(Fluoroorgano)fluoroboranes and -borates. 14. Preparation of potassium ((perfluoroorgano)ethynyl)trifluoroborates K[RFC=CBF3]

Article abstract of DOI:10.1021/om050590f

The first representatives of an unknown family of organoboron compounds, the ((perfluoroorgano)ethynyl)trifluoroborate salts K[R_FC=CBF ₃] (R_F = CF₃, C₃F₇, (CF₃)₂CF, C<

Full text of DOI:10.1021/om050590f

Organometallics 2005, 24, 5311-5317
5311
(Fluoroorgano)fluoroboranes and -borates. 14.
Preparation of Potassium
((Perfluoroorgano)ethynyl)trifluoroborates
K[RFCtCBF3]
Vadim V. Bardin,† Nicolay Yu. Adonin,‡ and Hermann-Josef Frohn*,‡
N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, SB RAS,
Acad. Lavrentjev Ave. 9, 630090 Novosibirsk, Russia, and Department of Chemistry,
Inorganic Chemistry, University Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany
Received July 13, 2005
The first representatives of an unknown family of organoboron compounds, the ((perfluoro-
organo)ethynyl)trifluoroborate salts K[RFCtCBF3] (RF ) CF3, C3F7, (CF3)2CF, C6F13, CF3-
CFdCF, C4F9CFdCF, C6F5), were prepared and characterized by multi-NMR spectroscopy
(11B, 13C, and 19F) and their vibrational spectra (IR and Raman).
Introduction
investigated approaches to the synthesis of ((perfluoro-
organo)ethynyl)trifluoroborate salts K[RFCtCBF3]. We
have included perfluorinated alkyl, alkenyl, and aryl
groups RF attached to C-2 of the ethynyl unit.5
Despite the remarkable progress in organoboron
chemistry, (alkynyl)fluoroborates remained unknown
until 1999, when Darses et al. reported the preparation
of the first two potassium (alkynyl)trifluoroborates,
K[RCtCBF3] (R ) Bu, Et3Si).1 Later Molander et al.
extended this series of salts with R ) C8H17, C6H5, C6H5-
CH2CH2, CClH2CH2CH2, CH2dC(CH3), Me3Si, and
t-BuMe2SiOCH2CH2.2 Both groups introduced (alkynyl)-
trifluoroborates successfully into Pd-catalyzed cross-
coupling reactions and demonstrated impressively the
application potential of alkynyltrifluoroborate salts.
It is well-known that the replacement of all or the
majority of hydrogen atoms by fluorine atoms in hydro-
carbons or in their organoelement derivatives caused
significant changes of their physical and chemical
properties. 3 In this regard the chemistry of organoboron
compounds is no exception. A recently published review
presented a number of peculiarities which were derived
from the combination of the specific properties of both
roots, organofluorine and organoboron chemistry, and
their co-action.4
Results and Discussion
Over the last few years we have reported a straight-
forward and widely applicable route to potassium
(polyfluoroalkyl)trifluoroborates,6-7 (polyfluoroalk-1-
enyl)trifluoroborates,8-11 and (polyfluoroaryl)trifluoro-
borates7,12 which is based on the nucleophilic addition
of (polyfluoroorganyl)lithium (or -magnesium halide) to
tris(alkoxy)boranes and the subsequent replacement of
the alkoxy groups by fluorine in the intermediate (poly-
fluoroorganyl)trialkoxyborates using aqueous solutions
of K[HF2] or K[HF2] in hydrofluoric acid (Scheme 1).
Scheme 1
B(OAlk)3
R′FM
8 M[R′FB(OAlk)3] K[HF2]8 K[R′FBF3]
M ) Li, MgX
We have continued our systematic studies in the field
of polyfluorinated organofluoroborates and -boranes and
We applied this reaction strategy to the synthesis of
potassium ((perfluoroorgano)ethynyl)trifluoroborates. In
general, the reactive key nucleophiles RFCtCM were
obtained by metalation of perfluoroorganoethynes RFCt
* To whom correspondence should be addressed. E-mail: frohn@
uni-duisburg.de.
† N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry.
‡ University Duisburg-Essen.
(5) Preliminary communication: Bardin, V. V.; Adonin, N. Yu.;
Frohn, H.-J. 14th European Symposium on Fluorine Chemistry,
Poznan, Poland, July 11-16, 2004; Adam Mickiewicz University:
Poznan, Poland, 2004; p B-P-31.
(6) Frohn, H.-J.; Bardin, V. V. Z. Anorg. Allg. Chem. 2001, 627, 15-
16.
(1) Darses, S.; Michaud, G.; Genet, J.-P. Eur. J. Org. Chem. 1999,
1875-1883.
(2) Molander, G. A.; Katona, B. W.; Machrouhi, F. J. Org. Chem.
2002, 67, 8416-8423.
(3) Peculiarities in reactivities of perfluorinated organic and orga-
noelement compounds with regard to their nonfluorinated analogues
are reported and discussed in monographs: Sheppard, W. A.; Sharts,
C. M. Organic Fluorine Chemistry; Benjamin: New York, 1969. Kirsch,
P. Modern Fluoroorganic Chemistry; Wiley: Weinheim, Germany,
2004. Chambers, R. D. Fluorine in Organic Chemistry; Blackwell:
Oxford, U.K., 2004. For more examples see the following handbooks:
Hudlicky, M. Chemistry of Organic Fluorine Compounds, 2nd revised
ed.; Ellis Horwood: New York, 1992. Methods of Organic Chemistry
(Houben-Weyl): Organo-Fluorine Compounds; Baasner, B., Hagemann,
H., Tatlow, J. C., Eds.; Thieme: Stuttgart, Germany, 2000; Vol. E10.
(4) Bardin, V. V.; Frohn, H.-J. Main Group Met. Chem. 2002, 25,
589-613.
(7) Abo-Amer, A.; Adonin, N. Yu.; Bardin, V. V.; Fritzen, P.; Frohn,
H.-J.; Steinberg, Ch. J. Fluorine Chem. 2004, 125, 1771-1778.
(8) Frohn, H.-J.; Bardin, V. V. Z. Anorg. Allg. Chem. 2001, 627,
2499-2505.
(9) Frohn, H.-J.; Adonin, N. Yu.; Bardin, V. V. Z. Anorg. Allg. Chem.
2003, 629, 2499-2508.
(10) Frohn, H.-J.; Bardin, V. V. J. Fluorine Chem. 2003, 123, 43-
49.
(11) Frohn, H.-J.; Bardin, V. V. Z. Anorg. Allg. Chem. 2003, 629,
2465-2469.
(12) Frohn, H.-J.; Franke, H.; Fritzen, P.; Bardin, V. V. J. Orga-
nomet. Chem. 2000, 598, 127-135.
10.1021/om050590f CCC: $30.25 © 2005 American Chemical Society
Publication on Web 09/27/2005

5312 Organometallics, Vol. 24, No. 22, 2005
Bardin et al.
CH, or in some cases they were generated in situ from
an appropriate precursor.
unknown compounds. We elaborated an easy route of
synthesis which consists of the nucleophilic substitution
of one fluorine atom in perfluoroalk-1-ene by ((trimeth-
ylsilyl)ethynyl)lithium followed by protodesilylation of
perfluorinated 1-(trimethylsilyl)alk-3-en-1-yne. For ex-
ample, the reaction of hexafluoropropene with Me3SiCt
CLi yielded 1-(trimethylsilyl)pentafluoropent-3-en-1-yne
(10; cis:trans ) 1:2),19 which was converted into pen-
tafluoropent-3-en-1-yne (11) by treatment with KF in
aqueous DMSO (Scheme 4).
Synthesis of RFCtCH. Perfluorinated organo-
ethynes RFCtCH are in general not commercially
available. This is in contrast to the fact that a consider-
able progress in their chemistry has been achieved.13
We employed short and reliable procedures for the
synthesis of RFCtCH compounds. We applied methods
which principally were described in the literature. Thus,
(pentafluorophenyl)acetylene (1) was prepared from
iodopentafluorobenzene in two steps (Scheme 2).14,15 We
should note that in our hands the formation of ((pen-
tafluorophenyl)ethynyl)trimethylsilane (2) was always
accompanied by a significant reduction of C6F5I to
C6F5H, which was not mentioned in the original re-
port.15 This side reaction diminished the isolated yield
of 2 to 45-48% under either the reported or modified
reaction conditions (temperature, reaction time).
