Intramolecular N-H Insertion of α-Diazocarbonyls Catalyzed by Cu(acac)2: An Efficient Route to Derivatives of 3-Oxoazetidines, 3-Oxopyrrolidines and 3-Oxopiperidines.

Cu(acac)2 was found to be an efficient catalyst for the intramolecular N–H insertion by carbenoids. The competitive intramolecular C–H insertion by carbenoids is not a problem in the diazo decomposition reaction with Cu(acac)2 as catalyst. The reaction provided derivatives of 3-oxoazetidine, 3-oxopyrrolidine and 3-oxopiperidine in moderate to good yields.