Application of trimethylvinylsilane as a convenient synthetic precursor of(Perfluoroalkyl)ethenes: An unusual fluoride-induced elimination-desilylation coupled reaction

[GRAPHICS] A convenient and effective method for the preparation of perfluoroalkylated ethenes is described. First, the free radical addition of perfluoroalkyl i odides to trimethylvinylsllane in the presence of AlBN gave iodoethylsilane intermediates (F(CF2)(n)CH2CHISiMe3, n = 4 (1), 6 (2), 8 (3), 10 (4); 94-9 9%). Then an unusual dehydrohalogenation-desilylation reaction was effected by tetrabutylammonium fluoride, and finally the product isolation (F(CF2)( n)CH=CH2 (5-8), 62-87%) was facilitated using a fluorous phase separation t echnique. This novel approach can also be applied to adjust short C-2 hydro carbon units to functionalized fluorinated segments (e.g., HOCH2(CF2)(8)CH= CH2 (11), 71%), All structures were verified by state-of-the-art multinucle ar one- and two-dimensional NMR experiments involving both homo- (F-19-F-19 ) and heteronuclear (H-1-C-13, F-19-C-13) correlations based on the GMQFCOP S and inverse H-1 and/or F-19 detected GHSQC, GHMQC sequences with broad-ba nd adiabatic C-13 decoupling.