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獅々堀 彊, 森中 秀夫, 菅 隆幸
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The biosynthesis of cyclic monoterpenoids involves presumably the cyclization of neryl pyrophosphate, but experimental evidence is scanty. We examined (i) the route for the formation of a first acyclic intermediate in the biosynthesis of the cyclic monoterpenoids, (ii) whether an aldehyde-type intermediate is involved in the isomerization of the acyclic intermediate to another intermediate which is facile for the cyclization, or not, and (iii) the participation of linaloyl pyrophosphate in the biosynthesis of the cyclic monoterpenoids. The following three points were clarified: (i) The trans condensation, but not the cis condensation, of isopentenyl pyrophosphate with dimethylallyl pyrophosphate occurs, resulting in the initial formation of geranyl pyrophosphate, but not neryl pyrophosphate, as an acyclic intermediate for the monoterpenoid biosynthesis. (ii) An aldehyde intermediate is not involved in the isomerization of geranyl pyrophosphate to an acyclic intermediate which directly leads to the formation of cyclic monoterpenoids, in contrast with the isomerization of farnesol via an aldehyde intermediate established in the microorganisms. (iii) Linaloyl pyrophosphate is the more favorable direct intermediate for the monoterpenoid biosynthesis than neryl and geranyl pyrophosphates. The direct cyclization of linaloyl pyrophosphate may take place in the biosynthesis of the cyclic monoterpenoids in the higher plants. However, the data obtained in the incorporation of the tracers cannot throughly rule out the possibility for the formation of cyclic monoterpenoids by the cyclization of neryl pyrophosphate.
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折谷 隆之, 山下 恭平
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There are many microorganisms which have the ability to hydrolyze (±)-terpenic alcohol acetates asymmetrically. Especially, some selected microorganisms (Bacillus subtilis, Trichoderma sp.) could hydrolyze (±)-monocyclic terpenealcohol acetates at the high concentration (2-10%) of the substrate to give the (R)-alcohols with their antipodal (S)-acetates in high optical purities. But, the axial (±)-acetates were not hydrolyzed. On the contrary, (±)-sec-acyclic alcohol acetates were hydrolyzed to the (S)-alcohols with the (R)-acetates in low optical purities by microorganisms. Also, (±)-1 and 2-decalyl acetates, consisted of each four isomers, were asymmetrically hydrolyzed by microorganisms to give (R)-trans, cis-1-decalol, (S)-cis, cis-1-decalol with their antipodal acetates and (S)-2-decalols with (R)-2-decalyl acetates respectively. From the cell free culture broth of selected microorganisms (Trichoderma sp.) were easily separated the stable esterase, which has the ability to hydrolyze the above (±)-acetates asymmetrically. By treatment with the esterase (RS)-O-acetyl allethrolone was separated to (-)(R)-allethrolone and (+)(S)-O-acetyl allethrolone. The latter was treated with alcoholic ammonia to give (+)(S)-allethrolone. This method was applied to separate the optically active diastereomers of 7-epi-α-cyperol, a bicyclic sesquiterpenealcohol. In order to clarify the substrate specificity of the esterase, (±)-2-acetoxycyclohexanone and (±)-2-cyclohexenyl acetate were treated with the esterase to give (-)-2-acetoxycyclohexanone and (±)-2-cyclohexenol respectively. This means that the esterase can distinguish the chirality caused from -CH_2- and =CO group, but can not that caused from -CH_2- and =CH- group.
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井上 博之, 上田 伸一, 上里 新一, 小林 孝次
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[10-^3H]-10-Hydroxygeraniol (7), [10-^3H]-iridodial (14), [10-^3H]-iridodial glucoside (17) and [10-^3H]-iridotrial (9) were administered to the cells of Gardenia jasminoides forma grandiflora and the incorporation of these substances into iridoid glucosides such as tarennoside (1), geniposide (2) and gardenoside (3) was examined. Consequently, it was established that 10-hydroxygeraniol (7) is incorporated into glucosides 1, 2, 3 etc. via iridodial (14) in the cultured cells of the Gardenia plant and that the nonequivalent carbons at C-9 and C-10 of 7, after the iridoid skeleton formation, randomize between the 3 and 11 positions. This fact was also confirmed by administration experiment of [9-^<13>C]-10-hydroxygeraniol (7). Administration of 3'-O-methyl derivatives (23), (21), (26) and (24) of iridodial glucoside (17), deoxyloganin (4), deoxygeniposide (20) and geniposide (2) to the cultured cells resulted in the transformation of 21 and 24 into 3'-O-methylloganin (22) and 3'-O-methylgardenoside (25), respectively, while any other conversion was not observed. These phenomena were also observed in the Gardenia cell cultures lacking the iridoid-producing ability. These results suggest that loganin (5) is not the biosynthetic precursor of 2 and 3.
