Direct Deoxygenation of Free Alcohols and Ketones.

This work presents a feasible method for the elimination of alcohol hydroxyls through the direct activation of typical alkyl alcohols using neutral boron radicals. This transformation necessitates a proficient reagent capable of swiftly activating the alcohol hydroxyl group to produce radicals, thereby circumventing numerous alternative side reactions associated with the alcohol hydroxyl group. To implement this method, we have created an innovative photocatalytic reaction system that oxidizes sodium tetraphenylboron to produce neutral boron radicals, which subsequently enable the direct homolytic conversion of alcohol hydroxyl groups. This deoxygenation technique necessitates no additional preactivation of the alcohol and yields favorable outcomes for the majority of alcohol substrates. The technique facilitates the direct methylene reduction of aldehydes and ketones. Mechanistic studies have established that the reaction likely initiates with the production of alcohols, thereafter undergoing dehydroxylation to yield methylene-reduced products.