Synthesis of furans and pyrroles via migratory and double migratory cycloisomerization reactions of homopropargylic aldehydes and imines

A novel gold-catalyzed divergent synthesis of furans and pyrroles employing readily available homopropargylic aldehydes and imines has been developed. The regiochemical outcome of this reaction is dependent on the substituent on the terminal alkyne of substrate. Thus, substrates possessing alkyl and aryl substituent at the alkyne moiety produce 2,3,5-substituted furans and pyrroles via a migratory cycloisomerization reaction. Whereas, their silicon analogues are capable of undergoing a double migratory process leading to 2,3,4-substituted heterocycles.