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Synthesis of Chiral Tertiary Boronic Esters by Oxime‐Directed Catalytic Asymmetric Hydroboration
Author(s) -
Shoba Veronika M.,
Thacker Nathan C.,
Bochat Andrew J.,
Takacs James M.
Publication year - 2016
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.201509137
Subject(s) - hydroboration , chemistry , stereocenter , enantioselective synthesis , organic chemistry , oxime , enantiomer , alkene , alkyl , boronic acid , catalysis , combinatorial chemistry , asymmetric carbon
Chiral boronic esters are useful intermediates in asymmetric synthesis. We have previously shown that carbonyl‐directed catalytic asymmetric hydroboration (CAHB) is an efficient approach to the synthesis of functionalized primary and secondary chiral boronic esters. We now report that the oxime‐directed CAHB of alkyl‐substituted methylidene and trisubstituted alkene substrates by pinacolborane (pinBH) affords oxime‐containing chiral tertiary boronic esters with yields up to 87 % and enantiomeric ratios up to 96:4 e.r. The utility of the method is demonstrated by the formation of chiral diols and O‐substituted hydroxylamines, the generation of quaternary carbon stereocenters through carbon–carbon coupling reactions, and the preparation of chiral 3,4,4‐trisubstituted isoxazolines.