Chemoselectivity Reversals in Quinoxalines: The Reaction of 5-Chloro-6-nitroquinoxaline with Nucleophiles.

5-Chloro-6-nitroquinoxaline 2, made in six steps from 2,3-dichloronitrobenzene, reacts 1) with piperidine to give 6-nitro-5-piperidinoquinoxaline as the only product; 2) with methoxide to give a 95:5 ratio of 5-methoxy-6-nitro- and 5-chloro-6-methoxyquinoxaline; 3) with p-thiocresolate to give the disubstitution product without showing any monosubstitution product.