PMID: 11925208Apr 2, 2002Paper

Intramolecularly competitive Ireland-Claisen rearrangements: scope and potential applications to natural product synthesis

The Journal of Organic Chemistry
Sang-phyo Hong SpMatthias C McIntosh

Abstract

A variety of bis-allylic esters were prepared by vinylmetal addition to cycloalkenones followed by esterification either in situ or in a separate operation. For chiral cyclohexenones, the vinyl additions generally occurred with >10:1 diastereoselectivity. Although in some cases the bis-allylic esters proved to be sensitive to silica gel or other adsorbents, all of the esters examined could be isolated in acceptable purity. The Ireland-Claisen rearrangement of the bis-allylic esters occurred with complete regioselectivity via the exocyclic alkene. The alkene stereochemistry and the stereochemistry at C-2 and C-3 of the pentenoic acid products were consistent with a chairlike transition state in the rearrangement. Substituents at the carbons adjacent to the allylic carbinol carbon (i.e., C-2 or C-6 in cyclohexenone-derived substrates) directed the stereochemical course of the rearrangement. The rearrangements generally proceeded so as to place the larger of the C-2 or C-6 substituents in the pseudoequatorial position with respect to the chairlike transition state. For a bis-allylic ester bearing both a C-2-CH(3) and a C-6-OMEM substituent, the rearrangement product resulted from the nominally smaller OMEM substituent occupying a ...Continue Reading

References

Jun 8, 1977·Journal of the American Chemical Society·T J ThamannT M Loehr

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Citations

Aug 11, 2006·Organic Letters·John M HutchisonMatthias C McIntosh
Feb 22, 2011·Chemistry : a European Journal·Marion BarbazangesPeter Turner
Jun 10, 2004·Chemical Reviews·Ana M Martín Castro
Aug 25, 2006·Organic Letters·Vince S C YehFrancis A Kerdesky
Oct 24, 2008·Chemical Reviews·J Michael Ellis, Michael T Crimmins

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