Synthesis of Cyclic Ethers with Fluorinated Side Chains.

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.