Synthesis of 2-amino-5-aryl-1,3,4-oxadiazole 2a under photoredox catalysis

February 28, 2024

• Title:       

  Synthesis of 2-amino-5-aryl-1,3,4-oxadiazole 2a under photoredox catalysis

• Image Source:

  Photocatalytic oxidative heterocyclization of semicarbazones: An efficient approach for the synthesis of 1,3,4-oxadiazoles

• Mark:

  Scheme 1

• Associated context:

  In view of the above discussion and our continued efforts towards developing straightforward, efficient, and cost-effective heterocyclization reactions, we envisaged that eosin Y catalyzed visible-light-initiated cyclization of substituted semicarbazones to the corresponding 5-substituted 2-amino-1,3,4-oxadiazoles could be feasible (Scheme 1). For this purpose, we focused on CBr4 in combination with eosin Y, which is easy to handle and absorbs visible  light to generate active radical species and hence was expected to be suitable for the cyclization.