Enantioselective synthesis of cyclic enol ethers and all-carbon quaternary stereogenic centers through catalytic asymmetric ring-closing metathesis.

Journal Article

The first examples of catalytic asymmetric ring-closing metathesis (ARCM) reactions of enol ethers are reported. To identify the most effective catalysts, various chiral Mo- and Ru-based catalysts were screened. Although chiral Ru catalysts (those that do not bear a phosphine ligand) promote ARCM in some cases, such transformations proceed in <10% ee. In contrast, Mo-based alkylidenes give rise to efficient ARCM and deliver the desired products in the optically enriched form. Thus, Mo-catalyzed enantioselective transformations allow access to various five- and six-membered cyclic enol ethers in up to 94% ee from readily available achiral starting materials. The first examples of catalytic ARCM that lead to the formation of all-carbon quaternary stereogenic centers are also disclosed. Mechanistic models that offer a plausible rationale for the identity of major enantiomers as well as the observed levels of enantioselectivity are provided. Representative examples demonstrate that the enol ether moiety and the unreacted alkene of the ARCM products can be discriminated with excellent site selectivity (>98%).

Full Text

Duke Authors

Cited Authors

  • Lee, A-L; Malcolmson, SJ; Puglisi, A; Schrock, RR; Hoveyda, AH

Published Date

  • April 19, 2006

Published In

Volume / Issue

  • 128 / 15

Start / End Page

  • 5153 - 5157

PubMed ID

  • 16608351

International Standard Serial Number (ISSN)

  • 0002-7863

Digital Object Identifier (DOI)

  • 10.1021/ja058428r

Language

  • eng

Conference Location

  • United States