On the Regioselectivity of Boron Trifluoride Catalyzed Ring Expansion of Cycloalkanones with Ethyl Diazoacetate

Abstract

Abstract From a synthetic point of view, the Lewis acid1 catalyzed homologation of cyclic ketones with diazo-acetic ester (1·2) is very useful. It provides a direct method for constructing less accessible ring systems from readily available ones.2-8 Moreover, the simultaneously formed β-keto ester functionality is highly suitable for further manipulation.9 Although the reaction has been established for more than a decade, little has been documented concerning the migratory apptitudes of unsymmetrical ketones except for the case of cyclobutanones.6 Such information is