Preference of 4-exo Ring Closure in Copper-Catalyzed Intramolecular Coupling of Vinyl Bromides with Alcohols

Yewen Fang and Chaozhong Li*
Joint Laboratory of Green Synthetic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, China
J. Am. Chem. Soc., 2007, 129 (26), pp 8092–8093
DOI: 10.1021/ja072793w
Publication Date (Web): June 9, 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.

, clig@mail.sioc.ac.cn

Abstract

Abstract Image

The copper-catalyzed intramolecular O-vinylation of γ-bromohomoallylic alcohols was investigated. With 10 mol % of CuI as the catalyst and 20 mol % of 1,10-phenanthroline as the ligand, the reactions of 3-bromo-3-buten-1-ols in refluxing CH3CN led to the convenient formation of the corresponding 2-methyleneoxetanes in good to excellent yields via a 4-exo ring closure. The configuration of the CC bond was nicely retained. This methodology was then successfully extended to the cyclization in 5-exo, 6-exo, and even 6-endo modes. Moreover, the competition experiments revealed that 4-exo cyclization is fundamentally preferred over other modes of cyclization. On the other hand, the corresponding Pd(0)-catalyzed O-vinylation showed the predominance of 5-exo over 4-exo cyclization.

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History

  • Published In Issue July 04, 2007
  • Received April 21, 2007

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