Synthesis of new biologically active isothiazolo[4,5-b]carbazole-type tetracyclic derivatives via an indole-2,3-quinodimethane approach

A number of isothiazolo[4,5-b]carbazole derivatives were prepared via a Diels Alder approach involving thermally induced indole-2,3-quinodimethane intermediates. Preliminary biological tests revealed a CSK-3 beta kinase inhibitor (29) and some free NH group containing compounds (17d, 19c, 29) displayed selective human carbonic anhydrase I inhibitory activities. (C) 2014 Elsevier Ltd. All rights reserved.