Variation in the site of lithiation of 2-(2-methylphenyl)ethanamine derivatives

J Org Chem. 2012 Dec 21;77(24):11210-5. doi: 10.1021/jo3023445. Epub 2012 Dec 10.

Abstract

Unexpectedly, lithiation of N'-(2-(2-methylphenyl)ethyl)-N,N-dimethylurea with 3 equiv of n-butyllithium in anhydrous THF at 0 °C takes place on the nitrogen and on the CH(2) next to the 2-methylphenyl ring (α-lithiation). The lithium reagent thus obtained reacts with various electrophiles to give the corresponding substituted derivatives in excellent yields. Similarly, lithiation of N-(2-(2-methylphenyl)ethyl)pivalamide under similar reaction conditions followed by reaction with benzophenone as a representative electrophile gave the corresponding α-substituted product in high yield. Surprisingly, no products resulting from lateral lithiation were observed under the conditions tried, which sharply contrasts with the reported results for lateral lithiation of tert-butyl (2-(2-methylphenyl)ethyl)carbamate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzene / chemistry*
  • Binding Sites
  • Ethylamines / chemistry*
  • Lithium / chemistry*
  • Substrate Specificity

Substances

  • 2-(2-methylphenyl)ethanamine
  • Ethylamines
  • Lithium
  • Benzene