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Ephedrines as Chiral Auxiliaries in Enantioselective Alkylation Reactions of Acyl Ephedrine Amides and Esters: A Review

Author(s):

Alejandro Cruz*, Itzia Irene Padilla-Martínez and María Esther Bautista-Ramírez   Pages 1 - 46 ( 46 )

Abstract:


The optical purity is very important in chiral compounds to be used as pharmaceuticals and additives in food industry. In modern chemistry, preparation of these compounds has been of capital importance in asymmetric synthesis. These compounds used as auxiliary reagents should control the stereochemistry of the reaction to produce new chiral compounds and must be recycled. In recent decades, Ephedra and some of their derivatives have been broadly used as catalyst chiral ligands or chiral inductors in asymmetric synthesis. To our knowledge, a review about the use of N-substituted Ephedra derivative compounds as chiral auxiliaries combined with organometallics in alkylation reactions of carbonyl compounds have been published. Now, in this paper, we present a bibliographic review about the use of ephedrines and their N-substituted derivatives as chiral auxiliaries, via the formation of their corresponding N-Acyl or O-Acyl derivatives, to be used in the C-C bond formation, just as α-alkylation. Opening reaction of epoxides and aziridines, aldolic condensation, Manich reaction, addition of nucleophiles to α,β-unsaturated ephedrine amides, Michael additions and the use of polymer supported N-Acyl or O-Acyl ephedrines are included in this review. Methods for acylation reactions and recovery of the auxiliary after the asymmetric induction are included. This methodology has been used to produce new chiral compounds as carboxylic acids, esters, aldehydes, alcohols, ketones, β-hydroxy acids, β-hydroxy esters, lactones, lactams, α- and β-amino acids, amino aldehydes, amino ketones and amino alcohols.

Keywords:

Ephedrines, N-acyl ephedrines, O-acyl ephedrines, alkylation reaction, asymmetric synthesis, enantioselectivity

Affiliation:

Department of Basic Sciences, National Polytechnic Institute-UPIBI, Av. Acueducto de Guadalupe S / N Col. Barrio la Laguna Ticomán, C.P. 07340, Department of Basic Sciences, National Polytechnic Institute-UPIBI, Av. Acueducto de Guadalupe S / N Col. Barrio la Laguna Ticomán, C.P. 07340, Department of Basic Sciences, National Polytechnic Institute-UPIBI, Av. Acueducto de Guadalupe S / N Col. Barrio la Laguna Ticomán, C.P. 07340



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