Reaction of 1,4-dibromohexafluoro-2-butene with O- and N-nucleophiles

Abstract

Reaction of 1,4-dibromohexafluoro-2-butene (I) with sodium methoxide, ethoxide or isopropoxide in the corresponding alcohols proceeds with allylic rearrangement under formation of 3-alkoxy-4-bromohexafluoro-1-butenes II-IV. A kinetic study has proven the SN2’ mechanism for reaction of I with potassium phenoxide leading to 4-bromo-3-phenoxyhexafluoro-1-butene (V). Also the reaction of I with ammonia, affording 3-amino-4-bromo-2,4,4-trifluoro-2-butenenitrile (IX), is compatible with the allylic rearrangement by SN2’ mechanism. On the contrary, reaction of I with diethylamine gave no rearrangement product and, after hydrolysis, afforded N,N-diethyl-4-bromo-2,3,3,4,4-pentafluorobutanamide (XVI) and N,N-diethyl-4-bromo-2,3,4,4-tetrafluoro-2-butenamide (XVII) in the ratio 85:15.