Metal Template for the Symmetrical [2 + 2]‐Dimerization of Ketenimines

Abstract

Reaction control by complexation with Cr(CO)4 was observed in the adduct 1 of R′NC and (CO)5CrC(R)OMe. Whereas free ketenimines dimerize to azetidines, diazetidines, or open-chain products, 1 affords the cyclobutane derivative 2 upon heating. The adduct can function as depository compound for 1,2-bis(imino)cyclobutanes.