An efficient synthesis of N3,4-diphenyl-5-(4-fluorophenyl)-2-isopropyl-1H-3-pyrrolecarboxamide, a key intermediate for atorvastatin synthesis

An efficient synthesis of N3,4-diphenyl-5-(4-fluorophenyl)-2-isopropyl-1H-3-pyrrolecarboxamide, a key intermediate for the synthesis of an effective HMG-CoA reductase inhibitor atorvastatin, is described. The synthesis is based on the 1,3-dipolar cycloaddition reaction of mesoionic munchnone (1,3-oxazolium-5-olate) with N1,3-diphenyl-2-propynamide leading to N-benzyl pyrrole, and N-debenzylation using sodium in liquid ammonia as key steps.