Addition of enamines or pyrroles and B(C6F5) 3 "frustrated Lewis Pairs" to alkynes

Article abstract of DOI:10.1021/om1008346

Reaction of 1-morpholinocyclohexene with B(C₆F₅) ₃ and phenylacetylene gave a mixture of two compounds, [C ₆H₁₀N(CH₂CH₂)₂O] [PhCCB(C₆F₅)₃

Full text of DOI:10.1021/om1008346

6422 Organometallics 2010, 29, 6422–6432
DOI: 10.1021/om1008346
Addition of Enamines or Pyrroles and B(C6F5)3
“Frustrated Lewis Pairs” to Alkynes
Meghan A. Dureen, Christopher C. Brown, and Douglas W. Stephan*
Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada, M5S 3H6
Received August 26, 2010
Reaction of 1-morpholinocyclohexene with B(C6F5)3 and phenylacetylene gave a mixture of
two compounds, [C6H10N(CH2CH2)2O][PhCCB(C6F5)3] (1a) and C6H9(2-PhCdC(H)B(C6F5)3)-
(N(CH2CH2)2O (1b). The analogous reaction with ethynylferrocene resulted in only the deprotona-
tion product, the alkynyl-borate salt [C6H10N(CH2CH2)2O][CpFe(C5H4)CCB(C6F5)3] (2). The
related reactions of pyrrole, phenylacetylene, and B(C6F5)3 led to the vinyl-borate addition product,
HNC4H4(2-PhCdC(H)B(C6F5)3) (3). In a similar fashion, reaction of N-methylpyrrole, phenyl-
acetylene, and B(C6F5)3 gave a 3:2 ratio of the products MeNC4H4(2-PhCdC(H)B(C6F5)3) (4a) and
MeNC4H4(3-PhCdC(H)B(C6F5)3) (4b), while the corresponding reaction of N-tert-butylpyrrole
with phenylacetylene and B(C6F5)3 provided a single product, tBuNC4H4(3-PhCdC(H)B(C6F5)3)
(5a). Variations in the aryl alkynes produced the corresponding addition complexes, tBuNC4H4-
(3-ArCdC(H)B(C6F5)3) (Ar = p-C6H4Br 5b, m-C6H4Cl 5c, p-C6H4CF3 5d, CpFe(C5H4) 5e).
Similarly MeNC4H2(2,5-Me2)(3-ArCdC(H)B(C6F5)3) (Ar = Ph 6a, p-C6H4Br 6b, m-C6H4Cl 6c,
p-C6H4CF3 6d, CpFe(C5H4) 6e) were derived from 1,2,5-trimethylpyrrole. The species 5a and 5b were
shown to rearrange to give tBuNC4H3(3-ArCdC(H)(C6F5)B(C6F5)2) (Ar = Ph 7a, CpFe(C5H4) 7b).
The related complexes RNC4H3(3-PhCdC(H)(C6F5)B(C6F5)2) (R=SiMe3 8, Ph 9) and MeNC4H-
(2,5-Me2)(3-PhCdC(H)(C6F5)B(C6F5)2) (10) were derived directly from the corresponding reactions
of the pyrrole, PhCCH, and B(C6F5)3. In the case of the reaction of N-tert-butylpyrrole, phenyl-
acetylene, and PhB(C6F5)2, phenyl group migration was observed, affording exclusively the species
tBuNC4H3(3-PhCdC(H)(Ph)B(C6F5)2) (11). Reaction of 5a or 4a/4b and tBu3P resulted in depro-
tonation and formation of the salts [tBu3PH][RNC4H3(X-PhCdC(H)B(C6F5)3)] (R = tBu, X = 3 12;
R = Me X=2 13a, 3 13b). Reaction of 5a-d or 6a-d with one equivalent of Et3PO mediated proton
transfer to generate a series of vinyl pyrroles tBuNC4H3(3-ArCdCH2) (Ar = Ph 14a, p-C6H4Br 14b,
m-C6H4Cl 14c, p-C6H4CF3 14d) and MeNC4H2(2,5-Me2)(3-ArCdCH3) (Ar = Ph 15a, p-C6H4Br
15b, m-C6H4Cl 15c, p-C6H4CF3 15d) and the byproduct Et3PO B(C6F5)3.
3
Introduction
alkynes,6 CO2,7 and N2O.8,9 While most of these early studies
have focused on the FLPs derived from sterically encum-
bered phosphines and boranes, we believe this reactivity has
some generality. Indeed, we and others have demonstrated
FLP reactivity using carbenes,10 amines,11,12 and pyridines.13
In the case of alkynes, we have shown that phosphines6 and
polyphosphines14 in the presence of B(C6F5)3 or Al(C6F5)3
effect facile addition to the C-C triple bond. Berke and
co-workers15 have shown that similar reactions tolerate
Since our initial reports of the activation of H2 by sterically
frustrated combinations of phosphines and boranes,1 we
have shown that such frustrated Lewis pairs (FLPs) activate
B-H2 and S-S bonds3 and react with olefins,4 dienes,5
*To whom correspondence should be addressed. E-mail: dstephan@
chem.utoronto.ca.
(1) Welch, G. C.; Juan, R. R. S.; Masuda, J. D.; Stephan, D. W.
Science 2006, 314, 1124–1126.
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pubs.acs.org/Organometallics
Published on Web 11/15/2010
2010 American Chemical Society

Article
Scheme 1. Products of FLP-Alkyne Addition Reactions
Organometallics, Vol. 29, No. 23, 2010 6423
Scheme 2. Reactions of an Enamine, Pyrrole, and
N-Methylpyrrole with B(C6F5)3
Figure 1. POV-Ray depiction of 1a. C: black, F: pink, O: red, N:
aquamarine, B: yellow-green. Hydrogen atoms are omitted for
clarity. Selected bond distances (A) and angles (deg): B(1)-
˚
C(1), 1.6354(16); C(1)-C(2), 1.3381(15); C(9)-C(10), 1.5040(16);
N(1)-C(10), 1.3010(14); C(2)-C(1)-B(1), 132.24(10); C(1)-
C(2)-C(9), 122.75(10).
Scheme 3. Synthesis of 1a,b and 2
variability in the borane (Scheme 1). However, we were in-
terested in probing the viability of C-based nucleophiles in
conjunction with the Lewis acid B(C6F5)3; these FLP-
alkyne addition reactions could provide a route to new
C-C bonds. To this end, we considered the possibility that
enamines and pyrroles might act as suitable C-based nucleo-
philes in such reactions. We noted that the reactions of
enamines16,17 or pyrroles18,19 and B(C6F5)3 to give zwitter-
ionic iminium-borates were sluggish. Resconi and co-workers
showed that a Lewis acid-base adduct of pyrrole and
B(C6F5)3 forms readily;20 however N-methylpyrrole reacts
with B(C6F5)3 over 4 days to form the zwitterion in which the
borane is C-bound, MeNC4H4(B(C6F5)3) (Scheme 2).18,21-23
In this paper, we exploit the slow direct reaction of en-
amines and pyrroles with B(C6F5)3, to demonstrate the
viability of such Lewis acid-base combinations in three-
component reactions involving terminal alkynes. The
nature of these products and their subsequent reactivity
is also probed.
Results and Discussion
The FLP-catalyzed hydrogenation of 1-morpholinocyclo-
hexene has been reported,24 implying that binding of the
enamine or ether fragment to the Lewis acid is weak. As such,
it was anticipated that 1-morpholinocyclohexene would be a
suitable enamine for reaction with B(C6F5)3 and terminal
alkynes. Addition of B(C6F5)3 to a solution of 1-morpho-
linocyclohexene with excess phenylacetylene in toluene re-
sulted in the immediate formation of an immiscible layer.
Subsequent workup afforded a microcrystalline solid. The 11B
NMR resonances at -16 and -20 ppm revealed this prod-
uct was a mixture of two compounds (1a and 1b, Scheme 3)
and were characteristic of the borate center in a vinyl-borate
zwitterion and an alkynylborate anion, respectively.6 On the
basis of further spectroscopic data these species were for-
mulated as [C6H10N(CH2CH2)2O][PhCCB(C6F5)3] (1a) and
C6H9(2-PhCdC(H)B(C6F5)3)(N(CH2CH2)2O (1b). Attempts
to separate these complexes on the basis of differences in
solubility were unsuccessful. Nevertheless, slow evaporation
from dichloromethane afforded X-ray quality crystals of
the addition product (Figure 1). The unsaturated β-carbon
of the enamine is the site of addition on the nucleophile,
(16) Blackwell, J. M.; Piers, W. E.; Parvez, M.; McDonald, R.
Organometallics 2002, 21, 1400–1407.
(17) Millot, N.; Santini, C. C.; Fenet, B.; Basset, J. M. Eur. J. Inorg.
Chem. 2002, 3328–3335.
(18) Focante, F.; Camurati, I.; Nanni, D.; Leardini, R.; Resconi, L.
Organometallics 2004, 23, 5135–5141.
(19) Focante, F.; Camurati, I.; Resconi, L.; Guidotti, S.; Beringhelli,
T.; D’Alfonso, G.; Donghi, D.; Maggioni, D.; Mercandelli, P.; Sironi, A.
Inorg. Chem. 2006, 45, 1683–1692.
(20) Guidotti, S.; Camurati, I.; Focante, F.; Angellini, L.; Moscardi,
G.; Resconi, L.; Leardini, R.; Nanni, D.; Mercandelli, P.; Sironi, A.;
Beringhelli, T.; Maggioni, D. J. Org. Chem. 2003, 68, 5445–5465.
(21) Kehr, G.; Roesmann, R.; Frohlich, R.; Holst, C.; Erker, G. Eur.
J. Inorg. Chem. 2001, 535–538.
(22) Resconi, L.; Guidotti, S. (Basell Technology Company B.V.,
Netherlands) WO Pat. Appl. 2001-EP1467 2001062764, 2001.
(23) Resconi, L.; Guidotti, S. (Basell Polyolefine GmbH, Germany)
WO Pat. Appl. 2002-EP5087 2002102811, 2002.
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Erker, G. Angew. Chem., Int. Ed. 2008, 47, 7543–7546.

6424 Organometallics, Vol. 29, No. 23, 2010
Scheme 4. Synthesis of 3, 4a-e, and 5a-e
Dureen et al.
