Synthesis of Cyclic Ethers with Fluorinated Side Chains

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Abstract
Di-tert-butyl peroxide initiated free radical addition of THF to various fluorinated alkenes (CF(2)=CH(2), CF(2)=CFH, CH(2)=CHCF(3), CF(2)=CFCF(3), CF(2)=CFC(5)F(11), CF(2)=CFOCF(2)CF(CF(3))OCF(2)CF(2)SO(2)F) gives either bidirectional addition products [CH(2)CH(2)CH(2)OCH(CF(2)CH(3)) (1), CH(2)CH(2)CH(2)OCH(CH(2)CHF(2)) (2), CH(2)CH(2)CH(2)OCH(CF(2)CH(2)F) (3), and CH(2)CH(2)CH(2)OCH(CFHCHF(2)) (4)] or unidirectional products [CH(2)CH(2)CH(2)OCH(CH(2)CH(2)CF(3)) (5), CH(2)CH(2)CH(2)OCH(CF(2)CHFCF(3)) (6), CH(2)CH(2)CH(2)OCH(CF(2)CHFC(5)F(11)) (7), and CH(2)CH(2)CH(2)OCH(CF(2)CHFOCF(2)CF(CF(3))OCF(2)CF(2)SO(2)F) (8)] depending on the structure of the alkene. Reaction of dioxane with CF(2)=CFOCF(2)CF(CF(3))OCF(2)CF(2)SO(2)F gives a single product, CH(2)OCH(2)CH(2)OCH(CF(2)CHFOCF(2)CF(CF(3))OCF(2)CF(2)SO(2)F) (9). In the case of hexafluoropropene or perfluoroallylbenzene, reaction with an excess of tetrahydrofuran gives only the monosubstituted products CH(2)CH(2)CH(2)OCH(CF(2)CHFCF(3)) (6) and CH(2)CH(2)CH(2)OCH(CF(2)CFHCF(2)C(6)F(5)) (11) respectively. When tetrahydrofuran is reacted with a 3:1 molar excess of the same two perfluoroalkenes, the disubstituted products CH(2)CH(2)CH(CF(2)CHFCF(3))OCH(CF(2)CHFCF(3)) (10) and CH(2)CH(2)CH(CF(2)CFHCF(2)C(6)F(5))OCH(CF(2)CFHCF(2)C(6)F(5)) (12) are formed respectively. When 18-crown-6 is reacted in the same way with fluoroalkenes in a 1:1 molar ratio, the monosubstituted products 18-crown-6-CH(2)CH(2)CF(3) (13), 18-crown-6-CF(2)CHFCF(3) (14), 18-crown-6-CF(2)CFHCF(2)C(6)F(5) (15), and 18-crown-6-CF(2)CHFOCF(2)CF(CF(3))OCF(2)CF(2)SO(2)F (16) are obtained. Polyfluorinated 18-crown-6 products containing three and two polyfluroalkyl/aryl groups are prepared when 18-crown-6 is reacted with a 3:1 molar excess of perfluoropropene and perfluoroallylbenzene to give 18-crown-6-(CF(2)CHFCF(3))(3) (17) and 18-crown-6-(CF(2)CFHCF(2)C(6)F(5))(2) (18), respectively. (Pentafluorophenoxy)trimethylsilane reacts with 11 in the presence of a catalytic amount of cesium fluoride to give compound 19, CH(2)CH(2)CH(2)OCH(CF(2)CFHCF(2)C(6)F(4)OC(6)F(5)). Two molecules of 11 are bridged by reaction with Me(3)SiOCH(2)CF(2)CF(2)CF(2)CH(2)OSiMe(3) to give CH(2)CH(2)CH(2)OCHCF(2)CFHCF(2)C(6)F(4)OCH(2)CF(2)CF(2)CF(2)CH(2)OC(6)F(4)CF(2)CHFCF(2)CHOCH(2)CH(2)CH(2) (20), while 12 forms the macroheterocycle OCHCH(2)CH(2)CHCF(2)CFHCF(2)C(6)F(4)OCH(2)CF(2)CF(2)CF(2)CH(2)OC(6)F(4)CF(2)CFHCF(2) (21) under similar reaction conditions. The lanthanum triflate complexes of 18-crown-6 (22) and 18-crown-6(CF(2)CFHCF(3)) (23) were prepared and the structures were obtained via single-crystal X-ray analysis. Although crystals suitable for single-crystal X-ray analysis could not be formed, lanthanum triflate complexes were formed with polyfluorinated ethers 15 and 16 to give the fluorinated complexes La(OSO(2)CF(3))(3)(18-crown-6-CF(2)CFHCF(2)C(6)F(5))(H(2)O) (24) and [La(OCH(2)CH(2))(5)OCH(2)CHCF(2)CFHOCF(2)C(CF(3))FOCF(2)CF(2)SO(2)F](3+)[CF(3)SO(3)(-)](3) (25) respectively. The acid salt La[N(SO(2)CF(3))(2)](3) (26) was also prepared and characterized, and reacted with dibenzo-18-crown-6 to give the complex dibenzo-18-crown-6-La[N(SO(2)CF(3))(2)](3) (27).