A 2-ethoxycarbonyl-5-pyrrolidylideneacetate (XV) was prepared by mild reduction of an ε-ethoxycarbonyl-ε-nitro-β-keto ester (XIV) with Raney nickel as catalyst. Further reduction of (XV) over platinum oxide and palladium-carbon as catalyst to 2-ethoxycarbonyl-5-pyrrolidineacetate (XVI) and subsequent saponification afforded 2-carboxy-5-pyrrolidineacetic acid (III). This is a new process for synthesis of proline derivatives similar to (III). During the course of this work, it was newly found that a γ, δ-unsaturated β-keto ester (V) took part in the Michael condensation as acceptor.
Ethyl 4-cyanobutyrate (IV) was prepared by selective elimination of the ester group in diethyl 2-cyanoglutarate (II) and reductive cyclization of (IV) afforded 2-piperidone (V). 4-Substituted compounds (XV a, b, c) of (IV) were prepared by selective elimination of the ester group in 2-substituted compounds (XII a, b, c) of (II), and reduction of (XV) afforded 5-substituted compounds (XVI a, b, c) of (V). A new synthesis of proline and its derivatives was outlined which involved refluxing 3, 3-dihalo-2-piperidones in a barium hydroxide solution to give pyrrolinecarboxylic acids, which were then hydrogenated to afford the desired amino acids.
Reaction of diethyl 2-cyanoglutarate (VII) with 1-dimethylamino-2-bromopropane, in the presence of a base, afforded a condensation product (X). Concentration of aqueous solution of saponified (X), in hydrochloric acidity, easily effected decarboxylation to form (XI). Reduction of its ester (XII) afforded the expected, 5-(2-dimethylaminopropyl)-2-piperidone (XIII). The fact that the side chain in (X), (XII), and (XIII) was a 2-dimethylaminopropyl group was proved by pyrolysis of the betaine derived from (XII) to give unsaturated ester (XVI), followed by reduction of (XIV) to a 2-piperidone derivative, which was identified with 5-propyl-2-piperidone (XVII). The formation mechanism of (X) from (VII) was explained by assuming a route through ethylenimmonium ion (IX).
Methyl 4-cyano-6-dimethylaminoheptanoate (V) was led to its methiodide (VII). It was treated with silver oxide and the dried residue obtained from the filtrate was subjected to pyrolysis to give (V) and (VI). Ethyl homolog (III) too gave (V) and (VI) after the same pyrolysis. It was experimentally proved that the latter reaction is not the Hofmann degradation but a pyrolysis of betaine (XIV) and that an unsaturated methyl ester (VI) was formed together with basic methyl 4-cyano-6-dimethylaminoheptanoate (V). As the reaction mechanism, the main reaction route of intermolecular stepwise nucleophilic substitution and elimination of betaine was proposed.
A new synthesis of proline and its 4-substituted derivatives was described. Refluxing 3, 3-dichloro-2-piperidone and its 5-substituted derivatives (IIa, b, c, d) in a barium hydroxide solution gave pyrrolinecarboxylic acid compounds (IIIa, b, c, d), which were hydrogenated to afford the expected aminoacids (IVa, b, c, d) in good yields. A 3, 4-dihydro-2H-pyrrolenine-2-carboxylic acid structure was postulated for the pyrroline-carboxylic acid compounds.
Application of sulfuryl chloride to 5-(2-dimethylaminopropyl)-2-piperidone (I), in the presence of thionyl chloride, to form the 3, 3-dichloride (III) and direct boiling of (III) with barium hydroxide solution afforded pyrrolinecarboxylic acid derivative (IV). It was then reduced to a proline derivative (V) and then derived to ethyl 1-ethoxycarbonyl-4-(2-dimethylaminopropyl)-2-pyrrolidinecarboxylate (VI). It was found that the treatment of the methiodide of (VI) with lead oxide rapidly resulted in the formation of a betaine. Pyrolysis of this betaine under a reduced pressure was found to afford methyl 1-ethoxycarbonyl-4-(2-dimethylaminopropyl)-2-pyrrolidinecarboxylate (VIII) and methyl 1-ethoxycarbonyl-4-allyl-(or propenyl)-2-pyrroli dinecarboxylate (VII). This is a new kind of pyrolysis of a betaine and its reaction mechanism was examined. 4-Allylproline (IX) and 4-propenylproline (X) were obtained by saponification of (VII).
