Palladium(0)-catalyzed cross-couplings of 2-bromophosphinine

Article abstract of DOI:10.1002/ejoc.201300710

A new Negishi-type cross-coupling of 2-bromophosphinine has been developed. The new method expands the scope of palladium-catalyzed couplings to monobromophosphinines, which have been considered as poor substrates so far. Moreover, aryl-, alkenyl-, and alkynylzinc bromides were found to be effective coupling partners. Copyright

Full text of DOI:10.1002/ejoc.201300710

SHORT COMMUNICATION
DOI: 10.1002/ejoc.201300710
Palladium(0)-Catalyzed Cross-Couplings of 2-Bromophosphinine
Nataliya Kostenko,[a] Cecilia Ericsson,[a] Magnus Engqvist,[a] Susana Villa Gonzalez,[b] and
Annette Bayer*[a]
Keywords: Phosphorus heterocycles / C-C coupling / Homogeneous catalysis / Phosphinines / Palladium
A new Negishi-type cross-coupling of 2-bromophosphinine
has been developed. The new method expands the scope of
palladium-catalyzed couplings to monobromophosphinines,
which have been considered as poor substrates so far. More-
over, aryl-, alkenyl-, and alkynylzinc bromides were found to
be effective coupling partners.
that can be introduced. However, Mao and Mathey recently
introduced an interesting, functionalizable phosphinine
building block when a phosphinine-2-carboxaldehyde was
transformed into an alkene through a Wittig reaction.[13] In
1993, Le Floch et al. described the palladium(0)-catalyzed
cross-coupling with organotin reagents.[14] They were able
to couple polybromophosphinines with trimethyltin deriva-
tives of furan, N-methylpyrrole, thiophene, and phenyl-
acetylene using Pd(dba)2 and monodentate phosphanes, e.g.
triphenylphosphane or tri-2-furylphosphane, as the catalyst
system. However, they discovered that mono- and di-
bromophosphinines were much poorer substrates for the
Stille coupling. For example, the alkynylation of mono-
bromophosphinines with trimethyl(2-phenylethynyl)stann-
ane could not be achieved. Clearly, the incorporation of the
phosphinine core into more complex structures still remains
a synthetic challenge.
During our efforts to explore phosphinines as potential
ligands in catalysis, we sought to broaden the scope of pal-
ladium(0)-catalyzed functionalization of 2-bromophosphin-
ines. Herein, we show that the previously described Stille-
type cross-coupling of organotin reagents can be extended
to monobromophosphinines. More importantly, we present
our preliminary results on the development of a Negishi-
type cross-coupling of organozinc reagents with 2-bromo-
phosphinine, which greatly increases the substituent diver-
sity introduced by the coupling reaction.
Introduction
Transition-metal catalysis is a powerful tool in organic
synthesis as illustrated by the wealth of reactions that rely
on the activation by metal complexes. The ligand on the
metal is a crucial component in this chemistry as it controls
the reactivity of the catalyst towards specific substrate
classes and the stereochemistry of the process. As such, the
development of new ligand systems that impose novel and
unique reactivity/selectivity profiles is a major goal of the
field. Phosphinines,[1] the higher homologues of pyridines,
are planar, aromatic phosphorus-containing heterocycles
with unique electronic, steric, and coordination properties,
which make them attractive scaffolds for ligand develop-
ment. The first reports of 1λ3-phosphinines, appeared in the
late 1960s.[2] Although phosphinines are isoelectronic to
pyridines, they exhibit quite different electronic properties.
Spectroscopic and theoretical investigations indicate that
phosphinines are better π-acceptor ligands, but less σ-do-
nating, than pyridines.[3] Because of their unusual proper-
ties, the application of functionalized phosphinines as li-
gands in homogeneous catalysis has received considerable
interest.[1b,1c,4]
The most successful strategies for the synthesis of com-
plex phosphinine-containing structures are based on pyryl-
ium salts[5] or 1,3,2-diazaphosphinines[6] as precursors. Al-
ternatively, a number of methods for the functionalization
of preformed phosphinines[1a] are known, such as direct
bromination,[7] phosphination,[8] ethylation,[9] and transfor-
mations of 2-metallated phosphinines (M = Li,[10] Mg,[7]
Zn,[10c–10e,11] and Zr[1a,12]). A major limitation of these
methods is the lack of versatility with respect to the groups
Results and Discussion
In order to find the optimal organometallic reagents for
the coupling of 2-bromo-4,5-dimethylphosphinine (1), the
reactivity of organomagnesium, -tin, and -zinc compounds
(Table 1) was investigated. In a Stille-type coupling utilizing
Pd2(dba)3 and 1,2-bis(diphenylphosphanyl)ethane (dppe)
(1:2) as the catalyst system with a catalyst loading of
10 mol-% Pd/1 at reflux in p-xylene or THF, an acetylenic
tin compound performed well providing 2a in 42 and 53%
yield, respectively (Table 1, Entry 1). Couplings with less
[a] Department of Chemistry, University of Tromsø,
9037 Tromsø, Norway,
E-mail: annette.bayer@uit.no
http://uit.no
[b] Department of Chemistry, NTNU,
Trondheim, Norway
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201300710.