In a similar fashion, reaction of N-methylpyrrole, phenyl-
acetylene, and B(C6F5)3 was carried out. The 11B NMR
spectrum was comprised of a single resonance at -16 ppm.
Duplicate para-fluorine resonances in the 19F NMR spec-
trum as well as complex resonances in the 1H NMR spectrum
indicated the product was derived from addition to both the
1
R- and β-carbons of the pyrrole. Integration of suitable H
resonances indicated a 3:2 ratio of the products MeNC4H4-
(2-PhCdC(H)B(C6F5)3) (4a) and MeNC4H4(3-PhCdC-
(H)B(C6F5)3) (4b), respectively (Scheme 4). Interestingly, a
similar distribution of products was observed in the reac-
tion of selenium-containing carbocations with N-methyl-
pyrrole.30 The species 4 are short-lived in CD2Cl2, degrading
within 20 min of dissolution, as evidenced by the evolution of
broad resonances at 3 and 2 ppm and a sharp resonance at
ca. -8 ppm in the 11B NMR spectrum. Hence spectroscopic
characterization of 4 was conducted quickly. It is of note that
the known zwitterion formed from direct reaction of N-methyl-
pyrrole and B(C6F5)3 was not observed as a byproduct,
although this species was reportedly formed in reactions
lasting 4-10 days.18 Nonetheless, this indicates that pyrrole
addition to alkyne is rapid. The analogous reaction of
N-methylindole, phenylacetylene, and B(C6F5)3 gave only
the product PhCHdC(C6F5)B(C6F5)2,15 consistent with the
view that N-methylpyrrole is a better nucleophile than the
related indole.
The corresponding reaction of N-tert-butylpyrrole with
phenylacetylene and B(C6F5)3, followed by immediate
precipitation with pentane, provided a single product,
tBuNC4H4(3-PhCdC(H)B(C6F5)3) (5a, Scheme 4). This
species, obtained in 86% yield, was a moisture-sensitive
microcrystalline product. NMR data were consistent with
exclusive β-carbon substitution, as is characteristic of elec-
trophilic addition to sterically hindered, N-substituted pyr-
roles.31 X-ray crystallographic characterization of 5a (Figure 2)
confirmed substitution at the β-position of the pyrrole and
the regiochemistry about the former alkynyl fragment. This
was consistent with nucleophilic attack at the more substi-
tuted carbon, congruent with the previous work with phos-
phines.4,6 While the metrical parameters are not extraor-
dinary, the C-C bond lengths within the pyrrole fragment
indicate the acidic proton is localized on the carbon R to both
the nitrogen and vinyl fragment, which allows for a contig-
uous π-system. The analogous reactions using a series of
electron-deficient aryl alkynes, ArCCH (Ar = p-C6H4Br,
m-C6H4Cl, p-C6H4CF3, and CpFe(C5H4)), produced the
corresponding addition complexes, tBuNC4H4(3-ArCdC-
(H)B(C6F5)3) (5b-e, Scheme 4). The solid-state molecular
structure of the ferrocenyl-substituted complex (5e, Figure 2)
was also determined and demonstrated similar structural
parameters to those of 5a. While this reaction appears to
have some generality with electron-deficient alkynes, analo-
gous reactions involving N-tert-butylpyrrole, B(C6F5)3, with
1-hexene, 1-hexyne, or 3,3-dimethyl-1-butyne, or triphenyl-
resulting in an iminium-vinyl-borate zwitterion. The analo-
gous reaction with ethynylferrocene resulted in only depro-
tonation to the corresponding alkynyl-borate salt, [C6H10-
N(CH2CH2)2O][CpFe(C5H4)CCB(C6F5)3], 2 (Scheme 3). It
is presumed that the steric demands of this terminal alkyne
kinetically favor deprotonation over addition. As to the
nature of the cation formed in the deprotonation pathway,
1-morpholinoenamine undergoes kinetic protonation at nitro-
gen, but tautomerizes to the thermodynamically favored
iminium ion in solution.25
Although the above alkyne addition pathway results in
divergent reactivity, it was anticipated that steric bulk in
weakly C-based nucleophiles could preclude adduct forma-
tion with the Lewis acid and facilitate addition. In this
regard, we noted that substituted pyrroles were worthy of
investigation, as they are less nucleophilic than 1-morphol-
inocyclohexene.26,27 In addition, as the pKa values of proton-
ated pyrrole, N-methylpyrrole, and 1,2,3-trimethylpyrrole
are -3.80, -2.90, and -0.24,28 respectively, it is reasonable
toassumethatthedeprotonation pathway willbe less favored.
To probe this hypothesis, a small-scale reaction of pyrrole,
phenylacetylene, and B(C6F5)3 was conducted in CD2Cl2.
This led to the formation of a vinyl-borate addition product,
HNC4H4(2-PhCdC(H)B(C6F5)3), 3 (Scheme 4), as evi-
denced by the characteristic, sharp 11B NMR resonance
(-16 ppm). However, upon standing, this signal vanished
and was replaced with broad resonances at -3.6 and -4.2
ppm arising from unknown degradation products. In order
to suppress the latter reaction pathway, the procedure was
scaled up and the initial zwitterionic product 3 was precipi-
tated out of solution by addition of a nonpolar solvent
immediately following addition of the Lewis acid. Although
1
this led to relatively low yields (57%), the H NMR spec-
trum was consistent with alkyne addition at the R-position
of the pyrrole. Electrophilic substitution at this position
is usually typically favored over attack at the β-carbon of
the pyrrole ring.29 The alacrity of this reaction is evidenced
by the absence of any byproducts despite the known reac-
tions of B(C6F5)3 and pyrrole,20 and B(C6F5)3 and phenyl
acetylene.15
borane or Et2O BF3 with phenylacetylene and N-tert-butyl-
3
pyrrole, did not afford similar products.
(25) Opitz, G.; Griesinger, A. Justus Liebigs Ann. Chem. 1963, 665,
101–13.
(26) Mayr, H.; Bug, T.; Gotta, M. F.; Hering, N.; Irrgang, B.; Janker,
B.; Kempf, B.; Loos, R.; Ofial, A. R.; Remennikov, G.; Schimmel, H.
J. Am. Chem. Soc. 2001, 123, 9500–9512.
Using 1,2,5-trimethylpyrrole as a nucleophile, a similar
series of complexes, MeNC4H2(2,5-Me2)(3-ArCdC(H)-
B(C6F5)3) (Ar = Ph 6a, p-C6H4Br 6b, m-C6H4Cl 6c,
p-C6H4CF3 6d, CpFe(C5H4) 6e), were synthesized (Scheme 5).
As reaction at the R-position was blocked by the methyl
(27) Kempf, B.; Hampel, N.; Ofial, A. R.; Mayr, H. Chem. Eur. J.
;
2003, 9, 2209–2218.
(28) Chiang, Y.; Whipple, E. B. J. Am. Chem. Soc. 1963, 85, 2763–
2767.
(29) Joule, J. A.; Smith, G. F. Heterocyclic Chemistry, 2nd ed.;
Van Nostrand Reinhold: New York, 1978.
(30) Halazy, S.; Hevesi, L. J. Org. Chem. 1983, 48, 5242–6.
(31) Anderson, H. J.; Loader, C. E. Synthesis 1985, 353–64.

Article
Organometallics, Vol. 29, No. 23, 2010 6425
Figure 3. POV-Ray depiction of 6a. C: black, P: orange, F: pink,
N: aquamarine, B: yellow-green, H: white. Hydrogen atoms
are omitted for clarity. 6a: C(1)-B(1), 1.6259(17); C(1)-C(2),
1.3558(16); C(2)-C(9), 1.4575(16); C(9)-C(12), 1.3583(16);
C(11)-C(12), 1.4324(18); C(11)-N(1), 1.3071(17); C(10)-N(1),
1.4705(15); C(9)-C(10), 1.5063(17); C(2)-C(1)-B(1), 131.37(11);
C(1)-C(2)-C(9), 119.02(11); C(11)-N(1)-C(10), 110.82(10).
metrical parameters to 5a and 5e. Complexes 6a-e were also
very moisture sensitive, and although more robust in solu-
tion than 5a-e, partial decomposition was observed over the
course of 12 h by 19F NMR spectroscopy.
A solution of 5a in CD2Cl2 was monitored by NMR
spectroscopy. After 24 h the reaction revealed the clean
and quantitative conversion to a new species with a sharp
11B NMR resonance at -7 ppm. Concurrently, 19F NMR
spectroscopy revealed three inequivalent pentafluorophenyl
rings. 1H NMR data suggested the new compound 7a
contained an iminium fragment, but the resonance for the
vinylic H cis to B had disappeared. A similar species, 7b, was
obtained from the analogous reaction with ethynylferrocene.
X-ray crystallography was used to determine the molecular
structures of these rearrangement products, confirming their
formulation as the zwitterionic bicyclic species tBuNC4H3-
(3-ArCdC(H)(C6F5)B(C6F5)2) (Ar=Ph 7a, CpFe(C5H4) 7b;
Figure 4), with rings containing a borate or iminium centers.
In both 7a and 7b the chiral centers are found to have
hydrogen substituents that are trans-disposed with respect
to each other in the solid state. However, the 1H resonances
arising from these H-substituents are quite broad, ostensibly
an effect of proximity to boron, and thus it is unclear if a
single diastereomer exists in solution.
Figure 2. POV-Ray depiction of 5a and 5e. C: black, P: orange,
F: pink, N: aquamarine, B: yellow-green, H: white. Hydrogen
˚
atoms are omitted for clarity. Selected bond distances (A) and
angles (deg): 5a: C(1)-B(1), 1.629(4); C(1)-C(2), 1.345(4); C(2)-
C(9), 1.454(4); C(9)-C(10), 1.354(4); C(10)-C(11), 1.416(4); N-
(1)-C(11), 1.295(4); N(1)-C(12), 1.473(3); C(9)-C(12), 1.501(4);
C(11)-N(1)-C(12), 108.6(2); C(2)-C(1)-B(1), 130.0(2); C(1)-
C(2)-C(9), 120.4(2). 5e: C(1)-B(1), 1.641(3); C(1)-C(2),
1.350(3); C(2)-C(13), 1.460(3); C(2)-C(3), 1.479(3); C(9)-C(10),
1.424(4); C(10)-(C11), N(1)-C(15), 1.294(3); N(1)-C(14),
1.469(3); C(15)-N(1)-C(14), 109.25(19); C(1)-C(2)-C(3),
123.01(19); C(13)-C(2)-C(3), 118.09(19).