Scheme 4
CF3CFdCF2 Me SiCtCLi8
3
g-75 °C
(E,Z)-CF3CFdCFCtCSiMe3 KF, aq DMSO8
e50 °C
10
(E,Z)-CF3CFdCFCtCH
11
Scheme 2
Synthesis of K[RFCtCBF3] Salts from RFCtCH.
The metalation of (perfluoroorgano)ethynes 11, 3, 4, and
1 with BuLi or EtMgBr and sequential reactions with
B(OAlk)3 and K[HF2]/aqueous HF resulted in potassium
((pentafluoroorgano)eth-1-ynyl)trifluoroborate 12 (cis:
trans ) 1:2) and 13-15, respectively (Scheme 5).
(Ph3P)2PdCl2, CuI
C6F5I + HCtCSiMe3 Et N, 48 h, 30-35 °C8
3
C6F5CtCSiMe3
2
C6F5CtCSiMe3 + KOH MeOH, 20 °C8 C6F5CtCH
Scheme 5
1
RFCtCH (1) EtMgBr or BuLi8
The synthesis of 3,3,4,4,5,5,5-heptafluoropent-1-yne
(3) and 3-(trifluoromethyl)-3,4,4,4-tetrafluorobut-1-yne
(4) was performed by a coupling reaction which was
offered for the preparation of CnF2n+1CtCH (n ) 4, 6,
8)16 and later modified (Scheme 3).17-18
(2) B(OMe)3;
11, 3, 4
(3) K[HF2], aq HF
K[RFCtCBF3]
12 (21%), 13 (45%), 14 (72%)
RF ) CF3CFdCF (11, 12), C3F7 (3, 13),
(CF3)2CF (4, 14)
Scheme 3
CF3CO2H, CH2Cl2
RFI + HCtCC(OH)(CH3)2 + Zn
8
(1) EtMgBr
C6F5CtCH
8 K[C6F5CtCBF3]
15 (64%)
(2) B(O-i-Pr)3;
(3) K[HF2], aq HF
(E,Z)-RFCHdClC(OH)(CH3)2
5, 6
1
5, 6 KOH, aq EtOH8 RFCtCC(OH)(CH3)2 NaOH8
Synthesis of RFCtCLi without Direct Metala-
tion of RFCtCH and Its Conversion into K[RFCt
CBF3] Salts. In some cases more convenient paths to
the nucleophile RFCtCLi are possible without the
primary preparation of (perfluoroorgano)ethynes: for
example, in the case of CF3CtCLi. Principally trifluo-
ropropyne is commercially available as a starting mate-
rial, but it is very expensive. Here the recent reports of
Brisdon et al. opened a suitable route to (trifluoropro-
pynyl)lithium by the reaction of 1,1,1,3,3-pentafluoro-
propane with 3 equiv of BuLi.20,21 CF3CtCLi generated
by this route reacted with B(OMe)3 to give lithium
(trifluoroprop-1-ynyl)trimethoxyborate (major) and li-
thium bis(trifluoroprop-1-ynyl)dimethoxyborate (minor),
which were both identified in solution by 11B and 19F
NMR spectroscopy. After treatment of the reaction
mixture with K[HF2] in aqueous HF, potassium (tri-
fluoroprop-1-ynyl)trifluoroborate (16) was the only
product and could be isolated. Probably, protodeboration
20 °C
7, 8
RFCtCH
3, 4
RF ) C3F7 (5, 7, 3), (CF3)2CF (6, 8, 4)
It is worth mentioning that the elimination of HI from
iodoalkene 6 (RF ) (CF3)2CF) with KOH in aqueous
ethanol was accompanied by partial reduction to trans-
(CF3)2CFCHdCHC(OH)(CH3)2 (9), while iodoalkene 5
did not undergo such a side reaction. However, alkyne
4 obtained in the next step was not contaminated with
olefin 9 or products derived from 9.
Perfluorinated alk-3-en-1-ynes RFCFdCFCtCH were
potential precursors for K[RFCFdCFCtCBF3] salts but
(13) Turbanova, E. S.; Petrov, A. A. Usp. Khim. 1991, 60, 1005-
1048; Chem. Abstr. 1991, 115, 135116.
(14) Neenan, T. X.; Whitesides, G. M. J. Org. Chem. 1988, 53, 2489-
2496.
(15) Zhang, Y.; Wen, J. J. Fluorine Chem. 1990, 47, 533-535.
(16) Abou-Ghazaleh, B.; Laurent, Ph.; Blancou, H.; Commeyras, A.
J. Fluorine Chem. 1994, 68, 21-24.
(19) The trans-CF3CFdCFCtCSiMe3 isomer was obtained by the
Pd-catalyzed cross-coupling reaction of trans-CF3CFdCFI with Me3-
SiCtCH.27
(17) Jennings, M. P.; Cork, E. A.; Ramachandran, V. J. Org. Chem.
2000, 65, 8763-8766.
(20) Brisdon, A. K.; Crossley, I. R. Chem. Commun. 2002, 2420-
2421.
(18) Konno, T.; Chae, J.; Kanda, M.; Nagai, G.; Tamura, K.; Ishihara,
T.; Yamanaka, H. Tetrahedron 2003, 59, 7571-7580.
(21) Brisdon, A. K.; Crossley, I. R.; Pritchard, R. G.; Sadiq, G.;
Warren, J. E. Organometallics 2003, 22, 5534-5542.

(Fluoroorgano)fluoroboranes and -borates
Organometallics, Vol. 24, No. 22, 2005 5313
of the [(CF3CtC)2B(OMe)2]- anion occurred more quickly
than its fluorodemethoxylation (Scheme 6).
The fact that the final product consisted only of salt
19 means that the conversion of the primary intermedi-
ate A into the nucleophile D proceeded more quickly
than its reaction with the electrophile B(O-i-Pr)3. In-
deed, the 19F NMR spectrum of the reaction mixture
from C6F13CBrdCH2 (17), BuLi (2 equiv), and B(O-i-
Pr)3 still showed a significant amount of nonreacted
substrate 17.
Scheme 6
(1) 3BuLi
CF3CH2CHF2 (2) B(OMe) 8
Li[CF CtCB(OMe ) ]
+
3
3 3
3
major
K[HF2]/HFaq
NMR Spectra of K[RFCtCBF3]. Signals in the 11
B
Li[(CF3CtC)2B(OMe)2]
8 K[CF3CtCBF3]
16 (53%)
NMR spectra of all ((perfluoroorgano)ethynyl)trifluo-
roborates are located between -2 and -3 ppm. This
indicates a weak shielding of the boron atom in
[RFCtCBF3]- anions with respect to those in perfluori-
nated alkenyltrifluoroborates and alkyltrifluoroborates,
whose 11B NMR signals are located at -0.2 to -0.7
ppm.4,23 Distinctions of the boron-bonded fluorine atoms
in the 19F NMR spectra of these classes of (perfluoro-
organyl)trifluoroborates are more interesting. The spec-
tra of ((perfluoroorgano)ethynyl)trifluoroborate salts
K[RFCtCBF3] either in acetonitrile or in acetone con-
minor
Principally potassium salts of long-chain ((perfluoro-
alkyl)ethynyl)trifluoroborates, e.g. potassium (perfluo-
ropent-1-ynyl)trifluoroborate (13), can be prepared from
1-iodoperfluoropropane in accordance with Scheme 3.
We decided to elaborate another route, which is dem-
onstrated for (perfluorooct-1-ynyl)lithium as a key nu-
cleophile. This route started with the easily available
olefin C6F13CBrdCH2 (17),22 which was treated with
LDA, and in situ generated C6F13CtCLi was finally
converted into the salt 18 as previously described
(Scheme 7).
tain the signal of the BF3 group (quartet 1:1:1:1, 1JFB
)
31-34 Hz) at -134 to -137 ppm, which shifts to low
frequencies (ca. 2 ppm) in the highly polar solvents
DMSO and D2O. Similar shifts from -142 to -144 ppm
or from -140 to -142 ppm are observed in the spectra
of potassium (perfluoroalkenyl)trifluoroborates K[RF-
CFdCFBF3] on going from solutions in MeCN to DMSO.