4756
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2013, 4756–4759

Palladium(0)-Catalysed Cross-Couplings of 2-Bromophosphinine
reactive[15] vinyl- and phenyltin reagents could not be obtained in 36% yield (Table 1, Entry 5). Alkenylation of 1
achieved under these conditions (Table 1, Entry 2 and 3). with vinylzinc bromide gave 2-vinylphosphinine 2c in 30%
Couplings with Grignard reagents gave a mixture of prod- yield (Table 1, Entry 6). The desired cross-coupling reac-
ucts. Analysis of the crude reaction mixture after coupling tions were accompanied by homocoupling of the organotin
of 2-bromophosphinine 1 and phenylmagnesium bromide reagent.
in THF at 40 °C by 31P NMR spectroscopy revealed a com-
The influence of the ligand on the coupling reaction with
petition between reaction at phosphorus (δP = 64.05 ppm) phenylzinc bromide was also explored. As a selection tool
and the halogen (δP = 183.66 ppm), which occurs in approx- for bidentate phosphorus(III) donor ligands, we chose the
imately equal amounts.
score plot from the principal component analysis described
by Fey et al.[16] All selected ligands were tested by using
method B. The reaction mixtures were analyzed by 31P
NMR spectroscopy, and consumption of starting material
and conversion to product were determined. Four ligands
3, 4, 6, and 7 (Figure 1) were identified as commercially
available ligands with significantly different properties than
dppe. None of these ligands induced the coupling reaction
of 1 and phenylzinc bromide. We continued the screening
experiments with dppp and ligands 5, 8, and 9, which are
closer to dppe in chemical space and thereby exhibit similar
properties. No coupling was observed with ligands 5 and 9.
With dppp and 8 complete consumption of 2-bromophos-
phinine 1 was observed after 24 h by 31P NMR spec-
troscopy. However, the isolated yields obtained from the
coupling of 1 and phenylzinc bromide with dppp and ligand
8 were 76 and 6%, respectively (Table 1, Entry 7 and 8).
Table 1. Optimization of the reaction conditions and reaction
scope.
Entry
1
M
R
Ligand Product
Yield [%]
42[a] /53[b]
SnMe3
dppe
2a
2[a]
SnMe3
SnMe3
Ph-
Vinyl-
dppe
dppe
2b
2c
0
0
3[a]
4[c]
ZnBr
dppe
2a
36
5[d]
6[d]
7[d]
8[d]
ZnBr
ZnBr
ZnBr
ZnBr
Ph-
Vinyl-
Ph-
dppe
dppe
dppp
8
2b
2c
2b
2b
41
30
76
6
[a] Reaction conditions: THF, 70 °C, 1.5 h. [b] Reaction conditions:
p-xylene, 110 °C, 1.5 h. [c] Reaction conditions: THF, 70 °C, 24 h.
[d] Reaction conditions: THF, 50 °C, 24 h.
Initial results employing organozinc reagents in the cou-
pling with 2-bromophosphinine 1 were promising. Alkynyl,
aryl-, and vinylzinc bromides were reactive in the desired
coupling reaction (Table 1, Entry 4–6). Negishi couplings
were carried out with Pd2(dba)3/dppe (1:2) as catalyst sys-
tem. The catalyst loading was 5–10 mol-% Pd/1. 31P NMR
analysis of reaction mixtures was utilized to determine the
conversion of starting material and provided valuable infor-
mation on the reaction conditions. It was established that
the phosphinine/RZnBr ratio necessary for complete con-
version of the 2-bromophosphinine 1 was dependent on the
method of preparation of the organozinc bromide reagent.