Scheme 5. Synthesis of 6a-e
The related complexes RNC4H3(3-PhCdC(H)(C6F5)-
B(C6F5)2) (R=SiMe3 8, Ph 9) were derived from the
corresponding reactions of N-(trimethylsilyl)pyrrole and
N-phenylpyrrole with PhCCH and B(C6F5)3, respectively
(Scheme 6). In these cases the intermediate species analogous
to 5 were not observed. The analogous compound MeNC4H-
(2,5-Me2)(3-PhCdC(H)(C6F5)B(C6F5)2) (10) was obtained
upon heating 6a to 60 °C. This species was isolated as a
mixture of diastereomers, as evidenced by inequivalent
11B NMR resonances at -8.1 and -8.8 ppm. This was also
supported by the solid-state molecular structure of 10, where
substituent, this reaction was also regioselective, although in
this case a chiral center was generated. The molecular
structure of 6a was determined by X-ray crystallography
(Figure 3), which revealed similar regiochemistry and

6426 Organometallics, Vol. 29, No. 23, 2010
Dureen et al.
Figure 5. POV-Ray depiction of 10. C: black, F: pink, N:
aquamarine, B: yellow-green. Hydrogen atoms are omitted for
˚
clarity. Selected bond distances (A) and angles (deg): B(1)-C(1),
1.690(4); C(1)-C(2), 1.528(4); C(2)-C(3), 1.345(4); C(3)-C(4),
1.518(4); N(1)-C(4), 1.491(4); N(1)-C(5), 1.293(4) C(6)-C(5),
1.478(4); B(1)-C(6), 1.680(4); C(6)-C(3), 1.502(4); C(6)-
B(1)-C(1), 98.9(2); C(5)-N(1)-C(4), 114.2(3); C(2)-C(3)-
C(4), 132.4(3).
Scheme 6. Synthesis of 7a,b and 8-10
Figure 4. POV-Ray depictionsof7a and 7b. C: black, Fe: purple,
F: pink, N: aquamarine, B: yellow-green. Hydrogen atoms
˚
are omitted for clarity. Selected bond distances (A) and angles
(deg): 7a: B(1)-C(1), 1.706(5); C(1)-C(2), 1.548(5); C(2)-C(3),
1.346(5); C(3)-C(4), 1.513(5); N(1)-C(4), 1.508(4); N(1)-C(5),
1.295(4); C(5)-C(6), 1.470(5); B(1)-C(6), 1.671(5); C(5)-N(1)-
C(4), 111.7(3); C(6)-B(1)-C(1), 99.2(2); C(2)-C(3)-C(4),
133.7(3). 7b: C(1)-B(1), 1.690(4); C(1)-C(2), 1.533(4); C(2)-
C(13), 1.342(4); C(13)-C(16), 1.497(4); N(1)-C(16), 1.511(4);
N(1)-C(15), 1.291(4); C(14)-C(15), 1.460(4); C(14)-B(1),
1.669(4); C(15)-N(1)-C(16), 111.6(2); C(14)-B(1)-C(1),
98.9(2); C(2)-C(13)-C(16), 133.3(3).
However, the corresponding reaction of N-tert-butylpyrrole,
phenylacetylene, and PhB(C6F5)2 proceeded via this same
process with phenyl group migration, exclusively leading to
the species tBuNC4H3(3-PhCdC(H)(Ph)B(C6F5)2) (11), as
evidenced by 19F NMR spectroscopy. The same selectivity
was not observed in the analogous reaction with ClB(C6F5)2,
where an inseparable mixture of products formed. These are
presumed to arise from 1,2-migrations of either C6F5 or Cl.
In an effort to halt this rearrangement, tBu3P was com-
bined with 5a, resulting in deprotonation of the pyrrole and
formation of the salt [tBu3PH][tBuNC4H3(3-PhCdC(H)-
B(C6F5)3)] (12) (Scheme 7). This formulation was confirmed
by an X-ray crystallographic study of 12 (Figure 6). The met-
rical parameters were unexceptional. In contrast to the pre-
cursor 5a, this species 12 proved to be stable in solution for
several weeks. Similar treatment of the mixture of 4a and 4b
with tBu3P afforded a mixture of the salts [tBu3PH]-
[MeNC4H3(2-PhCdC(H)B(C6F5)3)] (13a) and [tBu3PH]-
[MeNC4H3(3-PhCdC(H)B(C6F5)3)] (13b). In the case of 13a,
the molecular structure was confirmed crystallographically.
Employing a similar strategy, efforts to intercept the
borane intermediate during the rearrangement process were
undertaken by the addition of donor molecules. Treatment
the methyl group bound to the saturated C center was
disordered (Figure 5).
The formation of these rearrangement products is thought
to proceed via a 1,2-migration of one of the pentafluoro-
phenyl groups followed by a ring-closing addition via the
enamine fragment (Scheme 6). Such 1,2-migrations are com-
mon in the reactivity of borates and are involved in most of
the utilitarian reactions of organoboranes,32,33 and such
C6F5 transfer reactions account for reactivity of terminal
alkynes15 with B(C6F5)3 alone. Similar rearrangements were
not observed from the R-addition products such as 3 and 4a.
(32) Pelter, A.; Smith, K.; Brown, H. C., Borane Reagents; Academic
Press Limited: London, 1988.
(33) Aggarwal, V. K.; Fang, G. Y.; Ginesta, X.; Howells, D. M.; Zaja,
M. Pure Appl. Chem. 2006, 78, 215–229.

Article
Organometallics, Vol. 29, No. 23, 2010 6427
Figure 6. POV-Ray depiction of the cation of 12. C: black, P:
orange, F: pink, N: aquamarine, B: yellow-green, H: white.
Most hydrogen atoms are omitted for clarity. Selected bond
Figure 7. POV-Ray depiction of the cation of 13a. C: black, P:
orange, F: pink, N: aquamarine, B: yellow-green, H: white.
Most hydrogen atoms are omitted for clarity. Selected bond
˚
distances (A) and angles (deg): B(1)-C(1), 1.634(5); C(1)-C(2),
˚
distances (A) and angles (deg): B(1)-C(1), 1.633(3); C(1)-C(2),
1.343(4); C(2)-C(10), 1.479(4); C(9)-C(10), 1.373(5); N(1)-
C(9), 1.382(4); N(1)-C(12), 1.375(4); C(11)-C(12), 1.362(5);
C(1)-C(2)-C(10), 121.3(3); C(1)-C(2)-C(3), 123.3(3).
1.344(3); C(2)-C(9), 1.482(3); C(9)-C(10), 1.374(3); C(1)-
C(2)-C(9), 119.55(19) C(10)-C(11), 1.416(4); C(11)-C(12),
1.352(5); N(1)-C(12), 1.367(4); N(1)-C(9), 1.379(3); C(1)-
C(2)-C(3), 125.24(19); C(1)-C(2)-C(9), 119.55(19).
Scheme 7. Synthesis of 12 and 13a,b
Scheme 8. Generation of 14a-d and 15a-d
of 5a with thioethers, primary anilines, and triphenylphos-
phine sulfide had no effect on the rearrangement to 7a.
However, treatment of 5a with one equivalent of Et3PO
rapidly afforded a mixture of the borane adduct Et3PO
B(C6F5)3 and tBuNC4H3(3-PhCdCH2) (14a). An indepen-
3
dent synthesis of the adduct Et3PO B(C6F5) confirmed its
formation in this reaction. Quantitative formation of the
3
1
3-vinylpyrrole 14a is observed by H NMR spectroscopy.
The appearance of two characteristic doublets with chemical
shifts between 5.5 and 5.0 ppm with geminal coupling con-
stants of 1-2 Hz is consistent with known data for related
3-vinylpyrroles.34 In a similar fashion treatment of 5b-d and
6a-d afforded the series of vinyl pyrroles tBuNC4H3-
(3-ArCdCH2) (Ar = p-C6H4Br 14b, m-C6H4Cl 14c, p-C6H4-
CF3 14d) and MeNC4H2(2,5-Me2)(3-ArCdCH3) (Ar = Ph
15a, p-C6H4Br 15b, m-C6H4Cl 15c, p-C6H4CF3 15d) (Scheme 8).
It is of note that the ferrocenyl complexes 5e and 6e did not
react cleanly with Et3PO, and it remains unclear whether
the proton transfer reaction in this instance or the resulting
vinyl products are more reactive. The formation of the vinyl
pyrroles is thought to proceed via base-mediated proton
shuttling to C with B-C bond cleavage and formation of
the borane adduct. Similar reactivity was observed with the
use of other bases such as Ph3PO and Ph3P, although Et3PO
proved to be the fastest and most selective reagent. While the
vinyl pyrroles 14 and 15 were spectroscopically characterized,
exhaustive efforts to isolate these species proved futile.
Indeed, concentration of these species seemed to accelerate
degradation to unidentified mixtures of products. This may
be a result of the known ability of vinyl pyrroles to undergo
[4þ2] cycloadditions35 or N-alkyl pyrroles to undergo
Michael additions with electron-deficient alkenes.36 None-
theless, vinyl pyrroles are important synthons and intermedi-
ates in extensive synthetic chemistry,29,34,37,38 and installa-
tion of a vinyl group at the β-position typically involves
transformation of a formyl pyrrole,39 direct vinylation
via Michael-type additions36 or transition metal catalyzed
(35) Jones, R. A.; Marriott, M. T. P.; Rosenthal, W. P.; Sepulveda
Arques, J. J. Org. Chem. 1980, 45, 4515–4519.
(36) Noland, W. E.; Lee, C. K. J. Org. Chem. 1980, 45, 4573–4582.
(37) Jones, R. A. Pyrroles; Wiley: New York, 1990; Vol. 1.
(38) Gilchrist, T. L. Heterocyclic Chemistry, 3rd ed.; Longman:
Harlow, Essex, England, 1997.
(39) Trofimov, B. A.; Sobenina, L. N.; Demenev, A. P.; Mikhaleva,
(34) Jones, R. A. Pyrroles; Wiley: New York, 1990; Vol. 2.
