Electrophilic ipso -Iodocyclization of N -(4-Methylphenyl)propiolamides: Selective Synthesis of 8-Methyleneazaspiro[4,5]trienes

A novel and selective method for the synthesis of 8-methylenespiro[4,5]trienes via intramolecular electrophilic ipso-iodocyclization of N-(4-methylphenyl)propiolamides has been developed. In the presence of ICl or I 2, 8-methylene-1-azaspiro[4,5]trienes were selectively prepared from the electrophilic ipso-iodocyclization of N-(4-methylphenyl)propiolamides in moderate to good yields.