(Fluoroorgano)fluoroboranes and -borates -: Part 10 -: 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[C3F7OCF=CFBF3]

The nucleophilic hydrode fluorination of C3F7OCF=CF2 with the complex hydrides Li[AlH4], Li[BH4] or Na[BH4] proceeded nonstereoselectively 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 BF3.OMe2 or BF3.OEt2 yielded [C3F7OCF=CFPBu3] [BF4] (cis and trans) and, probably, [trans-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. (C) 2003 Elsevier Science B.V. All rights reserved.