Diethyl 3-cyanomethylglutarate (XIII) was prepared by selective elimination of the ester group in diethyl 3-(ethoxycarbonylcyanomethyl) glutarate (III) and reduction of (XIII) afforded ethyl 2-oxo-4-piperidineacetate (XIV). Selective elimination of the ester group from isopropyl, propyl, and 1-methyl-2-ethoxyethyl derivatives (IVa, b, c) of (III) formed (VIIa, b, c) and its reduction gave 5-isopropyl, 5-propyl, and 5-(1-methyl-2-ethoxycarbonyl) derivatives (VIIIa, b, c). (XIV) and (VIIIa, b, c) were derived to their 3, 3-dichlorides and a new process of using sulfuryl chloride alone or in the presence of thionyl chloride was devised for this dichlorination.
Examinations were made on the structure of the side chain in the condensate (IV) obtained by reaction of diethyl 3-(ethoxycarbonylcyanomethyl) glutarate (I) and 1-dimethylamino-2-bromopropane and it was proved to be 2-dimethylaminopropyl group. During this examination, a new pyrolysis of betaine was discovered and a presumption of its mechanism was forwarded. Saponification of (IV) and low-pressure concentration of its product as a hydrochloric acid solution was found to effect facile selective decarboxylation to form glutaric acid derivatives (V). Esterification of (V) and subsequent reduction afforded ethyl 2-oxo-5-(2-dimethylaminopropyl)-4-piperidine-acetate (VII).
Ethyl 2-oxo-5-isopropyl-4-piperidineacetate (Ia) was derived to its 3, 3-dichloride (IIa), boiled with barium hydroxide solution, and 2-oxo-3-chloro-5-isopropyl-3-piperideine-4-acetic acid (VIa) was isolated from its reaction product. Catalytic reduction of (VIa) afforded both DL-α- (VIIIa) and DL-β-dihydroallokainic acid (IXa) at the same time. (VIIIa) was also obtained by retrokainin inversion of (IXa) and its kainin inversion afforded DL-N-acetyl-β-dihydroallokainic anhydride (X). DL-N-Acetyl-β-dihydro allokainic acid (XI), formed by treatment of (X) with water, was also obtained by treatment of (IX) with acetic anhydride and water. L- and D-α-Dihydroallokainic acids (XVI and XVII) were obtained by optical resolution of (VIIIa) with d- and l-ephedrine. Treatment of ethyl 2-oxo-5-propyl-4-piperidineacetate (Ib) with barium hydroxide, same as (Ia) afforded 5-propyl analog (VIb) of (VIa) and two kinds of stereoisomers (VIIIb and IXb) of 2-carboxy-4-propyl-3-pyrrolidineacetic acid. The structure of pyrrolinecarboxylic acid derivatives (Va, b) as precursor of these products was presumed.
Ethyl 2-oxo-3, 3-dichloro-4-piperidineacetate (I) was boiled with barium hydroxide solution and the pyrrolinecarboxylic acid derivative thereby formed was catalytically reduced from which 2-carboxy-3-pyrrolidineacetic acid (cis-type) (III) was isolated. By heating its aqueous solution in a sealed tube, its isomeric trans-type compound (IV) was obtained. (III) was also obtained on saponification of 1-acetyl-cis-anhydride (VI) formed by the reaction of (IV) and acetic anhydride. (V), obtained on treatment of (VI) with water, was identified with the compound formed on application of acetic anhydride and water to (III). (III) and (IV) were respectively derived to methyl 1-ethoxycarbonyl-2-methoxycarbonyl-3-pyrrolidineacetate (VII and VIII).
