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Download fileBifunctional Catalyst Promotes Highly Enantioselective Bromolactonizations To Generate Stereogenic C–Br Bonds
journal contribution
posted on 2012-07-11, 00:00 authored by Daniel
H. Paull, Chao Fang, James R. Donald, Andrew D. Pansick, Stephen F. MartinA 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.