The 19F chemical shifts of the BF3 group in potassium
(perfluoroalkyl)trifluoroborates K[RFCF2CF2BF3] are
located at -152 to -153 ppm, and they are practically
unaffected by the change of solvent.4,23 This picture of
increasing shielding of the BF3 nucleus in the series
[RFCtCBF3]- < RFCFdCFBF3]- < [RFCF2CF2BF3]-
follows the increasing number of fluorine atoms at
carbon atom C-1 and reflects the diminishing of negative
charge on the fluorine atoms bonded to boron from
perfluorinated alkynyltrifluoroborates to alkyltrifluo-
Scheme 7
(1) B(O-i-Pr)3
C6F13CBrdCH2 2LDA8 C6F13CtCLi (2) K[HF] , aq HF8
2
17
K[C6F13CtCBF3]
18 (20%)
This reaction route gave an interesting and unex-
pected result when, instead of LDA, butyllithium was
used in the reaction sequence. The interaction of olefin
17 with 2 equiv of BuLi is described in Scheme 8 and
led to potassium (perfluorooct-3-en-1-ynyl)trifluorobo-
rate (19; cis:trans ) 1:2) in 44% yield. When the molar
ratio 17:BuLi was applied equal to 1:3, the isolated yield
of salt 19 increased to 66% and the ratio of cis to trans
changed to 5:6. We assume that the primary reaction
of olefin 17 and BuLi resulted in the 2-lithioalkene A,
which quickly eliminated LiF to form the polyfluori-
nated octa-1,2-diene B. The abstraction of one proton
from B followed by the elimination of one fluoride anion
resulted in enyne C, whose lithiation gave the carbon
nucleophile D (Scheme 8).
1
roborates. It is worth noting that the JFB coupling
constants in spectra of nonfluorinated organyltrifluo-
roborate anions always exceed those of their perfluori-
nated analogues, and both increase from alkynyl- to
alkyltrifluoroborates.4,23
The 13C NMR data concerning the chemical shifts
δ(C-1) and δ(C-2) and the nJCB coupling constants (n )
1, 2) of alkynylboron compounds are very limited.24 In
addition, reported spectra of the recently prepared
potassium alkynyltrifluoroborates K[RCtCBF3] did not
contain these data.2 The chemical shift δ(C-2) (broad
multiplet at 89 ppm) was reported only for the salt
K[C4H9CtCBF3].1 We have carried out a 13C and 13C-
{19F} NMR characterization on representative members
of the new ((perfluoroorgano)ethynyl)trifluoroborate
salts 16, 12, 14, and 15.
Scheme 8
C6F13CBrdCH2 BuLi8 C6F13CLidCH2 -LiF8
A
C5F11CFdCdCH2 BuLi8 C5F11CFdCdCH- f
B
C5F11CF-CtCH
8
The resonances of the carbon atom C-2 in the 13C-
{19F} NMR spectra of all K[RFCtCBF3] salts were
unresolved multiplets located in the narrow range from
72 to 76 ppm (Table 1). The resonances of the carbon
atom C-1 of 16 (RF ) CF3) and 14 (RF ) (CF3)2CF) were
found at 104 and 112 ppm, respectively. Replacement
of the perfluoroalkyl moiety RF by the unsaturated
-F-
C4F9CFdCFCtCH BuLi8
C
(1) B(O-i-Pr)3
C4F9CFdCFCtCLi (2) K[HF ], aq HF8
2
D
K[C4F9CFdCFCtCBF3]
(23) For a compilation of 11B and 19F NMR spectra of K[RBF3] (R )
polyfluoroalkyl, polyfluoroalkenyl, polyfluoroaryl), see the Supporting
Information.
19 (44-66%)
(22) Sautini, G.; LeBlanc, M.; Riess, J. G. Tetrahedron 1973, 29,
2411-2414.
(24) Kalinowski, H.-O.; Berger, S.; Brown, S. 13C NMR-Spektrosko-
pie; Thieme: Stuttgart, Germany, 1984.

5314 Organometallics, Vol. 24, No. 22, 2005
Table 1. 13C and 13C{19F} NMR Spectra of K[RBF3] Salts
Bardin et al.
R
solvent
13C NMR chem shift, ppm
coupling const, Hz
1J(C-1,B) ) 104
1J(C-1,B) ) 99
CF3CtCa
DMSO-d6
DMSO-d6
DMSO-d6
104.5 (q, C-1), 75.1 (C-2), 114.5 (C-3)
112.2 (q, C-1), 71.8 (C-2), 84.8 (C-3), 119.4 (C-4)
112.0 (C-1), 71.8 (C-2), 84.7 (dsept, C-3),
119.3 (dq, C-4)
CF3CF(CF3)CtCa
CF3CF(CF3)CtC
2J(C-4,F-3) ) 30; 1J(C-4,F-4) ) 286;
1J(C-3,F-3) ) 198; 2J(C-3,F-4) ) 36
1J(C-1,B) ) 100
cis-CF3CFdCFCtCa
cis-CF3CFdCFCtC
DMSO-d6
DMSO-d6
123.1 (q, C-1), 73.4 (C-2), 135.2 (C-3),
139.2 (C-4), 119.9 (C-5)
∼124 (C-1), 73.3 (C-2), 135.2 (dd, C-3),
2J(C-4,F-3) ) 29; 2J(C-4,F-5) ) 39;
1J(C-4,F-4) ) 258; 2J(C-3,F-4) ) 21;
1J(C-3,F-3) ) 248; 1J(C-5,F-5) ) 271;
2J(C-5,F-4) ) 36; 3J(C-5,F-3) ) 6
1J(C-1,B) ) 102
139.2 (dqd, C-4), 119.0 (qdd, C-5)
trans-CF3CFdCFCtCa
trans-CF3CFdCFCtC
DMSO-d6
DMSO-d6
125.0 (q, C-1), 74.3 (C-2), 137.8 (C-3),
141.8 (C-4), 119.5 (C-5)
∼124 (C-1), 74.2 (C-2), 137.8 (dd, C-3),
2J(C-4,F-3) ) 53; 2J(C-4,F-5) ) 40;
1J(C-4,F-4) ) 245; 2J(C-3,F-4) ) 44;
1J(C-3,F-3) ) 243; 1J(C-5,F-5) ) 270;
2J(C-5,F-4) ) 35; 3J(C-5,F-3) ) 8
1J(C-1,B) ) 106
141.8 (dqd, C-4), 119.2 (qdd, C-5)
C6F5CtCa
C6F5CtC
acetone-d6
acetone-d6
118.2 (q, C-1), 72.3 (C-2), 102.4 (C-R),
147.8 (C-â), 137.9 (C-γ), 140.6 (C-δ)
117.4 (C-1), 71.8 (C-2), 101.9 (t, C-R),
147.2 (dd, C-â), 137.9 (ddd, C-γ),
140.6 (td, C-δ)
2J(C-â,F-γ) ) 8; 1J(C-â,F-â) ) 251;
2J(C-δ,F-γ) ) 14; 1J(C-δ,F-δ) ) 252;
2J(C-γ,F-â) ) 15; 2J(C-γ,F-δ) ) 15;
1J(C-γ,F-γ) ) 248; 2J(C-R,F-â) ) 19
1J(C-1,B) ) 88; 1J(C-3,F-3) ) 263;
2J(C-2,F-3) ) 29
a
C3F7
D2O
D2O
121.5 (q, C-1), 112.9 (q, C-2), 120.8 (q, C-3)
a
C4F9
122.1 (q, C-1), 114.6 (C-2), 111.5 (q, C-3),
120.0 (qt, C-4)
33.3, 31.6, 29.5, 29.0, 25.6, 22.3, 20.2, 14.0
171.5 (q, C-1), 141.6 (C-2), 108.5 (C-3),
110.3 (C-4), 111.8 (C-5), 117.2 (C-6)
171.5 (C-1), 141.5 (tdd, C-2), 108.5 (m, C-3),
110.3 (m, C-4), 111.8 (m, C-5), 117.2 (tq, C-6)
1J(C-1,B) ) 87; 1J(C-4,F-4) ) 262;
2J(C-4,F-3) ) 19; 2J(C-3,F-4) ) 29
31
C8H17
DMSO-d6
DMSO-d6
trans-C4F9CFdCFa
1J(C-1,B) ) 87
trans-C4F9CFdCF
DMSO-d6
2J(C-2,F-3) ) 27; 2J(C-2,F-1) ) 38;
1J(C-2,F-2) ) 227; 2J(C-6,F-5) ) 33;
1J(C-6,F-6) ) 288
cis-C2F5CFdCFa
cis-C2F5CFdCF
C4H9CtCa
DMSO-d6
DMSO-d6
acetone-d6
165.8 (q, C-1), 139.8 (q, C-2), 109.6 (C-3),
118.7 (C-4)
165.7 (C-1), 139.7 (d, C-2), 108.5 (t, C-3),
118.6 (tq, C-4)
1J(C-1,B) ) 90; 2J(C-2,B) ) 10
1J(C-2,F-2) ) 252; 2J(C-4,F-3) ) 39;
1J(C-4,F-4) ) 287; 1J(C-3,F-3) ) 252
1J(C-3,H-3) ) 128; 1J(C-4,H-4) ) 125;
1J(C-5,H-5) ) 124; 1J(C-6,H-6) ) 125
1J(C-4,H-4) ) 127
91.9 (br m, C-1), 89.7 (C-2), 18.7 (C-3),
31.3 (C-4), 21.7 (C-5), 13.6 (C-6)
90.0 (C-1), 97.9 (C-2), 27.0 (C-3), 31.6 (q, C-4)
49.8, 30.9, 17.4 (m)
(CH3)3CCtCa
DMSO-d6
DMSO-d6
acetone-d6
32
CH2ClCH2CH2
trans-CH2ClCHdCH33
142.8 (m), 131.4, 49.7
a Data from the 13C{19F} spectrum.
