1-aza-1,3-enynes in synthesis of substituted 4H-[1,3]thiazino[3,2-a]benzimidazol-4-ols

Reactions of benzimidazole-2-thiol with N-alkyl-1-aza-1,3-enynes

“…According to [4,13], addition of azoles at multiple bond of 1-aza-1,3-enynes proceeded much less readily than in the cases of aromatic thiols [1]. Apparently, thiol group was the first to react with 1-aza-1,3-enynes, and then the pyrrole nitrogen atom of benzimidazole-2-thiol followed.…”

“…1-Aza-1,3-enynes are convenient and readily available synthons for synthesis of organic sulfur-containing polynuclear heterocyclic compounds [1][2][3][4][5][6]. Recently, considerable attention has been focused on the heterocyclization reactions of 1-aza-1,3-enynes resulting from addition of various nucleophilic reagents [3].…”

“…It was previously shown that interaction of N-tertbutyl-1-aza-1,3-enynes with benzimidazole-2-thiol led to formation of polynuclear heterocyclic sulfur compounds, benzo [4,5]imidazole [2,1-b] [1,3]thiazine-4-ols [11]. The reaction occurred in methanol and was accompanied by heterolytic cleavage of tert-butylamine; in the case of silicon-containing 1-aza-1,3-enine, desilylation was observed.…”

Reaction of tert-butylimine of phenylpropiolic aldehyde with substituted imidazole-2-thiones

“…It has been shown earlier that the interaction of Ntert-butyl-1-aza-1,3-enes with substituted benzimidazole-2-thiols leads to the formation of polynuclear sulfur-containing heterocyclic compounds, viz., benzo [4,5]imidazole [2,1-b] [1,3]thiazin-4-ols [1,2].…”

“…As in case of substituted benzimidazole-2-thiols[1,2] the initially formed imidazo[2,1-b][1,3]thiazine-5tert-butylamines (IIIa-IIIc) undergo hydrolysis with the formation of imidazo[2,1-b][1,3]thiazin-5-ols (IVa-IVc). The hydrolytic cleavage of tert-bytylamine from imidazo[2,1-b]-[1,3]thiazine-5-tert-bytylamines (IIIa-IIIc) is due to the presence of minor quantities of water in the solvent[3].As a result of the addition of 4-phenyl-2-imidazole-2-thione (IIc) to imine I, the formation of two DOI: 10.1134/S1070363215030391 R = R 1 = Me (а); R = R 1 = Ph (b); R = H, R 1 = Ph (c).…”