunaga, V. Balogh-Nair, K. Nakanishi, M. Watanabe, ...
Article type: Article
Session ID: 34
Published: September 10, 1981
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The purpose of this study on photoreception of modified bacteriorhodopsins involves obtaining information on the structure of the protein by chemically analyzing bacteriorhodopsins which are reconstituted with artificial retinals and the opsin, and by comparison of their properties with these of the native bacteriorhodopsin. We report structural contribution of the protein to the bathochromic shifts and photochemical behavior of artificial bacteriorhodopsin. 1) Hydroretinals and hydrorhodopsins were synthesized to investigate the protein circumstances. 'Opsin shift', one of the indicator, was defined as λ_<max> of the protonated Schiff base of n-butylamine minus λ_<max> of the corresponding pigment (cm^<-1>). Point charge model was proposed that another anion except a counter ion of the Schiff base would be located not on the side chain but near the cyclohexene ring. 2) Modification of cyclohexene ring to phenyl ring strongly affected the opsin shift, while introduction of bromine atom to side chain was less effective. 3) Irradiation upon bacteriorhodopsin involving Np-retinal gave rise to anomalous photoisomerization of retinal moiety.
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Yukio Masaki, Kazuhiko Sakuma, Kinji Hashimoto, Kenji Kaji
Article type: Article
Session ID: 35
Published: September 10, 1981
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A combination of regioselective sulfenylation of monoterpenoids (11) furnishing terminal allylic sulfides (12) and thermal elimination of phenylsulfenic acid from the corresponding sulfoxides constitutes a general method for conversion of the isopropylidene terminus of monoterpenoids to the 1,3-diene system (14). The general applicability of the method was demonstrated on the monoterpenoids possessing various functional groups. Several 1,3-dienes (14) thus obtained were transformed to furan derivatives (16) by photosensitized oxygenation followed by dehydration. Furans (16) were utilized effectively for syntheses of cyclic and acyclic furanoterpenes. Optically active natural evodone (2) was synthesized and the configuration of the asymmetric center was determined as (R) by cyclization of the optically active 4-(2-furyl)-butanoic acid derivative (19) which was prepared from R-(+)-citrone-llic acid (17) by the above sequence of reactions. The analogous cyclization of the furan derivative (16d) gave 6,7-dihydro-4(5H)-benzofuranone derivative (10), a synthetic key intermediate for linderalactone (8) and curzerenone (9). Carbon-carbon coupling of the furan derivative (16e) bearing a terminal allylic sulfonyl group with 3-furylmethyl bromide and trans 4-benzyloxy-2-methyl-2-butenyl bromide followed by reductive desulfonation and deprotection provided dehydrolasiosperman W and a synthetic intermediate (26) for plera-plysillin-2 (4) respectively.
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Sigeru Torii, Tsutomu Inokuchi, Goro Asanuma, Hidenori Ogawa
Article type: Article
Session ID: 36
Published: September 10, 1981
Released on J-STAGE: August 18, 2017
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Synthetic strategies for the preparation of (±)- and (+)-nootkatones (1), the latter of which is known as an important odoriferous constituent of grapefruit, are described. A) (±)-1 was obtained by allylic oxidation of (±)-valencene (18), starting from 4β,10β-dimethyloctalone ethylene acetal 4 by stereocontrolled functionalizations involving the introduction of isopropenyl group at the C-6 position and the formation of double bond at the C-1(10) position leading to 18. B-1) Two different synthetic strategies discussed for the preparation of (+)-1 involve following ideas: one is elongation of carbon chain of keto ester 23 by the intramolecular alkylation of 28, reduction of the exo-methylene group of 36, and subsequent oxidative fission of the enolic olefin of 37 leading to acetonyl ketone 25, a key precursor of (+)-1; the other deals with the functionalization of tricyclo[7.1.1.0]undec-7-ene derivative 43 prepared from nopadiene and ethyl α-acetoxyacrylate by the Diels-Alder reaction by i) reductive methylation of epoxy ketone 46 to introduce the angular methyl group, ii) 1,4-addition of methyl group of dienone 50, and iii) isomerization of 4β-methyl group to 4α-isomer 55.
