Cs2CO3-promoted one-pot synthesis of alkynylphosphonates, -phosphinates, and -phosphine oxides

Article abstract of DOI:10.1021/jo500312n

A novel and efficient Cs₂CO₃-promoted phosphorylation or phosphinylation of various 1,1-dibromo-1-alkenes with readily available trialkyl phosphites, ethyl diphenylphosphinite, or diethyl phenylphosphonite has been developed under metal-free conditions, providing a practical and powerful tool for one-pot synthesis of valuable alkynylphosphonates, -phosphinates, and -phosphine oxides in good to excellent yields.

Full text of DOI:10.1021/jo500312n

Note
pubs.acs.org/joc
Cs2CO3‑Promoted One-Pot Synthesis of Alkynylphosphonates,
-phosphinates, and -phosphine Oxides
Yulei Wang,† Jiepeng Gan,† Liu Liu,† Hang Yuan,† Yuxing Gao,*,† Yan Liu,*,† and Yufen Zhao†,‡
†Department of Chemistry, College of Chemistry and Chemical Engineering, and the Key Laboratory for Chemical Biology of Fujian
‡
Province and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen,
Fujian 361005, China
S
* Supporting Information
ABSTRACT: A novel and efficient Cs2CO3-promoted phosphoryla-
tion or phosphinylation of various 1,1-dibromo-1-alkenes with readily
available trialkyl phosphites, ethyl diphenylphosphinite, or diethyl
phenylphosphonite has been developed under metal-free conditions,
providing a practical and powerful tool for one-pot synthesis of
valuable alkynylphosphonates, -phosphinates, and -phosphine oxides in
good to excellent yields.
arbon−phosphorus bond construction for the synthesis of
owing to their ready availability and structural diversity.
Enormous efforts have also been devoted to construct C−P
bond following analogous protocols. Hayes and co-workers
demonstrated the synthesis of alkynylphosphonates from 1,1-
dibromoalkenes under the catalytic system of Pd(OAc)2, dppf,
or TFP, and propylene oxide in moderate yields early in 2000.2
However, recent examples of Cu- or Ni-catalyzed reactions of
vinyl dibromides with dialkyl phosphites or HP(O)Ph2 only
gave homologous vinyl phosphorus compounds12 rather than
alkynylphosphorus compounds since the Hirao reduction13 was
performed first. Even so, drawing from our experiences in the
field of P−C bond construction,14 we wondered whether the
use of appropriate P-nucleophiles would avoid the Hirao
reduction to realize a simple and general procedure for the
synthesis of alkynylphosphorus compounds. To our delight, we
found that three-coordinate trivalent phosphite esters such as
triethyl phosphite could proceed well in this context. Herein,
we describe a convenient and straightforward methodology for
the preparation of alkynylphosphonates, -phosphinates, and
-phosphine oxides through Cs2CO3-promoted and metal-free-
catalyzed phosphorylation or phosphinylation of a wide range
of 1,1-dibromo-1-alkenes.
To optimize the catalysis conditions, 1,1-dibromo-1-vinyl-
benzene 1a and triethyl phosphite 2a were chosed as the model
substrates. Initially, when a mixture of 1a (0.50 mmol), 2a
(0.55 mmol), NiCl2 (0.05 mmol), Zn (1 mmol), 2,2′-bipyridine
(bpy, 0.10 mmol), and K3PO4 (0.75 mmol) in toluene was
heated at 120 °C for 24 h under dry argon, the desired product
3a was formed in 28% 31P NMR yield. This result indicated
that our hypothesis was feasible, and hence, a deeper study of
the reaction was conducted. We found that 37% yield of the
desired product could be obtained under transition-metal-free
conditions in the presence of K3PO4 (Table 1, entry 1).
