Hydrolysis difluoromethylene group

Trifluoromethyl groups are very resistant to hydrolysis, unless they are allylic or benzylic, or vicinal to a carbon linked to hydrogen. In the last case, elimination of hydrogen fluonde leads to the formation of a difluoromethylene group which is key to additional reactions... 

The N-pyrrolylzinc chloride 53 undergoes Pd-catalyzed coupling with perfluoroalkyl iodides to afford the 2-substituted pyrroles 54 in good yield [52], Smaller amounts (15-20%) of 2-perfluoroalkanoyl pyrroles, which presumably arise by hydrolysis of the benzylic difluoromethylene group, are also formed. This reaction, which is performed in one pot, also affords 2-phenylpyrrole (75%) and 3-phenylpyrrole (5%) with iodobenzene. Some biphenyl (15%) is also formed. 

The difluoromethylene group in 2,2,4-trichloro-3,5,5-trifluoro-2,5-dihydrofuran (30) is activated towards acidic hydrolysis to give chlorofluoromaleic acid.152... 

Sulfur also facilitates the hydrolysis of a difluoromethylene group. Treatment of dodecafluoro-l,6-bis(methylsulfanyl)hexane with sulfuric acid affords octafluorohexanedioic acid (33).156... 

Prior hydrolysis of the difluoromethylene group in either the 3- or 17-cycIo-propenyl alcohols (13Sa and b) affords the corresponding cyclopropenones, which on treatment with the fluoramine reagent are converted cleanly into analogous 3 - and 17/9-allenic carbonyl fluorides (142) and (143) in this case a-isomers were not detected (Scheme 38). 

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