Doubly diastereoselective conjugate addition of homochiral lithium amides to homochiral alpha,beta-unsaturated esters containing cis- and trans-dioxolane units

Stephen G. Davies, Matthew J. Durbin, Euan C. Goddard, Peter M. Kelly, Wataru Kurosawa, James A. Lee, Rebecca L. Nicholson, Paul D. Price, Paul M. Roberts, Angela J. Russell, Philip M. Scott, Andrew D. Smith

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)

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-(alpha-methylbenzyl) amide to a range of homochiral alpha,beta-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 beta-amino ester (containing three contiguous stereocentres) is produced. Upon conjugate addition to a homochiral alpha,beta-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 alpha,beta-unsaturated esters containing a trans-dioxolane unit the stereocontrol of the homochiral lithium amide is dominant. Hydrogenolytic N-deprotection of the beta-amino ester products of conjugate addition gives access to polyoxygenated beta-amino acid derivatives.

Original languageEnglish
Pages (from-to)761-776
Number of pages16
JournalOrganic & Biomolecular Chemistry
Volume7
Issue number4
DOIs
Publication statusPublished - 2009

Keywords

  • DYNAMIC KINETIC RESOLUTION
  • BETA-AMINO ACIDS
  • CORRESPONDING BETA,GAMMA-UNSATURATED ESTERS
  • ASYMMETRIC-SYNTHESIS
  • ORGANIC-SYNTHESIS
  • (E)-ALPHA,BETA-UNSATURATED ESTERS
  • STEREOSELECTIVE-SYNTHESIS
  • ORGANOCOPPER REAGENTS
  • METAL CATALYSIS
  • DERIVATIVES

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