坂本 昌巳

The photochemistry of O-allyl and O-but-3-enyl thiocarbamates has been studied. Photolysis of benzene solutions of O-allyl N-phenylthiocarbamates gave S-allyl N-phenylthiocarbamates. The 1,3-allyl migration from the oxygen to the sulfur involves a concerted process. The same type of 1,3-migration took place in the conversion of O-benzyl N-phenylthiocarbamate into 5-benzyl N-phenylthiocarbamate. Irradiation of O-but-3-enylthiocarbamates produced iminooxolanes via aminothietane intermediates. In the case of O-but-3-enyl N-benzoyl-N-phenylthiocarbamates, 3-(benzoylsulfanylmethyl)-2- phenyliminooxolanes were obtained via a ring opening of the aminothietanes involving a 1,5-benzoyl shift.

The reaction of trifluoromethyltrimethylsilane with a variety of terpenoid carbonyl compounds and other carbonyl compounds used in perfumery gave the corresponding trifluoromethylated derivatives. Pentafluoroethylated compounds were similarly obtained from the reaction of pentafluoroethyltrimethylsilane with various substrates. (-)-2-Trifluoro-1-furyl ethanol has been obtained with high optical purity by enzymatic hydrolysis of 2-trifluoro-1-furyl ethyl acetate. © 1995.

A number of esters were prepared from the reaction of acid chlorides with ricinoleic acid polymers and screened for anti-rust properties and antimicrobial activity in spent coolants of water-based cutting fluids. Aqueous solutions of triethanolamine salts with decanoic acid, undecanoic acid and oleic acid esters of ricinoleic acid dimer, trimer, tetramer and hexamer showed good anti-rust properties for water-based cutting fluids. Dehydrates of ricinoleic acid polymers also showed good anti-rust properties for water-based cutting fluids. © 1994 AOCS Press.

Photochemical reactions of thioamides and thioimides are reviewed. Topics included are (1) photochemical [2 +2] cycloaddition reactions of thioamides and thioimides with alkenes, (2) photochemical hydrogen abstraction of thioamides and thioimides by the thiocarbonyl sulfur atom.

Irradiation of 3-cyano-2-alkoxypyridines gave dehydrogenated dimers, 1,8-dialkoxy-6,9-dicyanopyrido-[3,2-c]azocines, and heterophotodimers, 3,12-dicyano-4,8-dialkoxy-5,9-diazatetracyclo[4.3.3.0(2,7).0(3,10)]dodeca-4,8,11-trienes, in the presence of different pyridines.

The photochemistry of cyclic N-(α,β-unsaturated carbonyl)-thionocarbamates and -dithiocarbamates has been studied. Photolysis of a benzene solution of 3-(methacryloyl)thiazolidine-2-thione gave 4-methyl-2.9-dithia-6-azatricyclo[4.3.0.01.4]nonan-5-one (a tricyclic-β-lactam) (30%) and 2-(3′-methyl-2′-oxothietan- 3′-yl)-2-thiazoline (a β-thiolactone) (30%). Irradiation of 3-(2′-methylbut-2-enoyl)thiazolidine-2-thione. 3-(methacryloyl) oxazolidine-2-thione, and 3-(2′-methylbut-2-enoyl)oxazolidine-2-thione gave the corresponding β-lactams (33-67%), whereas that of the six-membered compounds, 3-(methacryloyl)- and 3-(2′-methylbut-2-enoyl)tetrahydro-1,3- oxazine-2-thione, led to β-thiolactones (33-66%). The ring transformation of this new ring system (thietane-fused penams and oxapenams) to β-thiolactones was confirmed by the fact that, on pyrolysis, the β-lactams gave the corresponding β-thiolactones in quantitative yield.

