A one-pot three carbon decarboxylative ring expansion of cyclic secondary amino acids. X-Ray crystal structure of a substituted 1-azacyclo-octa-2,4-diene

Abstract

Heating cyclic secondary α-amino acids with an excess of paraformaldehyde or formalin and methyl propiolate or dimethyl acetylenedicarboxylate leads to a decarboxylative ring expansion giving 8- and 9-membered cyclic aza-dienes via an azomethine ylide; the X-ray crystal structure of a substituted 1-azacyclo-octa-2,4-diene shows it to have an irregular tub conformation.