S 53 Shcherbakov, K. V. Reactions of 2(3)-ethoxycarbonyl-5,6,7,8-tetrafluorochromones with methylamine [Electronic resource] / K. V. Shcherbakov, Ya. V. Burgart, V. I. Saloutin // Russian Chemical Bulletin (Translation of Izvestiya Akademii Nauk, Seriya Khimicheskaya). - 2005. - Vol. 54, № 9. - P2157-2162. - Bibliogr. : p. 2162 (18 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): CHROMONE -- METHYLAMINE -- NUCLEOPHILIC SUBSTITUTION -- RING OPENING Аннотация: 2-Ethoxycarbonyl-5,6,7,8-tetrafluorochromone reacts with methylamine differently, depending on the solvent nature and the amount of the amine: in DMSO and MeCN, the fluorine atom at the C(7) atom is initially replaced and then the C(2) and/or C(9) are attacked, while in ethanol, the reaction involves the C(2) atom with opening of the pyrone ring. The reaction of 3-ethoxycarbonyl-5,6, 7,8-tetrafluoro-2-methylchromone with methylamine results, regardless of the solvent, in opening of the chromone ring and the formation of intermediate ethyl 3-(3,4,5,6-tetrafluoro-2-hydroxyphenyl)-2-(1-methylamino)ethylidene-3- oxopropionate, which undergoes intramolecular cyclization to give 5,6,7,8-tetrafluoro-3-(1-methylamino)ethylidene-3,4-dihydro-2H-benzopyran-2, 4-dione. \\\\Expert2\\nbo\\Russian Chemical Bulletin\\2005, 54 (9), 2157-2162.pdf |