A. P. Demenev

Reaction of Pyrrole Anions with Carbon Disulfide. Synthesis of Pyrrole-3-carbodithioates

Abstract 2,5-Disubstituted pyrroles react with carbon disulfide in the system KOH–DMSO with selective formation of pyrrole-3-carbodithioate anions from which pyrrole-3-carbodithioates were prepared by ethylation in 36–61% yield. From 2-methyl-5-phenyl(2-furyl- or 2-thienyl)pyrroles only pyrrole-3-carbodithioates are formed, with no isomeric pyrrole-4-carbodithioates being present. The reaction direction depends on pyrrole ring substitution: unsubstituted pyrrole selectively forms pyrrole-1-carbodithioate, whereas 2-methyl-, 2,3- and 2,4-dimethylpyrroles give exclusively pyrrole-2-carbodithioates under the same conditions.

Synthesis of 2-benzoylethynylpyrroles by cross coupling of 2-arylpyrroles with 1-benzoyl-2-bromoacetylene over aluminum oxide

Cross coupling of 2-arylpyrrole with benzoylbromoacetylene over aluminum oxide at room temperature gave 45–94% of 2-(benzoylethynyl)-5-arylpyrroles. Intermediate 2-(2-benzoyl-1-bromoethenyl)-5-arylpyrroles were isolated in up to 19% yield. The reaction was accompanied by formation of less than 5% of adducts of the initial pyrroles with the cross-coupling products, 2-benzoyl-1,1-bis(5-arylpyrrol-2-yl)ethenes.

Functionally substituted 1,3-diethenyl [1,2- c ][1,3]pyrrolothiazoles from pyrrole-2-carbodithioates

The reaction of pyrrole-2-carbodithioates with methylenoactive nitriles and 2-benzoyl-1-bromoacetylene in the KOH-DMSO system leads to functionally substituted pyrrolothiazoles in 59-85% yield.

Synthesis of Functionalized 2-(2-Pyrrolyl)pyrazolo[1,5-a]pyrimidines

Reactions of 5-amino-3-(2-pyrrolyl)pyrazoles with β-dicarbonyl compounds (acetylacetone and ethyl acetoacetate) lead to formation of up to 90% of polysubstituted pyrazolo[1,5-a]pyrimidines.

Synthesis of functionally-substituted pyrrolothiazolidines from pyrrole-2-carbodithioates, CH-acids, and haloacetylenes

Functionally substituted pyrrolothiazolidines have been synthesized by the sequential treatment of pyrrole-2-carbodithioates with methylene-reactive nitriles and haloacetylenes in a KOH-DMSO system.

The first chemoselective synthesis of functionalized 3-vinylpyrroles

Abstract 3-(1-Alkylthio-2-cyano-2-X-ethenyl)pyrroles (X=CN, CONH 2 , CO 2 Et) have been synthesized in 28–58% yields by the reaction of pyrrole-3-carbodithioates with CH-acids (malononitrile, cyanoacetamide, cyanoacetate) in the KOH–DMSO system.

Reaction of pyrrole-2-carbodithioates with CH-acids: Stereospecific synthesis of new functional 2-vinylpyrroles

New 2-(1-alkylthio-2-dicyanoethenyl)pyrroles or 2-(1-alkylthio-2-cyano-2-carbamoylethenyl)pyrroles of Z-configuration have been synthesized in 58-69% yields by the reaction of pyrrole-2-carbodithioates with CH-acids (malononitrile, cyanoacetamide) in KOH-DMSO. Condensation of ethyl 4,5,6,7-tetrahydroindole-2-carbodithioate with ethyl benzyl malonate affords a mixture (1 : 2) of 1-ethylthio-2-benzyloxycarbonyl-4,5,6,7-tetrahydrocyclohexa[c]pyrrolizine-3-one and 1-ethylthio-2-ethoxycarbonyl-4,5,6,7-tetrahydrocyclohexa[c]pyrrolizine-3-one.

Reactions of Pyrrole-1- and Pyrrole-2-carbodithioates with Activated Acetylenes

Pyrrole-1- and pyrrole-2-carbodithioates react with activated alkenes (KOH-DMSO, room temperature) along the nucleophilic addition mechanism regio- and stereospecifically to afford pyrrole-1-and pyrrole-2-carbodithioethenes. The adducts of pyrrole-2-carbodithioates under the reaction conditions undergo intramolecular cyclization into pyrrolothiazoles derivatives.

4-Dimethylaminoacetophenone O -vinyloxime: Synthesis and steric structure

Abstract4-Dimethylaminoacetophenone oxime was synthesized from 4-dimethylaminoacetophenone and hydroxylamine hydrochloride. Its reaction with acetylene in the system KOH-DMSO gave previously unknown 4-dimethylaminoacetophenone O-vinyloxime as the major product. According to the experimental data and quantum-chemical calculations, 4-dimethylaminoacetophenone O-vinyloxime is formed as the only E isomer with preferential s-trans conformation of the vinyloxy group, which is characterized by essentially nonplanar structure.

Solvatochromism of Heteroaromatic Compounds: XVII. Effect of Aprotic Inert Solvents on the Structure of 2-(2,2-Dicyanovinyl-1-methylthio)-5-methylpyrrole

The effect of aprotic inert media on the conformational structure of 2-(2,2-dicyanovinyl-1-methylthio)-5-methylpyrrole was studied by UV, NMR, and IR spectroscopy. Chloroform and less polar solvents stabilize only one of the four conformers. In more polar media, there is a dynamic equilibrium between all the possible conformers of the title compound. The state of the equilibrium depends both on the solvent and on the temperature.