抄録
Conditions for nitration of 8-acetyl-7-hydroxy-4-methylcoumarin (I) was examined and a method for obtaining the 3-nitre (II) and 6-nitro (III) compounds together in a good yield was established. II and III were respectively converted to the 3-amino (IV) and 6-amino (V) compounds by catalytic reduction, and V was derived to the 6-acetamido compound (VII) by acetylation under a mild condition. VII underwent dehydrative cyclization on being heated with phosphorus pentoxide or polyphosphoric acid to 9-acetyl-2, 5-dimethyl-7-oxo-7H-pyrano[3, 2-f]benzoxazole (VIII), which forms a phenyl-hydrazone with its acetyl group was applied in 9-position. Nitration reaction of I to 6-acetyl-7-hydroxy-4-methylcoumarin (IX) and a method was established for obtaining the mononitro (X) and dinitro (XI) compounds at the same time in a good yield. Catalytic reduction of X and XI respectively afforded the monoamino (XII) and diamino (XIII) compounds. The above acetylation and oxazole cyclization of V were applied to XII and a similar reaction took place, forming 9-acetyl-2, 7-dimethyl-5-oxo-5H-pyrano-[2, 3-e]benzoxazole (XV) via its acetamido compound (XIV). XV also forms a phenyl-hydrazone like VIII. These facts suggest that the mononitro compound (X) obtained by nitration of IX is 6-acetyl-7-hydroxy-4-methyl-8-nitrocoumarin and the dinitro compound (XIII) is a 3, 8-dinitro derivative.
