A new bifunctional asymmetric catalyst containing a Lewis acid and a Lewis base (1) was developed and applied to the catalytic asymmetric cyanosilylation of aldehydes. The products were obtained generally with excellent enantiomeric excess. The experiments using the control catalyst (5) and the catalyst containing more electron-rich phosphine oxide (6) suggest that the catalyst 1 should promote the
BINOLAM, a Recoverable Chiral Ligand for Bifunctional Enantioselective Catalysis: The Asymmetric Synthesis of Cyanohydrins
作者:Jesús Casas、Carmen Nájera、José M. Sansano、José M. Saá
DOI:10.1021/ol0262338
日期:2002.7.1
[reaction: see text] A new bifunctional catalytic system based on a monometallic aluminum complex is used for the efficient enantioselective cyanation of aldehydes. The ligand (S)- or (R)-2,2'-bis(diethylaminomethyl)-substituted binaphthol (BINOLAM) used is recovered for recycling. This methodology is used for the synthesis of a precursor of epothilone A.
High-Throughput Preparation of Optically Active Cyanohydrins Mediated by Lipases
作者:Juliana Christina Thomas、Bruno Bernardi Aggio、Alfredo Ricardo Marques de Oliveira、Leandro Piovan
DOI:10.1002/ejoc.201601028
日期:2016.12
Cyanohydrins are versatile compounds with high applicability in organic synthesis; they are used as starting materials for the synthesis of other chemical targets with high industrial added value. Lipase-mediated kinetic resolution reactions are a promising route for the synthesis of optically active cyanohydrins. These reactions can be carried out through the acylation of cyanohydrins or the deacylation
Highly Enantioselective Cyanosilylation of Aldehydes Catalyzed by a Chiral Oxazaborolidinium Ion
作者:Do Hyun Ryu、E. J. Corey
DOI:10.1021/ja0475959
日期:2004.7.1
excellent catalysts for the enantioselective cyanosilylation of a wide variety of aldehydes (see Table 1) using trimethylsilyl (TMS) cyanide and triphenylphosphine oxide as the source of a new reactive cyanide donor. This donor appears to be the isocyanophosphorane Ph3P(OTMS)(N=C:) (4). The novel process described herein has several advantages: predictability of absolute configuration of cyanohydrin products
使用三甲基甲硅烷基(TMS)氰化物和三苯膦氧化物作为新型活性氰化物供体的来源,手性恶唑硼烷鎓盐1和2是出色的催化剂,可用于多种醛的对映选择性氰基硅烷化反应(参见表1)。该供体似乎是异氰基膦Ph3P(OTMS)(N = C :)(4)。本文所述的新颖方法具有若干优点:从机理模型(3)可预测氰醇产物的绝对构型,产物的高收率和非常好的对映体纯度(> / = 90%),以及最后,容易且有效地回收氯仿。催化配体。
Design of a new bifunctional asymmetric catalyst from carbohydrates: application to catalytic asymmetric cyanosilylation of aldehydes and acetophenone
A new active Lewis acid–Lewis base bifunctionalasymmetric catalyst 7 was developed using carbohydrate as a scaffold and this catalyst was applied to the asymmetriccyanosilylation of aldehydes and acetophenone. The β-Ph group at the 6-position of 7 was found to be important for a high asymmetric induction (up to 80% ee) by bringing the Al and the phosphine oxide at optimum positions for a dual activation