Ethyl 2-oxo-5-(2-dimethylaminopropyl)-4-piperidineacetate (I) was derived to its 3, 3-dichloride (III) by the application of sulfuryl chloride and thionyl chloride and a pyrrolinecarboxylic acid derivative (IV) was obtained by boiling (III) in barium hydroxide solution. Ethyl 1, 2-diethoxycarbonyl-4-(2-dimethylaminopropyl)-3-pyrrolidineacetate (VI) was obtained from a proline derivative formed by reducution of (IV). Treatment of the methiodide of (VI) was found to effect rapid betainization and pyrolysis of this betaine under a reduced pressure was found to result in the formation of a mixed basic methyl and ethyl esters (VII) and a mixed unsaturated methyl and ethyl esters (VIII). Reaction mechanism of this new pyrolysis of betaine was presumed. Saponification of (VIII) afforded 2-carboxy-4-allyl-(and -propenyl)-3-pyrrolidineacetic acids.
Ethyl 2-oxo-3, 3-dichloro-5-(1-methyl-2-ethoxyethyl)-4-piperidineacetate (I) was derived to pyrrolinecarboxylic acid derivative (II) by boiling it in barium hydroxide solution and reduction of (II) afforded a proline derivative (III). Retrokainin inversion of (III) gave (IV) and its treatment with hydrobromic acid afforded methyl 1-ethoxycarbonyl-2-methoxycarbonyl-4-(1-methyl-2-hydroxyethyl)-3-pyrrolidineacetate (VI). Treatment of (VI) with phosphorus tribromide to form (VII), its dehydrobromination to (VIII), and saponification of (VIII) afforded DL-α-allokainic acid (IX), whose optical resolution gave L-α-allokainic acid (XI).
Method for determining unchanged Meprobamate in the urine was effected by the combination of paper partition chromatography, using the Ehrlich reagent, and colorimetry. By the use of this method, amount of unchanged Meprobamate excreted in the urine during 72 hours following oral administration of 1.6g. of Meprobamate in the male was determined. Results are indicated in Table IV and Fig. 1.
In order to examine the action of benzimidazoles against Trychophyton, 2-alkylthiobenzimidazole derivatives with thioether linkage in 2-position were prepared and their in vitro effect against Trychophyton was examined. These compounds were synthesized by the condensation of 2-mercaptobenzimidazoles with alkyl halide. Some considerations were made on the relationship between chemical structure and antifungal activity.
Density and surface area of cadmium phosphate catalyst, prepared from cadmium nitrate and sodium orthophosphate, were measured. The hydrogen adsorption by this cadmium phosphate becomes active from about 150°. Its activated adsorption began with comparatively rapid, initial adsorption followed by gradual adsorption. It was found that, in decomposition of isopropyl alcohol, dehydrogenation is chiefly effected and dehydration occurs in a slight degree at above 350°. Compared to cadmium oxide, the direction of decomposition is the same but the temperature at which activity appears is lower and the degree of activity is greater. Relationship between partial pressure and initial reaction velocity of isopropyl alcohol was examined using 4.5g. of this catalyst, at a reaction temperature of 250°, contact time 100-300min./mole, and benzene as the diluent, and it was found that the initial reaction velocity, at above partial pressure of 0.6, became approximately constant and namely the order of the reaction is nearly zero. Piperidine is dehydrogenated to pyridine by passage over this catalyst at 400°, 425°, or 450°, and the yield of pyridine was 32% of the piperidine used, at 450°.
Reduction of dihydrothiamines (VI: normal and iso compounds) (VII: pseudo compound) and thiamine (I) with sodium borohydride afforded tetrahydrothiamine (VIII) from (VI) and (I) when using a hydrous solvent, while dihydrothiamines were not reduced when using anhydrous solvent, and thiamine was reduced only to dihydro-thiamine. Pseudodihydrothiamine was not reduced even in a hydrous solvent. These facts suggest that isodihydrothiamine takes the ammonium-type structure (V) in a hydrous solvent. Spectral analysis of the hydrochloride of dihydrothiamine revealed their structures and the hydrochloride obtained from the pseudo compound was found to have undergone isomerization to the hydrochloride of isodihydrothiamine.
