Powerful kinetic diastereoselection in ruthenium-catalysed ring-closing metathesis of (homoallyl)vinylcyclopropanes

GC Lloyd-Jones*, M Murray, RA Stentiford, PA Worthington

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Homoallyl-substituted vinyl cyclopropanes 1a-c, which are readily prepared by reaction of allylindium reagents with alpha,beta-unsaturated ketones and aldehydes, undergo Ru-catalysed RCM reactions with Grubbs catalyst to give [4.1.0]bicyclooct-2-ene (norcarene) type bicyclic products. Noncyclisable 'trans' homoallyl-substituted vinyl cyclopropanes 1b and 1c are separated from their 'cis' diastereomers by RCM to 5b and 5c - but only with moderate efficiency due to a competing home-cross metathesis ('dimerisation') to give 7b and 7c, respectively. However, the four diastereomers of the (homoallyl)distyrylcyclopropane 14a obtained from indium-mediated reaction of dibenzylideneacetone and crotyl bromide undergo remarkable kinetic diastereoselection in their RCM reactions to give a 4,7-dimethyl[4.1.0]bicyclohept-2-ene-type product 15a. This process allows recovery of a single diastereomer (> 95%) of 14a without dimerisation being a significant side reaction. Furthermore, the RCM product 15a is obtained rich in one diastereomer (ca. 90%). The kinetic diastereoselection and lack of dimerisation can be rationalised by considering developing transannular interactions and a pseudo-A(1,3) strain model.

Original languageEnglish
Pages (from-to)975-985
Number of pages11
JournalEuropean Journal of Organic Chemistry
Issue number6
Publication statusPublished - Mar 2000

Keywords

  • indium
  • vinylcyclopropanes
  • ring closing metathesis
  • norcarenes
  • kinetic diastereoselection
  • OLEFIN METATHESIS
  • ALLENYLIDENE COMPLEXES
  • LIPPIA-INTEGRIFOLIA
  • CHEMISTRY
  • ROUTE
  • AFRICANONE
  • KETONES
  • BONDS

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