When a commercially available phenylzinc bromide solution
(final concentration ≈ 0.4 m in THF), prepared by reaction
of phenylbromide with metallic zinc, was applied, a 1:4 ra-
tio was necessary for complete conversion at 40 °C (method
A). In case of a phenylzinc bromide solution (final concen-
tration ≈ 0.6 m in THF/nBu2O) prepared by quenching a
solution of phenyllithium with 1.2–1.5 equiv. excess of
ZnBr2, complete conversion was observed at a ratio of 1:2
within 24 h at 50 °C (method B). The coupling product 2-
phenylphosphinine 2b was isolated in 40% yield indepen-
dent of the source of the organozinc reagent (Table 1, Entry
4). When the conditions of method B were applied to the
Figure 1. Ligands.
Conclusions
We have achieved a novel palladium-catalyzed Negishi-
coupling with 2-bromophosphinine. The new protocol can
be used to couple alkynyl-, phenyl-, and vinylzinc bromides.
With dppe as ligand, the isolated yields (30–40%) were at a
similar level as comparable coupling reactions employing
more reactive polybromophosphinines[14b] (40%). A better
ligand for the transformation was identified by the aid of a
score plot of the principal component analysis of bidentate
ligands. With dppp as ligand, the isolated yield for the cou-
pling of phenylzinc bromide with 1 improved to 76%. Our
protocol for the Negishi-coupling of 2-bromophosphinines
is a valuable new transformation allowing for the introduc-
tion of phosphinines into more complex structures.
Experimental Section
General Procedures: All oxygen-and/or water sensitive reactions
alkynylation of 1 with phenylethynylzinc bromide, 2a was were carried out under dry nitrogen using Schlenk techniques with
Eur. J. Org. Chem. 2013, 4756–4759
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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4757

N. Kostenko, C. Ericsson, M. Engqvist, S. V. Gonzalez, A. Bayer
SHORT COMMUNICATION
oven-dried glassware and dry solvents. THF, pentane, and p-xylene
were distilled from Na/benzophenone and dichloromethane from
1372 (w), 1331 (w), 1196 (w), 1133 (w), 1070 (w), 1015 (w), 757 (vs),
691 (s) cm–1. HRMS: calcd. for C15H13P 224.0749; found 224.0748.
P2O5
before
use. Tris(dibenzylideneacetone)dipalladium(0)
Phenylethynylphosphinine 2a could also be prepared according to
the procedure above in THF heated at reflux at 70 °C for 1.5 h.
Yield: 53%.
[Pd2(dba)3] was purchased from Alfa Aesar, zinc bromide (anhy-
drous), phenylacetylene, solutions of 1.6 m n-butyllithium in hex-
ane, 1.0 m vinylmagnesium bromide in THF, 0.5 m phenylzinc
bromide in THF, 1.8 m phenyllithium in di-n-butyl ether, and the
bidentate P,P-ligands 1,2-bis(diphenylphosphanyl)ethane (dppe)
and 1,2-bis(diphenylphosphanyl)propane (dppp), 3–5 and 7–9 were
commercially available from Sigma Aldrich. Ligand 6 was received
from Strem. All commercially available reagents were used as re-
ceived except for phenylacetylene, which was distilled under nitro-
gen prior to use. Starting materials were prepared according to lit-
erature methods: trimethyl(2-phenylethynyl)stannane[17] and 2-
bromo-4,5-dimetylphosphinine.[18] IR spectra were recorded with a
Model Varian 7000e FTIR Spectrometer. NMR spectra were re-
corded with an Oxford Varian 400 spectrometer operating at
400 MHz (1H), 100.64 MHz (13C), and 161.9 MHz (31P). The cou-
2a through Negishi Coupling: To a stirred solution of phenylacetyl-
ene (542 mg, 0.58 mL, 5.31 mmol, 2 equiv.) in THF (2.6 mL) was
added dropwise at –78 °C n-butyllithium (3.32 mL of a 1.6 m solu-
tion) in hexane. The pale yellow solution became cloudy white. Zinc
bromide (1.44 g, 6.37 mmol, 2.4 equiv.) in THF (2.4 mL) was then
added to the reaction mixture at –50 °C. The solution became col-
orless. It was left to stir at low temperature for 15 min, again cooled
to –60 °C, and then added to a solution of 2-bromophosphinine 1
(539 mg, 2.67 mmol, 1 equiv.), Pd2dba3 (61 mg, 0.066 mmol, 5 mol-
% in Pd), and dppe (53 mg, 0.133 mmol, 5 mol-%) in THF (1.5 mL)
while stirring. The reaction mixture was warmed up to room tem-
perature and then was heated at reflux at 50 °C for 24 h. The sol-
vent was then removed under reduced pressure, which resulted in
a deep green oily residue. The residue was dissolved in CH2Cl2
(approximately 15–20 mL) and filtered through 1–1.5 cm pad of
Celite. Celite (2 g) was added to the filtrate, and the solvent was
removed in vacuo. The coated Celite was loaded onto the top of a
silica gel packed column. Isolation by column chromatography was
performed with a pentane/CH2Cl2 (9:1) eluent mixture and gave a
by-product, 1,4-diphenylbutadiyne, in a first fraction and pure
product 2a in a second fraction. Yield: 214 mg (36%).
