3-[4-(diethylamino)-2-methylbenzoyl]-4-pyridinecarboxylic acid 、 4-[4-(diethylamino)-2-methylbenzoyl]-3-pyridinecarboxylic acid 、
二苯胺 以of acetic anhydride there was obtained an isomer mixture comprising 3-[4-(diethylamino)-2-methylphenyl]-3-(diphenylamino)furo[3,4-c]pyridine-1(3H)-one and 1-[4-(diethylamino)-2-methylphenyl]-1-(diphenylamino)furo[3,4-c]pyridine-3(1H)-one的产率得到乙酸酐