Magnesium mediated preparation of fluorinated alkylsilanes.

Abstract

Fluorinated alkylsilanes are prepd. by reacting a fluorinated alkyl sulfur contg. compd. with a silyl chloride in the presence of a reducing agent and a solvent at -40 to 20°C for 20 min to 6 h. The fluorinated alkylsilanes have the general formula R2R3R4Si-CF2-X, wherein R2, R3 or R4 independently is an C1-24-alkyl group that can be linear or branched or cyclic, a single or fused rings, and are optionally substituted with one or more halogen, hydroxy, or C1-8-alkoxy groups, where the substituent does do not participate in the reaction; or an aryl group of between 6 and 24 members in a single ring or in fused rings, wherein the members are C or hetero atoms of N, O or S, and the ring(s) are optionally substituted with 1-3 C1-8-alkyl groups, a halogen, an alc., or a C1-8-alkoxide and X is H or F. The reducing agent can be Mg or Zn. The solvent can be DMF, THF, DMSO, dioxane, dimethoxyethane, or tetrahydropyran. The fluorinated alkyl sulfur contg. compd. is a fluorinated alkyl sulfone, a fluorinated alkyl sulfoxide, or a fluorinated alkyl sulfide, such as Ph trifluoromethyl sulfone, trifluoromethyl sulfoxide or trifluoromethyl sulfide. The fluorinated alkyl sulfur contg. compd. can be Ph trifluoromethyl sulfide which is prepd. from trifluoromethane and di-Ph disulfide, thus providing an autocatalytic method. The fluorinated alkylsilane is subsequently used as a nucleophilic fluoromethylating agent. [on SciFinder(R)]