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Bifunctional Catalyst Promotes Highly Enantioselective Bromolactonizations To Generate Stereogenic C–Br Bonds

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journal contribution
posted on 11.07.2012, 00:00 authored by Daniel H. Paull, Chao Fang, James R. Donald, Andrew D. Pansick, Stephen F. Martin
A novel bifunctional catalyst derived from BINOL has been developed that promotes the highly enantioselective bromolactonizations of a number of structurally distinct unsaturated acids. Like some known catalysts, this catalyst promotes highly enantioselective bromolactonizations of 4- and 5-aryl-4-pentenoic acids, but it also catalyzes the highly enantioselective bromolactonizations of 5-alkyl-4­(Z)-pentenoic acids. These reactions represent the first catalytic bromolactonizations of alkyl-substituted olefinic acids that proceed via 5-exo mode cyclizations to give lactones in which new carbon–bromine bonds are formed at a stereogenic center with high enantioselectivity. We also disclose the first catalytic desymmetrization of a prochiral dienoic acid by enantioselective bromolactonization.