Yoshiwara Y,
Ogasawara M,
Sugiura M,
Kotani S.
*
Nakajim M.
Kumamoto University, Tokushima University, and Sojo University, Kumamoto, Japan
Catalytic Enantioselective Aldol Reaction of Unprotected Carboxylic Acids under Phosphine
Oxide Catalysis.
Angew. Chem. Int. Ed. 2018;
57: 15877-15881
Key words
aldol reaction - phosphine oxides - Lewis base catalysis - carboxylic acids
Significance
Nakajima and co-workers report the first example of a chiral Lewis base-catalyzed
SiCl4-mediated enantioselective aldol reaction of unprotected carboxylic acids. The method
is highly enantio- and diastereoselective, and it shows a broad substrate scope.
Comment
Previous works on asymmetric aldol reactions of unprotected carboxylic acids by various
groups (see, for example: K. Yu et al. J. Am. Chem. Soc. 2017, 139, 527) required stoichiometric chiral reagents to achieve enantioselectivity, but
in the presented method, the authors use SiCl4 to activate the carboxylic acid, permitting the use of only a catalytic amount of
a chiral Lewis base to achieve high enantioselectivity.
