Solvent-free, uncatalyzed asymmetric "ene" reactions of N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimines: a general approach to enantiomerically pure α-(trifluoromethyl)tryptamines

Org Biomol Chem. 2017 May 10;15(18):3930-3937. doi: 10.1039/c7ob00670e.

Abstract

A novel approach to regioselectively substituted and stereoselectively α-trifluoromethylated tryptamines is reported based on the ene reaction of Boc-protected 3-methyleneindolines with optically pure (R)- or (S)-tert-butanesulfinyltrifluoroacetaldimine. Boc- and sulfinylamido-protected α-trifluoromethyltryptamines are obtained in 60-70% yield and 85/15 dr by just heating equimolar amounts of the two reaction partners at 80-90 °C for 2-3 h without a solvent. The absolute configuration of the amino α-carbon has been assigned based on the vibrational circular dichroism (VCD) spectral analysis. The two protecting group can be chemoselectively removed allowing further regio- and stereoselective elaboration of the ene products to various biologically interesting compounds.

MeSH terms

  • Alkenes / chemistry*
  • Imines / chemistry*
  • Stereoisomerism
  • Tryptamines / chemistry*

Substances

  • Alkenes
  • Imines
  • Tryptamines
  • tryptamine