Chemical properties of 7-methoxy-1-phenyl-1H-pyrazolo [3, 4-d] pyridazine 5-oxide (V) obtained in the reaction of 7-methoxy-1-phenyl-1H-pyrazolo [3, 4-d] pyridazine (IV) with m-chloroperbenzoic acid were studied. Compound V reacted with nucleophiles to give 4 (R
2), 7 (R
1)-disubstituted 1-phenyl-1H-pyrazolo [3, 4-d] pyridazine or the ring fission product, methyl 4 (R
8)-substituted 1-phenyl-1H-pyrazole-5-carboxylate. The reaction of V with each of phosphoryl chloride and sulfuryl chloride gave VI (R
2=Cl, R
1=OCH
3) and XI (R
2=Cl, R
1=OH). In the case of the reaction of V with tosyl chloride, XII (R
3=CH (-Cl)-p-tosyl) was obtained together with VI and XI. The reaction of V with potassium hydroxide solution gave IX (R
2=H, R
1=OH, 5-oxide). The reaction of V with ethyl cyanoacetate in acetic anhydride gave XIII (R
2=NC-CH-CO
2C
2H
5, R
1=OCH
3). The Grignard reaction of V with methylmagnesium iodide and ethylmagnesium bromide gave XIVa (R
2=CH
3, R
1=OCH
3) and XIVb (R
2=C
2H
5, R
1=OCH
3), respectively. Application of the Reissert reaction to V resulted in the formation of XVI (R
3=CH=C (-OCH
3)-(4-formyl-1-phenyl-1H-pyrazol-5-yl). The reaction of V with acetic anhydride afforded XVII (R
2=OH, R
1=OCH
3), XVIII (R
3=CH (-COCH
3)-O-COCH
3), and XIX ((R
3=CH=)
2). The reaction of V with acetyl chloride afforded XI, XXa (R
3=CH (-COCH
3)-R
4, R
4=4-chloro-6, 7-dihydro-7-oxo-1-phenyl-1H-pyrazolo [3, 4-d] pyridazin-6-yl) and XXI (R
3=CH
2-R
4). A similar ring fission occurred in the reaction of V with benzoly chloride to afford XXb (R
3=CH (-COPh)-R
4), XXI, and XIX. The reaction of V with dimethyl acetylenedicarboxylate afforded 7-methoxy-1-phenyl-1H-pyrazolo [3, 4-d] pyridazinium 3-methoxy-1-methoxycarbonyl-2, 3-dioxopropylide (XXII), trimethyl 9-methoxy-1-phenyl-1H-pyrazolo [3, 4-d] pyrrolo [1, 2-b] pyridazine-4, 5, 6-tricarboxylate (XXIII), and methyl 5-methoxycarbonyl-6-methoxy-α-oxo-1-phenyl-1, 5H-cyclopenta [c]-pyrazol-5-ethanoate (XXIV). It is considered that the ring fission products are formed by the cleavage of pyridazine ring accompanied with the liberation of nitrogen.
抄録全体を表示