Atropisomeric amides as chiral, ligands: Using (-)-sparteine-directed enantioselective silylation to control the conformation of a stereogenic axis

J. Clayden*, Paul Johnson, J. H. Pink, Madeleine Helliwell

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

125 Citations (Scopus)

Abstract

An enantiomerically pure (1-trimethylsilyl)ethyl group, constructed by a (-)-sparteine-directed enantioselective quench of a laterally lithiated tertiary aromatic amide, exerts powerful thermo-dynamic control over the conformation of the adjacent tertiary amide substituent. Ortholithiation and functionalization of the amide in the 6-position allows the single amide conformer to be trapped as an enantiomerically and diastereoisomerically pure amide atropisomer. Protodesilylation of the amide gives functionalized atropisomeric amides with a stereogenic axis of single absolute configuration, whose barriers to racemization have been determined by polarimetry. Enantiomerically pure amides bearing phosphine substituents are effective ligands in a Pal-catalyzed allylic substitution reaction - the first use of a nonbiaryl atropisomer as a chiral ligand - and give products with 90% ee. The rate of racemization of the phosphine-substituted amide is powerfully influenced by the presence of palladium.

Original languageEnglish
Pages (from-to)7033-7040
Number of pages8
JournalJournal of Organic Chemistry
Volume65
Issue number21
Early online date19 Sep 2000
DOIs
Publication statusPublished - 20 Oct 2000

Fingerprint Dive into the research topics of 'Atropisomeric amides as chiral, ligands: Using (-)-sparteine-directed enantioselective silylation to control the conformation of a stereogenic axis'. Together they form a unique fingerprint.

Cite this