C
organophosphorus compounds is a fundamental and
significant research topic in both organic synthesis and
industrial processes during the past decades due to their
increasing importance in organic synthesis, materials, and
biology. Alkynyl-phosphorus compounds including alkynyl-
phosphonates, -phosphinates, and -phosphine oxides are an
important class of triple bond-containing, extremely versatile
chemicals in modern organic chemistry, which are widely
available for the preparation of structurally sophisticated
phosphorus-containing compounds via reductions, hydrations,
conjugate-addition reactions, metallacycle formation, and
unique cycloaddition reactions.1 Preparation of alkynylphos-
phorus compounds has aroused great interest among synthetic
chemists for their important roles over the past decades, but the
known highly efficient method is still rather limited. Apart from
their traditional preparation from readily hydrolyzable Ph2P(O)
Cl and Li or Mg acetylides,1a suffering from a lack of
functionality tolerance, several methods for the synthesis of
alkynylphosphonates or alkynylphosphine oxides have been
developed recently including Pd-catalyzed cross-coupling from
1,1-dibromo-1-alkenes with H-phosphites,2 Cu-catalyzed oxi-
dative coupling of terminal alkynes with H-phosphonates,3 Cu
or Cu/Pd-bimetallic catalyzed decarboxylation,4 and other
approaches.5 However, most of these methods suffer from poor
substrate scopes, the need of extra additives or unsatisfactory
yields, and in particular, the use of transition metals usually
leads to the production of waste and has plenty of hazards
associated with it.6 Thus, there is still a strong need for
developing more simple and efficient methods to prepare
alkynyl-phosphorus compounds.
On the other hand, 1,1-dibromo-1-alkenes as terminal alkyne
precursors are clearly emerging as fascinating and powerful
building blocks for organic synthesis,7 which can be
conveniently prepared by the Corey−Fuchs reaction8 and
widely used in the transition-metal-catalyzed synthesis of
disubstituted alkynes,7a,9 ynamides,7a,10 and ynol ethers7a,11
Received: February 10, 2014
Published: March 24, 2014
© 2014 American Chemical Society
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Note
a
Table 1. Optimization of Reaction Conditions
Table 2. Cs2CO3-Promoted Phosphorylation of gem-
Dibromoalkenes with Triethyl Phosphite
a
b
entry
base
catalyst
solvent
toluene
yield (%)
1
K3PO4
KOH
37
88
2
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
1,4-dioxane
DMF
c
3
KOH
87
4
NaOH
CsOH
45
5
88
6
K2CO3
Cs2CO3
NaOtBu
KOtBu
Et3N
7
7
91 (89)
8
72
66
0
9
10
11
12
13
14
15
16
17
18
19
20
DBU
3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
32
8
NiBr2
ZnBr2
PdCl2
toluene
toluene
toluene
toluene
toluene
toluene
toluene
26
trace
40
d
85
e
11
f
49
g
60
a
Reaction conditions: 1a (0.5 mmol), 2a (0.55 mmol), base (0.75
mmol), catalyst (0.05 mmol), solvent (1.5 mL), 120 °C, 24 h, under
b
Ar. 31P NMR yields; yield after purification by silica gel
c
chromatography in parenthese. Denotes use of semiconductor-grade
d
e
f
g
KOH. 12 h. At 100 °C. Using 0.5 mmol base. Under dry Air.
Obvious improvement in the yield of 3a was achieved when
stronger base KOH was used (entry 2). While some “transition-
metal-free” reactions turned out to be catalyzed by a trace
amount of Cu or Pd contamination,15 semiconductor-grade
KOH, 99.99% pure based on trace metal analysis, was also
examined (entry 3). Subsequently, a screening of various bases
such as NaOH, CsOH, K2CO3, Cs2CO3, t-BuOK, t-BuONa,
Et3N, and DBU illustrated that Cs2CO3 was the most effective
base to generate the desired product 3a in 91% yield (entries
4−11). The type of solvent was vital to the progress of the
reaction. It was found that toluene was the best solvent, 1,4-
dioxane afforded mild reaction yield, and DMF was a poor
solvent (entries 7, 12, and 13). Although NiBr2, ZnBr2, and
PdCl2 were reported to be very effective in promoting the
reaction of trialkyl phosphite and halohydrocarbon,16 it was not
available in the present reaction and gave poor yields (entries
14−16). Decreasing the reaction temperature to 100 °C led to
a lower yield of 11% (entry 18). The loading of Cs2CO3 was
also evaluated, and the use of 0.5 mmol of Cs2CO3 resulted in a
significant decrease in yield (entry 19). The reaction afforded a
lower yield of 60% under dry air (entry 20).
