125638-82-6Relevant articles and documents
Effect of Temperature on the Enantioselectivity in the Oxazaborolidine-Catalyzed Asymmetric Reduction of Ketones. Noncatalytic Borane Reduction, a Nonneglectable Factor in the Reduction System
Xu, Jiaxi,Wei, Tiezheng,Zhang, Qihan
, p. 10146 - 10151 (2003)
The effect of temperature on the enantioselectivity of the oxazaborolidine-catalyzed asymmetric borane reduction of ketones has been investigated carefully using alkyl aryl ketones with a variety of functional groups and a B-methoxyoxazaborolidine derived from trimethyl borate and (S)-α,α-diphenylprolinol as a catalyst. The reductions were carried out over a range of temperatures in THF and toluene with or without the catalyst. The reductive rates increase along with increasing reaction temperature with or without the catalyst by determining the conversion of the ketones to alcohols by GC analysis. However, the rates of the catalytic reductions increase faster than those without the catalyst. The results indicate that the noncatalytic borane reduction is an important factor to the enantioselectivity in the reduction. The highest enantioselectivities were usually obtained between 20 and 30 °C in the asymmetric reduction.
Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of Ketones
Liu, Xiaoqin,Wang, Qiaotian,Han, Caifang,Feng, Xiangqing,Du, Haifeng
, p. 663 - 666 (2019/05/21)
A highly enantioselective Piers-type hydrosilylation of simple ketones was successfully realized using a chiral frustrated Lewis pair of tri-tert-butylphosphine and chiral diene-derived borane as catalyst. A wide range of optically active secondary alcohols were furnished in 80%—99% yields with 81%—97% ee's under mild reaction conditions.
Co6H8(PiPr3)6: A Cobalt Octahedron with Face-Capping Hydrides
Ohki, Yasuhiro,Shimizu, Yuki,Araake, Ryoichi,Tada, Mizuki,Sameera,Ito, Jun-Ichi,Nishiyama, Hisao
supporting information, p. 15821 - 15825 (2016/12/16)
A square-planar Co4amide cluster, Co4{N(SiMe3)2}4(2), and an octahedral Co6hydride cluster, Co6H8(PiPr3)6(4), were obtained from metathesis-type amide to hydride exchange reactions of a CoIIamide complex with pinacolborane (HBpin) in the absence/presence of PiPr3. The crystal structure of 4 revealed face-capping hydrides on each triangular [Co3] face, while the formal CoII2CoI4oxidation state of 4 indicated a reduction of the cobalt centers during the assembly process. Cluster 4 catalyzes the hydrosilylation of 2-cyclohexen-1-one favoring the conjugate reduction. Generation of the catalytically reactive Co cluster species was indicated by a trapping experiment with a chiral chelating agent.
