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Enantioselective Addition of Boronates to Chromene Acetals Catalyzed by a Chiral Brønsted Acid/Lewis Acid System
Author(s) -
Moquist Philip N.,
Kodama Tomohiro,
Schaus Scott E.
Publication year - 2010
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201003469
Subject(s) - enantioselective synthesis , tartaric acid , chemistry , amide , catalysis , lewis acids and bases , acetal , brønsted–lowry acid–base theory , organic chemistry , aryl , combinatorial chemistry , alkyl , citric acid
Chiral α,β‐dihydroxy carboxylic acids catalyze the enantioselective addition of alkenyl and aryl boronates to chromene acetals. The optimal carboxylic acid is the easily available tartaric acid amide shown in the scheme. Spectroscopic and kinetic mechanistic studies demonstrate that an exchange process generates a reactive dioxoborolane intermediate leading to enantioselective addition to the pyrylium ion formed from the chromene acetal.