pling constants (J) are given in Hz. H and 13C chemical shifts (δ)
1
are reported in ppm relative to the residual peak[19] of the NMR
solvent. 1H and 13C chemical shifts were assigned by 2D NMR
experiments: H,H-COSY, HSQC, and HMBC. 31P NMR spectra
were recorded using an insertion NMR tube filled with PPh3 (δ =
–5.4 ppm) solution in C6D6 as a reference. Signal patterns are indi-
cated as s (singlet), d (doublet), t (triplet), q (quartet), or m (mul-
tiplet). The high- and low-resolution mass spectra were measured
with a MAT95XL Thermo-Finnigan instrument in EI-mode. Sam-
ples were introduced with a direct injection probe without pre-chro-
matographic treatment; source temperature 180 °C, probe tempera-
ture lower than 20 °C.
4,5-Dimethyl-2-phenylphosphinine (2b)
Method A: To a stirred solution of 2-bromophosphinine 1 (159 mg,
0.78 mmol, 1 equiv.), Pd2dba3 (17.9 mg, 0.020 mmol, 5 mol-% in
Pd), and dppe (15.6 mg, 0.039 mmol, 5.0 mol-%) in THF (1.2 mL)
was added at –30 °C a 0.5 m solution of phenylzinc bromide in
THF (6.27 mL, 3.1 mmol, 4.0 equiv.). The resulting mixture was
then heated overnight at 40 °C. After analysis with 31P NMR spec-
troscopy, which indicated the total disappearance of the starting
material, Celite (1 g) was added, and the solvent was evaporated
under reduced pressure. The resulting dark brown mixture was
chromatographed. The product 2b was eluted with pentane/CH2Cl2
(9:1) and isolated as a colorless, air-sensitive oil. Yield: 64 mg
The new phosphinines described in this work are sensitive to air
and unstable upon standing.
4,5-Dimethyl-2(2-phenylethynyl)phosphinine (2a) through Stille Cou-
pling: To a stirred solution of trimethyl(2-phenylethynyl)stannane
(551 mg, 2.08 mmol, 1.3 equiv.) with Pd2(dba)3 (80 mg, 0.08 mmol,
10 mol-% in Pd), and dppe (64 mg, 0.16 mmol, 10 mol-%) in p-
xylene (2.5 mL) was added a solution of 2-bromophosphinine 1
(325 mg, 1.6 mmol, 1 equiv.) in p-xylene (2.5 mL) at room tempera-
ture. The reaction mixture was heated at reflux at 110 °C for 1.5 h
while stirring. The solvent was then evaporated in vacuo. The re-
sulting deep brown oily residue was dissolved in dichloromethane
(2–3 mL), Celite (1 g) was added, and the solvent was removed
completely under reduced pressure. The coated Celite was loaded
onto the top of a silica gel packed column. A first fraction eluted
with pentane gave unreacted 1, the second fraction eluted with
pentane/CH2Cl2 (9:1) contained 1,4-diphenylbutadiyne resulting
from homocoupling of the tin reagent, and the third yielded prod-
uct 2a as a white powder, sensitive to air. The separation of the
5
(41%). 1H NMR (CDCl3): δ = 2.44 (d, JP,H = 3.6 Hz, 3 H, 4-
5
CH3), 2.47 (d, JP,H = 1.5 Hz, 3 H, 5-CH3), 7.34–7.38 (m, 1 H,
para-C6H5), 7,42–7.46 (m, 2 H, meta-C6H5), 7,63–7.66 (m, 2 H,
3
2
ortho-C6H5), 7.88 (d, JP,H = 5.5 Hz, 1 H, 3-H), 8.51 (d, JP,H
=
=
=
38.8 Hz, 1 H, 6-H) ppm. 13C NMR (CDCl3): δ = 22.8 (d, JP,C
2.2 Hz, 4-CH3), 23.3 (d, JP,C = 3.6 Hz, 5-CH3), 127.5 (d, JP,C
12.4 Hz, ortho-C6H5), 127.6 (d, JP,C = 1.8 Hz, para-C6H5), 129.0
(s, meta-C6H5), 136.3 (d, JP,C = 12.5 Hz, C-3), 139.7 (d, JP,C
4
3
3
5
2
3
=
=
2
2
16.6 Hz, C-4), 142.3 (d, JP,C = 15.7 Hz, C-5), 143.8 (d, JP,C
23.0 Hz, ipso-C6H5), 155.0 (d, 1JP,C = 49.8 Hz, C-6), 168.7 (d, JP,C
1
homocoupled by-product from the phosphinine was challenging.
