(-)-Ephedrine as an auxiliary for the asymmetric synthesis of atropisomeric amides by dynamic resolution under thermodynamic control

Jonathan Clayden*, Lai Wah Lai

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

49 Citations (Scopus)

Abstract

N,N-Dialkyl-2-formylbenzamides and N,N-dialkyl-2-formyl-1-naphthamides condense with (-)-ephedrine in refluxing toluene to give oxazolidines both as single diastereoisomers with respect to the new stereogenic centre and as single conformers with respect to the slowly-rotating Ar-CONR2 bond. In the naphthamide series, removal of the ephedrine auxiliary by hydrolysis returns the starting aldehyde (isolated by reduction to the more stable alcohol) in enantiomerically enriched form (up to 94% ee). Overall, the two-step sequence amounts to a dynamic resolution under thermodynamic control.

Original languageEnglish
Pages (from-to)3163-3166
Number of pages4
JournalTetrahedron Letters
Volume42
Issue number18
Early online date11 Apr 2001
DOIs
Publication statusPublished - 30 Apr 2001

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