Stereospecificity and stereoselectivity in electrophilic substitution reactions of non-α-heterosubstituted organolithiums and stannanes: A rotationally restricted amide as an internal stereochemical marker

J. Clayden*, M. Helliwell, J. H. Pink, N. Westlund

*Corresponding author for this work

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

44 Citations (Scopus)

Abstract

The complete stereochemical course of a tin-lithium exchange/electrophilic quench sequence has been unambiguously determined by stereochemical characterization (using X-ray crystallography or NOE studies) at every step. Pairs of diastereoisomeric stannanes of known stereochemistry bearing atropisomeric amide substituents undergo tin-lithium exchange with alkyllithiums to give diastereoisometic benzylic organolithiums whose stereochemistry can be assigned by NMR. For one atropisomer of the stannanes, the tin-lithium exchange is fully stereospecific and proceeds with retention of stereochemistry. The other atropisomer undergoes nonstereospecific tin-lithium exchange: The first reported example of a lack of stereospecificity in electrophilic substitution of tin for lithium. One of the diastereoisomeric atropisomeric organolithiums produced by the tin-lithium exchange is deuterated and alkylated with retention but stannylated with inversion of stereochemistry. The other is alkylated nonstereospecifically but stannylated with retention.

Original languageEnglish
Pages (from-to)12449-12457
Number of pages9
JournalJournal of the American Chemical Society
Volume123
Issue number50
Early online date22 Nov 2001
DOIs
Publication statusPublished - 19 Dec 2001

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