手性含硫噁唑硼烷催化芳酮不对称还原反应的量子化学研究

Quantum Chemical Study on Enantioselective Reduction of Aromatic Ketones Catalyzed by Chiral Sulfur - containing Oxazaborolidines

用ＨＦ方法在６－３１Ｇ基组下，对手性含硫恶唑硼烷催化乙酮不对称还原瓞地量子化学从头算研究，还原反应经历了催化剂－硼烷加合物、催人烷－酮加合物、催化剂－烷氧基硼烷加合物的生成以及催化剂－烷氧基硼烷加合物的离解过程，从化剂－硼烷轵事物、催化剂－硼中合物、催化剂－硼烷－酮加合物和催化剂－烷氧基硼烷加合物的生成分别为放热１、吸热、放热过程；催人』烷氧基硼烷加合物离解成催人睡烷基硼烷为吸热过程，催化剂。

In the present paper, the ah initio molecular orbital computations of the enantioselective reduction of acetophenone catalyzed by chiral sulfur - containing oxazaborolidine catalysts are carried out by use of the HF method with 6 - 31G* basis sets. In the reduction, catalyst - borane adducts, catalyst - borane - ketone adducts, and catalyst - alkoxyborane adducts are generated, and the further decomposition of catalyst -alkoxyborane adducts takes place. The formation of catalyst - borane adducts, catalyst- borane - ketone adducts, and catalyst - alkoxyborane adducts are exothermic, endothermic, and exothermic respectively, whereas the decomposition of catalyst - alkoxyborane adducts into catalyst and alkoxyborane is endothermic. Both catalyst - borane - ketone adducts and catalyst - alkoxyborane adducts have four stable structures. Among the four structures of the catalyst - borane - ketone adducts, the one with the greatest tendency for the hydrogen transfer to take place is the one with the second lowest energy, with a twisted boat structure. Each of catalyst -alkoxyborane adducts contains aB - O - B - N4 - membered ring . In spite of the great tensile stress of the 4 - membered ring, the catalyst - alkoxyborane adducts are quite stable.