Reductive Cyclization of Carbohydrate 2-Nitrophenylhydrazones to Chiral Functionalized 1,2,4-Benzotriazines and Benzimidazoles

摘要

The 2-nitrophenylhydrazones 2 of D-arabino-2-hexulopyranosonic acid. D-arabinose, D-galactose and D-galacturonic acid are used as precursors to form chiral functionalized 1,2,4-benzotriazines and benzimidazoles by reductive cyclization methods. Catalytic hydrogenation provided the amine derivatives which are cyclized and air oxidized in alkaline solution to yield the novel 1,2,4-benzotriazines 3 as the main products, while on acid catalysis the benzimidazoles 4 are formed.