Predicted outcomes: The additionreaction of organoboronicacids with aldehydes in the presence of K2CO3 catalyzed by CoI2/(R,R)‐BDPP gives chiral secondary alcohols in excellent yields with 90–99 % enantiomeric excess (see scheme; (R,R)‐BDPP=(2R,4R)‐(+)‐2,4‐bis(diphenylphosphino)pentane). This method provides an alternative to prepare an R and S enantiomeric pair by using the same chiral ligand and
预期的结果:在CoI 2 /(R,R)-BDPP催化下,在存在K 2 CO 3的情况下,有机硼酸与醛的加成反应可得到出色的手性仲醇,对映体过量90-99%(参见方案;(R,R)-BDPP =(2 R,4 R)-(+)-2,4-双(二苯基膦基)戊烷)。该方法提供了另一种通过使用相同的手性配体制备R和S对映体对的方法,并且可以预测反应的立体化学结果。
Cu
<sup>II</sup>
‐Catalyzed Asymmetric Hydrosilylation of Diaryl‐ and Aryl Heteroaryl Ketones: Application in the Enantioselective Synthesis of Orphenadrine and Neobenodine
作者:Yao‐Zong Sui、Xi‐Chang Zhang、Jun‐Wen Wu、Shijun Li、Ji‐Ning Zhou、Min Li、Wenjun Fang、Albert S. C. Chan、Jing Wu
DOI:10.1002/chem.201200379
日期:2012.6.11
With certain amounts of sodium tert‐butoxide and tert‐butanol as additives, catalytic amounts of an inexpensive and easy‐to‐handle copper source Cu(OAc)2⋅H2O, a commercially available and air‐stable non‐racemic dipyridylphosphine ligand, as well as the stoichiometric desirable hydride donor polymethylhydrosiloxane (PMHS), formed a versatile in situ catalyst system for the enantioselective reduction
Highly Enantioselective Synthesis of Chiral Benzhydrols via Manganese Catalyzed Asymmetric Hydrogenation of Unsymmetrical Benzophenones Using an Imidazole-Based Chiral PNN Tridentate Ligand
A series of Mn(I) catalysts containing imidazole-based chiral PNN tridentate ligands with controllable “side arm” groups have been established, enabling the asymmetricalhydrogenation of unsymmetrical benzophenones with outstanding activity (up to 13 000 TON) and excellent enantioselectivity (up to >99% ee). This protocol uses K2CO3 as an industrially desirable base and features a wide substrate scope
已经建立了一系列含有咪唑基手性PNN三齿配体和可控“侧臂”基团的Mn(I)催化剂,能够使不对称二苯甲酮进行不对称氢化,具有出色的活性(高达13000吨)和出色的对映选择性(高达> 99%ee)。该协议使用K 2 CO 3作为工业上可取的碱,并且具有广泛的底物范围和官能团耐受性。此外,催化剂中的亚胺基对于获得高活性和良好的对映选择性至关重要。
Substituent Position‐Controlled Stereoselectivity in Enzymatic Reduction of Diaryl‐ and Aryl(heteroaryl)methanones
directing group (bromo group) showcased the potential application of this substrate‐controlled bioreduction reaction. The combined use of substrateengineering and protein engineering, was demonstrated to be a useful strategy in efficiently improving stereoselectivity or switching stereopreference of enzymatic processes.
A chiral zinc complex of salen was found to be an efficient catalyst for the phenyl transfer of organozinc reagent to aromaticaldehydes and ketones. High enantioselectivities were obtained in reactions of both aromaticaldehydes and ketones (up to 97% and 92% ee, respectively).