Synthesis of 3,3-dimethyl-2-phenyl-3H-pyrrole from Isopropyl Phenyl Ketoxime and Acetylene: A Side Formation of 4,4-dimethyl-5-phenyl-1-vinyl-2-pyrrolidinone as Clue to the Reaction Mechanism

Abstract

Isopropyl phenyl ketoxime reacts with acetylene in the KOH/DMSO suspension (atmospheric pressure, 90 °C, 4 h) to afford 3,3-dimethyl-2-phenyl-3H-pyrrole (30%) and 4,4-dimethyl-5-phenyl-1-vinyl-2-pyrrolidinone (5%) that is likely originated from 4,4-dimethyl-5-phenyl-3,4-dihydro-2H-pyrrol-2-ol as the key reaction intermediate.