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木村 靖夫, 郷原 雅敏, 鈴木 昭憲
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Colletotrichin(I) is a phytotoxic substance isolated from fungi, and the structure has been rigorously established by X-ray chrystallography. In the course of our continuous searching for the related substances, we isolated two new compounds, colletotrichin B(II) and C(III) from the culture filtrate of Colletotrichum nicotianae. These compounds consist of unique norditerpene and polysubstituted γ-pyrone. The biosynthesis of these compounds was studied employing carbon magnetic resonance. All of the carbon atom signals were assigned from the multiplicities and by comparison of I with II, III and IV which was obtained by treatment with H_2O_2 in NaOH solution. The cmr spectra showed that I, II and III were biosynthesized through the combination of acetate-mevalonate-terpene pathway with acetate-polyketide pathway. From the data of labelled II and III together with those of I, the mechanism involving cyclization of geranyl-geranyl pyrophosphate, followed by epoxidation of terminal isopentenyl double bond, cleavage of Baeyer-Villiger type reaction would account for the biosynthetic pathway of colletotrichins as shown in scheme 2.
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安藤 哲, 吉田 茂男, 高橋 信孝
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Sex pheromones of Lepidoptera usually consist of unsaturated normal primary alcohols or their derivatives. The purposes of this study are to synthesize all the possible long chain (C_<10>-C_<18>) monoene slcohols and their derivatives (acetates, aldehydes etc), and to use these chemicals effectovely for getting much information about the lepidopterous sex pheromones by field trials and EAG tests. At first, the attractiveness of about one hundred compounds were tested in various environments from 1974 to 1977. In these screening tests, male insects of one hundred and forty-eight species which belong to sixteen families were attracted specifically. It is indicated that monoene alcohols and their derivatives consititute a main group of sex pheromones of Lepidoptera being native in Japan. Secondly, the measurement of the EAG (electroantennogram) activities of many synthetic compounds suggested that the sex pheromone of the rice green caterpillar (Naranga aenescens Moore; Noctuidae, Eustrotiinae), which is one of the most harmful lepidopterous pest insects of rice plant, consisted of Z-9-tetradecenyl acetate, Z-11-hexadecenyl acetate and some other compounds. This presumption was comfirmed by the analysis of the extract of the 1200 virgin females and the field trials to the synthetic pheromones. Namely, sex pheromone of this species was characterized as the mixture of Z-9-tetradecenyl acetate (compound I), Z-9-hexadecenyl acetate (compound II) and Z-11-hexadecenyl acetate (compound III) In field tests these chemicals were the most attractive in a ratio of 1:1:4. This ratio almost coincides with the analytical result of the sex pheromone of the insect.
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森 謙治, 玉田 重晴, 勝呂 利男, 増田 悟
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発行日: 1978/08/22
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All of the possible stereoisomers of two aliphatic chiral pheromones were synthesized in optically pure states to establish the absolute stereochemistries of the natural products as well as to know the stereochemistry-biological activity relationship. 3,11-Dimethyl-2-nonacosanone (1) is the female sex pheromone of the German cockroach, Blattella germanica. Four stereoisomers of 1 were synthesized from (R)-(+)-citronellol employing the Grignard coupling reaction (A+B→C) as the key-step. The absolute configuration of the natural pheromone was shown to be 3S, 11S. All of the four isomers exhibited the same range of biological activity. erythro-3,7-Dimethyl-2-pentadecyl acetate or propionate (2) are the female sex pheromones of pine sawflies, Neodiprion lecontei, N. sertifer and Diprion similis. Four possible stereoisomers of 2 were synthesized from (R)-(+)-citronellol and (+)- or (-)-tartaric acids. The key-step was the S_N2 attack of a chiral organocopper reagent (E) to a chiral epoxide (D) to give a chiral alcohol (2a). This reaction provided pure erythro alcohols.
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黒柳 正典, 福岡 正道, 義平 邦利, 名取 信策
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Pterosins and pterosides, 1-indanone derivatives isolated from bracken(Pteridium aquilinum var. latiusculum), and the derivatives exhibit CD Cotton effects associated with n→π transition of conjugated ketones in the range of 310-370nm. Snatzke's rule was applied to the compounds, which were shown in Fig 1 in octant type projection, and the conformations were discussed from the observation by the CD Cotton effects. The conformations of pterosin A type compounds having a hydroxymethyl group at the 2-position are affected by the intramolecular hydrogen bonding. In pterosin C and L type compounds bearring a hydroxyl group at the 3-position, the hydroxyl group exists in pseudoaxial conformation irrespective of the configuration at the 2-position. The results obtained by the compounds of the established stereochemistry by chemical methods were applied for the determination of the absolute configurations of pterosin D type compounds.
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白浜 晴久, 大沢 映二, 三角 俊二郎, 早野 清治, 大塚 俊一, 金元 祥郎, 松本 毅
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発行日: 1978/08/22
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Molecular mechanics calculation was performed on four stable conformations of humulene (CT, CC, TT, TC). Their heats of formation and atomic coordinates were obtained and the former two (CT, CC) were found to be equally more stable than others. These findings suggest that biosynthetically hirsutene is directly derived from the CC form of humulene rather than from the CT form through protoilludene. A process in which the three double bond planes rotate successively by 180°was proposed as the mechanism for interconversion of D- and L- forms of humulene. The energy barrier to the interconversion was estimated by the molecular mechanics calculations and shown to be 18.64kcal/mol. Humulen-9,10-epoxide was found to be converted to 6-acetoxyhumulen-7-ol on treatment with BF_3-AcOH. A possible reaction route was presented and was supported by isolation of the assumed intermediate 5. The steric courses of this and other transannular cyclization reactions of humulene were examined. In most of these reactions the stable conformation of reactant is conserved throughout the reactions.
