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Issue 4, 2009
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Doubly diastereoselective conjugate addition of homochiral lithium amides to homochiral α,β-unsaturated esters containing cis- and trans-dioxolane units

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Abstract

As part of a long-term goal directed towards the ab initio asymmetric synthesis of unnatural amino sugars, the doubly diastereoselective conjugate addition reactions of the antipodes of lithium N-benzyl-N-(α-methylbenzyl)amide to a range of homochiral α,β-unsaturated esters containing cis- and trans-dioxolane units was investigated. These reactions resulted in “matching” and “mismatching” effects. In the “matched” cases a single diastereoisomer of the corresponding β-amino ester (containing three contiguous stereocentres) is produced. Upon conjugate addition to a homochiral α,β-unsaturated ester containing a cis-dioxolane unit, in the “mismatched” case it is the stereocontrol of the substrate which is dominant over that of the lithium amide, whilst upon addition to homochiral α,β-unsaturated esters containing a trans-dioxolane unit the stereocontrol of the homochiral lithium amide is dominant. Hydrogenolytic N-deprotection of the β-amino ester products of conjugate addition gives access to polyoxygenated β-amino acid derivatives.

Graphical abstract: Doubly diastereoselective conjugate addition of homochiral lithium amides to homochiral α,β-unsaturated esters containing cis- and trans-dioxolane units

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Publication details

The article was received on 16 Oct 2008, accepted on 05 Nov 2008 and first published on 07 Jan 2009


Article type: Paper
DOI: 10.1039/B818298A
Citation: Org. Biomol. Chem., 2009,7, 761-776
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    Doubly diastereoselective conjugate addition of homochiral lithium amides to homochiral α,β-unsaturated esters containing cis- and trans-dioxolane units

    S. G. Davies, M. J. Durbin, E. C. Goddard, P. M. Kelly, W. Kurosawa, J. A. Lee, R. L. Nicholson, P. D. Price, P. M. Roberts, A. J. Russell, P. M. Scott and A. D. Smith, Org. Biomol. Chem., 2009, 7, 761
    DOI: 10.1039/B818298A

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