(Aldrich), Me3SiCtCH (Aldrich), DMSO (Aldrich), 2-methyl-
3-butyn-2-ol (Aldrich), 18-crown-6 (Aldrich), hexafluoropropene
(Bristol Organics), zinc dust (Fluka), KF (Riedel-de Hae¨n), 48%
HF (Riedel-de Hae¨n), CF3CO2H (Solvay), heptafluoropropyl
iodide (ABCR), and heptafluoroisopropyl iodide (ABCR) were
used as supplied. B(OMe)3 (Fluka) and B(O-i-Pr)3 (Fluka) were
distilled over sodium before use. Solvents (ether, dichloro-
methane) were purified by standard procedures. All manipula-
tions with organolithium compounds were performed under
an atmosphere of dry argon.
groups RF ) C6F5 (15), CF3CFdCF (12) caused a
significant shift of the C-1 resonance to 117-118 and
123-125 ppm, respectively. It is an interesting coinci-
dence that these values are very similar to those of
R-difluoromethylene groups in the spectra of (perfluo-
roalkyl)trifluoroborates K[RFCF2CF2BF3] (RF ) CF3,
C2F5), which themselves are strongly distinct from the
chemical shifts of C-1 in (perfluoroalkenyl)trifluorobo-
rates K[RFCFdCFBF3], located at 165-172 ppm (Table
1). In all cases the C-1 signals appear as 1:1:1:1 quartets
with 1JCB ) 99-106 Hz for ((perfluoroorgano)ethynyl)-
trifluoroborates and 1JCB ) 87-90 Hz for perfluorinated
alkyl- and alkenyltrifluoroborates. For comparison, the
signals of C-1 and C-2 in the 13C{19F} NMR spectra of
nonfluorinated alkynyltrifluoroborates K[RCtCBF3]
appear at lower frequencies. For example, the δ(C-1)
and δ(C-2) values are equal to 91.9 and 89.7 ppm (R )
C4H9) and 90.0 and 97.9 ppm (R ) t-C4H9), respectively
(Table 1). The resonances of C-1 and C-2 of alkyltri-
fluoroborates K[RCH2CH2BF3] are found at ca. 17-23
ppm and thus interfere with the 13C chemical shifts of
the methylene groups in the alkane chain (Table 1).
The salts K[RBF3] (R ) C4H9CtC,2 (CH3)3CCtC,25 C3F7,6
22
C4F926) and the alkene C6F13CBrdCH2 were prepared as
described in the literature. The yields of products were not
optimized in all cases.
Physical and Analytical Measurements. NMR spectra
were recorded on a Bruker AVANCE 300 (300.13 MHz, 1H;
96.29 MHz,11B; 75.47 MHz,13C; 282.40 MHz,19F) and a Bruker
DRX 500 (125.75 MHz, 13C; 470.59 MHz, 19F) FT spectrometer.
The chemical shifts are referenced to TMS (1H, 13C), BF3‚OEt3/
CDCl3 15% v/v (11B), and CCl3F (19F, with C6F6 as secondary
reference (-162.9 ppm)), respectively. FT-IR (pellets in KBr)
and FT-Raman (powder) spectra were measured on a Bruker
VECTOR 22 and Bruker IFS 66/FRA 106 spectrometer,
respectively. Elemental analysis was performed with
a
Experimental Section
(25) Kabalka, G. W.; Venkataiah, B.; Dong, G. Tetrahedron Lett.
2004, 45, 729-731.
(26) Frohn, H.-J.; Bardin, V. V. Z. Anorg. Allg. Chem. 2002, 628,
1853-1856.
Materials and Methods. 1,1,1,3,3-Pentafluoropropane
(Honeywell), 2.5
M BuLi in hexanes (Aldrich), K[HF2]

(Fluoroorgano)fluoroboranes and -borates
Organometallics, Vol. 24, No. 22, 2005 5315
3
4
HEKAtech EA3000 analyzer on the complexes [K‚18-crown-
6][RFCtCBF3]. The latter were prepared in 70-80% yield by
reaction of K[RFCtCBF3] (1 equiv) and 18-crown-6 (1.1 equiv)
in dichloromethane and subsequent crystallization by slow
evaporation (over days) of the solvent at 20 °C.
2JFF ) 59 Hz; JFF ) 38 Hz; JFF ) 8 Hz, 1F, F5trans), -107.2
(ddt JFF ) 59 Hz; JFF ) 117 Hz; JFF ) 20 Hz, 1F, F5cis),
2
3
4
-187.2 (ddt 3JFF(cis) ) 38 Hz; 3JFF(trans) ) 117 Hz; 3JFF ) 20 Hz,
1F, F4) ppm. H NMR (neat): δ 0.05 (s, 9H) ppm.
1
Synthesis of CF3CFdCFCtCH (11). Silane 10 (6.0 g, 26
mmol) was added dropwise to a stirred solution of KF (6.1 g,
105 mmol) and water (2 mL, 111 mmol) in DMSO (42 mL).
Under a slow flow of dry argon the reaction mixture was
warmed to 40-50 °C for 2.5 h. The product was collected in a
cold (-60 °C) trap which contained anhydrous ether (10 mL).
The 1H and 19F NMR spectra showed the formation of CF3-
CFdCFCtCH (13 mmol of trans-11, 6.7 mmol of cis-11) and
Me3SiF (8 mmol).