Homologs of cyanothiamine were synthesized. The route whereby 2-imino-3-(2-methyl-4-amino-5-pyrimidinyl) methyl-3a-methyl-5, 6, 7, 8-tetrahydrofuro [2, 3-d] thiazole is formed from cyanothiamine was examined. Cyanothiamine forms thiochrome on being warmed in acetic acid and N-[1-(2-thiacyclobutylidene) ethyl]-N-[(2-methyl-4-amino-5-pyrimidinyl) methyl] formamide when warmed in butanol. Treatment of cyanothiamine with conc. sulfuric acid afforded thiamine O-(hydrogen sulfate).
Boiling of 2-hydrazino-4-hydroxy-6-methylpyrimidine (VI) with formic acid for a short time afforded two kinds of crystals, one of m.p. 300° (decomp.) (B) and the other of m.p. 249-251° (C). The structure of 5-methyl-7-hydroxy-s-triazolo[4, 3-a]-pyrimidine (V) was assigned to (B) and 5-hydroxy-7-methyl-s-triazolo[4, 3-a]-pyrimidine (IV) to (C). (C) converts to crystals of m.p. 277-279° (A) on boilling it with formic acid for a long period or by its fusion, and the product (A) was found to be identical with the condensate of 5-amino-s-triazole (I) and ethyl acetoacetate. Bülow gave the structure of 5-methyl-7-hydroxy-s-triazolo [2, 3-a] pyrimidine (II) to (A) and Birr, (IV). The writer supports Bülow's structure.
Coloration with acetone and alkali hydroxide was examined with eight kinds of mononitrobenzene compounds in which a function possessing the same electric effect as that of nitro group was introduced into position meta to other substituent. It was thereby revealed that 5-nitroisophthalonitrile (VI), methyl 3-cyano-5-nitrobenzoate (VIII), and methyl 5-nitroisophthalate (V) were positive to this coloration reaction, showing a comparatively stable and marked deep red, reddish violet, and reddish orange colors.
In order to examine the effect of adjacent triple bond and phenyl group on the oxidation of methylene, oxidation of 1, 4-diphenyl-1-butyne with selenium dioxide was attempted. Further oxidation of its oxidation product with manganese dioxide and selective reduction of the unsaturated bond in both oxidation products, using palladium-barium sulfate as the catalyst were carried out. From infrared spectral measurement, it was suggested that the oxidized methylene group is not that adjacent to the phenyl ring but that adjacent to the triple bond and this was established through 2, 4-dinitrophenylhydrazone of an authentic sample synthesized by another route. The product formed by selenium dioxide oxidation was 1, 4-diphenyl-1-butyn-3-one and 1, 4-diphenyl-1-butyn-3-ol and not 1, 4-diphenyl-1-butyn-4-one or -4-ol.
Isolation of isochondodendrine (III) as the tertiary phenolic base, and magnoflorine (IV) and a new base, cyclanoline (V), as the quaternary bases, besides insularine (I) and cycleanine (II), from the rhizome of Cyclea insularis (MAKINO) DIELS (Japanese name “Miyakojima-tsuzurafuji”) was reported earlier. At that time, the presence of another new base had been assumed from paper chromatographic result and this had been tentatively named the third base. In the present series of work, this new component was examined and two kinds of bases were isolated in crystalline state. Both were biscoclaurine-type tertiary bases with one phenolic hydroxyl and, since they were unknown new bases, they were named insulanoline (third base) and norcycleanine (fourth base). It was found that their methylation afforded insularine (I) from insulanoline and cycleanine (II) from norcycleanine. The phenolic hydro-xyl in the two bases was assumed to be present in the 7-position of tetrahydroiso-quinoline ring since both bases are negative to the Gibbs reagent and from conside-ration of their biogenesis. Based on these facts, formula (VII) is proposed for insulanoline and formula (VIII) for norcycleanine.