= 47.6 Hz, C-2) ppm. 31P NMR (CDCl3/C6D6, PPh3): δ =
Yield: 150 mg (42%). 1H NMR (CDCl3): δ = 2.37 (d, JP,H
=
5
183.8 ppm; (THF/C D , PPh ): δ = 181.1 ppm. IR: ν = 3057 (w),
˜
4
6
6
3
3.4 Hz, 3 H, 4-CH3), 2.43 (d, JP,H = 2.0 Hz, 3 H, 5-CH3), 7.32–
7.38 (m, 3 H, meta-, para-C6H5), 7.53–7.56 (m, 2 H, ortho-C6H5),
3028 (w), 2974 (w), 2939 (w), 2916 (w), 2860 (w), 1945 (w), 1874
(w), 1801 (w), 1749 (w), 1685 (w), 1596 (w), 1483 (m), 1445 (m),
1431 (w), 1377 (w), 1322 (w), 1306 (w), 1270 (w), 1238 (w), 1190
(w), 1156 (w), 1119 (w); 1074 (w), 1030 (w), 1018 (w), 1009, (w),
773 (m), 736 (vs), 694 (vs) cm–1. HRMS: calcd. for C13H13P
200.0749; found 200.0745.
3
2
7.87 (d, JP,H = 4.6 Hz, 1 H, 3-H), 8.45 (d, JP,H = 38.9 Hz, 1 H,
6-H) ppm. 13C NMR (CDCl3): δ = 22.3 [d, 4J(P,C) = 2.5 Hz, 4-
3
2
CH3], 23.5 (d, JP,C = 3.7 Hz, 5-CH3), 91.5 (d, JP,C = 29.1 Hz, –
CϵC–C6H5), 95.1 (d, JP,C = 6.7 Hz, ϵC–C6H5), 123.7 (d, JP,C
3.3 Hz, ipso-C6H5), 128.4 (s, para-C6H5), 128.5 (s, meta-C6H5),
131.7 (d, JP,C = 2.9 Hz, ortho-C6H5), 139.5 (d, JP,C = 15.8 Hz, C-
4), 140.3 (d, JP,C = 12.0 Hz, C-3), 142.7 (d, JP,C = 15.8 Hz, C-5),
147.7 (d, 1JP,C = 42.7 Hz, C-2), 155.2 (d, 1JP,C = 52.1 Hz, C-6) ppm.
31P NMR (CDCl3): δ = 206.3 ppm; (C6D6): δ = 207.6 ppm, (pent-
3
=
2
Method B: To a 1.8 m phenyllithium solution in dibutyl ether
(2.63 mL, 5.15 mmol, 2.0 equiv.) was added a solution of zinc
bromide (1.44 g, 6.29 mmol, 2.4 equiv.) in THF (2.5 mL) while stir-
ring at –50 °C. The reaction mixture was stirred in a cooling bath
2
3
ane): δ = 211.4 ppm. IR: ν = 3053 (vw), 2980 (vw), 2943 (vw), 2911 for 30 min and then added to a stirred solution of 2-bromophos-
˜
(vw), 2853 (vw), 1683 (vw), 1592 (w), 1547 (w), 1487 (m), 1442 (m),
phinine 1 (532 mg, 2.58 mmol, 1 equiv.), Pd2dba3 (59 mg,
4758
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© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2013, 4756–4759

Palladium(0)-Catalysed Cross-Couplings of 2-Bromophosphinine
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L. Peruzzini, M. Gonsalvi), Springer, 2011, pp. 151–181.
