The chemistry of organoborates. Part I. New, high yield ketone syntheses by reaction of trialkylcyanoborates with acylating agents or N-phenylbenzimidoyl chloride

Abstract

From general considerations of the chemistry of organoborates it is clear that the reactions of organocyanoborates with electrophilic reagents have outstanding synthetic potential. The acylation reactions have been studied and it is shown that trialkylcyanoborates react with trifluoroacetic anhydride at low temperatures, with N-phenylbenzimidoyl chloride at room temperature, and with benzoyl chloride on warming to give cyclic intermediates which on oxidation give ketones in excellent yields. In contrast to the carbonylation of organoboranes this one-pot synthesis can be applied to 1,1,2-trimethylpropyl (thexyl) derivatives without the need for special conditions. Examples of the synthesis of fused and bridged polycyclic ketones and of functionalised and unsymmetrical ketones indicate the scope of the reaction.