Regioselective ring-opening of epoxides with ortho-lithioanisoles catalyzed by BF3 center dot OEt2


Erturk E., Tezeren M. A. , Atalar T., TİLKİ T.

TETRAHEDRON, vol.68, no.32, pp.6463-6471, 2012 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 68 Issue: 32
  • Publication Date: 2012
  • Doi Number: 10.1016/j.tet.2012.05.116
  • Title of Journal : TETRAHEDRON
  • Page Numbers: pp.6463-6471

Abstract

It is presented that a number of o-2-hydroxyalkylanisoles could be efficiently synthesized through the regioselective ring-opening reaction of epoxides with o-lithioanisoles in the presence of BF3 center dot OEt2 Lewis-acid catalyst. Sterically demanding o-lithioanisoles had to be generated by exploiting the combination of (BuLi)-Bu-n and a catalytic amount of TMEDA (0.20 equiv) in Et2O as the lithiator whereas 'normal' anisole could be lithiated at ortho-position by treatment with (BuLi)-Bu-n in THE as usual. Surprisingly, the availability of THE and a catalytic amount of TMEDA (0.20 equiv) in the reaction mixture was found to enhance the reaction yields dramatically. A complex aggregate formation by the co-operative ligation of THF and TMEDA to ortho-lithioanisole(s) was proposed to rationalize the high reactivity achieved in the ring-opening reaction of epoxides. (C) 2012 Elsevier Ltd. All rights reserved.