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瀬戸 治男, 鵜沢 洵, 佐々木 徹, 竹内 節男, 米原 弘
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From the fermentation broth of Streptomyces sp., an producing organism of the antibiotic pentalenolactone, were isolated two pentalenolactone related compounds. The structures of these metabolites named pentalenolactone G and compound II (Fig. 1) have been determined based on ^1H-nmr and ^<13>C-nmr spectral data. In structural determination of pentalenolactone G, extensive use was made of long range selective proton decoupling (LSPD) and selective ^<13>C-{^1H} NOE. In addition, a new technique ^<13>C-{^1H, ^1H}, LSPD has been shown to be useful to obtain structural information on carbons which were coupled to many protons. The structures of the two compounds imply strongly that pentalenolactone is biosynthesized from humulene as shown in Fig. 1.
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遠藤 次郎, 糸川 秀治
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Ten new sesquiterpenoids (3-12) were isolated from essetial oil of the subterranean part of Asarum caulescens collected in winter at Mt. Fujiwara in Mie Prefecture. Structures of these compounds, which were also derived by transannular rearrangement of germacrone-4,5-epoxide(2), were elucidated on the basis of chemical and spectral results. Transannular rearrangement reactions of 2 under various conditions showed that this compound was assumed to have two conformational isomers, (2-A and 2-B) in a ratio of about 5: 1.
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鈴木 輝明, 黒沢 悦郎
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Two novel skeletal components, bromo acetal-A and B, having bromine and cyclic acetal, have been isolated from marine alga, Laurencia nipponica Yamada (Japanese name; Urasozo). The structure of bromo acetal-A (4), C_<15>H_<19>O_2Br, mp 82-83°, was established by its physical properties and X-Ray diffraction analysis. Bromo acetal-B (5), C_<15>H_<21>O_3Br, mp 105-6°, which seems to be the precursor of 4, is alcoholic compound and its structure was determined by relating to that of 4 with chemical transformations.
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藤森 嶺, 春日 令子, 金子 肇, 野口 正雄, 坂村 貞雄, 古崎 昭雄, 羽柴 宣宏, 松本 毅
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A new tetracyclic sesquiterpene ketone, solanascone (1), was isolated from Nicotiana tabacum cv. Burley. ^1H and ^<13>C NMR, mass and IR spectra indicated that (1) was tetracyclic, and contained six or higher membered saturated ketone, a methylene adjacent to the ketonic function, two methyl groups attached to quaternary carbons and a methyl group attached to a tertiary carbon. A partial structure (I) was obtained from the double irradiation ^1H NMR experiments carried out on the europium shifted spectrum. The complete structure and stereochemistry of (1) was elucidated by X-ray crystallography of its oxime. Irradiation of (-)-solavetivone (2) in the methanol produced solanascone (1) by a [2+2] photocyclization. This result suggests that (2) may be a direct precursor of (1) and the absolute configuration of (+)-solanascone was shown to be as in the stereostructure (1).
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片山 正人, 丸茂 晋吾
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Sclerotinia fructicola, a pathogenic brown rot fungus of stone fruits, produced abundant asexual arthrospores when grown on an agar medium in darkness, whereas poorly or not at all under illumination of light. We found that the dark-induced sporulation of this fungus was attributed to production of sporogenic substances in the mycelia cultured in darkness. We now describe the isolation and structural elucidation of sporogenic substances produced by this fungus grown on an agar medium in darkness. 1) The major sporogenic substance, named sclerosporin, was a new fungal sesquiterpene (C_<15>H_<22>O_2) with a guaiane skeleton, inducing the sporulation at 0.001μg/ml, and its plain structure was elucidated as 1, using 180μg of the sample with the ultramicro-techniques. Two related metabolites, sclerosporal and sclerosporene, were isolated and their structures were determined as 3 and 4, respectively. 2) The minor active substance was identified as R-(-)-glycerol monolinolate (2) by synthesis. Interestingly, its antipodal S enantiomer did not show the sporogenic activity. 3) A new metabolite with sporogenic activity was produced in the submerged culture, although the sporulation did not occur under these conditions, and the compound was determined as dolichol-23.
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児玉 三明, 横尾 俊一, 島田 和明, 松木 安生, 山田 治民, 伊東 椒
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In addition to the 2E, 6E- and 2Z,6E-hedycaryols (1 and 2) reported previously, we have synthesized the remaining two (2E,6Z- and 2Z,6Z-) isomers (3 and 4) by the anion-induced cyclization of 2E,6Z-10,11-epoxyfarnesyl phenyl thioether and the subsequent desulfurization. Their structures were based on the spectra and chemical correlations. Transannular reactions (acid-catalyzed cyclization and Cope rearrangement) of all four isomeric hedycaryols were investigated in order to clarify the stereochemistry of the reactions. From the stereochemistry of the products from the acid-catalyzed cyclization (eudesmol or dihydrooccidentalol) and from Cope rearrangement at lower temperature (≤400°), the conformers with the lowest activation energy were deduced for each isomer (Chart, p.5). Both reactions occur from the same conformation for each isomer. When the Cope rearrangement was carried out at a higher temperature (〜500°), more complicated reactions took place (Table, p.6), disclosing the occurrence of the Cope rearrangement from less favorable conformers of original hedycaryol and that from the initially-formed elemol to another hedycaryol. The structure of "epielemol" isolated by Pentegova from Pinus sibirica was revised to 26.
