Chitosan as heterogeneous catalyst in Michael additions: the reaction of cinnamonitriles with active methylene moieties and phenols

The reaction of active methylene moieties, pyrazolones, thiazolylacetonitriles, phenols and alkyl pyridazinones with benzylidene-malononitrile in ethanol in presence of chitosan afforded aminopyrancarbonitriles, pyranopyrazole, thiazolopyridines, chromenes, and pthalazines in yields comparable to those obtained in ethanolic piperidine. Much lower yields were obtained in aqueous solutions.