Organoborane-catalyzed selective 1,2-reduction of alkynones with hydride transfer: Synthesis of benzyl alkynes

Abstract

Benzyl alkynes are important organic building blocks in organic synthesis. We report herein a B(C6F5)3-catalyzed site-selective 1,2-reduction of readily available alkynones to access benzyl alkyne derivatives. Under the developed conditions, an array of alkynone substrates are transformed into the corresponding benzyl alkyne products in good to excellent yields. This transformation displays many advantages including transition metal-free, mild reaction conditions, low catalyst loading (5 mol%), high yield (up to 99%), broad substrate scope and functional group tolerance. Moreover, the method’s utility is demonstrated by the diverse transformation of the benzyl alkyne products into other useful chemical compounds in only one-step operation. This protocol offers an expedient way to the synthesis of benzyl alkynes.