CYCLOCONDENSATION OF <i>N</i>-(PROP-2-YN-1-YL)- AND <i>N</i>-(PENTA-2,4-DIYN-1-YL)- <i>o</i>-PHENYLENEDIAMINES WITH PHENYL ISOTHIOCYANATE AND CARBON DISULFIDE

Abstract

The cyclocondensation of N-(prop-2-yn-1-yl)-o-phenylenediamines with phenyl isothiocyanate leads to the formation of 1-(prop-2-yn-1-yl)-1,3-dihydro-2H-benzimidazole-2-thiones irrespective of the substituent nature at the triple bond. Reactions of both mono- and diacetylenic derivatives of o-phenylenediamine with carbon disulfide in the presence of KOH proceed with the formation of two heterocyclic nuclei simultaneously. From N-(prop-2-yn-1-yl)-o-phenylenediamines containing an aryl substituent at the triple bond, and N-(penta-2,4-diyn-1-yl)-o-phenylenediamines 2-methylidene-2,3-dihydro[1,3]thiazolo[3,2-a]benzimidazoles are formed. The latter are readily isomerized under the action of base giving thiazolo[3,2-a]benzimidazoles. The cyclocondensation of N-(alk-2-yn-1-yl)-o-phenylenediamines with CS₂ leads to [1,3]thiazino[3,2-a]benzimidazoles.

Authors: R. V. Novikov, N. A. Danilkina, and I. A. Balova

English translation in Chemistry of Heterocyclic Compounds, 2011, 47 (6), pp 758-766

http://link.springer.com/article/10.1007/s10593-011-0831-z