HETEROCYCLIC ANALOGS OF 5,12-NAPHTHACENE- QUINONE. 12. SYNTHESIS OF 2-SUBSTITUTED DERIVATIVES OF 4,11-DIMETHOXY-5,10-DIOXOANTHRA[2,3- b ]FURAN-3-CARBOXYLIC ACIDS

The synthesis of anthrafurandiones, by means of which it is possible to obtain a series of previously unknown 2-substituted derivatives of 4,11-dimethoxy-5,10-dioxoanthra[2,3- b ]furan-3-carboxylic acids after protection of the hydroxy groups of the initial 2,3-dibromoquinizarin, was optimized. Unlike most of the analogs, 4,11-dimethoxy-5,10-dioxo-2-(trifluoromethyl)anthra[2,3- b ]furan-3-carboxylic acid ester is best synthesized from 2,3-dibromoquinizarin with subsequent methylation of the hydroxy groups. The heterocyclic ring of this ester was found to have low stability during the action of alkalis. This, together with the side deacetylation of the intermediate, is probably the main reason for its low yield at the heterocyclization stage. How to Cite Tikhomirov, A. S.; Shchekotikhin, A. E.; Luzikov, Yu. N.; Korolev, A. M.; Preobrazhenskaya, M. N. Chem. Heterocycl. Compd. 2014 , 50 , 271. [ Khim. Geterotsikl. Soedin. 2014 , 298.] For this article in the English edition see DOI 10.1007/s10593-014-1471-x