Synthesis of K[CF3CtCBF3] (16). A 2.5 M solution of
BuLi in hexanes (95 mL, 237 mmol) was added dropwise to
the stirred solution of CF3CH2CHF2 (11.8 g, 88 mmol) in ether
(300 mL) at -35 °C within 40 min, and the solution was kept
at -35 °C for 1 h before it was warmed to -15 °C and B(OMe)3
(9.9 g, 95 mmol) in ether (15 mL) was added dropwise with a
syringe. The reaction mixture was warmed to 0 °C during 2
h. The 19F and 11B NMR spectra showed the presence of
[CF3CtCB(OCH3)3]- (δ(F) -47.6 (s, F3) ppm; δ(B) 0.8 (s) ppm)
(main product)), [(CF3CtC)2B(OCH3)2]- (δ(F) -47.8 (s, F3)
ppm; δ(B) -4.0 (s) ppm), CF2dCdCF2 (δ(F) -63.4 (s) ppm),
the starting compounds B(OMe)3 (δ(B) 18.3 (s) ppm) and CF3-
CH2CHF2 (δ(F) -62.5 (m, 3F) and -115.2 (m, 2F) ppm), and
admixtures of unknown products (singlets at δ(F) -50.6,
-57.4, and -60.7 ppm). The solvents were partially evaporated
under reduced pressure at ca. 0 °C, and the solution was
poured into a solution of K[HF2] (20 g, 256 mmol) in water
(50 mL) and 40% HF (12 mL). The resulting suspension was
stirred overnight, diluted with water (50 mL), neutralized with
K2CO3, and saturated with KF. The product was extracted
with acetonitrile (3 × 50 mL), and the combined extracts were
dried with MgSO4. After evaporation of the solvent the brown
solid residue was washed with toluene (3 × 50 mL) and with
hexane (2 × 50 mL) and dried in a vacuum desiccator over
Sicapent to yield the white solid 16 (8.4 g, 53%). 19F NMR (CD3-
trans-CF3CFdCFCtCH (trans-11). 19F NMR (ether): δ
-67.4 (dd JFF ) 11 Hz; JFF ) 21 Hz, 3F, F5), -140.2 (dqd
3
4
3JFF(trans) ) 140 Hz; 4JFF ) 21 Hz; 4JFH ) 4 Hz, 1F, F3), -161.2
(dq JFF(trans) ) 140 Hz; JFF ) 11 Hz, 1F, F4) ppm. H NMR
3
3
1
4
(ether): δ 4.59 (d JHF ) 4 Hz) ppm.
cis-CF3CFdCFCtCH (cis-11). 19F NMR (ether): δ -67.4
(dd JFF ) 12 Hz; JFF ) 7 Hz, 3F, F5), -123.3 (dqd JFF(cis)
)
)
3
4
3
9 Hz; 4JFF ) 7 Hz; 4JFH ) 1 Hz, 1F, F3), -143.4 (dqd 3JFF(cis)
9 Hz; JFF ) 12 Hz; JFH ) 3 Hz, 1F, F4) ppm. 1H NMR
4
5
(ether): δ 4.48 (m) ppm.
Synthesis of K[cis- and trans-CF3CFdCFCtCBF3] (12).
A solution of 11 (cis:trans ) 1:2; 16 mmol) in ether (25 mL)
was cooled to -40 °C, and 3.3 M EtMgBr (5 mL, 16.5 mmol)
in ether was added using a syringe within 10 min. The reaction
mixture was always kept below -35 °C. Immediately a white
suspension was formed. Above -30 °C the complete dissolution
of the precipitate occurred. Subsequently the solution was
warmed to 20 °C within 1 h. After the mixture was cooled to
-30 °C, B(OMe)3 (2.2 g, 21 mmol) was added with a syringe.
A suspension was formed, which was stirred at -25 °C for 5
min and at 0 °C for 10 min before being poured into a stirred
suspension of K[HF2] (12 g, 153 mmol) in water (25 mL) and
MeOH (5 mL). After 1 h the organic solvents were evaporated
and the aqueous suspension was saturated with KF and
extracted with MeCN (50 mL). The extract was dried with
MgSO4, evaporated to dryness, and suspended in 24% HF (4
mL) to complete the fluorodemethoxylation of (perfluoroorga-
no)fluoromethoxyborates. After 20 min the suspension was
saturated with KF under cooling (cold water). Extraction with
MeCN (3 × 10 mL) followed. The extracts were dried with dry
KF, the solvent was removed under reduced pressure, and the
solid residue was dried under vacuum (0.13 hPa) for 4 h. The
salt K[CF3CFdCFCtCBF3] (cis-12:trans-12 ) 1:2) was ob-
tained in 21% yield (0.9 g). IR: νmax/cm-1 1698 (m), 1616 (w),
1377 (s), 1263 (s), 1215 (m), 1162 (s), 1055 (s), 1001 (s), 982
(s), 770 (w), 713 (w), 687 (w), 648 (w), 608 (w), 515 (w), 454
(w). Raman: νmax/cm-1 2197 ν(CtC), 1699 ν(CdC), 1381, 671.
19F NMR (MeCN) (cis-12): δ -67.6 (dd 3JFF ) 12 Hz; 4JFF ) 7
Hz, 3F, F5), -116.4 (m, 1F, F3), -136.2 (q 1JFB ) 32 Hz, BF3),
1
CN): δ -48.3 (s, 3F, F3), -137.0 (q JFB ) 32 Hz, 3F, BF3)
1
ppm. 11B NMR (CD3CN): δ -2.8 (q JBF ) 32 Hz) ppm.19F
1
NMR (acetone-d6): δ -47.3 (s, 3F, F3), -135.5 (q JFB ) 31
Hz, 3F, BF3) ppm. 11B NMR (acetone-d6): δ -2.4 (q 1JBF ) 31
Hz) ppm. 19F NMR (DMSO-d6): δ -47.9 (s, 3F, F3), -134.3 (q
1JFB ) 31 Hz, 3F, BF3) ppm. IR: νmax/cm-1 2241 (w) ν(CtC),
1724 (w), 1626 (m), 1286 (s), 1263 (s), 1223 (s), 1128 (s), 1080
(s), 1022 (s), 968 (s), 839 (s), 699 (w), 612 (w), 585 (s). Raman:
νmax/cm-1 2236 ν(CtC), 1404, 701, 279, 191. Anal. Calcd for
C3BF6K (199.93): C, 18.02; F, 57.01. Found: C, 18.0; F, 56.5.
Synthesis of CF3CFdCFCtCSiMe3 (10). A 2.5 M solution
of BuLi in hexanes (18 mL, 45 mmol) was added dropwise to
a cold (-50 °C) stirred solution of ethynyltrimethylsilane (5.0
g, 50 mmol) in ether (50 mL) at <-35 °C. The colorless solution
was kept at -15 to -20 °C for 30 min. After it was cooled to
-70 °C, the solution was added to a cold (-70 °C) stirred
solution of hexafluoropropene (10 g, 66 mmol) in ether (50 mL)
within 5 min. The solution was stirred at -75 °C for 1 h and
then warmed to ambient temperature overnight. After it was
washed with water and acidified with HCl, the aqueous phase
was extracted with ether (50 mL). The combined extracts were
washed with water and dried with MgSO4. The product 10 (6.2
g, 60%; cis:trans ) 31:69) was isolated by distillation (bp 100-
118 °C) (lit.27 bp for trans-CF3CFdCFCtCSiMe3 105-107 °C)
and contained an admixture (4%) of the isomer CF2dCFCF2Ct
CSiMe3.
-152.0 (dd JFF(cis) ) 12 Hz; JFF ) 12 Hz, 1F, F4) ppm. 11B
NMR (MeCN) (cis-12): δ -2.2 (q 1JBF ) 32 Hz) ppm. 19F NMR
(H2O) (cis-12): δ -67.5 (dd 3JFF ) 12 Hz; 4JFF ) 7 Hz, 3F, F5),
3
3
-120.2 (m, 1F, F3), -134.0 (q JFB ) 32 Hz, BF3), -147.0 (dd
1
trans-CF3CFdCFCtCSiMe3 (trans-10). 19F NMR (neat):
3JFF(cis) ) 12 Hz; JFF ) 12 Hz, 1F, F4) ppm. 11B NMR (H2O)
3
3
4
δ -68.7 (dd JFF ) 11 Hz; JFF ) 21 Hz, 3F, F5), -140.2 (dq
(cis-12): δ -2.8 (q JBF ) 32 Hz) ppm. 19F NMR (DMSO-d6)
1
3JFF ) 141 Hz; JFF ) 21 Hz, 1F, F3), -162.3 (dq JFF ) 141
Hz; 3JFF ) 11 Hz, 1F, F4) ppm. 1H NMR (neat): δ 0.08 (s, 9H)
ppm (lit.27 19F NMR (CDCl3): δ -68.4 (dd 12 Hz; 22 Hz, 3F,
F5), -139.9 (dq 142 Hz; 22 Hz, 1F, F3), -161.8 (dq 142 Hz; 12
4
3
(cis-12): δ -67.5 (dd 3JFF ) 13 Hz; 4JFF ) 7 Hz, 3F, F5), -115.8
(m, 1F, F3), -134.8 (q JFB ) 30 Hz, BF3), -152.7 (dd JFF
)
1
3
14 Hz; 3JFF(cis) ) 15 Hz, 1F, F4) ppm. 19F NMR (MeCN) (trans-
12): δ -67.7 (dd JFF ) 12 Hz; JFF ) 21 Hz, 3F, F5), -134.5
3
4
Hz, 1F, F4) ppm. H NMR (CDCl3): δ 0.28 (s) ppm.
