Chemistry of Heterocyclic Compounds, Vol. 38, No. 5, 2002 ... AE Shchekotikhin, DA Silaev, EP Baberkina, IG Makarov, VN Buyanov, ... The previously unknown 4,11-dimethoxynaphtho[2,3-f]indazole-5,10-dione has been obtained by the thermal cyclization of N-nitroso derivative of 2-acetamido-3-methyl-1,4-dimethoxyanthraquinone. ... Keywords: substituted N-acetyl-N-nitrosoanthraquinone, naphtho[2,3-f]indazoledione, thermal cyclization.