Perfluoroepoxyoxolanes in the synthesis of fluorine-containing heterocycles
摘要:
Perfluoro-3,4-epoxyoxolane and 3,4-epoxy-2-trifluoromethylpentafluorooxolane readily reacted with difunctional nucleophiles via opening of the oxirane ring and subsequent heterocyclization. Their reactions with thiourea and o-phenylenediamine gave new fluorine-containing fused heterocyclic compounds, 2-amino-3a-hydroxy-4,4,6,6,6a-pentafluoro-3a,4,6,6a-tetrahydrofuro[3,4-d][1,3]thiazole and 1,1,3,3-tetrafluoro- and 1-trifluoromethyl-1,3,3-trifluoro-1,3-dihydrofuro[3,4-b]quinoxalines, respectively. The molecular and crystalline structures of the products were determined by X-ray analysis.
Synthesis of Perfluoro- and 2-Trifluoromethylpentafluorodihydrofurans and Their Epoxy Derivatives
摘要:
Perfluorotetrahydrofuran-2-carboxylic acid was converted through a series of transformations into perfluoro-2,3-dihydrofuran and perfluoro-2,5-dihydrofuran; likewise, from (2-perfluorotetrahydrofuryl)difluoroacetic acid 2-trifluoromethylpentafluoro-2,3-dihydrofuran was obtained. Perfluoro-2,3-dihydrofuran and 2-trifluoromethylpentafluoro-2,3-dihydrofuran underwent isomerization into perfluoro-2,5-dihydrofuran and 2-trifluoromethylpentafluoro-2,5-dihydrofuran by the action of cesium fluoride. Treatment of perfluoro-2,5-dihydrofuran with SbF5 resulted in ring opening and formation of cis-perfluoro-2-butenoyl fluoride, while 2-trifluoromethylpentafluoro-2,3-dihydrofuran was converted into 2-trifluoromethylpentafluoro-2,5-dihydrofuran under the same conditions. Perfluoro-3,4-epoxytetrahydrofuran and 2-trifluoromethyl-3,4-epoxypenta-fluorotetrahydrofuran containing fused oxirane and tetrahydrofuran rings were synthesized by reactions of perfluoro-2,5-dihydrofuran and 2-trifluoromethylpentafluoro-2,5-dihydrofuran, respectively, with sodium hypochlorite.