Direct Synthesis of 2-(Cycloalkylamino)-3,4-Substituted Thiophenes via Selective Deprotonation-Cyclization of Aroyl Ketene N,S-Acetals

Abstract

Acyclic and cyclic aroyl ketene N,S-acetals undergo regioselective deprotonation-cyclization via dipole stabilized carbanion in the presence of LDA/THF to afford the corresponding 2-(cycloalkylamino)-4-aryl or 3,4-annelated thiophenes in moderate to good yields.