The unusual reactivity of C3F7OCF = CF2 with PBu3 and the complex hydrides M[EH4] (M: Li, Na; E: B, Al); preparation of potassium perfluoro-2-propoxyeth-1 -enyltrifluoroborate K[C3F7OCF¼CFBF3]

The nucleophilic hydrodefluorination of C3F7OCF = CF2 with the complex hydrides Li[AlH4], Li[BH4] or Na[BH4] proceeded non-stereoselectively and was accompanied by the formation of either cis- and trans-C3F7OCH = CFH and/or C3F7OCHFCF2H. The reaction of C3F7OCF = CF2 with PBu3 followed by treatment with BF3OMe2 or BF3OEt2 yielded [C3F7OCF = CFPBu3] [BF4] (cis and trans) and, probably, [f nms-Bu3PCF = CFPBu3] [BF4]2. The hydrolysis of the latter with pure water proceeded quickly while the former isomeric mixture formed the isomeric olefins C3F7OCF = CFH slowly. The usage of aqueous NaOH instead of water produced mainly trans-CHF = CHF. The metallation of C3F7OCF = CFH (cis:trans = 45:55) to C3F7OCF = CFLi and its subsequent reaction with B(OMe)3 and K[HF2] gave the salt K[C3F7OCF = CFBF3] in a different cis to trans ratio (25:75) with satisfactory yield.