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Y. Ohtsuka, S. Niitsuma, H. Tadokoro, T. Hayashi, Y. Sasahara, T. Oish ...
Article type: Article
Session ID: 37
Published: September 10, 1981
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We previously reported a new and an effective method for the construction of eight- to twelve-membered ketones by ring closure. The present method was developed with an intention of synthesizing natural products involving medium-membered ring system. As the first application of the method to medium-membered natural products synthesis, we report here the syntheses of (±)-isocaryophyllene (1) and (±)-caryophyllene (2) having unsaturated nine-membered ring. When the mesylate 9 (R=Ms) prepared from 3 was treated with t-BuOK in t-BuOH, demasking of the thiol protecting group and the concomitant cyclization took place and the thirteen-membered lactam sulfide 10Z was obtained in 56% yield. The LDA-promoted intramolecular cyclization of the corresponding sulfoxide 11Z afforded the nine-membered keto sulfoxide 12Z in quantitative yield. Epimerization of the ketone 13 derived from 12Z at C_1-position, followed by the Wittig reaction produced (±)-isocaryophyllene (1). On the other hand, (±)-caryophyllene (2) was stereoselectively synthesized starting from the cyclobutene 14. Treatment of the sulfone 25 having the desired trans-substituents on the cyclobutane ring with the E-chloride 28E prepared from the thiocarbamate 26 afforded 29 and the subsequent cyclization of 34 derived from 29 with t-BuOK in t-BuOH followed by oxidation afforded the lactam sulfoxide 35. In the same way as described in the synthesis of 1, (±)-caryophyllene (2) was successfully synthesized from 35 through intramolecular cyclization.
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C. Iwata, Y. Ida, K. Miyashita, T. Fusaka, T. Fujiwara, K. Tomita, M. ...
Article type: Article
Session ID: 38
Published: September 10, 1981
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1. A new spiro-annelation reaction-Copper(I) halide-catalyzed decomposition of phenolic α-diazoketones (4) gave spiro[4.5]deca-6,9-diene-2,8-dione (5) in high yield. 2. A unique regio- and stereo-selective reduction of cross-conjugated dienone-The regiospecific metal-ammonia reductions of both cis-2-hydroxy-1,5,5-trimethylspiro[5.5]undec-7,10-dien-9-one (7a) and its metal alkoxides (7b) and (7c) could be achieved as a result of the proximity of the hydroxy-group to afford 2t-hydroxy-1t,5,5-trimethyl-(6rC^7)-spiro[5.5]undec-7-en-9-one (9) in high yield. The reduction of 2-hydroxy-6,10-dimethylspiro[4.5]dec-6,9-dien-8-one (15) gave 2-hydroxy-6,10t-dimethyl-(5rC^1)-spiro[4.5]dec-6-en-8-one (16) as a main product. 3. (±)-Agarospirol (1), (±)-hinesol (2), and (±)-solavetivone (3) were synthesized by a new spiro-annelation reaction and a unique regio- and stereo-selective reduction of the cross-conjugated dienone.
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Keishiro Nagao, Masato Chiba, Isotaka Yoshimura, Sang-Won Kim
Article type: Article
Session ID: 39
Published: September 10, 1981
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A total synthesis of (±)-carpesiolin (1), an antibiotic substance, is described along a new, efficient and straightforward route to this class of sesquiterpenoides (pseudoguaianolides). This route features on the following three points: 1) the stereochemically defined introduction of C_<10> (pseudoguaianolide numbering) methyl group in a-orientation, 2) the regiospecific ring expansion reaction leading to the trans-perhydroazulenone skeleton, and 3) the complete stereo-control of other chiralities (C_6-C_8) on the 7-membered ring. The severe 1,3-diaxial interaction in the β-methyl ketone (4) caused a complete isomerization to its α-methyl isomer (3), which was ring-expanded regiospecifically to the perhydroazulenone (7). The ketone 7 was converted to the γ-lactone (16) in 5 steps, whose trifluoroacetate (17) on treatment with an acid was transformed into the alcohol (18) via an unexpected intramolecular acyl migration. The title compound 1 was synthesized in further 7 steps from 18. Application of this methodology to other pseudoguaianolides is in progress.