A. I. Chem. Rev. 2004, 104, 2481–2506.

6428 Organometallics, Vol. 29, No. 23, 2010
Dureen et al.
additions of activated alkyne.40-42 As such reactions are
often unselective due to the facility of electrophilic attack on
pyrroles,43 the present observation demonstrates that an
FLP-alkyne addition approach to vinyl pyrroles is viable,
although modifications are required to generate isolable
vinyl pyrroles.
Conclusions. Herein the addition of FLPs to aryl-alkynes has
been extended to enamines and pyrroles, providing the first
instances of C-C bond formations in FLP systems. In the case
of N-substituted pyrroles steric demands favor substitution at
the β- rather than the R-position. The resulting zwitterions
derived from β-substituted pyrrole/borane additions to alkynes
are also shown to be reactive. These species undergo a 1,2 aryl-
group shift from B to give bicyclic zwitterionic products.
Deprotonation with a strong base gives robust salts,
whereas weaker bases mediate proton shuttling to C, gen-
erating unstable vinyl pyrroles. The development of the other
applications of FLP chemistry in the formation of new C-C
bonds continues to be an area of interest in our laboratory.
were synthesized via a similar procedure, and hence only one
synthesis is described. 1a þ 1b: A solution of B(C6F5)3 (100 mg,
0.2 mmol) in toluene (3 mL) was added to a mixture of
1-morpholinocyclohexene (34 mg, 0.2 mmol) and phenylacety-
lene (20 mg, 0.2 mmol) in toluene (3 mL) in one portion. A
yellow layer immediately separated from the toluene layer, the
latter layer was decanted, and the former was triturated and
washed with pentane (3 ꢀ 5 mL) to afford a yellow solid (128 mg,
84%). The solid was determined from 11B and 19F NMR spectra
to be a 50:50 mixture of the products resulting from deprotona-
tion (1a) and addition (1b). 1H NMR (CD2Cl2): 7.3 (dm,
3JH-H = 7 Hz), 7.3-7.1 (m), 7.0 (m), 6.8 (m), 6.3 (s), 4.4 (dm,
JH-H = 14 Hz), 4.2 (dm, JH-H = 14 Hz), 4.4 (dt, JH-H = 12 Hz,
JH-H = 3 Hz), 3.9 (m), 3.8 (m, br) 3.8 (m), 3.7 (m), 3.6 (m), 3.2
3
3
(m), 3.1 (m), 3.0 (m), 2.7 (t, JH-H = 6 Hz), 2.3 (t, JH-H
=
6 Hz), 1.9-1.8 (m), 1.7 (m), 1.5 (m). 11B NMR (CD2Cl2): -16.3
(s, addition), -20.9 (s, deprotonation). 13C{1H} NMR (CD2Cl2),
partial: 198.1 (s), 194.7 (s), 148.7 (dm, 1JC-F = 238 Hz, m-C6F5),
141.2 (s), 139.0 (dm, 1JC-F = 247 Hz, p-C6F5), 131.7 (s), 128.9
(s), 128.2 (s), 127.3 (s), 127.2 (s), 127.1 (s), 67.0 (s), 66.7 (s), 64.1
(s), 53.9 (s), 53.6 (s), 52.1 (s), 45.9 (s), 42.6 (s), 34.0 (s), 31.4 (s),
29.5 (s), 27.6 (s), 27.5 (s), 25.4 (s), 24.8 (s), 23.6 (s), 19.01 (s), 19
F
3
Experimental Section
NMR (CD2Cl2): -132.6 (d, 6F addition, JF-F = 24 Hz,
3
o-C6F5), -133.0 (d, 6F deprotonation, JF-F = 22 Hz,
3
General Considerations. All manipulations were carried out
under an atmosphere of dry, O2-free N2 employing a Vacuum
Atmospheres glovebox and a Schlenk vacuum line. Solvents
were purified with a Grubbs-type column system manufactured
by Innovative Technology and dispensed into thick-walled
Schlenk glass flasks equipped with Teflon-valve stopcocks
(pentane, toluene, CH2Cl2) or were dried over the appropri-
ate agents and distilled into the same kind of storage flasks
(C6H5Br). All solvents were thoroughly degassed after purifica-
tion (repeated freeze-pump-thaw cycles). Deuterated solvents
were dried over the appropriate agents, vacuum-transferred into
storage flasks with Teflon stopcocks, and degassed accordingly
(C6D5Br, CD2Cl2). Toluene and pentane were stored over potas-
o-C6F5), -163.0 (t, 3F deprotonation, JF-F = 20 Hz,
p-C6F5), -163.4 (t, 3F addition, 3JF-F = 21 Hz, p-C6F5), -166.8
3
(t, 6F deprotonation, JF-F = 22 Hz, m-C6F5), -167.3 (t, 6F
addition, JF-F = 21 Hz, m-C6F5). Anal. Calcd for C36H23-
3
BNOF15 (781.374): C, 55.34; H, 2.97; N, 1.79. Found: C, 55.03;
H, 3.21; N, 1.76. X-ray quality crystals of the isomer resulting
from addition were grown from a concentrated solution in
dichloromethane.
1
2: purple powder, 122 mg, 70%. H NMR (CD2Cl2): 5.1 (t,
1H, JH-H = 2 Hz), 4.7 (s, br, 1H), 4.4 (s, 2H), 4.3 (t, 2H, JH-H =
2 Hz, CCp), 4.1 (s, 5H, Cp), 4.0 (t, 2H, JH-H = 2 Hz, CCp),
3.9 (m, 4H), 3.3 (m, 3H), 2.7 (t, 2H, 3JH-H = 7 Hz), 2.3 (t, 1H,
JH-H = 6 Hz), 2.0 (t, 1H, JH-H = 6 Hz), 1.9 (pentet, 2H),
1.8-1.5 (m, 3H). 11B NMR (CD2Cl2): -20.9 (s). 13C{1H} NMR
(250 K, CD2Cl2), partial: 194.8 (s), 182.5 (s), 160 (s), 148.8 (dm,
1JC-F = 238 Hz, o-C6F5), 138.9 (dm, 1JC-F = 240 Hz, p-C6F5),
137.2 (dm, 1JC-F = 239 Hz, m-C6F5), 115.7 (s), 78.0 (s), 72.6 (s),
71.2 (s), 70.1 (s), 68.1 (s), 66.9 (s), 56.0 (s), 54.7 (s), 53.8 (s), 37.6
(s), 33.8 (s), 27.8 (s), 23.5 (s), 19F NMR (CD2Cl2): -132.5 (d,
sium mirrors, while bromobenzene and dichloromethane were
stored over 4 A molecular sieves. H, 11B, 13C, 19F, and 31P
˚
1
NMR spectra were recorded at 25 °C on Varian 300 and 400
MHz and Bruker 400 MHz spectrometers. Chemical shifts are
given relative to SiMe4 and referenced to the residual solvent
signal (1H, 13C) or relative to an external standard (11B: Et2O
3
BF3; 19F: CFCl3; 27Al: Al(NO3)3; 31P: 85% H3PO4). In some
instances, signal and/or coupling assignment was derived from
two-dimensional NMR experiments. Chemical shifts are re-
ported in ppm, and coupling constants as scalar values in Hz.
Combustion analyses were performed in-house employing a
Perkin-Elmer CHN analyzer. N-tert-Butylpyrrole,44 N-(trimethyl-
silyl)pyrrole,45 and PhB(C6F5)246 were synthesized via literature
procedures; B(C6F5)3 was generously donated by NOVA Che-
micals Corporation; tri-tert-butylphosphine was purchased
from Strem Chemicals; all other reagents were purchased from
Aldrich. Phenyl acetylene was vacuum transferred from CaCl2
and stored at -35 °C in the glovebox. Liquids were stored over
3
3
6F, JF-F = 23 Hz, o-C6F5), -163.6 (t, 3F, JF-F = 20 Hz,
3
p-C6F5), -167.2 (t, 6F, JF-F = 23 Hz, m-C6F5). Anal. Calcd
for C40H27BNOF15Fe (889.295): C, 54.02; H, 3.06; N, 1.58.
Found: C, 54.70; H, 3.39; N, 1.40.
Synthesis of HNC4H4(2-PhCdC(H)B(C6F5)3) (3), MeNC4H9-
(2-PhCdC(H)B(C6F5)3) (4a), MeNC4H4(3-PhCdC(H)B(C6F5)3)
(4b), tBuNC4H4(3-ArCdC(H)B(C6F5)3) (Ar = Ph 5a, p-C6H4Br
5b, m-C6H4Cl 5c, p-C6H4CF3 5d, CpFe(C5H4) 5e), and
MeNC4H2(2,5-Me2)(3-ArCdC(H)B(C6F5)3) (Ar = Ph 6a,
p-C6H4Br 6b, m-C6H4Cl 6c, p-C6H4CF3 6d, CpFe(C5H4) 6e).
These compounds were synthesized via a similar procedure; there-
fore only one preparation is detailed. A solution of B(C6F5)3
(123 mg, 0.24 mmol) in dichloromethane was cooled to -35 °C in
a freezer. A solution of N-tert-butylpyrrole (29.6 mg, 0.24 mmol)
in pentane (1.5 mL) was added in one portion followed by the
dropwise addition of a solution of phenylacetylene (24.5 mg, 0.24
mmol) in pentane (1.5 mL). The solution was initially colorless
and became more yellow over the course of the addition. After the
phenylacetylene solution had been added, pentane (5 mL) was
addedinoneportiontoprecipitateayellow-whitemicrocrystalline
solid of 5a with cocrystallized CH2Cl2 (153 mg, 86%).
˚
4 A molecular sieves.
Synthesis of [C6H10N(CH2CH2)2O][PhCCB(C6F5)3] (1a),
C6H9(2-PhCdC(H)B(C6F5)3)(N(CH2CH2)2O (1b), and[C6H10N-
(CH2CH2)2O][CpFe(C5H4)CCB(C6F5)3] (2). These compounds
(40) Hong, P.; Cho, B.-R.; Yamazaki, H. Chem. Lett. 1980, 507–10.
(41) Tsukada, N.; Murata, K.; Inoue, Y. Tetrahedron Lett. 2005, 46,
7515–7517.
(42) Yi, C. S.; Zhang, J. Chem. Commun. 2008, 2349–2351.
(43) Alexander, R. S.; Butler, A. R. J. Chem. Soc., Perkin Trans. 2
1976, 696–701.
