The Intramolecular Allenolate Rauhut-Currier Reaction

An intramolecular Rauhut-Currier reaction utilizing alkynoates as the initial conjugate acceptor affords densely functionalized 5- and 6-membered rings from ynoate-enoate, ynoate-enenitrile, and alkynyl sulfone-enenitrile substrates. Trialkylphosphines catalyze the reaction, and TMSCN serves as a pronucelophile to effect turnover of the catalyst and the formation of a second C-C bond. Because of the highly electrophilic alkyne acceptor, this reaction yields products that cannot be easily accessed from the traditional Rauhut Currier reaction.