Heptafluoroisopropylsulfation Of Benzyl Halides

Since the fluorine element possesses unique electronic properties,such as small atomic radius and high electronegativity,a fluorinated group incorporated into organic molecules may improve their physicochemical properties.It was reported that the installation of a heptafluoroisopropylthio group(-SCF(CF₃)₂)into agrochemicals would result in profound changes of the agrochemical activity,which has received increasing attention.Although direct heptafluoroisopropylthiolation method still remains largely unexplored and the reported methods suffer from some limitations,such as unconventional operations and harsh reaction conditions.An efficient heptafluoroisopropylthiolation method is studied in this thesis.HFP/Cs F/S₈(HFP:hexafluoropropylene)is used as a reagent system to achieve heptafluoroisopropylthiolation of benzyl halides.HFP,Cs F and S₈are all easily available materials,and it is of practical value to construct-SCF(CF₃)₂group from this system.The synthetic utility is further demonstrated by a successful gram-scale reaction.HFP first combines with F^-to generate(CF₃)₂FC^-anion,which is captured by S₈to produce(CF₃)₂CFS^-anion.The nucleophilic substitution between benzyl halides and(CF₃)₂CFS^-anion provides the final products.The process could be extended to various electron-deficient,electron-neutral and electron-rich benzyl halides,and the desired products were obtained in moderate to good yields.Many functional groups could be tolerated,such as trifluoromethoxyl,halide,nitrile,carbonyl and ester groups.Although benzyl chlorides show lower reactivity,they can also be converted smoothly under these conditions.In the case of propargyl bromides,the expected products can be detected albeit in low yields.The protocol,featuring a low cost,may find great application in the synthesis of(CF₃)₂CFS-containing biologically active molecules.