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。
A Chiral Ruthenium-Monophosphine Catalyst for Asymmetric Addition of Arylboronic Acids to Aryl Aldehydes
A novel ruthenium catalyst on the basis of a chiral monophosphorus ligand is efficient for the asymmetricaddition of arylboronicacids to aryl aldehydes, providing a series of chiral diarylmethanols in excellent yields and enantioselectivities (up to 92% ee). Preliminary study has shown that this process is catalyzed by a Ru complex with a single monophosphorus ligand.
Isosterically designed chiral catalysts: Rationale, optimization and their application in enantioselective nucleophilic addition to aldehydes
作者:En Gao、Qiao Li、Lili Duan、Lin Li、Yue-Ming Li
DOI:10.1016/j.tet.2020.131648
日期:2020.11
enantioselective nucleophilic addition to aldehydes. In the presence of 10 mol% of chiral ligand 1b, enantioselective addition of diethylzinc to aldehydes provided the corresponding secondary alcohols in up to 90% isolated yield and up to 99% ee. Similarly, using 3e as chiral ligand, enantioselective arylation and alkynylation of aldehydes also proceeded readily, leading to the desired chiral alcohols in up to
Stereoselective reduction of chiral 3-(p-tolylsulfinyl)-2-thienyl ketones with diisobutylaluminum hydride (DIBAL) or lithium tri-sec-butylborohydride (L-Selectride) has been achieved. Reduction of the ketones with DIBAL in the presence of a Lewis acid or with L-Selectride afforded predominantly the thienyl carbinols, while the reduction with DIBAL alone gave the other diastereoisomeric alcohols as the major product. This method has been successfully applied to an efficient route to chiral thienyl alcohols.
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