Iridium-catalyzed anti-diastereo- and enantioselective carbonyl (trimethylsilyl)allylation from the alcohol or aldehyde oxidation level

J Am Chem Soc. 2010 Jul 7;132(26):9153-6. doi: 10.1021/ja103299f.

Abstract

Using the ortho-cyclometalated pi-allyl iridium precatalyst (R)-I derived from [Ir(cod)Cl](2), 4-cyano-3-nitrobenzoic acid, (R)-SEGPHOS, and allyl acetate, enantioselective transfer hydrogenation of alpha-(trimethylsilyl)allyl acetate in the presence of aldehydes 2a-i mediated by 2-propanol delivers products of (trimethylsilyl)allylation 4a-i in good isolated yields and with exceptional levels of anti-diastereoselectivity and enantioselectivity (90-99% ee). In the absence of 2-propanol, but under otherwise identical reaction conditions, carbonyl (trimethylsilyl)allylation is achieved directly from the alcohol oxidation level to furnish an equivalent set of adducts 4a-i with roughly equivalent isolated yields and stereoselectivities. To evaluate the synthetic utility of the reaction products 4a-i, adduct 4g was converted to the 1,4-ene-diol 5g via dioxirane-mediated oxidative desilylation with allylic transposition, the allylic alcohol 6g via protodesilylation with allylic transposition, and the gamma-lactam 7g via chlorosulfonyl isocyanate-mediated cycloaddition.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetates / chemistry
  • Alcohols / chemistry*
  • Aldehydes / chemistry*
  • Allyl Compounds / chemistry
  • Catalysis
  • Iridium / chemistry*
  • Nitrobenzoates / chemistry
  • Oxidation-Reduction
  • Silicon / chemistry
  • Stereoisomerism
  • Substrate Specificity
  • Trimethylsilyl Compounds / chemistry*

Substances

  • Acetates
  • Alcohols
  • Aldehydes
  • Allyl Compounds
  • Nitrobenzoates
  • Trimethylsilyl Compounds
  • Iridium
  • allyl acetate
  • Silicon