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手性噁唑硼烷催化α-和β-氨基酮不对称还原反应立体选择性的AM1过渡态模型研究 总被引:1,自引:0,他引:1
AM1 transition state (TS) models were developed for the enanfioselecfivifies in the reductions of α-and β-aminoketones catalyzed by (S)-4-benzyl-5,5-diphenyl-1,3,2-oxazaborolidine. The result showed that β-aminoketone gave better enanfioselectivity than its α-analog. Different chiralifies of the final products were obtained, R for the former and S for the latter. These semiempirical TS models are consistent with the experimental data. 相似文献
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The asymmetric catalysis reaction is considered to be an important way by which chiral compounds are generated. Chiral 1,3,2-oxazaborolidine, as an effective asymmetric catalyst, is used widely in the enantioselective reduction of prochiral ketones, imines, and carbon-carbon double bonds[1—3]. Up to now, a number of quantum chemical modeling investigations of the en-antioselective reduction of prochiral ketones with borane catalyzed by chiral oxazaborolidines have been carried out[4—7]. Howe… 相似文献
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Recent advances in the synthetic applications of the oxazaborolidine-mediated asymmetric reduction 总被引:1,自引:0,他引:1
Byung Tae Cho Author Vitae 《Tetrahedron》2006,62(33):7621-7643
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Density functional study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine 总被引:1,自引:0,他引:1
LI Ming ZHENG Wenxu & TIAN Anmin . Department of Chemistry Southwest-China Normal University Chongqing China . Department of Chemistry Sichuan University Chengdu China 《中国科学B辑(英文版)》2006,49(4):296-307
Chiral amino alcohols have interesting biological activities and are used widely as chiral ligands in metal-mediated organic reactions[1―3]. Although many amino alcohols can be derived from the available amino acids, the asymmetric synthesis is an important method to get novel amino alcohols. Tillyer et al.[4] reported a new, highly stereoselective synthesis of cyclic (1S,2R)-cis amino alcohols A from keto oxime ethers B, via the enantioselective reduction catalyzed by oxazaborolidine C in … 相似文献
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手性含硫恶唑硼烷催化芳酮不对称还原反应的量子化学研究 总被引:1,自引:0,他引:1
用HF方法在6-31G^*基组下,对手性含硫恶唑硼烷催化苯乙酮不对称还原反应进行了量子化学从头算研究。还原反应经历了催化剂-硼烷加合物、催化剂-硼烷-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。催化剂-硼烷加合物、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、吸热、放热过程;催化剂-烷氧基硼烷加合物离解成催化剂烷氧基硼烷为吸热过程。催化剂-硼烷-酮加合物和催化剂-烷氧基硼烷加合物都存在四种稳定的结构。最有利于氢转移的催化剂-硼烷-酮加合物结构是次低能量结构,并且具有扭曲的船形结构。催化剂-烷氧基硼烷加合物含有一个B-O-B-N四元环,尽管四元环有较大的张力,但加合物仍有较高的稳定性。 相似文献
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The ab initio molecular orbital method is employed to study the enantioselective reduction of acetophenone with borane catalyzed by thiszolidino[3,4-c]oxazaborolidine.Computation result shows that the controlling step for the reduction is the decomposition of the catalyst-alkoxyborane adduct and the reduction leads to S-alcohols.The transition atate of the hydride transfer from the borane moiety to the carbonyl carbon of acetophenone is a twisted chair structure with a B(2)-N(3)-BBH3-HBH3-CCo-OCO6-membered ring. 相似文献