A multistep flow process for the synthesis of highly functionalized benzoxazoles

Org Lett. 2013 Nov 1;15(21):5546-9. doi: 10.1021/ol402706a. Epub 2013 Oct 22.

Abstract

An efficient and scalable transformation of 3-halo-N-acyl anilines to the corresponding benzoxazoles within a continuous flow reactor is reported. This transformation proceeds via base-mediated deprotonation, ortho-lithiation, and intramolecular cyclization to provide unstable lithiated benzoxazole moieties. The subsequent in-line electrophilic quench results in the formation of substituted benzoxazoles in high yield and quality. Continuous flow technology allowed for accurate temperature control and immediate in-line quench while minimizing the hold-up time for the unstable lithiated intermediates thereby minimizing associated byproduct formation.

MeSH terms

  • Aniline Compounds / chemistry*
  • Benzoxazoles / chemical synthesis*
  • Benzoxazoles / chemistry
  • Catalysis
  • Cyclization
  • Molecular Structure
  • Stereoisomerism

Substances

  • Aniline Compounds
  • Benzoxazoles