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F. Kido, Y. Noda, T. Maruyama, A. Yoshikoshi
Article type: Article
Session ID: 40
Published: September 10, 1981
Released on J-STAGE: August 18, 2017
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α-Methyl-(2) and α-phenylthio-β-vinylbutenolides (3) have been developed as new lactone annulation reagents. These reagents were prepared as shown in Scheme 1 and 2. Carbanions of 1,3-di-carbonyls or of α-cyanoketones conjugatively added to these reagents and the adducts underwent aldol-like cyclization under reaction conditions to give annulation products, some of which were recgnized as useful synthetic intermediates for natural lactones and furans. The former butenolide 2 reacted with methyl 2-formyl-6-methyl-5-heptenoate (11) to yield a mixture of annulation products 12a and 12b, which were converted into furoventalene (4), respectively (Scheme 1 and 2). Reaction of some β-diones and α-cyanoketones with the latter butenolide (3) resulted in formation of annulated products in good yields (Table 1). The annulation products were dehydrated and then oxidized to lead to sulfoxides, which on treatment with acetic an-hydride and pyridine, afforded rearranged products (Table 2). The rearranged product 25a was transformed into hydroxylactone 30 (Scheme 4). As an application of these reactions, the total synthesis of paniculide A (5) has been attempted starting with the rearranged product 27 (Scheme 5 and 6).
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K. Tanaka, F. Uchiyama, A. Asada, T. Ikeda, K. Sakamoto, Y. Inubushi
Article type: Article
Session ID: 41
Published: September 10, 1981
Released on J-STAGE: August 18, 2017
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Starting from protoanemonin (7), synthetic investigation of dl-coriamyrtin (1) was undertaken. The 1,6 adduct (6) from (7) and (8) was subjected to react with isopropenylmagnesium bromide-CuI to afford the compound (9) and (10). All trials to convert these compounds to the (4) type compounds possessing the correct stereo-chemistries for the present synthesis were unfruitful. On the other hand, a series of reactions of (27) from (6), acidic methanolysis, isopropenylmagnesium bromide-CuI and acidic hydrolysis, gave stereoselectively the compound (4) in four steps. The compound (4) was derived to the lactone (3) by the mixed-anhydride method and treatment of (3) with NBS gave the bromo-ether (31). After several unfruitful trials for introducing the C_1 unit to the carbonyl group at C_9 of (31), (32) and (33), the prolactone (34) was treated with Ph_3P=CH_2 and Me_2S=CH_2 to give (37) and (36), respectively. The subsequent conversions of (36) and (37) to the natural product, however, were unsuccessful. The Wittig reaction of the saturated ketone (34) under the reaction condition reported by Conia gave the exomethylene compound (47), which was transformed to the bromo-ether (49). Oxidation of (49) by the Sharpless methods gave a single product (51), in good yield. Dehydration of (51), followed by epoxidation afforded a diastereomeric mixture of diepoxides (53). Separation and definite identification of the synthetic product with bromo-coriamyrtin are in progress.
