Condensation of methyl 4-acetylphenylcarbamate with isatin in the presence of diethylamine afforded methyl 4-[(3-hydroxy-2-oxo-2,3-dihydro-1H-indol-3-yl)acetyl]phenylcarbamate which was converted into the corresponding chalcone on heating in glacial acetic acid in the presence of hydrochloric acid.
By the reaction of methyl {4(3)-[2-(2-oxo-1,2-dihydro-3Н-indol-3-ylidene)acetyl]phenyl} carbamates with ethyl 3-aminocrotonate at boiling in the mixture toluene-anhydrous ethanol, 2 : 1, ethyl 5phenyl}carbamates with ethyl acetoacetate in the presence of ammonium acetate and 20 mol% of 1-methyl-3-butylimidazolium chloride or 1-methyl-3-octylimidazolium tetrafl uoroborate at boiling in anhydrous ethanol led to the formation of the corresponding 3-pyrrol-3'-yloxindoles with a carbamate function.
Acylation of 2-aminobenzenethiol with methyl chloroformate in pyridine gave dimethyl 2,2′-disulfanediylbis(2,1-phenylene)dicarbamate instead of expected methyl 2-suylfanylphenylcarbamate. Heating of the product with zinc dust in glacial acetic acid led to the formation of 1,3-benzothiazol-2(3H)-one. Alkylation of the latter with 1,2-dibromoethane and allyl bromide, as well as acylation with chloroacetyl chloride, afforded the corresponding 3-substituted derivatives. 3-[3-(Pyridin-2-yl)-4,5-dihydroisoxazol-5-ylmethyl]-1,3-benzothiazol-2(3H)-one was synthesized with high regioselectivity by 1,3-dipolar cycloaddition of 3-allyl-1,3-benzothiazol-2(3H)-one to pyridine-2-carbonitrile oxide generated from N-hydroxypyridine-2-carboximidoyl chloride hydrochloride by the action of triethylamine.Derivatives of 2-aminobenzenethiol are widely used in the synthesis of heterocyclic compounds [1, 2]. Acylation of 2-aminobenzenethiol is not selective, and the reaction direction depends on the conditions and the nature of acylating agent. It is known that acylation of 2-aminobenzenethiol with acid chlorides in the presence of bases yields 2-substituted 1,3-benzothiazoles [3] and that the reaction with chloroacetyl chloride in methylene chloride occurs exclusively at the nitrogen atom [4]. Acylation of 2-aminobenzenethiol with acetic and propionic anhydrides in aqueous medium in the presence of sodium hydrogen carbonate was accompanied by formation of 2-methyl-and 2-ethyl-1,3-benzothiazoles, respectively (in addition to the corresponding N-acyl derivatives) [5]. Ethyl 3-(4-oxo-2,3,4,5-tetrahydro-1,5-benzothiazepin-5-yl)propionate or N- [2-(carboxyethylsulfanyl)phenyl]-β-alanine were formed in the reaction of acrylic acid with 2-aminobenzenethiol, depending on the reactant ratio [6].We found that acylation of 2-aminobenzenethiol with methyl chloroformate in anhydrous pyridine gives dimethyl 2,2′-disulfanediylbis(2,1-phenylene)dicarbamate (I) instead of expected methyl 2-suylfanylphenylcarbamate (Scheme 1). Compound I was synthesized previously by acylation of 2,2′-disulfanediyldianiline with methyl chloroformate [7].The structure of disulfide I was confirmed by the IR, 1 H NMR, and mass spectra. The IR spectrum of I lacked absorption band at 2550 cm -1 , which is typical of stretching vibrations of SH group but contained absorption bands at 3380 and 1740 cm -1 due to stretching vibrations of NH and C=O groups in addition to absorption bands corresponding to vibrations of the benzene ring. No SH signal (δ 3.27 ppm [8]) was observed in the 1 H NMR spectrum of I. In the mass spectrum of compound I, ion peaks with m/z 364 [M] + and m/z 182 were present, which indicated the formation of disulfide structure.
via condensation of chalcone (I) with hydrazine hydrate or cycloaddition reactions of (I) with diazomethane and nitrile oxide generated from oxime (V)
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