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野依 良治, 早川 芳宏, 清水 富士雄, 山田 守彦, 西沢 麦夫, 山本 尚, 丸岡 啓二, 橋本 信介, 野崎 一
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The intramolecular version of ironcarbonyl promoted reaction of polybromo ketones and olefin or diene substrates has been applied to the synthesis of certain terpenoids. The reductive cyclization of 1 and 2 affords the oxoguaian skeleton 12 and 13, respectively, in a stereospecific manner. (±)-Camphor and (±)-campherenone has been synthesized from the dibromo ketone 15 and 16, respectively, realizing a chemical analogue of biosynthesis.
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原山 尚, 長 秀連, 高谷 宗男, 犬伏 康夫
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The stereochemistry of Diels-Alder (D.A.) adducts of 2,5-dialkylcyclohexenones with butadiene has been chemically clarified. The key intermediate (21) for synthesis of 8-deoxyserratinine type of alkaloids and dl-chamaecynone (29) have been synthesized by taking advantage of this type of D.A. reaction. The study on the stereochemistry of the D.A. adduct (2) of dienophile (1) with butadiene in the presence of AlCl_3 suggested that butadiene approached the dienophile (1) from the side opposite to the C-5 methyl group. The result of re-investigation of the reported reaction of carvone with butadiene by heating method showed that reported structures should be revised in such a way that the structure (7) for the major product is replaced by the formula (8) and the structure (8) for the minor product by the formula (7). Moreover, addition of Lewis acid much improved the yield and stereoselectivity of this reaction. In connection with synthetic study on 8-deoxyserratinine type of alkaloids, the D.A. reaction of dienophile (22) obtained from (23) in five steps with butadiene provided the desired key intermediate (21). The D.A. reaction of a new dienophile (31) with a new diene (30) gave the main product (32), which has the same four chiral centers as those of chamaecynone (29), accompanied with the compounds (37) and (38). The compound (32) was converted in four steps into dl-chamaecynone (29).
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市原 耿民, 木村 凌治, 生方 信, 寺山 善彦, 森安 宏一, 丹尾 式希, 山田 誠一郎, 坂村 貞雄
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Retro-Diels-Alder reactions were used for a) protective group of the double bond in α,β-unsaturated carbonyl moiety, b) synthesis of α-alkyl-α,β-unsaturated carbonyl compounds from α,β-unsaturated carbonyl compounds. In the reaction, dimethylfulvene (cyclopentadiene) was used as a diene since retro-Diels-Alder reaction of the adducts proceeds smoothly at rather low temperature. Utility of retro-Diels-Alder reaction was demonstrated by the syntheses of several natural products, for example, plumbagin (5), epoformin (9a), hinokinin (20), and dehydrolappaol A dimethyl ether (26). Further efforts for stereoselective synthesis of coronafacic acid (29) are in progress.
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村井 章夫, 小野 光則, 安孫子 淳, 正宗 直
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Phytuberin (1) is a novel sesquiterpene qualified as a representative phytoalexin together with rishitin in the genus Solanum and characterized structurally by the presence of two fused hydrofuran rings. We describe herein a biomimetic and stereoselective synthesis of 1, starting from (+)-α-cyperone (40), which has been prepared easily from commercially available (-)-carvone via (-)-2-carone and (-)-α-santonin. The proposed biogenesis suggested that the biosynthesis of 1 would proceed via oxidative cleavage of a C-1-C-2 bond of a hypothetical intermediate with an eudesmane skeleton followed by formation of C-2-O-C-5 and C-1-O-C-4 bonds. The present synthesis was performed in line with this pathway as a result of many alternate, unsuccessful approaches and consisted of two stages: (i) preparation of an eudesmane with a β-hydroxyl group at C-5 and oxygenated functions at C-1 and/or C-2; namely, conversion of 40 into (+)-β-rotunol (4) (Scheme 1), and (ii) modification of 4 for the relevant cleavage and subsequent transformation into 1 via formyl γ-lactone (53), one of the most plausible precursors of 1 from the biogenetic viewpoint (Scheme 2). The summarized result indicates completion of the synthesis of phytuberin (1), β- and α-rotunol (4 and 3) and also establishes the undecided absolute configuration (R) at C-7 of phytuberin (1).
