Kinetic resolution of α-acetoxy carboxylic acids with homochiral superQuats

Bew, S.P., Davies, S.G. and Fukuzawa, S.-I. (2000) Kinetic resolution of α-acetoxy carboxylic acids with homochiral superQuats. Chirality, 12 (5-6). pp. 483-487. ISSN 0899-0042

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Abstract

Preliminary investigations focused on the kinetic resolution of (±)-α- acetoxy mandelic carboxylic acid chloride with isopropyl SuperQuat and isopropyl Evans' homochiral auxiliaries. The addition of 2 equiv. of the acid chloride to the lithium salts of the auxiliaries (SuperQuat and Evans') at - 100°C in the THF afforded the corresponding N-acyl auxiliaries in high chemical yields (95% and 89%) and d.e.'s of 66% and 40%, respectively. Using the same mandelic acid chloride but incorporating SuperQuat auxiliaries derived from (S)-phenylglycine and (S)-phenylalanine yielded the corresponding N-acyl SuperQuats in 86% and 90% and d.e.'s of 66% and 30%, respectively. Substituting the phenyl group within the α-acetoxy mandelic acid chloride for a n-butyl, tert-butyl and cyclohexyl group changed the d.e. significantly when kinetically resolved with isopropyl SuperQuat. The yields were all similar, i.e., ~90% but the d.e.'s varied considerably, with values of 20%, 50%, and 82%, respectively. Attempted kinetic resolution of α- methoxyphenylacetyl chloride using the lithium salt of isopropyl SuperQuat revealed a diasteroselectivity of 45%, significantly lower than that obtained with the corresponding α-acetoxy carboxylic acid chlorides. (C) 2000 Wiley- Liss, Inc.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
University of East Anglia > Faculty of Science > Research Groups > Synthetic Chemistry
Faculty of Science > School of Environmental Sciences
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Depositing User: Pure Connector
Date Deposited: 02 Feb 2015 14:00
Last Modified: 25 Jul 2018 10:26
URI: https://ueaeprints.uea.ac.uk/id/eprint/51974
DOI:

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