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Highly effective and recyclable chiral auxiliaries: a study of the synthesis and use of three 4-isopropyl-5,5- diaryloxazolidin-2-ones

Alexander, Karen and Cook, Stuart and Gibson, Colin L. and Kennedy, Alan R. (2001) Highly effective and recyclable chiral auxiliaries: a study of the synthesis and use of three 4-isopropyl-5,5- diaryloxazolidin-2-ones. Journal of the Chemical Society, Perkin Transactions 1, 2001 (13). pp. 1538-1549. ISSN 1472-7781

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Abstract

A series of three 5,5-diaryl substituted oxazolidin-2-ones (diphenyl, dinaphthyl and ditolyl) have been synthesised. Studies on the benzylation of the lithium enolates of N-acyl derivatives reveal that the yields obtained were sensitive to the method of quenching the reaction. This was particularly acute for the 5,5-diphenyl system where effective yields (69%) and high diastereoselectivities (dr 98 2) are only observed when the reactions were quenched into aqueous buffer. Methylation studies on the N-acyl derivatives showed that the most advantageous results (58-69%, dr 91 9) were only observed using the sodium enolates. The 5,5-ditolyl-4-isopropyloxazolidin-2-one proved to be more efficacious in terms of efficiency and diastereoselectivity (dr 97 3). Subsequent, simple alkaline hydrolyses of the alkylation products allowed for the high recovery and recyclability of the 5,5-diaryl substituted oxazolidin-2-ones without any deleterious endocyclic cleavage. In addition, the acyl portions were recovered in high yield from the alkaline hydrolyses without any evidence of racemisation.

Item type: Article
ID code: 1252
Keywords: benzylation, lithium enolates, diastereoselectivities, aqueous buffer, recyclability, Chemistry, Chemistry(all)
Subjects: Science > Chemistry
Department: Faculty of Science > Pure and Applied Chemistry
Related URLs:
    Depositing user: Catriona Mccallum
    Date Deposited: 20 Jun 2006
    Last modified: 04 Sep 2014 10:42
    URI: http://strathprints.strath.ac.uk/id/eprint/1252

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