1,5-Asymmetric induction in boron-mediated aldol reactions of beta-oxygenated methyl ketones

Chem Soc Rev. 2008 Mar;37(3):451-69. doi: 10.1039/b701081h. Epub 2007 Nov 14.

Abstract

This tutorial review describes that high levels of substrate-controlled, 1,5-stereoinduction are obtained in the boron-mediated aldol reactions of beta-oxygenated methyl ketones with achiral and chiral aldehydes. Remote induction from the boron enolates gives the 1,5-anti adducts, with the enolate pi-facial selectivity critically dependent upon the nature of the beta-alkoxy protecting group. This 1,5-anti aldol methodology has been strategically employed in the total synthesis of several natural products with remarkable pharmacological activities. At present, the origin of the high level of 1,5-anti induction obtained with the boron enolates is unclear, although a model based on hydrogen bonding between the beta-alkoxy oxygen and the formyl aldehyde hydrogen has recently been proposed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Aldehydes / chemistry*
  • Biological Products / chemistry
  • Boron / chemistry*
  • Hydrogen Bonding
  • Ketones / chemistry*
  • Stereoisomerism

Substances

  • Aldehydes
  • Biological Products
  • Ketones
  • Boron