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0.065 mmol, 5 mol-% in Pd), and dppp (53 mg, 0.129 mmol, 5 mol-
%) in THF (2.2 mL) at –50 °C. The reaction mixture was warmed
up to room temperature, and then it was heated at 50 °C for 24 h
while stirring. After monitoring by 31P NMR spectroscopy, which
indicated the total disappearance of the starting material, the prod-
uct 2b was isolated as described above. Yield: 392 mg (76%).
4,5-Dimethyl-2-vinylphosphinine (2c): To a stirred 1.0 m solution of
vinylmagnesium bromide in THF (5.14 mL, 5.14 mmol, 2.0 equiv.)
was added THF (7.3 mL) and subsequently a solution of zinc
bromide (1.39 g, 6.17 mmol, 2.4 equiv.) in THF (2.3 mL) at –50 °C.
The reaction mixture became cloudy white and was stirred at low
temperature for 30 min. The prepared solution was then added to
a stirred solution of 2-bromophosphinine 1 (522 mg, 2.57 mmol,
1 equiv.), Pd2dba3 (59 mg, 0.064 mmol, 5 mol-% in Pd), and dppe
(51 mg, 0.129 mmol, 5 mol-%) in THF (2.2 mL) at –50 °C. The re-
action mixture was warmed up to room temperature while stirring,
and then it was heated at 50 °C for 24 h. 2c was isolated as de-
scribed for 2b (obtained through Negishi coupling) as a yellow, air-
1
sensitive oil. Yield: 116 mg (30%). H NMR (CDCl3): δ = 2.37 (d,
5
5JP,H = 3.6 Hz, 3 H, 4-CH3), 2.42 (d, JP,H = 1.7 Hz, 3 H, 5-CH3),
3
5.21 (br. d, J = 10.7 Hz, 1 H, vinyl-CH2, cis), 5.96 (ddd, JH,H
=
4
2
17.4, JP,H = 3.5, JH,H = 1.0 Hz, 1 H, vinyl-CH2, trans), 6.98 (dt,
3JH,H = 17.4, JH,H = 11.0, JH,P = 11.0 Hz, 1 H, vinyl-CH), 7.67
3
3
3
2
(d, JP,H = 5.9 Hz, 1 H, 3-H), 8.43 (d, JP,H = 38.4 Hz, 1 H, 6-H)
ppm. 13C NMR (CDCl3): δ = 22.4 (d, JP,C = 2.4 Hz, 4-CH3), 23.1
4
3
3
(d, JP,C = 3.8 Hz, 5-CH3), 113.6 (d, JP,C = 22.8 Hz, vinyl-CH2),
135.2 (d, JP,C = 13.5 Hz, C-3), 139.3 (d, JP,C = 17.3 Hz, C-4),
139.6 (d, JP,C = 28.7 Hz, vinyl-CH), 142.6 (d, JP,C = 16.3 Hz, C-
5), 154.6 (d, JP,C = 48.5 Hz, C-6), 164.3 (d, JP,C = 45.1 Hz, C-2)
2
2
2
3
1
1
ppm. 31P NMR (CDCl3):
δ
=
183.8 ppm; ([D6]THF): δ =
[7] P. Le Floch, D. Carmichael, F. Mathey, Bull. Soc. Chim. Fr.
1992, 129, 291–294.
184.4 ppm. IR: ν = 3123 (w), 3074 (w), 3049 (w), 2972 (w), 2938
˜
(w), 2906 (w), 2844 (w), 2171 (w),1591 (w), 1569 (w), 1544 (w),
1485 (m), 1440 (m), 1371 (m), 1328 (w), 1194 (w), 1132 (w),1069
(w), 1014 (m), 755 (vs), 690 (vs) cm–1. HRMS: calcd. for C9H11P
150.0593; found 150.0591.
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15, 1597–1603.
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801.
Supporting Information (see footnote on the first page of this arti-
cle): Copies of the 1H NMR and 13C NMR spectra of the products
are presented.
Acknowledgments
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The authors gratefully acknowledge the financial support from the
Research Council of Norway (grant number 165850/V30) and the
University of Tromsø for a scholarship to N. K.
808.
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Received: May 16, 2013
Published Online: June 21, 2013
Eur. J. Org. Chem. 2013, 4756–4759
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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