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Updated: May 8, 2026

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Umpolung reactivity of N-sulfonylhydrazones and imino esters to access functionalized oxazoles
Mohammad Junaid1, Pokhriyal Yamini1, Dongari Yadagiri1
1Department of Chemistry, Laboratory of Organic Synthesis & Catalysis Indian Institute of Technology Roorkee, Roorkee, Uttarakhand-247667, India. yadagiri.dongari@cy.iitr.ac.in.
Abstract:
We report the synthesis of functionalized oxazoles via 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 precursor molecules such as HDAC6 inhibitors and angiotensin II receptor blockers.
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