Phthalazino(2,3-b)phthalazine-5,12-dione prepn - from the 5,7,12-trione via 2-(o-carboxybenzyl)1(2H)-phthalazinone

摘要

Anti-inflammatory phthalazino 2,3-b phthalazine-5(14H), 12(7H)-dione is prepd. by (a) reducing phthalazino 2,3-b -phthalazine-5(14H),7,12-trione with an alkali metal borohydride (esp. NaBH4) in an inert O-contg. organic solvent (esp. dioxan or THF); (b) treating the resulting 7-hydroxyphthalazino 2,3-b phthalazine-5(14H), 12(7H)-dione with dil. acid or lower alkanol in the presence of acid; and (c) reducing the resulting 2-(o-carboxybenzyl)-1(2H)-phthalazine or lower alkyl ester thereof with a reducing metal (e.g., Zn, Sn or Al) in an acid medium or with H2 in the presence of a hydrogenation catalyst.