Under the optimal reaction conditions, we next explored the
phosphorylation of various 1,1-dibromo-1-alkenes with triethyl
phosphite to examine the generality of the methodology. As
shown in Table 2, various valuable alkynylphosphonates can be
conveniently and efficiently obtained by this novel Cs2CO3-
promoted phosphorylation reaction of 1,1-dibromo-1-alkenes,
and the corresponding products were produced in good to
excellent yields (3a−t). In general, the transition-metal-free
conditions are compatible with a range of functional groups.
a
Reaction conditions: 1(0.5 mmol), 2a (0.55 mmol), Cs2CO3 (0.75
b
c
mmol), toluene (1.5 mL), 120 °C, 24 h, under Ar. 100 h. Using 2a
1.1 mmol and Cs2CO3 1.5 mmol. ND, not detected.
d
Thus, both electron-rich and electron-deficient 1,1-dibromo-1-
alkenes were suitable for this method. A variety of
functionalities, such as methyl (3b−d), phenyl (3e), alkoxyl
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Note
(3f), nitro (3g), cyano (3h), trifluoromethyl (3i), fluoro (3j),
chloro (3k), bromo (3l), and carboxyl (3m) groups, were all
tolerated. Generally, electron-poor substrates showed better
reactivity and higher yields than electron-rich ones. Notably,
heteroaromatic gem-dibromoalkenes such as 1n−p could also
be used as substrates to give high yields up to 96%.
Interestingly, styryl gem-dibromoalkene (1s) having a reactive
allene unit could also be used in the reaction to give the desired
alkynylphosphonates selectively in 82% yield in spite of a longer
reaction time of 100 h without damaging the other
functionalities. More interestingly, as exemplified by entry 20,
two phosphonate groups were easily introduced into bis-
dibromide such as 1,4-bis(2,2-dibromovinyl)benzene 1t, thus
affording the corresponding product 3t in 90% yield without
the generation of monophosphorylation product. Unfortu-
nately, the reaction did not occur using alkyl-substituted gem-
dibromoalkenes as substrates such as octyl gem-dibromoalkene
1u, probably since aromatic groups could stabilize the
carbanion intermediate B (see Scheme 2) but alkyl groups
destabilized it (entry 21).
It is worth noting that the reaction can also proceed well on
gram scale with comparable yield (Scheme 1).
Scheme 1. Reaction performed on grams scale
To understand the mechanism, several control reactions have
been carried out (Scheme 2). Without bases, no desired
product was observed. Examining the reaction of 1,1-dibromo-
1-vinylbenzene 1a with 1.5 equiv of Cs2CO3 at 120 °C in
toluene for 24 h gave 1-(2-bromoethynyl)benzene in 91% yield.
Subsequent treatment of 1-(2-bromoethynyl)benzene with 1.1
equiv of triethyl phosphite in toluene at 120 °C for 24 h under
argon afforded the desired alkynylphosphonate 3a in 99% 31P
NMR yield in the presence or absence of bases. Based on these
results, it is reasonable that the reaction pathway first
proceeded via the HBr elimination reaction to provide
intermediate A.17 Then A reacted with triethyl phosphate
leading to the formation of quaternary phosphonium salt C.
Finally, C underwent Michaelis−Arbuzov-type reaction to give
the desired product 1c.1a,18
In conclusion, we have successfully developed a simple and
highly efficient approach to prepare a series of valuable
alkynylphosphonates, -phosphinates, and -phosphine oxides
starting from readily available 1,1-dibromo-1-alkenes. Impor-
tantly, this reaction is performed without the need of a
transition-metal catalyst, a ligand, or an additive, and various
valuable products can be conveniently obtained in a one-pot
process. The remarkable functional group tolerance, opera-
tional simplicity of the procedure, and good to excellent yields
mean that this reaction will find broad applications in various
fields.
