Reductive cyclization of carbohydrate 2-nitrophenylhydrazones to chiral functionalized 1,2,4-benzotriazines and benzimidazoles

The 2-nitrophenylhydrazones 2 of D-arabino-2-hexulopyranosonic acid, D-arab inose, D-galactose and D-galacturonic acid are used as precursors to form c hiral functionalized 1,2,4-benzatriazines and benzimidazoles by reductive c yclization 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 b enzimidazoles 4 are formed.