SYNTHESIS OF 1,2,6-TRISUBSTITUTED INDOLES FROM 6-PROPARGYLCYCLOHEX-2-ENONES AND PRIMARY AMINES

Abstract

The synthesis of 1,2,6-trisubstituted indoles from accessible 6-propargylcyclohex-2-enones and primary amines is reported. Simple acidcatalyzed amination–cyclization reaction followed by air oxidation of the corresponding intermediated 4,5-dihydroindoles was found to be suitable to obtain the desired indoles. The reaction tolerates a variety of functional groups on the starting cyclohex-2-enones and primary amines. A mechanistic pathway involving nucleophilic addition/cyclization/aromatization is proposed.