To gain more insight into the substrate scope, various P-
nucleophiles were investigated (Table 3). In addition to triethyl
Table 3. Cs2CO3-Promoted Phosphorylation/
Phosphinylation of gem-Dibromoalkenes with
a
P‑Nucleophiles
EXPERIMENTAL SECTION
■
General Information. All reactions were carried out in Schlenk
tubes under an argon atmosphere. Toluene was freshly distilled over
sodium and benzophenone under Ar. Triethyl phosphite was
purchased and further purified by extraction with petroleum ether
and water system. The 1,1-dibromo-1-alkenes were prepared from the
corresponding aldehydes. All the other reagents were purchased from
commercial sources and used without further purification. Column
chromatography was performed on silica gel 300−400 mesh. H, 13C,
1
and 31P NMR spectra were measured on a 400 MHz spectrometer
with CDCl3 as solvent using tetramethylsilane (TMS) as internal
standard and 85% H3PO4 as external standard for 31P NMR. HRMS
spectra were recorded on a FT-MS apparatus. The CAS numbers of
known compounds are listed.
a
Reaction conditions: 1 (0.5 mmol), 2 (0.55 mmol), Cs2CO3 (0.75
b
mmol), toluene(1.5 mL), 120 °C, 24 h, under Ar. 30 h.
General Procedure for the Synthesis of 3a−z. An oven-dried
Schlenk tube with 0.75 mmol of Cs2CO3 was evacuated and purged
with argon more than three times. A mixture of 1,1-dibromo-1-alkene
(0.50 mmol) and P-nucleophiles (0.55 mmol) in toluene (1.5 mL) was
added to the tube and stirred at 120 °C for 24 h. The suspension was
filtered and washed with EtOAc (3 × 5 mL). The combined solvent
was removed under reduced pressure. The residue was purified by
silica gel chromatography using a mixture of petroleum ether and ethyl
acetate as eluent.
phosphite 2a, triisopropyl phosphite 2b could also be used in
the reaction to give the desired product 4a in 81% yield (entry
1). Gratifyingly, ethyl diphenylphosphinite 2c also exhibited
good compatibility. Thus, the corresponding alkynylphosphine
oxides 3v, 3w, and 3x were obtained in 67%, 75%, and 82%
yields, respectively (entries 2−4). In addition, diethyl phenyl-
phosphonite 2d could also be transformed to the correspond-
ing phosphinylated products in high yield (entries 5 and 6).
Obviously, this protocol with broad substrate scope afforded a
general and practical protocol for the preparation of various
valuable alkynylphosphonates, -phosphinates, and -phosphine
oxides.
Diethyl (Phenylethynyl)phosphonate (3a) (CAS No. 3450-67-7).
1
106 mg, 89% yield. H NMR (CDCl3, 400 MHz): δ 7.56−7.54 (m,
2H), 7.46−7.42 (m, 1H), 7.38−7.34 (m, 2H), 4.25−4.18 (m, 4H),
1.41−1.37 (t, J = 7.1 Hz, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ
132.7 (d, JC−P = 2.5 Hz), 130.7, 128.6, 119.6 (d, JC−P = 5.6 Hz), 99.1
(d, JC−P = 52.7 Hz), 78.4 (d, JC−P = 300.3 Hz), 63.2 (d, JC−P = 5.4 Hz),
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Note
Scheme 2. Mechanistic Studies
16.1 (d, JC−P = 7.0 Hz). 31P NMR (162 MHz, CDCl3): δ −6.04.
HRMS m/z (ESI): calcd for C12H15O3P [M + Na]+ 261.0657, found
261.0660.
8.24−8.22 (d, J = 8.5 Hz, 2H), 7.73−7.7 (d, J = 8.8 Hz, 2H), 4.27−
4.20 (m, 4H), 1.42−1.38 (t, J = 7.2 Hz, 6H). 13C{1H} NMR (100
MHz, CDCl3) δ 148.5, 133.5 (d, JC−P = 2.4 Hz), 126.1 (d, JC−P = 5.6
Hz), 123.7, 95.5 (d, JC−P = 51.7 Hz), 83.1 (d, JC−P = 293.0 Hz), 63.6
(d, JC−P = 5.6 Hz), 16.1 (d, JC−P = 6.8 Hz). 31P NMR (162 MHz,
CDCl3): δ −7.45. HRMS m/z (ESI): calcd for C12H14NO5P [M +
Na]+ 306.0507, found 306.0509.
