A Multistep Flow Process for the Synthesis of Highly Functionalized Benzoxazoles

作者:Sedelmeier Joerg*; Lima Fabio; Litzler Alain; Martin Benjamin; Venturoni Francesco
来源:Organic Letters, 2013, 15(21): 5546-5549.
DOI:10.1021/ol402706a

摘要

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.

  • 出版日期2013-11-1