The Reaction of Quinoxaline‐ and Phenazine‐N‐Oxides with Thionyl Chloride and Paratoluenesulfonyl Chloride

Abstract

Abstract2,3‐Diphenylquinoxaline‐N‐oxide 1 with thionyl chloride gives only 5‐chloro‐ and 6‐chloro‐quinoxaline and very little deoxygenation. Phenazine‐N5‐oxide 2, in the same conditions, gives mainly 2‐chlorophenazine and minor amounts of 1‐chlorophenazine, but here deoxygenation is an important pathway. Freshly recrystallized para‐toluenesulfonyl chloride gives a high chlorination‐to‐tosyloxylation ratio. All these results point to a variable ability of acid chlorides to yield homocycle chlorination or acyloxylation; this is confirmed by the observation that phenazine‐N5‐oxide and phosphoryl chloride give fair amounts of aryl phosphate.