Diethyl (o-Tolylethynyl)phosphonate (3b) (CAS No. 139961-20-
9). 102 mg, 81% yield. 1H NMR (CDCl3, 400 MHz): δ 7.50−7.48 (d, J
= 7.6 Hz, 1H), 7.33−7.29 (t, J = 7.9 Hz, 1H), 7.22−7.20 (d, J = 7.6
Hz, 1H), 7.17−7.13 (t, J = 7.7 Hz, 1H), 4.24−4.17(m, 4H), 2.44(s,
3H), 1.40−1.36 (t, J = 6.9 Hz, 6H). 13C{1H} NMR (100 MHz,
CDCl3): δ 141.8 (d, JC−P = 2.0 Hz), 133.0 (d, JC−P = 2.6 Hz), 130.7,
129.8, 125.8, 119.4 (d, JC−P = 5.3 Hz), 98.2 (d, JC−P = 52.6 Hz), 82.0
(d, JC−P = 299.7 Hz), 63.2 (d, JC−P = 5.2 Hz), 20.5, 16.1 (d, JC−P = 7.0
Hz). 31P NMR (162 MHz, CDCl3): δ −5.85. HRMS m/z (ESI): calcd
for C13H17O3P [M + Na]+ 275.0813, found 275.0814.
Diethyl (m-Tolylethynyl)phosphonate (3c) (CAS No. 1315481-71-
0). 101 mg, 80% yield. 1H NMR (CDCl3, 400 MHz): δ 7.36−7.34 (m,
2H), 7.26−7.23 (m, 2H), 4.24−4.16(m, 4H), 2.32(s, 3H), 1.40−1.37
(t, J = 7.1 Hz, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ 138.4, 133.1
(d, JC−P = 2.5 Hz), 131.6, 129.7 (d, JC−P = 2.4 Hz), 128.5, 119.3 (d,
JC−P = 5.7 Hz), 99.4 (d, JC−P = 53.5 Hz), 77.9 (d, JC−P = 300.6 Hz),
63.2 (d, JC−P = 5.4 Hz), 21.1, 16.1 (d, JC−P = 7.0 Hz). 31P NMR (162
MHz, CDCl3): δ −5.90. HRMS m/z (ESI): calcd for C13H17O3P [M +
Na]+ 275.0813, found 275.0810.
Diethyl (p-Tolylethynyl)phosphonate (3d) (CAS No. 176100-−86-
0). 106 mg, 84% yield. 1H NMR (CDCl3, 400 MHz): δ 7.43−7.41 (d, J
= 8.0 Hz, 2H), 7.16−7.14 (d, J = 8.0 Hz, 2H), 4.23−4.15 (m, 4H),
2.35(s, 3H), 1.39−1.35 (t, J = 7.1 Hz, 6H). 13C{1H} NMR (100 MHz,
CDCl3): δ 141.3, 132.6 (d, JC−P = 2.3 Hz), 129.6, 116.4 (d, JC−P = 5.6
Hz), 99.6 (d, JC−P = 53.3 Hz), 77.8 (d, JC−P = 300.6 Hz), 63.1 (d, JC−P
= 5.4 Hz), 21.7, 16.1 (d, JC−P = 7.0 Hz). 31P NMR (162 MHz,
CDCl3): δ −5.68. HRMS m/z (ESI): calcd for C13H17O3P [M + Na]+
275.0813, found 275.0809.
Diethyl ((4-Cyanophenyl)ethynyl)phosphonate (3h) (New Com-
1
pound). Oil; 128 mg, 97% yield. H NMR (CDCl3, 400 MHz): δ
7.67−7.62 (m, 4H), 4.24−4.17 (m, 4H), 1.40−1.36 (t, J = 7.1 Hz,
6H). 13C{1H} NMR (100 MHz, CDCl3): δ 133.1 (d, JC−P = 2.4 Hz),
132.2, 124.3 (d, JC−P = 5.6 Hz), 117.7, 114.1, 96.9 (d, JC−P = 52.1 Hz),
82.5 (d, JC−P = 293.6 Hz), 63.5 (d, JC−P = 5.6 Hz), 16.1 (d, JC−P = 6.8
Hz). 31P NMR (162 MHz, CDCl3): δ −7.29. HRMS m/z (ESI): calcd
for C13H14NO3P [M + Na]+ 286.0609, found 286.0603.