1
(dd 3JFF(trans) ) 140 Hz; 4JFF ) 21 Hz, 1F, F3), -136.1 (q 1JFB
)
cis-CF3CFdCFCtCSiMe3 (cis-10). 19F NMR (neat):
δ
32 Hz, BF3), -167.7 (dd JFF ) 140 Hz; JFF ) 12 Hz, 1F, F4)
3
3
-68.7 (dd JFF ) 12 Hz; JFF ) 7 Hz, 3F, F5), -123.5 (dq
3
4
ppm. 11B NMR (MeCN) (trans-12): δ -2.2 (q JBF ) 32 Hz)
1
3JFF ) 10 Hz; JFF ) 7 Hz, 1F, F3), -145.4 (dq JFF ) 10 Hz;
4JFF ) 12 Hz, 1F, F4) ppm. 1H NMR (neat): δ 0.05 (s, 9H) ppm.
CF2dCFCF2CtCSiMe3.19F NMR (neat): δ -85.3 (ddd
4
3
ppm. 19F NMR (H2O) (trans-12): δ -67.7 (dd JFF ) 12 Hz;
3
4JFF ) 21 Hz, 3F, F5), -137.4 (dd JFF(trans) ) 140 Hz; JFF
)
3
4
21 Hz, 1F, F3), -133.9 (q JFB ) 32 Hz, BF3), -164.0 (dd
3JFF(trans) ) 140 Hz; 3JFF ) 12 Hz, 1F, F4) ppm. 11B NMR (H2O)
(trans-12): δ -2.8 (q 1JBF ) 32 Hz) ppm. 19F NMR (DMSO-d6)
1
4
3
4JFF ) 8 Hz; JFF ) 20 Hz; JFF ) 20 Hz, 2F, F3), -95.9 (ddt
(27) Yang, Z.-Y.; Burton, D. J. J. Fluorine Chem. 1991, 53, 307-
326.
(trans-12): δ -67.8 (dd JFF ) 13 Hz; JFF ) 21 Hz, 3F, F5),
3
4

5316 Organometallics, Vol. 24, No. 22, 2005
Bardin et al.
3
4
-134.4 (dd JFF(trans) ) 141 Hz; JFF ) 21 Hz, 1F, F3), -134.8
saturated with KF, and extracted with MeCN (3 × 40 mL).
The combined extracts were dried with anhydrous KF and
evaporated to dryness. Subsequent drying under vacuum gave
the white solid 13 (2.0 g, 45%). 19F NMR (CH3CN): δ -80.3 (t
1
3
3
(q JFB ) 30 Hz, BF3), -168.6 (dd JFF(trans) ) 141 Hz; JFF
)
12 Hz, 1F, F4) ppm.
[K‚18-crown-6][CF3CFdCFCtCBF3]. Anal. Calcd for
C17H24BF8KO6 (526.27): C, 38.80; H, 4.60. Found: C, 39.08;
H, 4.62.
3
4JFF ) 8.7 Hz, 3F, F5), -95.3 (m, 2F, F3), -126.9 (t JFF ) 6
Hz, 2F, F4), -136.6 (q 1JFB ) 31 Hz, BF3) ppm. 11B NMR (CH3-
1
CN): δ -2.6 (q JBF ) 31 Hz) ppm. IR: νmax/cm-1 2228 (vw)
Synthesis of C3F7CHdCIC(OH)(CH3)2 (5). A three-
necked flask (100 mL) equipped with a magnetic stirrer, a
reflux condenser, and a septum inlet was charged with zinc
dust (3.3 g, 50 mmol), CH2Cl2 (50 mL), 2-methyl-3-butyn-2-ol
(4.2 g, 50 mmol), and C3F7I (14.8 g, 50 mmol) in succession.
Then CF3CO2H (1.16 g, 10 mmol) was added with a syringe to
the stirred suspension and the reaction mixture was refluxed
gently. After 10 min the evolution of heat ceased and the
suspension was stirred for a further 2 h at ambient temper-
ature. Zinc was removed by filtration and washed with CH2-
Cl2 (20 mL). The combined CH2Cl2 solutions were evaporated
under reduced pressure to give product 5 (E:Z ) 86:14; yellow
oil, 16.7 g), which was used for the preparation of 7 without
further purification.
ν(CtC), 1612 (vw), 1352 (s), 1280 (s), 1248 (s), 1232 (s), 1182
(s), 1126 (s), 1041 (s), 996 (s), 945 (m), 772 (w), 727 (s), 687
(w), 659 (w), 627 (w), 601 (w), 536 (w). Raman: νmax/cm-1 2229
ν(CtC), 1454, 774, 687, 189.
[K‚18-crown-6][CF3CF2CF2CtCBF3]. Anal. Calcd for
C17H24BF10KO6 (564.27): C, 36.19; H, 4.29. Found: C, 36.37;
H, 4.36.
Synthesis of CF3CF(CF3)CHdCIC(OH)(CH3)2 (6). Prod-
uct 6 (E:Z ) 88:12; yellow oil, 16.2 g, 42 mmol, 76%) was
prepared as described for compound 5 from zinc dust (3.3 g,
50 mmol), CH2Cl2 (50 mL), 2-methyl-3-butyn-2-ol (4.3 g, 51
mmol), i-C3F7I (16.7 g, 56 mmol), and CF3CO2H (1.15 g, 10
mmol) and used for the preparation of 8 without further
purification.
(E)-C3F7CHdCIC(OH)(CH3)2 ((E)-5). 19F NMR (CH2Cl2):
(E)-CF3CF(CF3)CHdCIC(OH)(CH3)2 ((E)-6). 19F NMR
4
4
δ -81.9 (t JFF ) 9 Hz, 3F,CF3), -110.7 (qd JFF ) 9 Hz;
3
3JFF ) 13 Hz, 2F, CF3CF2CF2), -128.8 (m, 2F, CF3CF2CF2)
(CH2Cl2): δ -78.3 (d JFF ) 8.3 Hz, 6F, 2CF3), -189.0 (dsept
3JFH ) 22 Hz; 3JFF ) 8.3 Hz, 1F, CF) ppm. 1H NMR (CH2Cl2):
δ 6.73 (d 3JHF ) 22 Hz, 1H, CHdC), 2.3 (br, OH), 1.45 (m, 6H,
2CH3) ppm.
1
4
ppm. H NMR (CH2Cl2): δ 6.76 (t JHF ) 13 Hz, 1H, CHdC),
3.10 (OH), 1.46 (m, 6H, 2CH3) ppm.
(Z)-C3F7CHdCIC(OH)(CH3)2 ((Z)-5). 19F NMR (CH2Cl2):
(Z)-CF3CF(CF3)CHdCIC(OH)(CH3)2 ((Z)-6). 19F NMR
4
4
δ -82.0 (t JFF ) 9 Hz, 3F, CF3), -114.1 (qd JFF ) 9 Hz;
3
3JFH ) 11 Hz, 2F, CF3CF2CF2), -129.3 (m, 2F, CF3CF2CF2)
(CH2Cl2): δ -78.9 (d JFF ) 7.6 Hz, 6F, 2CF3), -187.3 (dsept
3JFH ) 21 Hz; 3JFF ) 7.6 Hz, 1F, CF) ppm. 1H NMR (CH2Cl2):
δ 6.37 (d 3JHF ) 16 Hz, 1H, CHdC), 2.3 (br, OH), 1.45 (m, 6H,
2CH3) ppm.
1
4
ppm. H NMR (CH2Cl2): δ 5.82 (t JHF ) 11 Hz, 1H, CHdC),
3.10 (OH), 1.46 (m, 6H, 2CH3) ppm.
Synthesis of C3F7CtCC(OH)(CH3)2 (7). A three-necked
flask (100 mL) equipped with a magnetic stirrer, a reflux
condenser, and a dropping funnel was charged with KOH (2.9
g, 50 mmol), water (4 mL), and ethanol (10 mL). A solution of
5 in ethanol (2 mL) was added dropwise, and the reaction
mixture was stirred for 1 h at ambient temperature, then
diluted with water and acidified with HCl, and finally ex-
tracted with ether. The extract was dried with MgSO4, and
the solvent was removed on a rotary evaporator to give a
yellow liquid (10 g) which contained residual ether (2 g), cis-5
(3 mmol), and 7 (27 mmol) (1H, 19F NMR). This liquid was used
for the preparation of 3 without purification.
