Enantioselective Synthesis of β-Lactone Catalyzed by a Chiral Oxazaborolidine

Significance

There are few reports of stereoselective syntheses of β-lactones from ketenes and aldehydes. Utilizing the highly successful borane-mediated enantioselective reduction of ketones with chiral oxazaborolidine catalyst, a catechol derivative was synthesized and found to catalyze the reaction with moderate yields and moderate to good enantioselectivity. This work provides the first example of a reaction of α-branched aldehydes with ketenes.