β-Boronic aldehydes: Expanding the utility of olefin isomerization-Claisen rearrangements

ORGN 953

Benjamin D. Stevens, bes7@pitt.edu1, Christopher J. Bungard, christopher_bungard@merck.com2, and Scott G Nelson, sgnelson+@pitt.edu1. (1) Department of Chemistry, University of Pittsburgh, 1401 Chevron Science Center, Pittsburgh, PA 15260, (2) Sr Research Chemist, Medicinal Chemistry, Merck, West Point, 770 Sumneytown Pike, P.O. Box 4, West Point, PA 19486-0004
The iridium catalyzed isomerization-Claisen rearrangement (ICR) is a powerful synthetic tool that provides access to diastereomerically enriched α, β-disubstituted aldehydes from simple diallylethers. Although the versatility of this transformation has been well documented, the reaction is invariably limited to substrates possessing α-alkyl groups. We have recently investigated a variant of the ICR reaction that enables the synthesis of β-boronic aldehydes 2 from vinyl boronic esters 1. Aldehydes 2 are versatile intermediates that may be readily derivatized through either oxidation or Suzuki crosscoupling sequences. The products arrived at via this route (3, 4) are unavailable from the standard ICR protocol. This presentation will address the practical application of β-boronic aldehyde methodology to complex molecule synthesis and theoretical aspects regarding the potential for internal B-O Lewis acid-base complexation (see 5).

 

New Reactions and Methodology
1:00 PM-5:00 PM, Thursday, 14 September 2006 Moscone Center -- Room 133, Oral

Division of Organic Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006