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Y. Hayashi, T. Matsumoto
Article type: Article
Session ID: 42
Published: September 10, 1981
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Reactions of nor-diterpenoid dilactones isolated from Podocarpus plants have been investigated. The 7: 8,9: 11-dienolide type [C] dilactones, the least available but biologically the most active members, are mainly derived from naturally abundant dilactone components of α-pyrone type [A] and 7: 8-epoxy-9: 11-enolide type [B] for total-synthetic and biological purposes. From nagilactone E (5), for example, a combined sequence of hydrogenolysis of 7: 8-epoxide group and dehydration gives nagilactone F (7), 3β-hydroxynagilactone F (8) and 2: 3-dehydronagilactone F (19), which have been found from natural sources. From nagilactone A (1), photo-hydration and concomitant double bond migration of its acetate results in a lactol (22), which is reduced to 1β-hydroxynagilactone F (9), another natural type [C] dilactone. Derivation of the type [A] or [B] from others is not successful. Some attempts for conversion of the ring A functional groups have also been studied.
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T. Tokoroyama, H. Koike, A. Kondo, K. Hirotsu, Y. Ezaki
Article type: Article
Session ID: 43
Published: September 10, 1981
Released on J-STAGE: August 18, 2017
CONFERENCE PROCEEDINGS
FREE ACCESS
The lecture concerns with synthetic studies on analogs of triptolides, highly active antileukemic plant constituents, from resin acids and will be composed of five parts. (1) Synthesis of B/C ring analogs from levopimaric acid 3. Stereoselective introduction of the hydroxyepoxide system in triptolides 1 and 2 to a abietane skeleton was explored from levopimaric acid 3, culminating in the synthesis of methyl 14β-hydroxy-7β:8β, 9β:11β,12α:13α-triepoxyabietan-18-oate 33, a complete B/C ring model of triptolides. (2) X-Ray crystallographic analysis of triepoxide 34. To confirm the stereochemistrt of oxygen functionalities in the synthesized triptolide analogs, X-ray crystallographic analysis of triepoxide 34, epimeric with 33 in the configuration of 7,8-epoxide ring, has been carried out. (3) Antitumor screening tests of triptolide analogs. The result of antitumor tests (KB test and life-promoting test on L-1210 afflicted mice) of stereoisomeric epoxides obtained above will be mentioned. (4) Synthesis of A ring analog of triptolide 1 from dehydro-abietic acid 36. The construction of 18→19)-3-butenolide system in triptolide 1 has been accomplished in two ways via unsaturated aldehyde 42. One of the methods involves sensitized photooxygenation of the diene 59 and may have biosynthetic implication. (5) Synthesis of A ring analog of tripdiolide 2. The studies on the synthesis of A ring moiety of tripdiolide from the intermediate 60 will be presented.
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Hirotaka Shibuya, Shinji Tsujii, Yoshio Yamamoto, Kazuya Murakawa, Kao ...
Article type: Article
Session ID: 44
Published: September 10, 1981
Released on J-STAGE: August 18, 2017
CONFERENCE PROCEEDINGS
FREE ACCESS
This paper reports our synthetic studies on the optically active taxa-4 (20),11-diene deriv. (1), in which segment A-II (23) and segment B (3) are utilized as the building blocks. I. Synthesis of Segment A-II (23) The allyl alcohol (17), which was synthesized from d-camphor (10) through the similar reaction pathway as carried out in the synthesis of segment A-I (2), was converted to the aldehyde (19) via 18. 19 was treated with alkali to convert to 21 whose 1R configuration is same as the C-1R configuration in the taxane-skeleton. 21 was then smoothly converted to segment A-II (23). II. Coupling of Segment A-II (23) and Segment B (3) The coupling was effected by use of t-BuLi in DME-HMPA (3: 1) to furnish 24, which, via 25, was readily converted to the hydroxy-ketone (26). III. Examination for the Construction of Taxane-Skeleton Thioketal-mesylate (28a), -bromide (28b), ketal-mesylate (30a), and -bromide (30b) were prepared from 26 via 27 and their cyclization (formation of the B-ring of taxane-skeleton) was examined under various basic conditions, but without success. Then, after some model experiments (32-37), 29 was converted to the 12-membered lactone (40). Examination utilizing 40 and the other related compounds towards the formation of the 8-membered B-ring of taxane-skeleton has been carried out and the results will be discussed.
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