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宮下 正昭, 熊沢 利昭, 吉越 昭
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The 3-methylfuran structure is frequently found in terpenoids. We recently reported a one-step preparation of 2-alkylfurans by the reaction of aliphatic 2-nitroolefins and 1,3-dicarbonyl compounds, 1-nitropropene, however, gave an α-oximinodihydrofuran derivative 4 in the reaction with dimedone in place of the anticipated furan 3 under similar reaction conditions. As a reagent for this purpose, 1-nitro-1-phenylthiopropene (10) was prepared from phenylthioacetic acid and submitted to the reaction with dimedone (KF, xylene, 110°), yielding a mixture of 11a, 11b, and 12. After separation, the α-phenylthiodihydrofurans 11a and 11b were converted into 15 by oxidation followed by phenylsulfenic acid elimination, respectively. On a similar procedure, (±)-evodone (23) was synthesized from 5-methylcyclohexane-1,3-dione. The reaction of the dione 24 with 10 gave a mixture of 39 and 40. When submitted to oxidation and subsequent elimination, the mixture afforded only isoligularone (26). Although thermal isomerization of 26 to ligularone (25) is the known transformation, the direct preparation of 25 from 39 is also being studied now.
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鳥居 滋, 井口 勉, 山藤 哲夫, 河合 清人
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Stereocontrolled syntheses of (±)-isopetasol (1), (±)-dehydrofukinone (2), and (±)-β-costol (3) are presented, involving the Diels-Alder reaction of 3-methoxycarbonyl-2-cyclohexene-1-ones with butadiene. Functionalization of the bridge-head methyl group at the C-10 carbon on (1), (2), and (3), the C-4 methyl group of (1) and (2), the C-3 hydroxy group of (1), and the C-7 branched group of (3) were well controlled stereochemically.
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山川 浩司, 佐藤 毅
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The total syntheses of (±)-ligularone 15, (±)-furanoeremphilone 30, (±)-9,10-dehydrofuranoeremophilane 32, (±)-furanoeremophilane 41, (±)-furanoligularane 44, (±)-3β-hydroxyfuranoeremophilane 48 and (±)-3β-furanoligularanol 51 are described. Ketal-dione 24 derived from Diels-Alder adduct 11 was reduced with NaBH_4 to give 25a and 26a. Ketal 25a and 26a were hydrolyzed in aq-AcOH to afford 28 and 27 in good yield, respectively. Treatment of 27 with red phosphorus and iodine in AcOH gave 3,6-dione 13, which has already been converted into ligularone 15. Treatment of 28 with red phosphorus and iodine in AcOH gave 18, 20, 21, 22 in 8%, 20%, 20%, 30% yield, respectively. 10βH and 10αH-furanoeremophilone 30 and 35 were synthesized from 20 and 21. Reduction of 30 with LiAlH_4 followed by dehydration with POCl_3 gave 9,10-dehydrofuranoeremophilane 32 in good yield. Diketone 20 was reduced with NaBH_4 to give 33 and 34 in 81% and 7% yield, respectively and 21 was reduced in a similar manner to give 36 in 93% yield. Acetylation of 31 followed by reduction with Li in liq-NH_3 gave furanoeremophilane 41 in quantitatively. In a similar manner, 42, 46 and 49 gave furanoligularane 44, 3β-hydroxyfuranoeremophilane 48 and 3β-furanoligularanol 51 in good yield, respectively.
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安東 政義, 赤羽 厚, 田島 潔, 高瀬 嘉平
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発行日: 1978/08/22
公開日: 2017/08/18
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I) Saussurea lactone, a typical elemanolide has been synthesized via a novel fragmentation reaction of an epoxymesylate (7). The starting material is an acetal (1) which was prepared from α-santonin. Deacetalization of 1 with boiling 50% AcOH aq gave a β,γ-unsaturated ketone (2). Reduction of 2 with LiAl(t-BuO)_3H and successive treatment with m-chloroperbenzoic acid gave an epoxide (6). Mesylation of 6 afforded epoxymesylate (7). Fragmentation reaction of 7 with Al(i-PrO)_3 in boiling toluene gave an ester (9) which was transformed into a lactone (10). Acetylation of 10 and successive reduction of the resulting acetate (11) with Li in liquid ammonia gave a hemiacetal (12) which was transformed into saussurea lactone by Collins oxidation. II) Arborescin has been synthesized in 11 steps from epoxyacetal (13). Treatment of 13 with Al(i-PrO)_3 in boiling toluene gave allyl alcohol (14). Catalytic hydrogenation of 14 and successive benzoylation gave a benzoate (16). Deacetalization of 16 with 50% AcOH aq gave a ketone (17) which was transformed into a mesylate (20) by reduction with LiAl(t-BuO)_3H and successive mesylation of the resulting β-alcohol (19). Solvolytic rearrangement of 20 gave benzoates (21) and (22). Epoxidation of 22 gave 1β,10β-epoxide (24) and 1α,10α-epoxide (23). Hydrolysis of 24 gave an alcohol (25) which was transformed into arborescin by mesylation and successive treatment of the resulting mesylate with LiBr and Li_2CO_3 in DMF. The same treatment of 23 gave an epoxide (28) and an allyl alcohol(29). From these results the stereochemistry of the epoxide ring of arborescin has been determined to be β-orientation.