(44) Morimoto, T.; Furuta, H. Supramol. Chem. 2007, 19, 493–500.
(45) Smith, C. J.; Tsang, M. W. S.; Holmes, A. B.; Danheiser, R. L.;
Tester, J. W. Org. Biomol. Chem. 2005, 3, 3767–3781.
(46) Deck, P. A.; Beswick, C. L.; Marks, T. J. J. Am. Chem. Soc. 1998,
120, 1772–1784.
1
3: off-white powder, 38 mg, 57%. H NMR (CD2Cl2): 9.4
(s, 1H, CdCH), 9.0 (s, br, 1H, NH), 7.8 (d, 1H, 3JH-H = 8 Hz,
CHdCH), 7.6 (d, 1H, JH-H = 8 Hz, CHdCH), 7.3 (m, 3H,
3
3
Ph), 6.9 (d, 2H, JH-H = 7 Hz, o-Ph), 4.7 (s, 2H, CH2). 11B
NMR (CD2Cl2): -16.1 (s). 19F NMR (CD2Cl2): -131.6 (d, 6F,
3
3JF-F = 22 Hz, o-C6F5), -162.2 (t, 3F, JF-F = 19 Hz,

Article
Organometallics, Vol. 29, No. 23, 2010 6429
3
p-C6F5), -166.8 (t, 6F, JF-F = 21 Hz, m-C6F5). Anal. Calcd
for C30H11BNF15 (681.213): C, 52.90; H, 2.60; N, 1.90. Found:
C, 52.39; H, 1.89; N, 2.18.
4a þ 4b: white microcrystalline solid, 706 mg, 87%. Ratio of
major (2-vinyl) to minor (3-vinyl) isomer (3:2). 1H NMR
(CD2Cl2): 8.3 (s, 1H major isomer), 8.3 (s, 1H minor isomer),
8.2 (s, 1H minor isomer), 7.5 (d, 1H major isomer, JH-H = 6
Hz), 7.2-7.0 (m), 6.9 (d, 2H, JH-H =7 Hz), 6.8 (m, 2H), 5.8
(s, 1H), 5.2 (s, 2H, minor isomer), 4.8 (s, 2H, major isomer), 3.7
(s, 3H minor isomer), 3.4 (s, 3H major isomer). 11B NMR
(CD2Cl2): -16.2 (s, br). 19F NMR (CD2Cl2): -131.9 (d, 6F
3
minor and major isomers, JF-F = 22 Hz, o-C6F5), -162.5
3
(t, 3F, major isomer, JF-F = 20 Hz, p-C6F5), -163.1 (t, 3F
3
minor isomer, JF-F = 20 Hz, p-C6F5), -166.9 (t, 6F major
isomer, 3JF-F = 21 Hz, m-C6F5), -167.2 (t, 6F minor isomer,
3JF-F = 21 Hz, m-C6F5). Anal. Calcd C31H13BNF15 (695.240):
C, 53.55; H, 1.88; N, 2.01. Found: C, 53.69; H 1.94; N, 2.01.
5a: yellow-white microcrystalline solid of 5a with cocrystal-
lized CH2Cl2 (153 mg, 86%). 1H NMR (CD2Cl2): 8.3 (dd, 1H,
4
3JH-H = 7 Hz, JH-H = 2 Hz, CHdN), 8.2 (s, 1H, CdC-H),
7.1-7.0 (m, 3H, Ph), 6.8 (dm, 2H, 3JH-H = 7 Hz, o-Ph), 5.8 (d,
3
4
1H, JH-H = 2 Hz, CHCHdN), 5.2 (d, 2H, JH-H = 2 Hz,
NCH2), 1.6 (s, 9H, tBu). 11B NMR (CD2Cl2): -16.2 (s). 13C{1H}
NMR (250 K, CD2Cl2), partial: 167.3 (s), 168.9 (s), 128.3(s),
127.9 (s), 126.8 (s), 117.8 (s), 62.4 (s), 60.7 (s), 29.6(s). 19F NMR
(CD2Cl2): -131.9 (d, 6F, 3JF-F = 22 Hz, o-C6F5), -162.8 (t, 3F,
3
3JF-F = 20 Hz, p-C6F5), -167.0 (t, 6F, JF-F = 21 Hz,
m-C6F5). Anal. Calcd for C34H19BNF15 CH2Cl2 (822.253): C,
3
51.13; H, 2.57; N, 1.70. Found: C, 51.35; H, 2.74; N, 1.83. X-ray
quality crystals were grown from a concentrated solution in
dichloromethane.
1
5b: yellow powder, 153 mg, 96%. H NMR (CD2Cl2): 8.3
(m, 1H, CHdN), 8.25 (s, 1H, CdCH), 7.2 (d, 2H, 3JH-H=8 Hz),
6.7 (d, 2H, 3JH-H=8 Hz), 5.9 (d, 1H, 3JH-H=2 Hz, CHCHdN),
4
t
5.2 (d, 2H, JH-H=2 Hz, NCH2), 1.6 (s, 9H, Bu). 11B NMR
(CD2Cl2): -16.3 (s). 19F NMR (CD2Cl2): -131.8 (d, 6F, 3JF-F
=
23 Hz, o-C6F5), -162.8 (t, 3F, 3JF-F=21 Hz, p-C6F5), -167.0
(t, 6F, 3JF-F=21 Hz, m-C6F5). Anal. Calcd for C34H18BNF15Br
(816.216): C, 50.03; H, 2.22; N, 1.72. Found: C, 49.86; H, 2.33;
N, 1.74.
5c: yellow powder, 111 mg, 74%. 1H NMR (CD2Cl2): 8.3 (m,
1H, CHdN), 8.26 (s, 1H, CdCH), 7.1 (dm, 1H, 3JH-H = 8 Hz),
7.06 (t, 1H, JH-H = 8 Hz), 6.8 (dm, 1H, JH-H = 8 Hz),
3
3
3
6.7 (m, 1H), 5.9 (d, 1H, JH-H = 2 Hz, CHCHdN), 5.2
(d, 2H, JH-H = 2 Hz, NCH2), 1.6 (s, 9H, Bu). 11B NMR
4
t
(CD2Cl2): -16.3 (s). 19F NMR (CD2Cl2): -131.7 (d, 6F,
3JF-F = 23 Hz, o-C6F5), -162.5 (t, 3F, JF-F = 20 Hz,
3
3
p-C6F5), -167.0 (t, 6F, JF-F = 21 Hz, m-C6F5). Anal. Calcd
for C34H18BNF15Cl (771.765): C, 52.92; H, 2.35; N, 1.81.
Found: C, 52.79; H, 2.44; N, 1.93.
5d: yellow powder, 145 mg, 90%. H NMR (CD2Cl2): 8.33
1
3
(m, 1H, CHdN), 8.29 (s, 1H, CdCH), 7.4 (d, 2H, JH-H = 8
3
3
Hz), 7.0 (d, 2H, JH-H = 8 Hz), 5.8 (d, 1H, JH-H = 2 Hz,
CHCHdN), 5.2 (d, 2H, 4JH-H = 2 Hz, NCH2), 1.6 (s, 9H, tBu).
11B NMR (CD2Cl2): -16.3 (s). 19F NMR (CD2Cl2): -63.2
3
(s, 3F, CF3), -131.8 (d, 6F, JF-F = 22 Hz, o-C6F5), -162.3
(t, 3F, 3JF-F = 21 Hz, p-C6F5), -166.9 (t, 6F, 3JF-F = 21 Hz,
m-C6F5). Anal. Calcd for C35H18BNF18 (805.319): C, 52.20; H,
2.25; N, 1.34. Found: C, 53.03; H, 2.87; N, 1.74.
5e: green powder, 194 mg, 76%. 1H NMR (CD2Cl2): 8.5 (m,
3
1H, CHdN), 8.0 (s, 1H, CdCH), 7.6 (d, 2H, JH-H = 2 Hz,
4
CHCHdN), 5.2 (d, 2H, JH-H = 2 Hz, NCH2), 4.1 (t, 2H,
3JH-H = 2 Hz, CCp0), 4.05 (s, 5H, Cp), 4.0 (t, 2H, 3JH-H = 2 Hz,
CCp0), 1.7 (s, 9H, tBu). 11B NMR (CD2Cl2): -16.0 (s). 19F NMR
3
(CD2Cl2): -131.1 (d, 6F, JF-F = 22 Hz, o-C6F5), -163.1 (t,
3
3
3F, JF-F = 22 Hz, p-C6F5), -167.2 (t, 6F, JF-F = 23 Hz,
m-C6F5). Anal. Calcd for C38H23BNF15Fe 1/2CH2Cl2 (881.703):
3
C, 51.76; H, 2.74; N, 1.59. Found: C, 51.71; H, 3.09; N, 1.71.
X-ray quality crystals were grown by layering of a solution in
dichloromethane with pentane.

6430 Organometallics, Vol. 29, No. 23, 2010
Dureen et al.
6a: white powder, 140 mg, 97%. 1H NMR (CD2Cl2): 7.9
(s, 1H, CdCH), 7.1-7.0 (m, 3H, Ph), 6.8 (d, 2H, 3JH-H = 7 Hz,
o-Ph), 5.7 (s, 1H, CHCMedN), 5.1 (m, 1H, NCHMe), 3.5
(s, 3H, N-Me), 2.4 (d, 3H, JH-H = 2 Hz, CMedN), 1.8 (d,
(t, 3F, 3JF-F = 21 Hz, p-C6F5), -164.3 (m, 2F, m-C6F5), -164.6
(s, br, 1F, m-C6F5), -165.6 (m, 3F, m-C6F5). Anal. Calcd for
C34H19BNF15 (737.321): C, 55.39; H, 2.60; N, 1.90. Found: C,
54.92; H, 2.92; N, 1.58. The product crystals were suitable for
X-ray diffraction.
3
3H, JH-H = 8 Hz, NCHMe). 11B NMR (CD2Cl2): -16.3
3
(s). 19F NMR (CD2Cl2): -131.8 (d, 6F, JF-F = 23 Hz,
7b: red crystals, 32 mg, 52%. 1H NMR (CD2Cl2): 8.6 (s, 1H,
o-C6F5), -163.3 (t, 3F, 3JF-F = 20 Hz, p-C6F5), -167.3 (t, 6F,
3JF-F = 22 Hz, m-C6F5). Anal. Calcd for C33H17BNF15
(723.293): C, 54.80; H, 2.37; N, 1.94. Found: C, 54.54; H,
2.76; N, 2.04. X-ray quality crystals were grown by slow cooling
of a solution in dichloromethane.
