66212-46-2Relevant academic research and scientific papers
Application of chiral ligands: Carbohydrates, nucleoside-lanthanides and other Lewis acid complexes to control regio- and stereoselectivity of the dipolar cycloaddition reactions of nitrile oxides and esters
Gucma, Miroslaw,Golbiewski, W. Marek,Krawczyk, Maria
, p. 13112 - 13124 (2015/02/19)
Chiral Lewis acid mediated 1,3-dipolar cycloaddition reactions of 4-trifluoromethylbenzonitrile oxide to methyl crotonate as well to β-substituted acrylates and (Z)-pent-2-en-1-yl esters were examined. Excellent enantioselectivities with moderate to good regioselectivities were achieved for crotonates with complexes of BiBr3 with (+)-(4,6-benzylidene)methyl-α-d-glucopyranoside C, with the l-ascorbic acid I-FeCl3 system, and with lipase Candida antarctica. High enantiomeric excess was observed for isopropyl ester and benzyl ester. The outstanding ee values were achieved for acrylates with β-t-butyl, cyclohexyl, and 1,3-benzodioxol-5-yl groups in cycloadditions catalyzed by C-Yb(OTf)3 and the (+)-2-hydroxy-3-pinanone N-TiCl4 system. High enantioselectivities were found in reactions of (Z)-pent-2-en-1-yl esters mediated by complexes N-Mg(OTf)2 and N-TiCl4.
Reaction of Chiral Lithium Diorganocopper Reagents, LiRR*Cu, with α,β-Unsaturated Esters of Chiral Alcohols
Gustafsson, Bill,Hansson, Anna-Tora,Ullenius, Christina
, p. 113 - 118 (2007/10/02)
Conjugate addition of organometallic reagents to chiral esters of trans-3-phenyl-2-propenoic or trans-2-butenoic acid has been studied.The reagents were PhMgBr, LiPh2Cu, LiMe2Cu, LiMeR*Cu, and LiPhR*Cu.The chiral ligand R* was the 2-(1-dimethylaminoethyl)phenyl group.The assymmetric induction varied between 0.3 and 49percent and was in some cases improved by the presence of the R* ligand.The influence of substituents on the β-carbon of the α,β-unsaturated esters on the stereochemical course of the reaction is related to their coordination ability.The directing effects of the chiral ester functions are discussed.
