Diastereoselective Synthesis of Pyrazolo[1,2‐a][1,2,4]triazine Derivatives via Cross‐1,3‐dipolar Cyclizations of Azaoxyallyl Cations with N,N′‐Cyclic Azomethine Imines.

A cross‐1,3‐dipolar cycloaddition reaction of α‐halohydroxamates (in situ generated azaoxyallyl cations) with N,N′‐cyclic azomethine imines was developed. The synthetic protocol provided facile and rapid access to pyrazolo[1,2‐a][1,2,4]triazine derivatives in good yields and excellent diastereoselectivities under mild metal‐free conditions. [ABSTRACT FROM AUTHOR]