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山崎 和男, 木原 智加子, 板野 加代子, 笠井 良次, 田中 治, 金 済勲
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発行日: 1978/08/22
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In continuation of our studies of application of ^<13>C NMR to chemistry of glycosides, the structure of a glucoside(3) of Siegesbeckia pubescens (Compositae) including absolute configuration of its aglycone(2) was established mainly by means of ^<13>C NMR. Comparison of the spectrum of 3 with that of darutoside, the glucoside previously isolated from S. orientalis proved the identity of both compounds, leading to revise the location of the glucosyl-linkage of darutoside proposed by Diara et al. Significant influences of an adjacent OH function on the glycosylation shifts have been observed (see Chart 3). In order to find the generality of such an effect, stereo-selective synthesis of glucosides of cyclohexane-1, 2-diols (trans: 6R and 6S; cis: 7) by enzymic trans-glucosylation were studied. On glycosylation with α-amylase and maltose (donor), a racemic mixture of 6R and 6S yielded selectively mono-β-D-glucoside of 6R(8), and 7 gave exclusively 11 though the reaction of the later proceeded evidently more slowly than that of 6R. In contrast to this, glycosylation with β-glucosidase (emulsin) using amygdalin or salicin as the donors yielded less stereospecifically a mixture of glucosides, 9 and 10 from a mixture of trans diols(6R+6S), and 12 and 13 from cis diol(7) respectively. The configuration as well as the conformation of these glucosides were investigated and the glycosylation shifts were discussed in comparison with the former results.
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林 雄二, 松本 武, 植村 元一, 是枝 正人
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発行日: 1978/08/22
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^<13>C-nmr spectra have been determined with some twenty members of the biologically active nor-diterpenoid dilactones obtained from Podocarpus nagi. The assignment of each carbon signal was confirmed by proton selective decouplings, J_<C-H> measurements and analogies with the model compounds (Table 1〜4). Detailed analyses were performed firstly with nagilactones, B (3), C (15), D (17) and E (22), and their acetates, relatively abundant dilactones in natural sources, and the results were then adjusted by comparisons with the spectra of other minor related lactones. Characteristic shieldings were observed on the particular carbon atoms, C^7, C^<11>, C^<14> and C^<15>, which would be caused by significant non-bonded interactions in these rigid molecules. Acetylation of the hydroxyl groups on ring A and B also gave rise to some shielding on the neighboring carbon atoms which may be interpreted by γ-effect of the acetyl carbonyl group.
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林 修一, 松尾 昭彦, 野崎 浩, 久司 佳彦, 中山 充, 広井 満, 高岡 大輔
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In a course of continuous investigations on liverworts, eight new diterpenoids containing a novel fused 3.6.6.5-tetracyclic ring system, verrucosane and isoverrucosane were isolated from an ethanolic extract of Mylia verrucosa, and the stractures were determined as 2,9-dihydroxyverrucosane[1], 9-acetoxy-2-hydroxyverrucosane[2], 9-oxo-2-hydroxyverrucosane[3], 2-acetoxy-11-hydroxyverrucosane[17], 11-acetoxy-2-hydroxyverrucosane[18], 2-hydroxyverrucosane[27], 2-hydroxyisoverrucosane [24] and 9-acetoxy-2,x dihydroxyverrucosane[28] on the basis of chemical and spectroscopic evidence. The stracture and absolute configuration thus determined of [1] was identical with that investigated by the X-ray crystal stracture analysis of p-bromobenzoate of [1].
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北沢 栄一, 小木曽 彰, 高橋 秀次, 桑野 晴光, 田村 千尋, 畠 忠
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Pharmacological screening directed towards to find antipeptic ulcer substances of plant origin led us to find that extract of a crude drug named Plau-noi in Thailand, identified with stems of Croton sublyratus Kurz (Euphrbiaceae), showed significant inhibitory activities against Shay-ulcer in rat and reserpine-ulcer in mouse. From the active fractions, furanoditerpene A, B, C, D, E, and F were isolated together with 18-hydroxygeranylgeraniol (1) showing anti-reserpine ulcer activity. Structural elucidation of the furanoditerpenoids and the anti-Shay ulcer activity of B, C, D, and E will be discussed. The structure and absolute configuration of A were determined by the spectral data and the X-ray crystallographic analysis of p-bromobenzoate (3). Sodium borohydride reduction of A and B gave the identical diol (7). Oxidation of B and C with Cornforth reagent gave the identical ketone (5). Sodium borohydride reduction of C and D gave the identical triol(14). Acetylation of D and E with acetic anhydride-pyridine gave the identical triacetate(12). From results of the above chemical interconversion, the absolute structures of A, B, C, D, and E were clarified. Finally, the structure of F was determined by the chemical correlation with bacchotricuneatin B (16).
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藤森 薫, 末永 仁士, 山本 悟, 金沢 礼三, 神川 忠雄, 野老山 喬
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発行日: 1978/08/22
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This paper deals with two approaches toward the total syntheses of clerodane diterpenes. Cascarillone 34 has been elaborated by our second approach, which represents the first total synthesis of cis-clerodane diterpene. The first approach starts from the intermediate 4, in which the stereochemistry at C-8, C-9 and C-10 has been secured by Diels-Alder reaction. 4 is converted to the keto-lactone 9, of which methylation after blocking of C-3 methylene group affords cis-decalin derivative 11. The transformation of 11 to 15, a critical intermediate for the synthesis of cis-clerodane diterpene 16 has been accomplished. The second approach takes advantage of the reported stereospecific formation of 30 by conjugate addition. The kinetically formed enolate in the reaction is trapped by formaldehyde and the further annelation procedures give a key intermediate 33. The application of conjugate addition-alkylation method to 33 yields a mixture of dimethylated products 36. The side chain construction on 36 by established procedures produces cascarillone 34.
