The selectivity observed with 2,4,7-triamino-6-methylsulfonyl-pteridine when reacted with "hard" aliphatic amines and "soft" aryl-thiols resulting in amine exchange at the 2-, 4-, and 7-positions and displacement of the 6-methylsulfonyl moiety, respectively, was further investigated in other ring systems. The substrates tested were disubstituted with amino- and methylsulfonyl- moieties, and included the benzene, pyridine, pyrazine, quinoxaline, quinazoline and pteridine ring systems. The methylsulfonyl moiety is preferentially displaced by both thiols and amines with quinoxaline and quinazoline substrates, and is more reactive towards displacement by thiol than amine nucleophiles. Amine exchange occurs with the quinoxaline substrate subsequent to displacement of the methylsulfonyl moiety and apparently takes place by an AE mechanism. The nucleophilic aromatic substitution patterns generally observed with benzenes pyridine, pyrazines, quinoxalines, quinazolines, and pteridines are reviewed.
College and Department
Physical and Mathematical Sciences; Chemistry and Biochemistry
BYU ScholarsArchive Citation
McCausland, Calvin Wilson, "Hard and soft nucleophilic substitution patterns in amino-methylsulfonylazines" (1976). Theses and Dissertations. 8307.