Synthesis of CF3CF(CF3)CtCC(OH)(CH3)2 (8). The prepa-
ration of 8 from 6 (42 mmol), KOH (3.0 g, 53 mmol), water (4
mL), and ethanol (25 mL) was performed analogously to the
synthesis of 7. After removal of the solvent on a rotary
evaporator (25 °C, bath), the yellow liquid residue (15 g) was
distilled. The fraction which boiled in the range 90-105 °C
(9.1 g) consisted of ethanol (3.5 g), 8 (4.8 g, 19 mmol), and
trans-CF3CF(CF3)CHdCHC(OH)(CH3)2 (9; 0.8 g, 3 mmol) (1H,
19F NMR) was used for the preparation of 4 without further
purification.
CF3CF(CF3)CtCC(OH)(CH3)2 (8). 19F NMR (EtOH): δ
3
3
C3F7CtCC(OH)(CH3)2 (7). 19F NMR (ether): δ -80.5 (t
-77.8 (d JFF ) 10.5 Hz, 6F, 2CF3), -167.1 (sept JFF ) 10.5
Hz, 1F, CF) ppm. 1H NMR (EtOH): δ 1.44 (m, 6H, 2CH3) ppm.
trans-CF3CF(CF3)CHdCHC(OH)(CH3)2 (9). 19F NMR
4JFF ) 8 Hz, 3F, CF3), -98.4 (tq 3JFF ) 5 Hz; 4JFF ) 8 Hz, 2F,
3
CF3CF2CF2), -127.2 (t JFF ) 5 Hz, 2F, CF3CF2CF2) ppm.
3
(EtOH): δ -77.9 (d JFF ) 7.3 Hz, 6F, 2CF3), -186.0 (dsept
Synthesis of C3F7CtCH (3). NaOH pellets (1.8 g, 45
mmol) were added to a ether solution of 7 (27 mmol, see above).
The mixture was stirred at 100-105 °C (bath) for 40 min.
Product 3 (15 mmol, 56%) was collected in a cold (-40 °C)
receiver with anhydrous ether (4 mL). 19F NMR (ether): δ
3JFH ) 21 Hz; JFF ) 7.5 Hz, 1F, CF) ppm. H NMR (EtOH):
3
1
3
3
δ 6.34 (d JHH ) 15.7 Hz; 1H, RFCHdCH), 5.75 (dd JHH
)
3
15.7 Hz; JHF ) 21 Hz, 1H, RFCH)CH), 1.25 (m, 6H, 2CH3)
ppm.
-79.9 (t 4JFF ) 8.7 Hz, 3F, F5), -99.1 (tdq 3JFF ) 4 Hz; 4JFH
)
Synthesis of CF3CF(CF3)CtCH (4). NaOH powder (4.5
g, 112 mmol) was added to the solution of 8 (19 mmol, see
above). The mixture was stirred at 75-80 °C (bath) for 40 min.
Product 4 (12 mmol, 64%) was collected in a cold (-50 °C)
receiver with anhydrous ether (1 mL). 19F NMR (ether): δ
-77.0 (d 3JFF ) 10 Hz, 6F, 2CF3), -168.1 (dsept 4JFH ) 6 Hz;
5.7 Hz; JFF ) 8.7 Hz, 2F, F3), -126.5 (t JFF ) 4 Hz, 2F, F4)
4
3
ppm. H NMR (ether): δ 3.63 (t JHF ) 5.6 Hz, 1H, H1) ppm
1
4
(lit. 19F NMR (CCl4): δ -81.5 (t 10 Hz), -101.5 (m), -128.4 (t
1
5 Hz) ppm. H NMR (CCl4): δ 2.9 ppm.28 19F NMR (neat): δ
-100.0 (F3) ppm. H NMR (neat): δ 3.0 ppm)29).
1
1
4
3JFF ) 10 Hz, 1F, F3) ppm. H NMR (ether): δ 3.66 (d JHF
)
Synthesis of K[CF3CF2CF2CtCBF3] (13). A solution of
3 (15 mmol) in ether (50 mL) was cooled to -60 °C, and 2.5 M
BuLi (5 mL, 12.5 mmol) was added using a syringe within 10
min, ensuring that the internal temperature did not rise above
-55 °C. The solution was stirred at -55 °C for 1 h and then
cooled to -70 °C and transferred with a cannula into the cold
(-80 °C) stirred solution of B(OMe)3 (1.8 g, 17 mmol) in ether
(50 mL). After additional stirring at -65 °C for 1 h, the solution
was warmed to 0 °C within 2 h and then added to the stirred
solution of K[HF2] (7.8 g, 100 mmol) in water (40 mL) and 48%
HF (15 mL). The reaction mixture was stirred for 2 h,
6 Hz, 1H, H1) ppm. (lit.30 19F NMR (neat): δ -90.7 and -171.8
ppm; JFF ) 9.9 Hz; JFH ) 6.0 Hz; JFH ) 0.4 Hz. 1H NMR
(neat): δ 2.35 ppm).
Synthesis of K[CF3CF(CF3)CtCBF3] (14). Salt 14 was
obtained by metalation of 4 (12 mmol) in ether solution (50
mL) with 2.5 M BuLi (4.8 mL, 12 mmol), subsequent alkyny-
lation of B(OMe)3 (1.6 g, 15 mmol) in ether (50 mL), and
(30) Cullen, W. R.; Waldman, M. C. J. Fluorine Chem. 1971/72, 1,
41-50.
(31) Molander, G. A.; Ito, T. Org. Lett. 2001, 3, 393-396.
(32) Molander, G. A.; Yun, C.-S.; Ribagorda, M.; Biolatto, B. J. Org.
Chem. 2003, 68, 5534-5539.
(28) Hudlicky, M. J. Fluorine Chem. 1981, 18, 383-405.
(29) Burton, D. J.; Spawn, T. D. J. Fluorine Chem. 1988, 38, 119-
123.
(33) Molander, G. A.; Ribagorda, M. J. Am. Chem. Soc. 2003, 125,
11148-11149.

(Fluoroorgano)fluoroboranes and -borates
Organometallics, Vol. 24, No. 22, 2005 5317
fluorodemethoxylation of lithium (perfluoroalkynyl)trimeth-
oxyborate with K[HF2] (7.1 g, 91 mmol) in water (30 mL) and
48% HF (10 mL), as described for the synthesis of salt 13. The
yield of 14 was 2.6 g (72%). 19F NMR (CH3CN): δ -77.6 (d
3JFF ) 10.8 Hz, 6F, 2CF3), -136.5 (q 1JFB ) 31 Hz, BF3), -162.5
F2,6), -156.9 (t 3JFF ) 20 Hz, 1F, F4), -163.6 (m, 2F, F3,5) ppm.
IR: νmax/cm-1 2206 (vw) ν(CtC), 1634 (w), 1528 (s), 1500 (s),
1378 (w), 1301 (w), 1239 (w), 1142 (s), 1086 (s), 1055 (s), 989
(s), 952 (s), 744 (w), 702 (w), 596 (w), 561 (w), 534 (w), 522
(w), 483 (w), 470 (w). Raman: νmax/cm-1 2207 ν(CtC), 1657,
1442, 955, 563, 435, 390, 172.
3
(sept JFF ) 11 Hz, 1F, F3) ppm. 11B NMR (CH3CN): δ -2.6
4
1
(dq JBF ) 2 Hz; JBF ) 31 Hz) ppm. 19F NMR (DMSO-d6): δ
[K‚18-crown-6][C6F5CtCBF3]. Anal. Calcd for C20H24BF8-
KO6 (562.30): C, 42.72; H, 4.30. Found: C, 42.0; H, 4.76.
Synthesis of K[C4F9CFdCFCtCBF3] (19). (A) BuLi (2.5
M in hexanes, 8 mL, 20 mmol) was added to the precooled
solution of C6F13CBrdCH2 (4.30 g, 10 mmol) in 50 mL of ether
at -70 °C. The reaction mixture was stirred at -78 °C for 2
h, and B(O-i-Pr)3 (1.88 g, 10 mmol) was added in one portion.
