Cobalt-Porphyrin-Catalyzed Intramolecular Buchner Reaction and Arene Cyclopropanation of In Situ Generated Alkyl Diazomethanes

Cobalt(II)-porphyrin catalyzed intramolecular Buchner reaction and arene cyclopropanation of alkyl diazomethanes in situ generated from N-tosylhydrazones to give a range of bicyclic cycloheptatriene fused pyrrolidines and tetracyclic cyclopropane fused pyrrolidines in good to high yields and with high chemo- and regio-selectivity. The obtained cyclopropane fused pyrrolidines can be readily converted to other N-heterocycles with potential synthetic and biological interests.