Convenient protocols for Mizoroki–Heck reactions of aromatic bromides and polybromides with fluorous alkenes of the formula H2CCH(CF2)n−1CF3 (n = 8, 10)

Abstract

The fluorous alkenes H₂CCHR_fn (R_fn = (CF₂)_n−1CF₃; n = 8, 10) undergo the Mizoroki–Heck reaction with a variety of aromatic monobromides and polybromides such as 1,3- and 1,4-C₆H₄Br₂, 1,3,5-C₆H₃Br₃, 1,3,5-C₆H₃Br₂Cl, 1,4-XC₆H₄Br (X = CF₃, R_f8, COCH₃, CN, 1,4-OC₆H₄Br), 1,2-O₂NC₆H₄Br, 5-bromoisoquinoline, 5-bromopyrimidine, 3-bromo-5-methoxypyridine, and 3,5-dibromopyridine (sixteen examples, 78% average isolated yield). Typically, 1.2–2.4 equiv. of alkene are employed per Ar–Br bond, together with Pd(OAc)₂ catalyst (4–5 mol%/Ar–Br bond), n-Bu₄N⁺ Br⁻ (0.8–1.0 equiv./Ar–Br bond), NaOAc (1.2–2.4 equiv./Ar–Br bond), and 3 : 1 w/w DMF/THF as solvent (120 °C). No effort is necessary to exclude air or moisture, and reactions may be conducted on >10 g scales. Only E isomers of the products Ar(CHCHR_fn)_m are detected. Thirteen representative examples are hydrogenated (Pd/C, balloon pressure H₂), giving Ar(CH₂CH₂R_fn)_m (92% average isolated yield).