Open AccessStudies on Heteropentalenes. IV. Heteroannelations to Pyrrolo-[2,1-b]benzothiazole and Pyrrolo[2,1-b]thiazoles
Author(s) -
Noritaka Abe,
Tarozaemon Nishiwaki,
Toshimasa Omori,
Emiko Harada
Publication year - 1982
Publication title -
bulletin of the chemical society of japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.145
H-Index - 99
eISSN - 1348-0634
pISSN - 0009-2673
DOI - 10.1246/bcsj.55.200
Subject(s) - benzothiazole , chemistry , reagent , hydrazine (antidepressant) , cycloaddition , medicinal chemistry , nitrile , organic chemistry , stereochemistry , catalysis , chromatography
2,3-Dibenzoylpyrrolo[2,1-b]benzothiazole (2) and 6,7-dibenzoylpyrrolo[2,1-b]thiazoles (5a-b) have been synthesized by utilizing the cycloaddition reactions of imidazo[2,1-b]benzothiazole and imidazo[2,1-b]thiazoles, respectively, with dibenzoylacetylene followed by the elimination of a nitrile from each of the cycloadducts. Heteroannelations to 2 and 5 have been achieved by their reactions with hydrazine, aminoacetonitrile, ethyl glycinate, and phosphorus pentasulfide. The annelations by the second and third reagents proceed fairly regioselectively. Facile dimerizations of thieno[3',4':3,4]pyrrolo[2,1-b]benzothiazole and thieno[3',4':3,4]pyrrolo[2,1-b]thiazoles to be produced by the reactions with the last reagent are also described