Isolation of two kinds of new tertiary bases, insulanoline and norcycleanine, from the rhizome of Cyclea insularis (MAKINO) DIELS was described in the preceding paper, and it was also shown that both bases possessed only one phenolic hydroxyl and that they formed insularine (I) and cycleanine (XVIII), respectively, by methylation. Further studies were now carried out on insulanoline and its structure was established. Cleavage reaction of O-ethylinsulanoline (III) in liquid ammonia with sodium resulted in the reaction exactly as in the case of insularine (I), as shown in Chart 1, and a part was decomposed into two moles of coclaurine-type bases, forming a levorotatory bisected base A (IV) and l-N-methylcoclaurine (bisected base B) (V), and another part formed a non-crystalline bis-type bisected base C (VIa) by cleavage of the depsidan ring at the benzyl ether position. The second cleavage reaction of methylated compound (VIb) of the bisected base C (VIa) with liquid ammonia-sodium afforded the bisected base A (IV) and l-O, O, N-trimethylcoclaurine (VII). The bisected base was compared with the racemic compound synthesized according to the scheme showm in Chart 2 and was established as l-1-(3-methyl-4-hydroxybenzyl)-2-methyl-6-methoxy-7-ethoxy-1, 2, 3, 4-tetrahydroisoquinoline (IV). From these expeirmental results, the structure of insulanoline was found to be represented by formula (II) and that the steric configuration of the two asymmetric centers (rotatory direction) are both levorotatory type.
Tetracyclines have remarkable antibacterial action and, under the assumption that the A-ring characteristic to tetracyclines might be responsible for this activity, it seemed of interest to synthesize this A-ring and similar compounds, and to examine relationship between chemical structure and antibacterial activity. Therefore, 4-benzamidocyclohexane-1, 3-dione (I), a compound with benzamido group attached to 4-position of cyclohexane-1, 3-dione, the fundamental skeleton of the A-ring in tetracyclines, was syntheized by catalytic alkaline reduction of 2, 4-dihydroxybenz-anilide. During this reduction, it was found that difficulty reduced compounds can easily be reduced by suitably adjusting the alkalinity. Further, the enol ethyl ether (II) and 3-amino compounds of (I) were prepared and they were found to still retain the dione groups, through analytical values and from ultraviolet and infrared absorption spectra.
In continuation of the work on the syntheses of compounds related to the A-ring in tetracyclines, 4-dimethylaminocyclohexane-1, 3-dione, structurally closer to the A-ring, was prepared by the reduction of corresponding resorcinol. Formation of the desired compound was established through analytical values and from ultraviolet and infrared absorption spectra.
In connection with the syntheses of the A-ring analogs of tetracyclines, 2-carbamoylcyclohexane-1, 3-dione and its derivative, 2-methylcarbamoylcyclohexane-1, 3-dione, were synthesized by catalytic alkaline reduction of the corresponding resorcinol derivatives and their formation was established through analytical values and from ultraviolet and infrared absorption spectra.
Separation of steroid and triterpenoid was attempted by submitting about 50 kinds of these substances to reverse-phase chromatography, using liquid paraffin as the stationary phase, and the effect of substituents on Rf values was assumed as follows: 1) Substituents that give positive offect on Rf value are -OH, =O, and -Cl, in that order when substituted in the same position with the same steric configuration while in cholestane type, 3β-OH is stronger than 3α-OH. Double bond also gives positive effect on the Rf value. 2) Acetylation or benzoylation of -OH, or increase of =CH2 gives negative effect on the Rf value. 3) Triterpenoids of oleanane type have greater Rf value than those of ursane type. 4) The substituents which give positive effect on Rf value in triterpenoids of oleanane type, when substituted in the same position and taking the same steric configuration, are -CH2OH, -COOH, and -CH3 in descending order.
