On the alkylation of α-bromo ketones by trialkylboranes

Abstract

The reaction of 2-halocycloalkanones with organoboranes in the presence of base has been studied. The transfer of an alkyl group from boron to carbon is the rate-limiting step, and the nature of the intermediate is discussed. 2-Bromocyclopentanones react faster than 2- bromocyclohexanones than 2-bromocycloheptanones, but α-chloro- and α- iodo-cyclohexanones do not undergo alkylation. The stereochemistry of reagent and product is discussed and an efficient one-pot alkylation of cycloalkanones is described.