A. V. Popov

Reactions of N-(2,2,2-trichloroethylidene)- and N-(2,2-dichloro-2-phenylethylidene)arenesulfonamides with biuret

N-(2,2,2-Trichloroethylidene)- and N-(2,2-dichloro-2-phenylethylidene)arenesulfonamides react with an equimolar amount of biuret to give 1-(1-arylsulfonylamino-2,2,2-trichloroethyl)- or 1-(1-arylsulfonylamino-2,2-dichloro-2-phenylethyl)biurets. The reactions with 2 equiv of N-(polychloroethylidene)arenesulfonamides involve both amino groups in the biuret molecule, yielding the corresponding 1,5-bis(1-arylsulfonylamino-2,2,2-trichloroethyl)- and 1,5-bis(1-arylsulfonylamino-2,2-dichloro-2-phenylethyl)biurets.

Synthesis and structure of 1-tert-butyl-substituted 3(5)-alkylpyrazoles from 2-chlorovinyl ketones

Reactions of alkyl, halomethyl 2-chlorovinyl ketones with tert-butylhydrazine in the presence of triethylamine afford unsymmetrical 1-(tert-butyl)-3- and -5-disubstituted pyrazoles. The reaction direction is governed by the ketone ability of the nucleophilic substitution of chlorine and of the dehydrochlorination leading to acetylene ketones. 2-Chlorovinyl ketones react with tert-butylhydrazine along two routes giving mixtures of 1-(tert-butyl)-3- and -5-alkylpyrazoles. The content of 3-alkyl-1-(tert-butyl)pyrazole in the formed isomers mixture grows up to 73% with growing length of the alkyl chain of the ketone and up to 87 and 94% at introducing halogen atom in the alkyl fragment of the chloroenone.

Reduction of N-(polychloroethylidene)- and N-(1-hydroxypolychloroethyl) arenesulfonamides with adamantane in the presence of superacids

N-(2,2,2-Trichloroethylidene)-, N-(2,2-dichloro-2-phenylethylidene)-, and N-(1-hydroxy-2-polychloroethyl) arenesulfonamides reacted with adamantane in carbon tetrachloride in the presence of oleum or concd. H2SO4-P4O10 mixture to give the corresponding N-(2-polychloroethyl)arenesulfonamides as a result of reduc-tion of the azomethine and OH group, respectively.

Unexpected reaction of dibenzyl disulfide with hydrazine

The reaction of hydrazine with dichalcogenides in aqueous alkaline medium is known to result in reductive cleavage of dichalcogenides giving thiols [1] and other chalcogenols [2], and hydrazine therewith is oxidized into nitrogen. We found that the reaction of dibenzyl disulfide with excess hydrazine hydrochloride in DMF in the presence of sodium or potassium carbonates at heating to 100°C unexpectedly afforded benzalazine. The process was accompanied by hydrogen sulfide evolution. It is presumable that under the conditions of the reaction the dibenzyl disulfide suffered 1,2-elimination with the formation of benzylthiol and thiobenzaldehyde. The latter underwent condensation with hydrazine to give the final benzalazine that apparently existed in the reaction mixture as thioaminal or hemiaminal, but was isolated at acidifying the reaction mixture in the individual state in 38% indicating a good yield of the intermediate thioaldehyde.

Ratio of 1,3- and 1,5-dialkyl-substituted pyrazoles obtained from chlorovinyl alkyl ketones and alkylhydrazines, 3(5)-pyrazoles and alkyl bromides

Unsymmetrically substituted 1,3- and 1,5-dialkylpyrazoles and 1,3-dialkyl-5-chloropyrazoles were prepared. 2-Chlorovinyl ketones react with C1-C8-alkylhydrazines along two routes giving mixtures of 1-R′-3-R- and 1-R′-5-R-pyrazoles with the prevalence of 1,3-isomer. The proportion of 3-substituted 1-alkylpyrazole in the isomers mixture grows from 60 to 94–97% with growing length of the alkyl chain in the hydrazine. The alkylation of 1-unsubstituted 3(5)-alkylpyrazoles with alkyl bromides afforded predominantly (by 16–50%) 1,3-disubstituted pyrazoles. 1,3-Dialkyl-5-chloropyrazoles form from 2,2-dichlorovinyl alkyl ketones and functionalized alkylhydrazines. It was suggested to synthesize 1,3-dialkyl-substituted pyrazoles by dechlorination of unsymmetrically substituted 1,3-dialkyl-5-chloropyrazoles in the presence of complex nickel catalyst and water as the proton source.

