Chiral Phosphoramide-Catalyzed Enantioselective Addition of Allylic Trichlorosilanes to Aldehydes. Preparative Studies with Bidentate Phosphorus-Based Amides

Scott E. Denmark,* Jiping Fu, and Michael J. Lawler
Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801
J. Org. Chem., 2006, 71 (4), pp 1523–1536
DOI: 10.1021/jo052203h
Publication Date (Web): January 17, 2006
Copyright © 2006 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.

, denmark@scs.uiuc.edu

Abstract

Abstract Image

On the basis of the mechanistic insight that more than one Lewis basic moiety (phosphoramide) is involved in the rate- and stereochemistry-determining step of enantioselective allylation, bidentate chiral phosphoramides were developed. Different chiral phosphoramide moieties were connected by tethers of methylene chains of varying length. The rate and enantioselectivity of allylation with allyltrichlorosilane promoted by the bidentate phosphoramides was found to be highly dependent on the tether length. A new phosphoramide based on a 2,2‘-bispyrrolidine skeleton has been designed and afforded good yield, efficient turnover, and high enantioselectivity in allylation reactions. The synthesis of enantiopure 2,2‘-bispyrrolidine was easily accomplished on large scale by photodimerization of pyrrolidine followed by resolution with l(or d)-tartaric acid. The scope of the allylation reaction was examined with variously substituted allylic trichlorosilanes and unsaturated aldehydes. This method has been applied to the construction of stereogenic, quaternary centers by the addition of unsymmetrically γ-disubstituted allylic trichlorosilanes.

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History

  • Published In Issue February 17, 2006
  • Received October 21, 2005

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