Denitrative imino-diaza-Nazarov cyclization: synthesis of pyrazoles

Abstract

An iodine-catalyzed denitrative imino-diaza-Nazarov cyclization (DIDAN) methodology has been developed for the synthesis of pyrazoles with high to excellent yields by using α-nitroacetophenone derivatives and in situ generated hydrazones. The key transformation of this oxidative 4π-electrocyclization proceeds through an enamine–iminium ion intermediate. This rapid one-pot DIDAN protocol results in the selective generation of C–C and C–N bonds and cleavage of a C–N bond.