Enantioselective cyanosilylation of aldehydes catalyzed by novel camphor derived Schiff bases-titanium(IV) complexes
作者:Ewelina Błocka、Mariusz J. Bosiak、Mirosław Wełniak、Agnieszka Ludwiczak、Andrzej Wojtczak
DOI:10.1016/j.tetasy.2014.03.001
日期:2014.4
Five tridentate Schiff bases have been prepared from (1R,2S,3R,4S)-3-amino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol and salicylaldehydes. X-ray structure investigation revealed differences in their molecular conformation, and their titanium(IV) complexes have been studied with NMR techniques. Among them the complex with the Schiffbase obtained from 2-hydroxy-3-isopropylbenzaldehyde, is the most selective
Enantioselective cyanosilylation of aldehydes catalyzed by a multistereogenic salen–Mn(<scp>iii</scp>) complex with a rotatable benzylic group as a helping hand
A multistereogenic salen–Mn(iii) complex bearing an aromatic pocket and two benzylic groups as helping hands was found to be efficient in the catalysis of asymmetric cyanosilylation.
Enzymatic kinetic resolution of racemic cyanohydrins via enantioselective acylation
作者:Qing Xu、Yongli Xie、Xiaohong Geng、Peiran Chen
DOI:10.1016/j.tet.2009.11.074
日期:2010.1
Enzymatickineticresolution of a series of aromatic and aliphatic cyanohydrins in organic media has been investigated. The behavior of potential lipases, molecular sieves, acyl reagent, reaction temperature, and organic solvents on the kineticresolution was studied. The influence of substrate structure, steric, and electronic nature and position of the aryl substituent on the enantioselectivity was
Preparation of optically active cyanohydrins from 2-substituted benzaldehydes using a hydroxynitrile lyase from <i>Pouteria sapota</i> seeds immobilized on celite
Abstract The HNL from the defatted meal of the seeds of Pouteria sapota (PsHNL) was extracted with water, and the aqueous extract was immobilized over celite or lyophilized and used as semi-purified PsHNL. The aqueous extract was mixed with celite, ratios 1:1, 1:2 and 1:4, and lyophilized. The immobilized PsHNLdir-celite catalysed the addition of HCN to 1b in buffer saturated-DIPE (microaqueous system)
Novel bimetallic complexes [LiRu[(S)-phgly](2)[(S)-binap]}]X (X = Cl, Br) are readily synthesized by mixing Ru[(S)-phgly](2)[(S)-binap] and LiX. A single-crystal X-ray analysis reveals the structure. These bimetallic complexes efficiently catalyze asymmetric hydrocyanation of aldehydes with a substrate-to-catalyst molar ratio of 500-2000 at -78 to -60 degrees C. A range of aromatic, heteroaromatic, and alpha,beta-unsaturated aldehydes as well as a tert-alkyl aldehyde is converted to the cyanohydrins in high enantiomeric excess (up to 99%).