Quantum chemical study on enantioselective reduction of aromatic ketones catalyzed by chiral cyclic sulfur-containing oxazaborolidines. Part 3. Structures of catalyst–alkoxyborane adducts

✍ Scribed by Ming Li; Rugang Xie; Xairong Hu; Anmin Tian

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 174 KB
• Volume: 78
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(2000)78:4<261::aid-qua8>3.0.co;2-m

✦ Synopsis

The chiral cyclic sulfur-containing oxazaborolidine catalyst reacts with aromatic ketone in the presence of borane to form the catalyst-alkoxyborane adduct with a B-O-B-N four-membered ring. The ab initio molecular orbital method is employed to study the structures of the catalyst-alkoxyborane adduct. All the calculated systems are optimized completely by means of the Hartree-Fock method at 6-31g * basis sets. The B-O-B-N four-membered ring is stable, although there is strong tensile stress in the four-membered ring. The catalyst-alkoxyborane adduct exists in four stable structures. Among these structures, the largest energy difference is only about 4 kJ/mol. In the catalyst-alkoxyborane adduct, the B(2)-N(3) bond in the catalyst is weakened greatly.