2
CHdN), 5.1 (s, br, 1H), 4.9 (m, br, 1H), 4.7 (d, 1H, JH-H
=
2
17 Hz, NCHH0), 4.6 (d, 1H, JH-H = 17 Hz, NCHH0), 4.4
(s, 1H, CpCC), 4.35 (s, 1H, CpCC), 4.3 (s, 1H, CpCC), 4.25
t
(s, 1H, CpCC), 3.8 (s, 5H, Cp), 1.4 (s, 9H, Bu). 11B NMR
(CD2Cl2): -6.3 (s). 13C{1H} NMR (CD2Cl2): 186.4 (s, CdN),
69.9 (s, CpCC), 69.5 (s, CpCC), 69.2 (s, Cp), 68.8 (s, CpCC),
66.2 (s), 62.7 (s), 56.7 (s), 54.4 (s, NCHH0), 34.7 (s, CMe3),
28.7 (s, CMe3). 19F NMR (CD2Cl2): -133.0 (d, 2F, 3JF-F = 23
Hz, o-C6F5), -134.4 (m, 2F, o-C6F5), -141.1 (s, br, 1F,
o-C6F5), -141.8 (s, br, 1F, o-C6F5), -160.1 (t, 1F, 3JF-F = 20
1
6b: yellow powder, 151 mg, 96%. H NMR (CD2Cl2): 8.0
=
(s, 1H, CdCH), 7.3 (d, 2H, 3JH-H = 8 Hz), 6.7 (d, 2H, 3JH-H
8 Hz), 5.7 (s, 1H, CHCMedN), 5.1 (m, 1H, NCHMe), 3.6
(s, 3H, N-Me), 2.4 (d, 3H, JH-H = 2 Hz, CMedN), 1.8 (d,
3
3H, JH-H = 8 Hz, NCHMe). 11B NMR (CD2Cl2): -16.4
3
(s). 19F NMR (CD2Cl2): -131.8 (d, 6F, JF-F = 23 Hz,
3
Hz, p-C6F5), -160.9 (t, 1F, JF-F = 20 Hz, p-C6F5), -161.2
3
(t, 3F, 3JF-F = 21 Hz, p-C6F5), -164.4 (m, 3F, m-C6F5), -165.5
(m, 3F, m-C6F5). Anal. Calcd for C48H23BNF15Fe (845.252): C,
54.00; H, 2.74; N, 1.66. Found: C, 53.63; H, 2.97; N, 1.37. The
product crystals were suitable for X-ray diffraction.
o-C6F5), -162.9 (t, 3F, JF-F = 21 Hz, p-C6F5), -167.0 (t,
6F, 3JF-F = 22 Hz, m-C6F5). Anal. Calcd for C33H16BNF15Br
(802.189): C, 49.14; H, 2.01; N, 1.75. Found: C, 49.24; H, 2.29;
N, 1.77.
6c: yellow powder, 145 mg, 98%. 1H NMR (CD2Cl2): 7.9 (s,
Synthesis of RNC4H3(3-PhCdC(H)(C6F5)B(C6F5)2) (R =
SiMe3 8, Ph 9). These compounds were generated in a similar
fashion; therefore only one synthesis is specified. 8: A solution of
N-trimethylsilylpyrrole (14 mg, 0.1 mmol) and phenylacetyl-
ene (10 mg, 0.1 mmol) in dichloromethane (2 mL) was cooled
to -35 °C, at which point B(C6F5)3 (51 mg, 0.1 mmol) in dichlo-
romethane (1 mL) was added. The solution was allowed to warm
to room temperature over the course of 20 min, after which
pentane (10 mL) was added and the reaction mixture cooled
to -35 °C. The supernatant liquid was decanted, and the result-
ing white powder dried in vacuo (60 mg, 80%). 1H NMR
(CD2Cl2): 8.8 (s, 1H, CHdN), 7.5-7.4 (m, 4H, Ph), 7.3 (tm,
1H, 3JH-H = 7 Hz, p-Ph), 5.5 (s, br, 1H), 5.3 (m, br, 1H), 4.8 (d,
1H, CdCH), 7.1 (dm, 1H, 3JH-H = 8 Hz), 7.06 (t, 1H, 3JH-H
=
8 Hz), 6.8 (dm, 1H, 3JH-H = 8 Hz), 6.6 (m, 1H), 5.7 (s, 1H, CH-
CMedN), 5.1 (m, 1H, NCHMe), 3.5 (s, 3H, NMe), 2.4 (d, 3H,
J
H-H = 2 Hz, CMedN), 1.8 (d, 3H, 3JH-H = 8 Hz, NCHMe).
11B NMR (CD2Cl2): -16.4 (s). 19F NMR (CD2Cl2): -131.8 (d,
3
3
6F, JF-F = 22 Hz, o-C6F5), -162.7 (t, 3F, JF-F = 20 Hz,
p-C6F5), -167.1 (t, 6F, 3JF-F = 23 Hz, m-C6F5). Anal. Calcd
for C33H16BNF15Cl (757.738): C, 52.31; H, 2.13; N, 1.85.
Found: C, 52.20; H, 2.39; N, 1.88.
6d: yellow powder: 149 mg, 96%. 1H NMR (CD2Cl2): 8.0 (s,
1H, CdCH), 7.3 (d, 2H, 3JH-H = 8 Hz), 6.9 (d, 2H, 3JH-H = 8
Hz), 5.7 (s, 1H, CHCMedN), 5.1 (m, 1H, NCHMe), 3.6 (s, 3H,
NMe), 2.4 (d, 3H, JH-H = 2 Hz, CMedN), 1.8 (d, 3H, 3JH-H
=
2
2
1H, JH-H = 18 Hz, NCHH0-), 4.6 (d, 1H, JH-H = 18 Hz,
NCHH0-), 0.4 (s, 9H, SiMe3). 11B NMR (CD2Cl2): -6.4 (s).
13C{1H} NMR (CD2Cl2), partial: 199.1 (s, CdN), 148.8 (dm,
1JC-F = 241 Hz, o-BC6F5), 142.7 (s), 139.5 (dm, 1JC-F = 235
Hz, p-BC6F5), 136.2 (dm, 1JC-F = 250 Hz, m-BC6F5), 136.7 (s),
136.5 (s), 129.3 (s), 128.4 (s), 127.9 (s), 58.9 (s), 54.4 (s), 34.8 (s),
22.9 (s), 14.4 (s), -1.5 (s, SiMe3). 19F NMR (CD2Cl2): -133.4
(m, 2F, o-C6F5), -134.4 (d, 2F, 3JF-F = 20 Hz,o-C6F5), -142.3
(s, br, 1F, o-C6F5), -142.7 (s, br, 1F, o-C6F5), -160.3 (t,
8 Hz, NCHMe). 11B NMR (CD2Cl2): -16.4 (s). 19F NMR
3
(CD2Cl2): -63.2 (s, 3F, CF3), -131.8 (d, 6F, JF-F = 22 Hz,
o-C6F5), -162.8 (t, 3F, 3JF-F = 22 Hz, p-C6F5), -167.0 (t, 6F,
3JF-F = 22 Hz, m-C6F5). Anal. Calcd for C34H16BNF18
(791.292): C, 51.61; H, 2.04; N, 1.77. Found: C, 51.46; H,
2.32; N, 1.77.
6e: purple-copper powder, 153 mg, 94%. 1H NMR (CD2Cl2):
7.7 (s, 1H, CdCH), 7.3 (s, 1H, CHCMedN), 5.1 (5.1 (m, 1H,
NCHMe), 4.1 (s, 2H, CCp0), 4.0 (s, 5H, Cp), 3.95 (s, 2H, CCp0),
3.6 (s, 3H, NMe), 2.6 (s, 3H, CMedN), 1.7 (d, 3H, JH-H =
3
3
1F, JF-F = 20 Hz, p-C6F5), -161.0 (t, 1F, JF-F = 20 Hz,
p-C6F5), -161.6 (t, 3F, 3JF-F = 21 Hz, p-C6F5), -164.5 (m, 2F,
m-C6F5), -164.6 (s, br, 1F, m-C6F5), -165.6 (m, 3F, m-C6F5).
Anal. Calcd for C33H19BNF15Si (753.395): C, 52.61; H, 2.54; N,
1.86. Found: C, 51.91; H, 2.90; N, 1.92.
3
7 Hz, NCHMe). 11B NMR (CD2Cl2): -16.1 (s). 19F NMR
3
(CD2Cl2): -131.9 (d, 6F, JF-F = 23 Hz, o-C6F5), -163.2 (t,
3
3
3F, JF-F = 22 Hz, p-C6F5), -167.3 (t, 6F, JF-F = 21 Hz,
m-C6F5). Anal. Calcd for C37H21BNF15Fe (831.215): C, 53.46;
H, 2.55; N, 1.69. Found: C, 53.78; H, 3.04; N, 169.