The results of molecular orbital calculation suggested that 5-thioxo-1, 5-dihydro-2 H-pyrrol-2-ones (monothiomaleimides) would have higher reactivity to thiols than corresponding maleimides. N-phenyl- and N-alkyl-substituted monothiomaleimides were prepared, and their anti-microbial activity were examined. These compounds showed good bacteriostatic activity against Gram positive bacteria such as B. subtilis and good growth inhibitory activity against yeast similar to maleimides. However they did not show bacteriostatic activity against Gram negative bacteria. Antifungal activity of N-alkyl-substituted monothiomaleimides against filamentous fungi was decreased in proportion to the increase of alkyl chain length. QSAR study of N-alkyl-substituted monothiomaleimides showed good correlarion between bacteriostatic activity against B. subtilis and hydrophobic substitution coefficient (pi). Partition coefficients (log P) of N-ethylmaleimide and its monothio analog were 0.325 and 1.909, respectively. These results suggested that conversion of carbonyl moiety to thiocarbonyl moiety increased the hydrophobicity of those compounds. For the reason that increasing of hydrophobicity is more remarkable than increasing of the reactivity to SH group, it is considered that these compounds did not show better antimicrobial activity than maleimides which are lead compounds.

Quantitative structure activity relationship of 2-arylthio-N-methylmaleimides against B. subtilis was examined, and the effects of substituents on benzene ring of those compounds were correlated with bacteriostatic activity. For p-substituted compounds, following correlative equation was introduced ; log(1/MIC)=-0.302 I+0.096 sigma+4.597 n=11, s=0.032, r=0.989, F=87.54 Also for o-subsituted compounds, following correlative equation was introduced log(1/MIC)=3.221 I+1.519 pi+2.626 R-0.643 B4+5.202 n=9, s=0.120, r=0.961, F=23.12

A number of N,N′-diacylalkyldiamines were prepared from the reaction of acid chlorides with 1,8-diaminooctane and 1,12-diaminododecane and screened for anti-rust properties and antimicrobial activity in spent coolants of water-based cutting fluids. Aqueous solutions of N,N′-dihexanoyl-1,8-diaminooctane and N,N′-isobutyroyl-1,12-diaminododecane showed good anti-rust properties for water-based cutting fluids. Aqueous emulsions of N,N′-dibutyroyl-, dipentanoyl-, dihexanoyl- and dioctanoyl-1,12-diaminododecane showed good lubricities and antimicrobial activity for water-based cutting fluids. © 1993 the American Oil Chemists' Society.

Photolysis of chiral crystals of an achiral N-isopropyl-N-tiglylbenzoylformamide in the solid state proceeded [2 + 2] cycloaddition to give a chiral oxetane, 5,7-dimethyl-3-isopropyl-1-phenyl-6-oxa-3-azabicyclo[3.1.1]-heptane-2,4-dione, in high chemical and optical yields.

Photolysis of 3-acetyl-2-alkoxy-4,6-dimethylpyridines gives cyclobutenols, 2-alkoxy-3,6-dimethyl-3-hydroxy-cyclobuta[c]pyridines, in good yields via Norrish Type II cyclizations whereas 3-acetyl-2-methylpyridine does not cyclize to cyclobutenol.

The reactions of 2-(trifluoromethyl)propenoic acid (I) with unsaturated Grignard reagents have been examined. Vinylmagnesium bromide with I gave 2-difluoromethylene-4-pentenoic acid (II) and analogous acids were obtained from propenyl and butenyl magnesium halides. The iodolactonization of II gave 2-difluoromethylene-4-iodomethyl-gamma-lactone (III). 2-Monofluoromethylene-4-penten-1-ol (IV) was obtained by the reduction of II with lithium aluminium hydride.

This paper concerns a preparative method of β-lactam formation using N-[(3R)-3, 7-dimethyl-6-octen-1-ylidene]-N-cyclohexylamine [I] derived from 1-citronellal. The reaction of [I] with ethyl bromoacetate in the presence of zinc gave a β-lactam 4-[(2R)-2, 6-dimethyl-5-hepten-1-yl]-(1-cyclohexyl)azetidin-2-one [II]. Instead of β-lactam for-mation, N-[(3R)-3, 7-dimethyl-1, 6-octadien-1-yl]-N-cyclohexyl-2-methylpropionamide[III] was obtained from the reaction of [I] with isobutyryl chloride and triethylamine. © 1992 Allured Publishing Corp.

