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Quantum chemical study on enantioselective reduction of aromatic ketones catalyzed by chiral cyclic sulfur‐containing oxazaborolidines. Part 1. Structures and properties of catalysts
Author(s) -
Li Ming,
Xie Rugang,
Hu Changwei,
Wang Xin,
Tian Anmin
Publication year - 2000
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(2000)78:4<245::aid-qua6>3.0.co;2-i
Subject(s) - borane , ketone , adduct , chemistry , enantioselective synthesis , catalysis , organic chemistry , medicinal chemistry
The ab initio molecular orbital method is employed to study the structures and properties of chiral cyclic sulfur‐containing oxazaborolidine, as a catalyst, and its borane adducts. All the structures are optimized completely by means of the Hartree–Fock method at 6‐31g* basis sets. The catalyst is a twisted chair structure and reacts with borane to form four plausible catalyst–borane adducts. Borane–sulfur adducts may be formed, but they barely react with aromatic ketone to form catalyst–borane–ketone adducts, because they are repulsed greatly by the atoms arising from the chair rear of the catalyst with a twisted chair structure. Borane–N adduct has the largest formation energy and is predicted to react easily with aromatic ketone to form catalyst–borane–ketone adducts. The formation of the catalyst–borane adducts causes the B BH3 H BH3 bond lengths of the BH 3 moiety to be increased and thus enhances the activity of the enantioselective catalytic reduction. The borane–N adduct is of great advantage to hydride transfer. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 78: 245–251, 2000