9: white powder, 75 mg, 50%. 1H NMR (CD2Cl2): 8.7 (s, 1H,
CHdN), 7.6 (d, 2H, 3JH-H = 7 Hz, o-Ph), 7.5 (d, 2H, 3JH-H
=
7 Hz, o-Ph), 7.4(t, 2H, 3JH-H = 7 Hz), 7.3-7.2 (m, 4H), 5.6 (s, br,
=
Synthesis of tBuNC4H3(3-ArCdC(H)(C6F5)B(C6F5)2) (Ar =
Ph 7a, CpFe(C5H4) 7b). These compounds were generated in a
similar fashion; therefore only one synthesis is specified. 7a: A
solution of 5a (50 mg, 0.07 mmol) in dichloromethane (5 mL)
was left at room temperature for 36 h, at which point it was
layered with pentane (5 mL) and cooled to -35 °C for 12 h. The
supernatant liquid was decanted, and the resulting colorless
crystals were dried in vacuo (28 mg, 56%). 1H NMR (CD2Cl2):
8.6 (s, 1H, CHdN), 7.5-7.4 (m, 4H, Ph), 6.8 (tm, 1H, 3JH-H = 7
Hz, p-Ph), 5.5 (s, br, 1H), 5.1 (m, br, 1H), 4.9 (d, 1H, 2JH-H = 17
Hz, NCHH0), 4.7 (d, 1H, 2JH-H=17 Hz, NCHH0), 1.4 (s, 9H,
tBu). 11B NMR (CD2Cl2): -6.8 (s). 13C NMR (CD2Cl2): 186.2
1H), 5.5 (d, 1H, 2JH-H=17 Hz, NCHH0), 5.1 (d, 1H, 2JH-H
17 Hz, NCHH0), 5.1 (s, br, 1H). 11B NMR (CD2Cl2): -6.1 (s).
13C{1H} NMR (CD2Cl2), partial: 188.9 (s, CdN), 148.4 (dm,
1
1JC-F = 241 Hz, o-BC6F5), 147.4 (dm, JC-F = 241 Hz,
o-BC6F5), 143.8 (s), 137.6 (dm, JC-F = 250 Hz, m-BC6F5),
1
137.6 (s), 136.3 (s), 134.0 (s), 132.2 (s), 131.2 (s), 129.3 (s),
129 0.1 (s), 128.7 (s), 127.9 (s), 122.7 (s), 121.5 (s), 64.4 (s, br,
C-B), 62.1 (s), 37.1 (s, br, C-B). 19F NMR (CD2Cl2): -133.4
(d, 2F, 3JF-F = 20 Hz, o-C6F5), -134.4 (d, 2F, 3JF-F = 22 Hz,
o-C6F5), -142.2 (s, br, 1F, o-C6F5), -142.5 (s, br, 1F, o-C6F5),
-159.8 (t, 1F, 3JF-F=21 Hz, p-C6F5), -160.7 (t, 1F, 3JF-F = 21
Hz, p-C6F5), -161.3 (t, 3F, 3JF-F=22 Hz, p-C6F5), -164.1 (m, 2F,
m-C6F5), -164.5 (s, br, 1F, m-C6F5), -165.4 (m, 3F, m-C6F5).
Anal. Calcd for C36H15BNF15 (757.311): C, 57.10; H, 2.00; N, 1.85.
Found: C, 56.57; H, 2.36; N, 1.86.
1
(s, CdN), 148.6 (dm, JC-F = 240 Hz, o-BC6F5), 148.2 (dm,
1
1JC-F = 240 Hz, o-BC6F5), 143.1 (s), 139.1 (dm, JC-F=250
Hz), 137.4 (dm, JC-F = 247 Hz), 136.5 (s), 135.0 (s), 129.3
1
(s), 128.5 (s), 127.9 (s), 62.9 (s), 61.7 (m, br, CB), 57.2 (s), 38.4
(m, br, CB), 28.6 (s, CMe3). 19F NMR (CD2Cl2): -133.4 (m,
2F, o-C6F5), -134.2 (m, 2F, o-C6F5), -142.4 (s, br, 1F,
o-C6F5), -142.8 (s, br, 1F, o-C6F5), -160.0 (t, 1F, 3JF-F = 22
Synthesis of MeNC4H(2,5-Me2)(3-PhCdC(H)(C6F5)B(C6F5)2)
(10) and tBuNC4H3(3-PhCdC(H)(Ph)B(C6F5)2) (11). These
compounds were generated in a similar fashion; therefore only
one synthesis is specified. A solution of 6a (38 mg, 0.05 mmol) in
3
Hz, p-C6F5), -160.9 (t, 1F, JF-F = 20 Hz, p-C6F5), -161.5

Article
Organometallics, Vol. 29, No. 23, 2010 6431
bromobenzene (1 mL) was heated to 60 °C for 3 h. The solution
was cooled to room temperature and layered with pentane
(2 mL). Block-like crystals formed upon diffusion, the super-
natant was then decanted, and the crystals were dried under
reduced pressure (14 mg, 37%). The product was a mixture of
diastereomers in a ratio of 4 to 1. 1H NMR (CD2Cl2): 7.4-7.1
(m, major þ minor isomers, Ph), 5.2 (s, br, 1H major þ minor
isomer), 5.1 (m, br, 1H minor isomer), 4.9 (s, br, 1H major
(s, 1H minor isomer, CdCHB(C6F5)3), 6.9-6.8 (m), 6.8 (s,
major isomer CdCHB(C6F5)3), 6.4 (m, 1H major isomer and
1H minor isomer), 6.1 (t, 1H minor isomer JH-H = 3 Hz), 5.9
(m, 1H major isomer and 1H minor isomer), 5.7 (dd, 1H major
isomer JH-H = 4 Hz, JH-H = 2 Hz,), 5.1 (d, 1H, 1JH-P = 428
Hz, PH), 3.5 (s, 3H minor isomer, NMe), 3.3 (s, 3H minor
3
isomer, NMe), 1.6 (d, 27H, JH-P = 16 Hz, PtBu). 11B NMR
(CD2Cl2): -16.1 (s, br). 19F NMR (CD2Cl2): -131.6 (d, 6F
3
3
isomer), 4.7 (q, 1H major þ minor isomer, JH-H = 7 Hz,
minor isomer, JF-F = 22 Hz, o-C6F5), -131.7 (d, 6F minor
4
NCHMe), 3.2 (d, 3H major isomer, JH-H = 2 Hz, NMe),
3
isomer, JF-F = 22 Hz, o-C6F5), -165.0 (t, 3F major isomer,
=
4
3.18 (d, 3H minor isomer, JH-H = 3 Hz, NMe), 2.3 (s, 3H
3JF-F = 21 Hz, p-C6F5), -165.5 (t, 3F minor isomer, 3JF-F
minor isomer, -C(Me)dN), 2.2 (s, 3H major isomer, CMedN),
1.7 (d, 3H major isomer, 3JH-H = 7 Hz, NCHMe), (d, 3H minor
isomer, 3JH-H = 7 Hz, NCHMe), 11B NMR (CD2Cl2): -8.1 (s,
major isomer), -8.8 (s, minor isomer). 19FNMR(CD2Cl2):-129.3
(d, 2F, 3JF-F = 20 Hz, o-C6F5), -129.7 (s, br, 2F minor isomer,
o-C6F5), -134.0 (s, br, 2F major isomer, o-C6F5), -134.3 (s,
br, 2F minor isomer, o-C6F5), -141.7 (dd, 1F major isomer,
20 Hz, p-C6F5), -168.0-168.5 (t, 6F major isomer þ 6F minor
isomer, m-C6F5). 31P{1H} NMR (CD2Cl2): 61.3 (s). Anal. Calcd
for C43H40BNF15P (897.561): C, 57.54; H, 4.49; N, 1.56. Found:
C, 57.00; H, 4.44; N, 1.43.
In Situ Generation of tBuNC4H3(3-ArCdCH2) (Ar = Ph 14a
p-C6H4Br 14b, m-C6H4Cl 14c, p-C6H4CF3 14d) and MeNC4H2-
(2,5-Me2)(3-ArCdCH3) (Ar = Ph 15a, p-C6H4Br 15b, m-C6H4-
Cl 15c, p-C6H4CF3 15d). These compounds were generated in a
similar fashion; therefore only one preparation is described
(15a). NMR data were collected within 30 min for all samples.
14a: 1H NMR (CD2Cl2): 7.5 (dd, 2H, 3JH-H = 8 Hz, 4JH-H = 2
4
3JF-F = 23 Hz, JF-F = 6 Hz, o-C6F5), -143.2 (m, major þ
minor isomer, o-C6F5), -160.2 (t, 1F major isomer, 3JF-F = 20
3
Hz, p-C6F5), -160.6 (t, 1F minor isomer, JF-F = 20 Hz,
3
p-C6F5), -161.3 (t, 1F major isomer, JF-F=20 Hz, p-C6F5),
-161.4 (t, 1F minor isomer, 3JF-F = 19 Hz, p-C6F5), -161.6 (t,
1F minor isomer, 3JF-F = 21 Hz, p-C6F5), -161.65 (t, 1F major
Hz, o-Ph), 7.4-7.3 (m, 3H, m-Ph and p-Ph), 6.8 (t, 1H, 3JH-H
=
3 Hz, CHdCHN), 6.7 (m, 1H, CRdCHN), 6.2 (m, 1H,
3
2
CHdCHN), 5.3 (d, 1H, JH-H = 2 Hz, CHH0), 5.0 (d, 1H,
isomer, JF-F = 21 Hz, p-C6F5), -164.2 (m, major þ minor
isomer, m-C6F5), -164.8 (tm, 1F major isomer, 3JF-F = 22 Hz,
m-C6F5), -165.7 (m, major þ minor isomer, m-C6F5), -166.1
(m, major þ minor isomer, m-C6F5). Anal. Calcd for
C33H17BNF15 (723.294): C, 54.80; H, 2.37; N, 1.94. Found: C,
54.35; H, 2.61; N, 1.48.
2JH-H = 2 Hz, CHH0), 1.5 (s, 9H, tBu).
14b: 1H NMR (CD2Cl2): 7.5 (d, 2H, 3JH-H = 8 Hz), 7.3 (d,
2H, 3JH-H = 8 Hz), 6.8 (t, 1H, 3JH-H = 3 Hz, CHdCHN), 6.7
(t, 1H, 4JH-H = 2 Hz, CRdCHN), 6.2 (dd, 1H, 3JH-H = 3 Hz,
4JH-H = 2 Hz, CHdCHN), 5.3 (d, 1H, 2JH-H = 2 Hz, CHH0),
5.0 (d, 1H, 2JH-H = 2 Hz, CHH0), 1.5 (s, 9H, tBu).
11: white powder, 200 mg, 62%. 1H NMR (CD2Cl2): 9.0
3
(s, 1H, CHdN), 7.5 (d, 2H, JH-H =8 Hz, o-Ph), 7.4 (t, 2H,
14c: 1H NMR (CD2Cl2): 7.4 (m, 1H), 7.4-7.35 (m, 1H),
3JH-H = 8 Hz, m-Ph), 7.3 (t, 1H, 3JH-H = 8 Hz, p-Ph), 7.1 (d,
2H, 3JH-3H = 8 Hz, o-Ph), 7.0 (t, 2H, 3JH-H = 8 Hz, m-Ph), 6.9
(t, 1H, JH-H = 7 Hz, p-Ph), 5.0 (d, 1H, JH-H = 17 Hz,
3
7.3 (m, 2H), 6.8 (t, 1H, JH-H = 3 Hz, CHdCHN), 6.7 (t,
4
3
1H, JH-H = 2 Hz, CRdCHN), 6.2 (dd, 1H, JH-H =3 Hz,
4JH-H = 2 Hz, CHdCHN), 5.4 (d, 1H, 2JH-H = 2 Hz, CHH0),
5.0 (d, 1H, 2JH-H = 2 Hz, CHH0), 1.5 (s, 9H, tBu).
