selective n-acetylation and subsequent friedel-crafts acylation with phthalic anhydride produced 2-acetyl-5,12-dihydroxy-1,2-dihydro-2-azanaphthacene-6,11-dione , which was protected as its dimethyl ether and epoxidized to an acylated aza brigl 's anhydride .
C0031783
phthalic anhydride
C0003030
anhydride