A Facile Dipolar Entry to Diverse Dihydro‐1 H‐1,2,4‐Triazoles

Abstract

Aza‐annulation: A dipolar annulation reaction between Huisgen zwitterions and various iminoesters as well as ketimines provides a facile and efficient route to diverse dihydro‐1 H‐1,2,4‐triazoles. The method was extended to generate a library of 3,3′‐triazolylspirooxindoles.

Divergent Reactivity of Nitrocyclopropanes with Huisgen Zwitterions and Facile Syntheses of 3-Alkoxy Pyrazolines and Pyrazoles

“…The Huisgen zwitterions are a class of classical and famous 1,3-dipolar intermediates, generally in situ formed from Ph 3 P and dialkyl azodicarboxylates . Recent renewed interest from chemists has disclosed that Huisgen zwitterions could readily undergo a series of annulation reactions with various electrophiles, affording unique and efficient approaches to aza-heterocycles . We are also interested in exploring new annulations of Huisgen zwitterions and have achieved some recent successes in the synthesis of complex aza-heterocycles. , As part of our continuous efforts, recently we investigated the possible reactions of nitrocyclopropanes with Huisgen zwitterions and found an unprecedented annulation reaction leading to facile syntheses of 3-alkoxy pyrazolines and pyrazoles.…”