Vinylidene chloride → 4-Bromo-3-chloro-3,4,4-trifluorobutanoic acid

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Reaction Steps

A new method to prepare the desired 3,4,4-trifluoro-3-butenoic acid (IV) involves a one pot reaction of 1-chloro-1,2-dibromotrifluoroethane (VI) or 1,1,2-trichlorotrifluoroethane (X) with vinylidene chloride in the presence of ammonium persulfate/sodium formate/air in DMF to give directly 4-bromo-3-chloro-3,4,4-trifluorobutanoic acid (VIII) or novel compound 3,4-dichloro-3,4,4-trifluoro-butanoic acid (XI). The reaction conditions to prepare XI from X are similar to those described in Hu, Chang-Ming; Qing, Feng-Ling; Zhang, Hong-Gen; J. Fluorine Chem., 1990, (49) 275-280. The information of XI in the above reaction was confirmed by GC/MS (EI): m/z 212 (M+ +2), 210 (M+), 195, 193, 157, 155, 127, 125, 107, 105, 89, 69, 45. Dehalogenation of VIII or XI with zinc gives IV. ##STR5## The compounds of formula XVII can also be prepared by an alternate method to prepare selected compounds of formula I as exemplified with XV shown in Scheme 4. The reaction sequence shown in Scheme 4 using novel intermediate XII and XIII exemplified by XIV can also be carried out by substituting XI in place of VIII to prepare compounds of formula XVII. ##STR6##

Provenance & Evidence