Diethyl ((4-(Trifluoromethyl)phenyl)ethynyl)phosphonate (3i)
(CAS No. 1315481-74-3). 119 mg, 78% yield. 1H NMR (CDCl3,
400 MHz): δ 7.65−7.63 (d, J = 8.3 Hz, 2H), 7.60−7.58 (d, J = 8.4 Hz,
2H), 4.24−4.16 (m, 4H), 1.39−1.35 (t, J = 7.2 Hz, 6H). 13C{1H}
NMR (100 MHz, CDCl3): δ 132.9 (d, JC−P = 2.5 Hz), 132.2 (q, JF−C
=
33.1 Hz), 125.5 (q, JF−C = 3.9 Hz), 123.4 (q, JF−C = 272.2 Hz), 123.3
(d, JC−P = 5.7 Hz), 96.6 (d, JC−P = 52.3 Hz), 80.7 (d, JC−P = 295.6 Hz),
63.4(d, JC−P = 5.6 Hz), 16.1 (d, JC−P = 7.0 Hz). 31P NMR (162 MHz,
CDCl3): δ −6.96. HRMS m/z (ESI): calcd for C13H14F3O3P [M +
Na]+ 329.0530, found 329.0527.
Diethyl ((4-Fluorophenyl)ethynyl)phosphonate (3j) (CAS No.
1
176100-85-9). 110 mg, 86% yield. H NMR (CDCl3, 400 MHz): δ
7.58−7.54 (dd, JF−H = 5.8 Hz, J = 8.8 Hz, 2H), 7.09−7.05 (m, 2H),
4.24−4.16 (m, 4H), 1.42−1.38 (dt, JH−P = 0.5 Hz, 7.1 Hz, 6H).
13C{1H} NMR (100 MHz, CDCl3): δ 163.9 (d, JF−C = 255.9 Hz),
134.8 (dd, JC−P = 2.4 Hz, JF−C = 8.8 Hz), 129.0 (d, JF−C = 22.4 Hz),
115.7 (dd, JF−C = 3.6 Hz, JC−P = 5.7 Hz), 97.8 (d, JC−P = 53.0 Hz), 78.4
(d, JC−P = 300.5 Hz), 63.2(d, JC−P = 5.6 Hz), 16.1 (d, JC−P = 7.1 Hz).
31P NMR (162 MHz, CDCl3): δ −6.18. HRMS m/z (ESI): calcd for
C12H14FO3P [M + Na]+ 279.0562, found 279.0559.
Diethyl ((4-Phenylphenyl)ethynyl)phosphonate (3e) (CAS No.
1
912486-03-4). 143 mg, 91% yield. H NMR (CDCl3, 400 MHz): δ
7.64−7.55 (m, 6H), 7.46−7.43 (m, 2H), 7.39−7.35 (m, 1H), 4.28−
4.20 (m, 4H), 1.43−1.40 (t, J = 7.1 Hz, 6H). 13C{1H} NMR (100
MHz, CDCl3): δ 143.5, 139.7, 133.1 (d, JC−P = 2.4 Hz), 129.0, 128.2,
127.2, 127.1, 118.3 (d, JC−P = 5.5 Hz), 99.1 (d, JC−P = 52.9 Hz), 79.0
(d, JC−P = 300.4 Hz), 63.2 (d, JC−P = 5.5 Hz), 16.1 (d, JC−P = 6.9 Hz).
31P NMR (162 MHz, CDCl3): δ −6.54. MS-ESI: m/z 337.5 [M +
Na]+.
Diethyl ((4-Chlorophenyl)ethynyl)phosphonate (3k) (CAS No.
1
176511-86-7). 114 mg, 84% yield. H NMR (CDCl3, 400 MHz): δ
7.47−7.45 (d, J = 8.6 Hz, 2H), 7.34−7.32 (d, J = 8.6 Hz, 2H), 4.24−
4.15 (m, 4H), 1.39−1.35 (dt, J = 0.6 Hz, 7.1 Hz, 6H). 13C{1H} NMR
(100 MHz, CDCl3): δ 137.1, 133.8 (d, JC−P = 2.5 Hz), 129.0, 118.0 (d,
JC−P = 5.7 Hz), 97.6 (d, JC−P = 53.0 Hz), 79.6 (d, JC−P = 298.9 Hz),
63.3(d, JC−P = 5.3 Hz), 16.1 (d, JC−P = 7.0 Hz). 31P NMR (162 MHz,
CDCl3): δ −6.42. HRMS m/z (ESI): calcd for C12H14ClO3P [M +
Na]+ 295.0267, found 295.0266.
