A Convenient and General Approach to Alkyl-, Alk-1-enyl-, and Aryldifluoroboranes

Abstract

A simple and general procedure, especially useful for the small scale preparation of alkyl-, alk-1-enyl-, and aryldifluoroboranes RBF 2 was elaborated. Suspensions of the easily available and storable K [RBF 3 ] salts undergo fluoride abstraction when treated

Polyfluoroorganotrifluoroborates and -difluoroboranes: interesting materials in fluoroorgano and fluoroorgano-element chemistry

“…The volatility is responsible for the remarkable loss of yield during the separation. The 19 F resonance of the BF 2 group of 9 at À73.8 ppm is similar to that of C 8 H 17 BF 2 (À73.2 [13]) and deshielded relative to C 6 F 13 BF 2 (À78.3 ppm [5]). Even in the 11 B mode 9 (d = 27.5) behaves like C 8 H 17 BF 2 (d = 28.4) and different to C 6 F 13 BF 2 (d = 19.2 ppm).…”

Bis(perfluoroorganyl)bromonium salts [(RF)2Br]Y (RF=aryl, alkenyl, and alkynyl)

“…Tris(pentafluorophenyl)borane [18], C 6 F 5 SiF 3 [33], C 6 F 5 SiMe 3 [34], Li[C 6 [38], and solutions of cis-C 2 F 5 CF5 5CFBF 2 , trans-CF 3 CF5 5CFBF 2 [39], CF 3 CCBF 2 [40] in PFB or PFP were prepared as described. Salt K[C 6 F 13 BF 3 ] [41] and solutions of C 6 F 5 BF 2 [42] and C 6 F 13 BF 2 [41] in PFB or PFP were prepared by modified procedures (see below). Bromine trifluoride was prepared by bubbling of fluorine (25%, v/v in N 2 ) into dry bromine at 8-20 8C and AsF 5 from AsF 3 with undiluted F 2 at 20 8C.…”

A well feasible and general route to (organoethynyl)difluoroboranes, RHCCBF2, and their perfluorinated analogues, RFCCBF2

“…19 F NMR (PFP, À20 8C): d À72.2 (br s, t 1/2 = 153 Hz, BF 2 ), À79.1 (t, 4 J(F 5 , F 3 ) = 8 Hz, 3F, F 5 ), À100.6 (t, 3 J(F 3 , F 4 ) = 4 Hz, q, 4 J(F 3 , F 5 ) = 8 Hz, 2F, F 3 ), À125.6 (t, 3 J(F 4 , F 3 ) = 4 Hz, 2F, F 4 ). 11 B NMR (PFP, À20 8C): d 15.5 (br s, t 1/2 = 100 Hz).…”

“…19 F NMR (PFP, À30 8C): d À74.9 (br s, t 1/2 = 45 Hz, 2F, BF 2 ), À134.0 (m, 2F, F ortho ), À148.1 (t, 3 J(F para , F meta ) = 19 Hz, t, 4 J(F para , F ortho ) = 4 Hz, 1F, F para ), À161.2 (m, 2F, F meta ). 11 …”

“…Our approach is based on the abstraction of fluoride from K[RBF 3 ] salts with an appropriate fluoride anion acceptor. This procedure was successfully employed in the preparation of alkyldifluoroboranes, alkenyldifluoroboranes, aryldifluoroboranes [11], and their partially fluorinated and perfluorinated analogues [12]. In order to demonstrate the general character of this method, a representative series of (organoethynyl)difluoroboranes, RCBBCBF 2 , containing different types of alkyl and perfluoroorgano groups R was prepared in solutions and characterised by multi-NMR spectroscopy.…”