Issue 17, 2015

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

Abstract

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.

Graphical abstract: 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

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
08 déc. 2014
Accepted
16 janv. 2015
First published
26 janv. 2015

RSC Adv., 2015,5, 13112-13124

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

M. Gucma, W. M. Gołębiewski and M. Krawczyk, RSC Adv., 2015, 5, 13112 DOI: 10.1039/C4RA15975F

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