A convenient method for the lactonization of 3-(2,2-dichlorocyclopropyl) alkanoic acids 1 a-k), 3-cyclopropylalkanoic acids (3 a-d, 5 a-e), and bicyclic 2-cyclopropylalkanoic acids (7 a-d) using acidic materials is presented. When a mixture of 3-(dichlorocyclopropyl)alkanoic acids (1 a-k) and 1% aqueous sulfuric acid solution was stirred at 85-degrees-C for 16 h, gamma-lactones (2 a-k) were obtained in good yield (Table 1). Similarly in the case of 3-cyclopropylalkanoic acids (3 a-d, 5 a-e), either delta- or gamma-lactones (4 a-d, 6 a-e) were obtained selectively depending on the substitution pattern of the cyclopropane ring (Tables 2, 4, and 5). But in the case of bicyclic 2-cyclopropylalkanoic acids (7 a-d), phosphoric acid in benzene turned out to be the best choice to give gamma-lactones (8 a-d) in good yield (Table 3). The mechanism of this lactonization have been discussed on the basis of the well-known concept of acid-catalyzed cyclopropane cleavage. An allylic cation intermediate is suggested for the cleavage of 3-(dichlorocyclopropyl)alkanoic acids (1 a-k) by acids to produce vinyl-gamma-lactones (2 a-k) is illustrated in Scheme 6. On the other hand 3-cyclopropylalkanoic acids (3 a-d, 5 a-e) and bicyclic 2-cyclopropylalkanoic acids (7 a-d) were cleaved by acids to lead to stable tertially carbocation intermediates which gave lactones (4 a-d, 6 a-e, 8 a-d) as shown in Schemes 7, 8 and 9. These reactions are particularly useful because dichloro- and cyclopropylalkanoic acids are readily available and delta- or gamma-lactone is one of the important structural units of natural products.

Photochemical hydrogen abstraction from N-acyltetrahydro-1,3-thiazine-2-thiones, N-acyloxazolidine-2-thiones and N-acyltetrahydro-1,3-oxazine-2-thiones have been studied. Irradiation of N-(diphenyl-acetyl)-and N-(alkoxyacetyl)tetrahydro-1,3-thiazine-2-thiones in benzene at 40-degrees-C gave bicyclic lactams, 5,7-dithia-1-azabicyclo[4.3.0]nonan-9-ones, accompanied by Norrish Type-II cleavage products, whereas N-acetyl and N-isobutyryl derivatives gave only cleavage products. Photolysis of N-(diphenylacetyl)-, N-(methoxyacetyl)-and N-(ethoxyacetyl)-tetrahydro-1,3-thiazine-2-thiones at 0-degrees-C followed by acetylation afforded cepham analogues, 6-acetylthio-5-thia-1-azabicyclo[4.2.0]octan-8-ones. N-Acyloxazolidine-2-thiones underwent Norrish Type-II cleavage to give oxazolidine-2-thione and the corresponding esters (O-acylmethanols) as the sole products on irradiation in methanol. N-Acetyl- or N-isobutyryltetrahydro-1,3-oxazine-2-thiones underwent only Norrish Type-II cleavage whereas N-(alkoxyacetyl)tetrahydro-1,3-thiazine-2-thiones underwent cleavage and also gave 5-oxa-7-thia-1-azabicyclo[4.3.0]nonan-9-ones.

Photochemical δ-hydrogen abstraction from acyclic and semicyclic monothioimides have been studied. Photolysis of acyclic monothioimides possessing a benzylic hydrogen atom at the δ-position gave γ-lactams, via a 1,5-diradical intermediate, accompanied by thioamides were generated by γ-hydrogen abstraction. Irradiation of the five-membered semicyclic monothioimide, N- (3-phenylpropionyl)pyrrolidine-2-thione, yielded 5-mercapto-4-phenyl-1-azabicyclo[3.3.0]octan-2-one. For N-(3-phenylbutyryl) pyrrolidine-2-thione, disproportionation, involving 1,6-hydrogen migration, was the main path. Photolysis of the six-membered semicyclic monothioimide, N-(3-phenylbutyryl)piperidine-2-thione, gave an unsaturated thiol, via a 1,4-hydrogen shift of a 1,5-diradical intermediate, accompanied by cyclisation product and piperidine-2-thione.