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秋田 弘幸, 内藤 隆信, 穴沢 昭, 大石 武
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発行日: 1978/08/22
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Ozonolysis of phenolic dehydroabietic acid derivatives was investigated and products obtained by the cleavage of the aromatic ring by means of ozonolysis was found to be governed by the substitution pattern of the hydroxyl group in the aromatic ring. I) Ozonolysis of the 12-hydroxy compound (8) gave the pentanor-labdane type compounds (36), (37), and (38), the cleavage being taken place at the dotted line a. II) Ozonolysis of the 11,12-hydroxy compound (10), 14-hydroxy compound (24), and 13,14-dihydroxy compound (34) afford the drimane type compounds. In these case, the cleavage took place at the dotted line b. By use of the above method, we succeeded in the syntheses of the optically active (+)-isodrimenin (39), (+)-confertifolin (41), (+)-valdiviolide (42), and (+)-winterin (43). Then ozonolysis of the 6-substituted-14-hydroxy compounds (60) and (61) gave the 6-substituted confertifolin derivatives (58) and (59) which were converted into the optically active (+)-fragrolide (55) and (+)-bemadienolide (56). III) Ozonolysis of the 13-hydroxy compound (28) gave the pallescensins A type compound (49), the cleavage being taken place at the dotted line c. 49 was successfully converted into the optically active (+)-pallescensins A (50). In addition, we report the short syntheses of (+)-confertifolin (41) and (+)-isodrimenin (39) from β-ionone (75).
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鈴木 政信, 高柳 久男, 上原 忠夫, 加藤 忠弘
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発行日: 1978/08/22
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Having achieved the biogenetic type synthesis of cembrenoids starting from chloro ketone (2), easily prepared from 1, we have further continued the synthetic efforts on the construction method of the secotaxane skeleton (3), which is biogenetically related with cembrenoid. We have also accomplished the synthesis of several kinds of naturally occurring cembrenoids. These results are discussed in this symposium. I. Synthesis of Secotaxane skeleton Our synthetic strategy of secotaxane skeleton is based on the slight modification of the biogenetic scheme in such a way that C_8-C_9 bond of III is connected after construction of A ring by C-C bond formation between isopropyl cation and C_<10>-position of an intermediate (II)(C_8-C_9 is not bonded). The seco-cembrene (II) is prepared by head to tail coupling reaction of two geranyl units, both of which are properly functionalized by X and Z groups so as to make the C_8-C_9 bonding at the final stage. Based on this plan, we have succeeded in the synthesis of neocembrene (8) and secotaxane skeleton (3) as illustrated in the schemes. II. Synthesis of several kinds of cembrenoids The naturally occurring cembrenoids, 2-hydroxy- (15) and 1,14-dehydro-6,7-oxidonephthenols (17), and cembrenol (23) were prepared from chloro ketone (2) as indicated in the synthetic schemes. The present synthesis supports unequivocally the assigned structures of these oxygenated cembrenoids.
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菊池 徹, 新宮 徹朗, 横井 利夫, 丹羽 峰雄
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発行日: 1978/08/22
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(1) Homonuclear INDOR technique was applied to assignments of methyl resonances of friedelin and its related triterpenes in the presence of NMR shift reagent, Pr(FOD)_3. Thus the methyl signals of friedelin (Ia), epifriedelanol acetate (IIa), friedelanol acetate (IIIa), 16-ketofriedelane (IV), 16β-acetoxyfriedelane (V), 16α-acetoxyfriedelane (VI), shionone (VII), epishionol acetate (VIII), and shionol acetate (IX) were successfully assigned. In addition, D and E rings of friedelin (Ia) in chloroform solution were suggested to be in boat conformation. (2) Structures of pachysandienol-A (X) and -B (XI), new triterpenes isolated from Pachysandra terminalis SIEB. et ZUCC., were determined by chemical and spectroscopic methods. Their methyl resonances were also assigned.
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村江 達士, 並河 美鈴, 細川 和男, 宮崎 浩, 石橋 正兀, 露木 孝彦, 高橋 武美
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セッションID: 75
発行日: 1978/08/22
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The benzene-MeOH (3:1) extract of a fossil plant found from Nakatsugo-South deposit (Ningyo-Toge Uranium deposit) were separated roughly by column chromatography and preparative TLC. Each fraction was examined by GC-MS. The main components have been classified into the following groups; a) methyl esters of the fatty acids (1, C_nH_<2n+1>CO_2CH_3, n=12-21), b) hydroxyl and/or methoxyl substituted derivatives of phenolic acids(4-9), c) phenolic aldehydes (2 and 3), d) an acetophenone derivative (10), e) a series of substances which show a characteristic fragment ion at m/e 99, and f) triterpene and nortriterpene ketones. The substances of the group e have not been identified yet. The nortriterpene ketones were further separated by GC and the structures 11 and 12 have been proposed for them from their 270MHz FT-PMR, FT-IR, and mass spectra. The syntheses of 11 and 12 from lanosterol are in progress.
