Condensed pyridazines. V Reactions of 7-(methylsulfonyl)-1-phenyl-1H-1,2,3-triazolo[4,5-d]pyridazine with methoxide ion, Grignard reagents, hydrazines, and amines.

Abstract

Nucleophiles were found to react with 7- (methylsulfonyl) -1-phenyl-1H-1, 2, 3-triazolo [4, 5-d] -pyridazine (1) in three ways, depending on the nature of the reagent. One is substitution of the methylsulfonyl group in 1 by the reagent. The second one is addition of the reagent to the 4, 5-double bond in 1. The third one is the addition of the reagent, followed by ring fission of the pyridazine moiety.Thus, the reaction of 1 with sodium methoxide resulted in substitution of the methylsulfonyl group, giving 7-methoxy-1-phenyl-1H-1, 2, 3-triazolo [4, 5-d] pyridazine. (2). The addition was found to proceed in the reaction with alkylmagnesium halides and hydrazines, giving the corresponding 4-alkyl- (3a-d) and 4-hydrazino-4, 5-dihydro-7- (methylsulfonyl) -1-phenyl-1H-1, 2, 3-triazolo [4, 5-d] -pyridazines (4a, b), respectively. The reaction with primary and cyclic amines resulted in ring fission, giving the corresponding 4- (alkyliminomethyl) - (5b, c) and 4- [di (cyclic amino) methyl] -5- (methylsulfonylmethyl) -1-phenyl-1 H-1, 2, 3-triazoles (6d-f), respectively.On the other hand, the reaction of 7-chloro-1-phenyl-1H-1, 2, 3-triazolo [4, 5-d] pyridazine (7) with sodium methoxide, hydrazine, and amines resulted in the substitution of the chlorine atom, giving 2, 7-hydrazino- (11), and 7-alkylamino-1-phenyl-1H-1, 2, 3-triazolo [4, 5-d] pyridazines (12a-g), respectively, but neither addition nor ring fission was observed.