Selenium‐Containing Heterocycles from Isoselenocyanates: Synthesis of 2‐Methylidene‐1,3‐selenazolidine Derivatives.

Abstract

A convenient and unequivocal synthesis of the title compounds from isoselenocyanates, malononitrile or 2-cyanoacetate, and 1,2-dibromoethane or a-halogenated carboxylic acid derivatives is reported. The proposed reaction mechanism involves in situ cyclization of different halogenated compounds with an intermediate keten-N,Se-acetal, generated by the base promoted nucleophilic addition of the acidic cyanomethylenes to aliphatic and aromatic isoselenocyanates. Chemical and spectroscopic evidence for the structures of the new compounds is presented.