Novel addition reactions of new cyclic sulphur ylides, 9-alkyl-10-cyano-9-thiaphenanthrenes with acetylenic electrophiles

Abstract

The addition reactions of 10-cyano-9-methyl-9-thiaphenanthrene(1a) with dimethyl or diethyl acetylenedicarboxylate afforded the novel spiro products (2a) and (2b), respectively; these underwent a thermal 1,5-rearrangement to give the corresponding nine-membered sulphur-containing heterocyclic compounds (4a) and (4a), respectively, while the 9-ethyl derivative (1b) gave a seven-membered 1:1-adduct (3)from the reaction with dimethyl acetylenedicarboxylate.