Umpolung Reactivity of N-Sulfonylhydrazones and Imino Esters to Access Functionalized Oxazoles

Abstract

We report the synthesis of functionalized oxazoles via an umpolung reactivity of N-sulfonylhydrazones and imino esters. The reaction involves light-induced N–S bond cleavage of N-sulfonylhydrazones to produce nucleophilic diazo intermediates in the presence of Cs2CO3, which then react with electrophilic N-centered imino esters under mild conditions. The method offers high functional-group tolerance, good yields, and scalability, enabling the synthesis of biologically active molecule precursors such as HDAC6 inhibitors and angiotensin II receptor blockers.