Stirring was continued for an additional 1 h. After it was
gradually warmed to -20 °C, the mixture was poured into a
solution of K[HF2] (8 g, 102 mmol) in water (45 mL) and 48%
HF (3 mL). This mixture was stirred at 20 °C for 1 h and then
extracted with acetonitrile (5 × 20 mL). The combined extracts
were treated with 10 g of KF and formed two phases. The
organic phase was separated, and the aqueous phase was
extracted once more with acetonitrile (2 × 10 mL). The
combined extracts were evaporated under reduced pressure.
The solid residue was dried under high vacuum (0.013 hPa)
for 2 h and then over Sicapent in a vacuum desiccator
overnight. Salts cis-19 and trans-19 (1:2) (1.81 g, 44%) were
obtained.
3
1
-77.1 (d JFF ) 11 Hz, 6F, 2CF3), -134.0 (q JFB ) 29 Hz,
BF3), -162.1 (qsept JFB ) 2 Hz; JFF ) 11 Hz, 1F, F3) ppm.
IR: νmax/cm-1 1616 (w), 1326 (s), 1299 (s), 1245 (s), 1212 (s),
1232 (s), 1180 (s), 1164 (s), 1091 (s), 1015 (s), 997 (s), 972 (s),
725 (m), 637 (m), 596 (w), 558 (w), 527 (w), 483 (w). Raman:
νmax/cm-1 2218 ν(CtC), 1271, 1171, 779, 723, 640, 561, 331,
168.
5
3
[K‚18-crown-6][CF3CF(CF3)CtCBF3]. Anal. Calcd for
C17H24BF10KO6 (564.27): C, 36.19; H, 4.29. Found: C, 36.44;
H, 4.28.
Synthesis of K[C6F13CtCBF3] (18). A solution of diiso-
propylamine (1.01 g, 10 mmol) in 40 mL of ether was cooled
to -78 °C, and BuLi (2.5 M in hexanes, 4 mL, 10 mmol) was
gradually added. The resulting solution was stirred at -78
°C for 15 min, warmed to 10 °C within 30 min, and stirred at
this temperature for 10 min. After the mixture was cooled to
-78 °C, a solution of C6F13CBrdCH2 (2.15 g, 5 mmol) in 10
mL of ether was added dropwise. The solution was stirred at
-78 °C for 1 h before B(O-i-Pr)3 (940 mg, 5 mmol) was added.
After it was stirred at -78 °C for 1 h, the solution was
gradually warmed to 20 °C. The ether solution was poured
into a solution of K[HF2] (4 g) and 48% aqueous HF (1.5 mL)
in water (20 mL). The reaction mixture was stirred at 20 °C
until ether was evaporated. The mixture was extracted with
acetonitrile (5 × 10 mL). The combined extracts were dried
with KF, and the solvent was evaporated to give the salt 18
(450 mg, 20%). 19F NMR (CH3CN): δ - 80.0 (tt 4JFF ) 10 Hz;
3JFF ) 2 Hz, 3F, F8), - 93.0 (m, 2F, F3), -120.0 (m, CF2),
-121.4 (m, CF2), -121.7 (m, CF2), -125.0 (m, CF2), -135.5 (q
(B) When the above synthesis was repeated with 50% more
BuLi (2.5 M in hexanes, 12 mL, 30 mmol), the salts cis-19 and
trans-19 (5:6) were obtained in 66% yield (2.7 g). 19F NMR
(CH3CN) (cis-19): δ -80.1 (tt 3JFF ) 2.5 Hz; 4JFF ) 10 Hz, 3F,
3
3
F8), -109.1 (d JFF(cis) ) 13 Hz, 2F, F3), -114.9 (dt JFF ) 13
Hz; JFF ) 13 Hz, 2F, F5), -122.9 (m, 2F, F6), -125.4 (m, 2F,
4
F7), -135.3 (q 1JFB ) 33 Hz, BF3), -148.3 (m, 2F, F4) ppm. 11
B
NMR (CH3CN) (cis-19): δ -2.2 (q 1JBF ) 32 Hz) ppm. 19F NMR
3
4
(CH3CN) (trans-19): δ -80.2 (tt JFF ) 2.5 Hz; JFF ) 10 Hz,
3F, F8), -131.3 (dt 3JFF ) 141 Hz; 4JFF ) 25 Hz, 2F, F3), -116.3
1JFB ) 31 Hz, BF3) ppm. 11B NMR (CH3CN): δ -2.5 (q 1JBF
31 Hz) ppm.
)
(dt JFF ) 14 Hz; JFF ) 13 Hz, 2F, F5), -123.6 (m, 2F, F6),
3
4
-125.4 (m, 2F, F7), -135.2 (q JFB ) 33 Hz, BF3), -163.9 (dt
1
Synthesis of K[C6F5CtCBF3] (15). A three-necked flask
(100 mL) equipped with a magnetic stirrer, a thermometer,
and a septum inlet was charged with (pentafluorophenyl)-
acetylene (1; 910 mg, 4.74 mmol) and ether (60 mL). The
solution was cooled to -95 °C (acetone-liquid N2 bath) and
2.5 M BuLi in hexanes (1.8 mL, 4.5 mmol) was added slowly
with a syringe, precluding an internal temperature above -90
°C. The mixture was stirred at -90 to -95 °C for 2 h before
B(O-i-Pr)3 (940 mg, 5.0 mmol) was added with a syringe. A
white suspension resulted, which was stirred at -90 °C for 1
h, warmed to -20 °C, and poured into a solution of K[HF2] (8
g, 102 mmol) in water (45 mL) and 48% HF (3 mL). The
mixture was stirred at 20 °C for 1 h, before being extracted
with acetonitrile (5 × 20 mL). The combined extracts were
treated with 10 g of KF and formed two phases. The organic
phase was separated, and the aqueous phase was again
extracted with acetonitrile (2 × 10 mL). The combined extracts
were evaporated under reduced pressure. The solid residue
was dried under high vacuum (0.013 hPa) for 2 h and then
over Sicapent in a vacuum desiccator overnight. The white salt
15 (910 mg, 64%) was obtained as a powder. 19F NMR (CH3-
3JFF ) 141 Hz; 3JFF ) 14 Hz, 2F, F4) ppm. 11B NMR (CH3CN)
(trans-19): δ -2.1 (q JBF ) 32 Hz) ppm. IR: νmax/cm-1 1692
1
(m), 1614 (w), 1363 (s), 1340 (s), 1243 (s), 1212 (s), 1140 (s),
1087 (s), 1031 (s), 1001 (s), 943 (m), 860 (m), 814 (m), 747 (m),
727 (m), 646 (w), 624 (w), 601 (w), 579 (w), 533 (w). Raman:
νmax/cm-1 2198 ν(CtC), 1692 ν(CdC), 1342, 749, 621, 386, 152.
[K‚18-crown-6][C4F9CFdCFCtCBF3]. Anal. Calcd for
C20H24BF14KO6 (676.29): C, 35.52; H, 3.58. Found: C, 35.4;
H, 3.58.
Acknowledgment. We gratefully acknowledge fi-
nancial support by the Deutsche Forschungsgemein-
schaft, the Russian Foundation for Basic Research
(Grant 04-03-04002-NNIO_a), and the Fonds der Che-
mischen Industrie. We thank Honeywell for generous
donation of chemicals.
Supporting Information Available: Tables S1-S3, com-
piling the 11B and 19F NMR spectra of K[RFBF3] (RF
)
polyfluoroalkyl, polyfluoroalk-1-enyl, polyfluoroaryl). This
material is available free of charge via the Internet at
http://pubs.acs.org.
1
CN): δ -134.3 (q JFB ) 33 Hz, BF3), -138.4 (m, 2F, F2,6),
-156.9 (t 3JFF ) 20 Hz, 1F, F4), -163.6 (m, 2F, F3,5) ppm. 11
B
1
NMR (CH3CN): δ -1.9 (q JBF ) 34 Hz) ppm. 19F NMR
1
(acetone-d6): δ -134.3 (q JFB ) 33 Hz, BF3), -137.9 (m, 2F,
OM050590F