Organocatalytic Vinyl and Friedel−Crafts Alkylations with Trifluoroborate Salts

Sandra Lee and David W. C. MacMillan*
Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544, and Division of Chemistry, California Institute of Technology, Pasadena, California 91125
J. Am. Chem. Soc., 2007, 129 (50), pp 15438–15439
DOI: 10.1021/ja0767480
Publication Date (Web): November 22, 2007
Copyright © 2007 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, dmacmill@princeton.edu

Abstract

Abstract Image

Herein we report the first use of vinyl and heteroaryl trifluoroborate salts as viable substrates for amine-catalyzed conjugate additions. The application of LUMO-lowering iminium catalysis has enabled the highly regio- and enantioselective 1,4-addition of rationally designed trifluoroborate salt nucleophiles to α,β-unsaturated aldehydes. Imidazolidinone 2•HCl was found to catalyze the addition of various BF3K-derived heteroaryl and vinyl species to a range of enals with excellent levels of enantioselectivity. Importantly, the use of these salts can enable nontraditional regiocontrol as part of a Friedel−Crafts pathway. Boronic acids can also be employed as viable π-nucleophiles for these asymmetric conjugate additions provided that in situ activation to the corresponding boronate species is accomplished. While BF3K salts are routinely employed in transition metal catalysis, to our knowledge, this is the first use of this activation group for organic catalysis or Friedel−Crafts alkylations.

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History

  • Published In Issue December 19, 2007
  • Received September 6, 2007

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