Sulfonation of unsymmetrically substituted 5-chloropyrazoles

In recent time, much attention has been given to halopyrazoles that are base compounds for the synthesis of linear, polycyclic, and other pyrazole derivatives [1, 2]. Reactions of various alkyl(aryl)hydrazines and unsymmetrical dialkylhydrazines with 2,2-dihalovinyl ketones gave unsymmetrical 1,3-disubstituted 5-halopyrazoles which showed a low reactivity of the halogen atom toward nucleophilic substitution [1–10]. Introduction of an electron-withdrawing group (e.g., formyl, acyl, nitro, etc.) into the 4-position of 5-halopyrazoles made it possible to accomplish reactions with participation of the 5-halogen atom [1, 2, 11, 12]. Reactions of 5-chloro-4-nitropyrazoles with carboncentered nucleophiles, in particular acetoacetic, arenesulfonylacetic, and cyanoacetic acid esters, afforded the corresponding C-alkylation products containing a number of pharmacophoric groups [11, 12].

N-alkylation of N-(2,2,2-trichloroethyl)arenesulfonamides

Intramolecular cyclization and intermolecular addition reactions with sulfonamide derivatives underlie widely used syntheses of sulfonamide drugs [1, 2]. N-(Polyhaloalkyl)sulfonamides are convenient reagents for the preparation of various sulfonamide derivatives such as biologically active N-sulfonyl-substituted amino acids [3, 4], amidines [5], and aminocarbonyl [6] and heterocyclic compounds [6–12]. On the other hand, reactions involving the NH group of N-(polychloroethyl)sulfonamides have been poorly studied; only their intramolecular heterocyclizations [5, 6] and reactions with methyl vinyl ketone [13] have been reported. In continuation of our systematic studies on the reactivity of N-(polychloroethyl)sulfonamides the present communication reports on reactions of N-(2,2,2-trichloroethyl)arenesulfonamides with propyl, allyl, and propargyl bromides, which were carried out with a view to develop synthetic approaches to new haloalkylsulfonamide derivatives containing an alkyl, allyl, or propargyl group on the nitrogen atom. Such derivatives attract interest from the viewpoints of their subsequent trans-formations and biological activity. N-(2,2,2-Trichloroethyl)arenesulfonamides Ia and Ib were found to react with propyl, allyl, and propargyl bromides in the presence of inorganic base to give the corresponding N-substituted derivatives II–IV. These reactions required fairly severe conditions (heating to 100°C), which may be due to low nucleophilicity of the sulfonamide nitrogen atom. The best yields of compounds II–IV were obtained using dimethylformamide as solvent and sodium carbonate as base. When sodium hydroxide was used instead of Na2CO3, the yields were considerably lower because of side processes.

N -(2,2,2-trichloroethylidene)- and N -(2,2-dichloro-2-phenylethylidene)-4-methoxybenzenesulfonamides from 4-methoxy- N , N -dichlorobenzenesulfonamide, trichloroethylene, and phenylacethylene

Reaction of 4-methoxy-N,N-dichlorobenzenesulfonamide with trichloroethylene and phenylacetylene underlies an effective method developed for the synthesis of highly reactive 4-methoxy-N-(2,2,2-trichloroethylidene)- and 4-methoxy-N-(2,2-dichloro)-2-phenylethylidene)benzenesulfonamides, valuable reagents for the preparation of new difficultly accessible derivatives of the sulfonamide series.

Directed synthesis of 3-(2,2-dichlorocyclopropyl)pyrazoles

Abstract1-Alkyl-3-(2,2-dichlorocyclopropyl)-1H-pyrazoles have been synthesized by cyclopropanation of the corresponding 3-vinylpyrazoles with dichlorocarbene generated from chloroform or sodium trichloroacetate and tested for insecticidal activity.

Synthesis of new imidazo[2,1-b][1,3]thiazole derivatives from 2-amino-4-(2,2-dichlorovinyl)-1,3-thiazole and N-(2,2-dichloro-2-phenylethylidene)arenesulfonamides

Abstract2-Amino-4-(2,2-dichlorovinyl)-1,3-thiazole reacted with highly electrophilic N-(2,2-dichloro-2-phenylethylidene)- and N-(2,2,2-trichloroethylidene)arenesulfonamides through the exocyclic amino group to give products of nucleophilic addition to the azomethine bond, N-[2,2-di(or 2,2,2-tri)chloro-1-(1,3-thiazol-2-ylamino)ethyl]arenesulfonamides in good yields. Intramolecular heterocyclization of the latter afforded N-[3-(2,2-dichloroethyl)-6-phenylimidazo[2,1-b][1,3]thiazol-5-yl]arenesulfonamides.