2
t
NCHH0), 4.8 (m, br, 2H), 4.7 (s, br, 1H), 1.4 (s, 9H, Bu). 11B
NMR (CD2Cl2): -3.7 (s). 13C{1H} NMR (CD2Cl2), partial:
14d: 1H NMR (CD2Cl2): 7.6-7.5 (m, 4H), 6.8 (t, 1H,
3JH-H = 3 Hz, CHdCHN), 6.7 (m, 1H, CRdCHN), 6.2 (m,
1H, CHdCHN), 5.4 (d, 1H, 2JH-H = 1 Hz, CHH0), 5.0 (d, 1H,
2JH-H = 1 Hz, CHH0), 1.5 (s, 9H, tBu). 19F NMR (CD2Cl2):
-63.7 (s, 3F, CF3).
1
187.0 (s, CdN), 148.7 (dm, JC-F = 238 Hz, o-BC6F5), 147.9
(dm, 1JC-F = 238 Hz, o-BC6F5), 145.6 (s), 145.1 (s), 138.8 (dm,
1JC-F = 240 Hz), 137.2 (dm, 1JC-F = 247 Hz), 136.9 (s), 133.4
(s), 129.1 (s), 128.2 (s), 128.0 (s), 127.98 (s), 127.4 (s), 124.3 (s),
62.4 (s), 61.1 (m, br, CB), 57.0(s), 49.8 (m, br, CB), 28.6 (s,
15a: To an intimate mixture of 6a (14.4 mg, 0.02 mmol) and
triethylphosphine oxide (2.7 mg, 0.02 mmol) was added CD2Cl2
(0.8 mL). The reaction mixture went from a clear yellow solution
to a very pale orange solution within a few seconds and was
transferred to an NMR tube. 1H NMR (CD2Cl2): 7.4 (dd, 2H,
3JH-H = 8 Hz, 4JH-H = 2 Hz, o-Ph), 7.3-7.2 (m, 3H, m-Ph and
p-Ph), 5.7 (s, 1H, CHdCMe), 5.3 (d, 1H, 2JH-H = 2 Hz, CHH0),
5.1 (d, 1H, 2JH-H = 2 Hz, CHH0), 3.4 (s, 3H, NMe), 2.2 (s, 3H,
CMe), 2.0 (s, 3H, CMe).
3
CMe3). 19F NMR (CD2Cl2): -132.8 (dd, 2F, JF-F = 25 Hz,
3JF-F = 9 Hz, o-C6F5), -134.1 (s, br, 2F, o-C6F5), -160.7
(t, 1F, 3JF-F = 23 Hz, p-C6F5), -162.0 (t, 1F, 3JF-F = 22 Hz,
p-C6F5), -164.9 (m, 2F, m-C6F5), -166.1(m, 2F, m-C6F5).
Anal. Calcd for C34H24BNF10 (647.368): C, 63.08; H, 374; N,
2.16. Found: C, 62.73; H, 3.79; N, 2.30.
Synthesis of [tBu3PH][tBuNC4H3(3-PhCdC(H)B(C6F5)3)]
(12), [tBu3PH][MeNC4H3(2-PhCdC(H)B(C6F5)3)] (13a), and
[tBu3PH][MeNC4H3(3-PhCdC(H)B(C6F5)3)] (13b). These com-
pounds were generated in a similar fashion; therefore only one
preparation is described. 12: Dichloromethane (5 mL) was
added to an intimate mixture of 5a (80 mg, 0.1 mmol) and tBu3P
(22 mg, 0.1 mmol) to afford a clear, colorless solution. Removal
of solvent under reduced pressure and subsequent trituration
and washing with pentane (2 ꢀ 3 mL) afforded 93 mg of a white
powder (91%). 1H NMR (CD2Cl2): 7.0 (s, br, s, 1H, CdCHB-
15b: 1H NMR (CD2Cl2): 7.4 (d, 2H, 3JH-H = 8 Hz), 7.3 (d,
2H, 3JH-H = 8 Hz), 5.7 (s, 1H, CHdCMe), 5.3 (d, 1H, 2JH-H
=
2
2 Hz, CHH0), 5.1 (d, 1H, JH-H = 2 Hz, CHH0), 3.4 (s, 3H,
NMe), 2.2 (s, 3H, CMe), 2.0 (s, 3H, CMe).
15c: 1H NMR (CD2Cl2): 7.4 (m, 1H), 7.3-7.2 (m, 3H,), 5.7 (s,
2
1H, C(H)dC(Me)), 5.3 (d, 1H, JH-H = 2 Hz, CHH0), 5.1 (d,
1H, 2JH-H = 2 Hz, CHH0), 3.4 (s, 3H, NMe), 2.2 (s, 3H, CMe),
2.0 (s, 3H, CMe).
15d: H NMR (CD2Cl2): 7.6 (d, 2H, JH-H=8 Hz), 7.5 (d,
1
3
(C6F5)3), 6.9 (m, 3H, Ph), 6.9 (m, 2H, Ph), 6.7 (t, 1H, JH-H =
3 Hz, pyrrole), 6.2 (m, 2H, pyrrole), 5.1 (d, 1H, 1JH-P = 428 Hz,
2H, 3JH-H=8 Hz), 5.7 (s, 1H, CHdCMe), 5.4 (d, 1H, 2JH-H
=
3
t
PH), 1.6 (d, 27H, JH-P = 16 Hz, PtBu), 1.4 (s, 9H, Bu). 11B
2
2 Hz, CHH0), 5.2 (d, 1H, JH-H = 2 Hz, CHH0), 3.4 (s, 3H,
NMe), 2.2 (s, 3H, CMe), 2.0 (s, 3H, CMe). 19F NMR (CD2Cl2):
-63.6 (s, 3F, CF3),
NMR (CD2Cl2): -15.9 (s). 19F NMR (CD2Cl2): -131.5 (d,
3
3
6F, JF-F = 21 Hz, o-C6F5), -165.4 (t, 3F, JF-F = 21 Hz,
p-C6F5), -168.3 (t, 6F, 3JF-F = 21 Hz, m-C6F5). 31P{1H} NMR
(CD2Cl2): 61.2 (s). Anal. Calcd for C46H46BNF15P (939.642): C,
58.80; H, 4.93; N, 1.49. Found: C, 58.52; H, 5.0; N, 1.79. X-ray
quality crystals were grown by layering a solution in dichloro-
methane with pentane.
Synthesis of Et3PO B(C6F5)3. To a solution of B(C6F5)3
3
(47 mg, 0.092 mmol) in pentane (2 mL) was added Et3PdO
(20 mg, 0.15 mmol) in one portion, which instantly afforded a
white precipitate (40 mg, 68%). 1H NMR (CD2Cl2): 2.0 (dq, 6H,
2JH-P = 12 Hz, 3JH-H = 7 Hz, CH2CH3), 1.1 (dq, 9H, 2JH-P
=
18 Hz, 3JH-H = 7 Hz, CH2CH3). 11B NMR (CD2Cl2): -2.7 (s,
br). 19F NMR (CD2Cl2): -134.4 (m, 6F, o-C6F5), -159.1 (t, 3F,
13a þ 13b: white powder, 93 mg, 90%. Ratio of major
(2-vinyl) to minor (3-vinyl) isomer: 2:1. 1H NMR (CD2Cl2): 7.0

6432 Organometallics, Vol. 29, No. 23, 2010
Dureen et al.
3JF-F = 20 Hz, p-C6F5), -165.0 (m, 6F, m-C6F5). 31P{1H}
NMR (CD2Cl2): 78.1 (s). Anal. Calcd for C24H15BOF15P
(646.145): C, 44.61; H, 2.34. Found: C, 44.12; H, 2.82.
were carried out by using full-matrix least-squares techniques
on F, minimizing the function w(Fo - Fc)2 where the weight w is
2
2
defined as 4Fo /2σ(Fo ) and Fo and Fc are the observed and
calculated structure factor amplitudes, respectively. In the final
cycles of each refinement, all non-hydrogen atoms were assigned
anisotropic temperature factors in the absence of disorder or
insufficient data. In the latter cases atoms were treated isotropi-
cally. C-H atom positions were calculated and allowed to ride on
the carbon to which they are bonded assuming a C-H bond
X-ray Crystallography. Crystals were coated in Paratone-N
oil in the glovebox, mounted on a MiTegen Micromount, and
placed under an N2 stream, thus maintaining a dry, O2-free
environment for each crystal. The data were collected on a
Bruker Apex II diffractometer employing Mo KR radiation
˚
(λ = 0.71073 A). Data collection strategies were determined
˚
using Bruker Apex software and optimized to provide >99.5%
complete data to a 2θ value of at least 55°. The data were
collected at 150((2) K for all crystals. The frames were inte-
grated with the Bruker SAINT software package using a
narrow-frame algorithm. Data were corrected for absorption
effects using the empirical multiscan method (SADABS). Non-
hydrogen atomic scattering factors were taken from the litera-
ture tabulations.47 The heavy atom positions were determined
using direct methods employing the SHELXTL direct methods
routine. The remaining non-hydrogen atoms were located from
successive difference Fourier map calculations. The refinements
length of 0.95 A. H atom temperature factors were fixed at 1.20
times the isotropic temperature factor of the C atom to which they
are bonded. The H atom contributions were calculated, but not
refined. The locations of the largest peaks in the final difference
Fourier map calculation as well as the magnitude of the residual
electron densities in each case were of no chemical significance.
Acknowledgment. D.W.S. gratefully acknowledges fi-
nancial support of NSERC of Canada. D.W.S. is grateful
for the support of a Canada Research Chair and a Killam
Research Fellowship from the Killam Foundation.
Supporting Information Available: This material is available
free of charge via the Internet at http://pubs.acs.org.
(47) Cromer, D. T.; Waber, J. T. Int. Tables X-Ray Crystallogr. 1974,
4, 71–147.