Highly Diastereo- and Enantioselective Allylboration of Aldehydes using alpha-Substituted Allyl/Crotyl Pinacol Boronic Esters via in Situ Generated Borinic Esters

Jack L. -Y. Chen, Helen K. Scott, Matthew J. Hesse, Christine L. Willis, Varinder K. Aggarwal*

*Corresponding author for this work

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

74 Citations (Scopus)
323 Downloads (Pure)

Abstract

Readily available, alpha-substituted allyl/crotyl pinacol boronic esters often give low E/Z selectivity (with Z favored) in reactions with aldehydes. We found that addition of nBuLi to the pinacol boronic ester followed by trapping of the alkoxide with TFAA leads to an intermediate allyl borinic ester which undergoes allylboration with very high E selectivity. The substrate scope includes primary to tertiary alkyl alpha-substituents, crotyl substrates, and the previously unreported beta-methallyl pinacol boronic esters. The latter give very high Z selectivity under standard conditions which is completely reversed to high E selectivity under the new conditions. Monitoring the reaction by B-11 NMR confirmed that the reaction proceeds through a borinic ester intermediate.

Original languageEnglish
Pages (from-to)5316-5319
Number of pages4
JournalJournal of the American Chemical Society
Volume135
Issue number14
DOIs
Publication statusPublished - 24 Mar 2013

Structured keywords

  • BCS and TECS CDTs

Keywords

  • BETA-METHYLHOMOALLYL ALCOHOLS
  • PURE ALLYLBORONIC ESTERS
  • HIGH OPTICAL PURITY
  • ENANTIOMERICALLY PURE
  • ASYMMETRIC-SYNTHESIS
  • STEREOSELECTIVE-SYNTHESIS
  • HOMOALLYLIC ALCOHOLS
  • GRIGNARD-REAGENTS
  • ALLYL
  • BORANES

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