Photolysis of N- (α, β-unsaturated carbonyl)thioamides gave thietane-fused β-lactams in good yields, whereas some of the thioimides formed thiones via β-hydrogen abstraction of the thiocarbonyl group. Substituents at the α-position to the carbonyl carbon lead to a preference for [2 + 2]-cyclisation over β-hydrogen abstraction. From a sensitisation experiment this reaction was shown to proceed via an nπ* triplet excited state.

Photochemical hydrogen abstraction from N-acyltetrahydro-1,3-thiazine-2- thiones, N-acyloxazolidine-2-thiones and N-acyltetrahydro-1,3-oxazine-2-thiones have been studied. Irradiation of N-(diphenyl-acetyl)-and N-(alkoxyacetyl) tetrahydro-1,3-thiazine-2-thiones in benzene at 40°C gave bicyclic lactams, 5,7-dithia-1-azabicyclo[4.3.0]nonan-9-ones, accompanied by Norrish Type-II cleavage products, whereas N-acetyl and N-isobutyryl derivatives gave only cleavage products. Photolysis of N- (diphenylacetyl) -, N- (methoxyacetyl) -and N- (ethoxyacetyl) -tetrahydro-1,3-thiazine-2-thiones at 0°C followed by acetylation afforded cepham analogues, 6-acetylthio-5-thia-1-azabicyclo[4.2.0] octan-8-ones. N-Acyloxazolidine-2-thiones underwent Norrish Type-II cleavage to give oxazolidine-2-thione and the corresponding esters (O-acylmethanols) as the sole products on irradiation in methanol. N-Acetyl- or N-isobutyryltetrahydro-1, 3-oxazine-2-thiones underwent only Norrish Type-II cleavage whereas N-(alkoxyacetyl)tetrahydro-1,3-thiazine-2-thiones underwent cleavage and also gave 5-oxa-7-thia-1 -azabicyclo[4.3.0]nonan-9-ones.

Many 3-aminopropyl alkyl ethers were prepared and their characteristics as water-based cutting fluids were examined. 3-Aminopropyl octyl-, decyl- and dodecyl ethers showed good lubricities and antimicrobial properties for a water-based cutting fluid.

Various oxo-dimethylallyl compounds were prepared from intermediates which are obtained by the reaction of allylic Grignard reagents with carboxylic acid derivatives. For example, the reaction of prenylmagnesium chloride with ethyl hexanoate gave 3,3-dimethyl-4-prenyl-1-nonen-4-ol (1) in 92% yield. The thermolysis of 1 at the temperature of 693 K gave 2-methyl-2-decen-5-one (2) in 81% yield. Furthermore, 3,3-dimethyl-1-alken-4-ones (E) were prepared by the methylation of 1-alken-4-ones (C), which are obtained by the reaction of allylmagnesium chloride with carboxylic acids (A).

This paper concerns the reactions of menthone (I) with alkyl-amines and amino acids in the presence of sodium cyanoborohydride. The reaction of (I) with propylamine gave 3-propylamino-p-menthane (65% yield, cis/trans = 57:43). N-(2-Isopropyl-5-methylcylohexan-l-yl) glycine methyl-ester was obtained from (I) and glycine methylester. © 1990 Taylor &amp Francis Group, LLC.

Various 2-alkyl-γ-butyrolactones were prepared from 2-acetyl-γ-butyrolactone· via two steps: Alkylation of 2-acetyl-γ-butyrolactone followed by deacetylation. For example, 2-hexyl-γ-butyrolactone was prepared as follows: Reaction of 2-acetyl-γ-butyrolactone with n-hexyl bromide using sodium hydride as a base in dimethylformamide gave 2-acetyl-2-hexyl-γ-butyrolactone with 83% yield. Deacetylation with sodium methoxide gave 2-hexyl-γ-butyrolactone with 85% yield.