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塩島 憲治, 増田 和夫, 上田 博之
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発行日: 1978/08/22
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Hexane extraction of the fresh leaves of Adiantum monochlamys collected in October afforded a triterpenoid, m.p.154-157°, [α]_D +19.4°, as a main constituent(0.12%), which has been concluded to be adian-5-ene ozonide(1). 1 was proved to be identical with a sole crystalline product of ozone-oxidation of adian-5-ene(2) in a hexane solution. To compare with the case of adian-5-ene, various mono-enes of hopane and migrated hopane series were subjected to ozone-oxidation. The results obtained were quite interesting because only two of the ten compounds gave the stable ozonides, three gave epoxides and the othersafforded quite complicated mixtures as shown as follows: a. Only stable epoxides were obtained, neohop-18-ene(α- and β-epoxides); pteron-14-ene (β-epoxide) fern-7-ene(α-epoxide) b. Stable ozonides were obtained, hop-17(21)-ene(α and β-ozonide, 1:1); adian-5-ene(α-O-O-) c. Various products including decomposition products of epoxides and/or ozonides were obtained, neohop-13(18)-ene, fern-9(11)-ene, adian-1(10)-ene, filic-3-ene, hop-21-ene etc. Glutin-5-ene (migrated oleanene) gave also a stable ozonide(α-O-O-). There have been reported various reaction mechanisms of ozone-oxidation, among which P.R. Story's proposal seems to be favourable to explain the above results.
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池田 道正, 佐藤 吉史, 佐々 武史, 三浦 勇吉
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N. fasciculare (Nigakuritake) is one of the bitter and poisonous toadstool and a harmful fungus for mushroom cultivation in the north east of Japan. In addition, there is no herbage throughout the year at a site of innumerable breeding of the toadstool. Three new polyhydroxy tetracyclic triterpenes (fasciculol A, 1; fasciculol B, 2; fasciculol C, 3) and four their depsipeptides (F-D, 4; F-E, 5; F-F, 6; F-G, 7) as plant growth inhibitors and a new fungal metabolite, 8 have been isolated from the fresh fruit bodies of N. fasciculare. Their structures have been elucidated on the basis of spectral data and chemical evidence.
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阿部 フミ子, 山内 辰郎
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Neriaside (1) and oleaside (XVII) were obtained as minor cardenolides from the oven-dried leaves of Nerium odorum Sol. They afforded, on acid hydrolysis, aglycones, neriagenin (II) and oleagenin (XVIII), respectively and diginose as a sugar component. The structure of II and XVIII were established respectively as 3β,14α-dihydroxy-8(14)-seco-8-oxo-5β-card-20(22)-enolide and 3β-hydroxy- 15(14→8)abeo-14-oxo-(8R)-5β-card-20(22)-enolide, by chemical and spectral studies and by the direct comparison of their derivatives XI and XIX with the authentic samples converted from adynerigenin acetate. It is to be noted that XVII is observed as a major glycoside in Nerium oleander, being considered as a key substance to identify N. odorum and N. oleander, chemically.
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入江 鐐三, 笹倉 政之, 池田 隆文
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6β-Bromo-4,4-dimethyl-1α,2α-epoxy-3α,5α-oxidocholestane (1) was obtained from 4 by bromination with NBS. On acidic treatment, the bromo-epoxy-oxide (1) was transformed into 5β-bromo-4,4-dimethyl-3α,6α-oxido-5(10→1βH)abeo-10(19)-cholesten-2α-ol (2a), which gave a diol (11) on reduction. On oxidation with lead tetraacetate, the diol (11) gave a dialdehyde (13). When the diol (11) was oxidized with m-chloroperbenzoic acid and successive acetylation, acetoxyl alcohols (9b) and (14) were obtained. On the basis of the similarity of both NMR spectra of 9a and 9b, the structure of 2a was determined.
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藤本 善徳, 粟田 則男, 村上 和夫, 森崎 益雄, 池川 信夫
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Previously we reported that fucosterol epoxide(3) is a key intermediate in the conversion of sitosterol(1) into cholesterol (5) in silkworm, Bombyx mori. A detailed study on this dealkylation mechanism, especially on which of the stereoisomers, 24R, 28R(3b) or 24S, 28S(3a) of fucosterol epoxide is the actual intermediate has been undertaken. [24R, 28R]- and [24S,28S]-fucosterol epoxides were chemically synthesized and their configurations were unequivocally determined by interrelation with sitosterol and clionasterol. The cell free systems which convert fucosterol to fucosterol epoxide and also the epoxide to desmosterol and cholesterol were developed. The data obtained by the incubations with the cell free system as well as in vivo experiments show that the stereospecificity both in the formation of the epoxide from fucosterol and its conversion to desmosterol is not so rigid. It may be considered that the dealkylation reaction would proceed via both 24R,28R(3b)- and 24S,28S(3a)-epoxides as an intermediate.
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寺田 澄男, 林 紘司, 三橋 博
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