Diastereoselective (3+3) Cycloaddition of Azomethine Imines with In Situ Formed Azaoxyallyl Cations from α‐Halohydroxamate

Abstract A diastereoselective (3+3) cycloaddition of azomethine imines and in situ‐ generated azaoxyallyl cations from α ‐halohydroxamate promoted by a Brønsted base has been developed. A series of pyrazolo [1,2‐a][1,2,4]triazin‐6‐ones were accessed with up to 95% yields and diastereoselectivities greater than 20:1. The asymmetric version of this reaction was explored and moderate enantioselectivity was achieved after screening a series of cinchonine‐derived chiral catalysts. magnified image