Earlier reports described the isolation of β- and γ-sitosterols from the easily eluted portion of alumina chromatography of acetylated sterol mixture obtained from Phellodendron amurense RUPR. In the present series of work, the more difficultly eluted portion of the same sterol mixture was repeatedly submitted to alumina chromatography and 7-dehydrostigmasterol was isolated from it as the third component of Phellodendron. The compound was identified by catalytic reduction and paper chromatography.
It was found that, since perchloric acid hardly reacts with ethylene glycol, it could be used for acidification of a mixed solvent containing ethylene glycol. Titration curves were examined by using the solvent system of ethylene glycol·isopropanol (1:1 by volume) and ethylene glycol·dioxane (1:1 by volume) as the titration solvent, and perchloric acid and p-toluenesulfonic acid as the titration acid, in various combinations. It was thereby learned that they all gave similar titration curves. Titration with 0.002N solution was attempted to establish semimicro method and accurate titration was effected, except in the case of weak bases like narcotine and papaverine.
Reduction of 5-methoxyisoquinoline (I) with liquid ammonia-sodium-methanol by the Birch method, followed by hydrolysis with 10% sulfuric acid afforded 1, 2, 3, 4-tetrahydroderivative (II) in nearly quantitative yield. Further treatment of (II) with liquid ammonia-lithium-methanol resulted in recovery of the starting material. The same treatment of 2-methyl-5-methoxy-1, 2, 3, 4-tetrahydroisoquinoline (III) with liquid ammonia-lithium-methanol, followed by treatment with 10% sulfuric acid give α, β-unsaturated ketonic base in 4% yield, besides recovery of the majority of the starting material. The same reduction of 2-methyl-7-methoxy-1, 2, 3, 4-tetrahydroisoquinoline (VI) afforded a base assumed to be 2-methyl-7-oxo-Δ8-octahydroisoquinoline (VII) in 40-50% yield. (VII) shows anomalous absorption in its ultraviolet spectrum, similar to 2-methyl-6-oxo-Δ5(10)-octahydroisoquinoline. Catalytic reduction of (VII) with palla-dium-barium sulfate or platinum oxide respectively gave 2-methyl-7-oxodecahydroiso-quinoline (VIII) and 2-methyl-7-hydroxy-decahydroisoquinoline.
Examinations were made on the presence of alkaloids in Xanthoxylum ailanthoides SIEB. et ZUCC. (Fagara ailanthoides (SIEB. et ZUCC.) ENGL.) (Japanese name ‘Karasuzansho’) (Rutaceae family, growing wild in the suburbs of Kyoto city, known dictaminine (IV) and skimmianine (V) were isolated as tertiary bases, magnoflorine (II) as the water-soluble quaternary base, and a minute amount of a base (flavianate, m. p. 189° (decomp.)), from the wood. The bark yielded the water-soluble quaternary base, laurifoline (I), but it contained almost no tertiary base.
Examination of alkaloids contained in Phellodendron amurense RUPR. var. sachalinense FR. SCHM. (Japanese name ‘Hiroha-kihada’), native to the Hokkaido, revealed the presence of berberine, palmatine (non-phenolic), and jatrorrhizine (phenolic) as the berberine-type quaternary bases, and magnoflorine as the aporphine-type quaternary base. It was found that the new quaternary base isolated from this plant, phellodendrine, is a benzylisoquinoline type represented by the composition C20H26O4-N+=C16H12(OCH3)2(OH)2N+(CH3)2. Since the methine base obtained on the primary Hofmann degradation of O, O-dimethylphellodendrine iodide is identical with laudanosine methyl-methine and from the various coloration reaction of phellodendrine, the structural formula (I) is assumed for phellodendrine. From the mother liquor of phellodendrine iodide, a small amount of crystalline iodide, m. p. 269.5-270.5° (decomp.), was isolated.
2-Chloro-5-nitropyridine reacts with thioacetamide in ethanol in the presence of an activated copper powder and potassium carbonate to form 5-nitro-2-pyridinethiol. This reaction mechanism seems to be similar to that of 2-chloro-5-nitropyridine and thiourea.