N-Phenylmaleimideに対するAryldiazomethaneの付加による3-置換Pyrrolo[3,4-c]pyrazole-4,6(1H, 5H)-dione誘導体の合成

抄録

1, 3-Dipo1ar addition reaction of N-phenylmaleimide (II) with diazomethane (Ia), phenyldiazomethane (Ib), p-anisyldiazomethane (Ic), and p-tolyldiazomethane (Id) afforded the corresponding 5-phenyl-3, 3a-dihydropyrrolo[3, 4-c]pyrazole-4, 6(5H, 6aH)-dione (IIIa-d). Reaction of II with ethyl diazoacetate (If) and p-nitrophenyldiazomethane (Ig) gave, on the other hand, 5-phenyl-1, 3a-dihydropyrrolo[3, 4-c]pyrazole-4, 6(5H, 6aH)-dione (Vf, g). The addition products (IIIa-d, Vf, g) were smoothly dehydrogenated into the corresponding 5-phenylpyrrolo[3, 4-c]pyrazole-4, 6(1H, 5H)-dione (VIa-d, f, g) with bromine in acetic acid. 2-Furyldiazomethane (Ie) reacted with II to give the condensed cyclopropane derivative (IVe) and the adduct (Ve).