Diethyl ((3,4-Dimethoxyphenyl)ethynyl)phosphonate (3f) (CAS
1
No. 947504-11-2). 129 mg, 87% yield. H NMR (CDCl3, 400 MHz):
δ 7.16−7.14 (d, J = 8.5 Hz, 1H), 6.99 (s, 1H), 6.80−6.78 (d, J = 8.5
Hz, 1H), 4.22−4.14 (m, 4H), 3.86 (d, J = 1.2 Hz, 3H), 3.83 (d, J = 1.0
Hz, 3H), 1.38−1.34 (m, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ
151.5, 148.8, 126.9 (d, JC−P = 2.6 Hz), 114.9 (d, JC−P = 2.1 Hz), 111.4
(d, JC−P = 5.8 Hz), 99.7 (d, JC−P = 53.9 Hz), 77.0(d, JC−P = 302.1 Hz),
63.1 (d, JC−P = 5.2 Hz), 56.0, 55.9, 16.1 (d, JC−P = 7.1 Hz). 31P NMR
(162 MHz, CDCl3): δ −5.53. HRMS m/z (ESI): calcd for C14H19O5P
[M + Na]+ 321.0868, found 321.0866.
Diethyl ((4-Bromophenyl)ethynyl)phosphonate (3l) (CAS No.
1
1345719-55-2). 130 mg, 82% yield. H NMR (CDCl3, 400 MHz): δ
7.50−7.48 (d, J = 8.6 Hz, 2H), 7.40−7.38 (d, J = 8.6 Hz, 2H), 4.23−
4.15 (m, 4H), 1.39−1.36 (t, J = 7.1 Hz, 6H). 13C{1H} NMR (100
MHz, CDCl3): δ 133.9 (d, JC−P = 2.3 Hz), 132.0, 125.4, 118.5 (d, JC−P
= 5.7 Hz), 97.6 (d, JC−P = 52.7 Hz), 79.7 (d, JC−P = 297.1 Hz), 63.3 (d,
JC−P = 5.5 Hz), 16.1 (d, JC−P = 7.0 Hz). 31P NMR (162 MHz, CDCl3):
Diethyl ((4-Nitrophenyl)ethynyl)phosphonate (3g) (CAS No.
1
287960-25-2). 128 mg, 91% yield. H NMR (CDCl3, 400 MHz): δ
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The Journal of Organic Chemistry
Note
δ −5.90. HRMS m/z (ESI): calcd for C12H14BrO3P [M + Na]+
338.9762, found 338.9762.
(162 MHz, CDCl3): δ −6.82. HRMS m/z (ESI): calcd for C18H24O6P2
[M + Na]+ 421.0946, found 421.0940.
Methyl ((4-Diethoxyphosphoryl)ethynyl)benzoate (3m) (New
Diisopropyl (Phenylethynyl)phosphonate (3u) (CAS No. 204009-
80-3). 108 mg, 81% yield. H NMR (CDCl3, 400 MHz): δ 7.54−7.52
(m, 2H), 7.44−7.40 (m, 1H), 7.37−7.31 (m, 2H), 4.81−4.76 (m, 2H),
1.40−1.37 (dd, J = 6.3 Hz, 2.4 Hz, 12H). 13C{1H} NMR (100 MHz,
CDCl3): δ 132.5 (d, JC−P = 2.3 Hz), 130.5, 128.5, 119.9 (d, JC−P = 5.3
Hz), 98.1 (d, JC−P = 52.7 Hz), 79.9 (d, JC−P = 299.3 Hz), 72.3 (d, JC−P
= 5.6 Hz), 23.9 (d, JC−P = 4.3 Hz), 23.6 (d, JC−P = 4.6 Hz). 31P NMR
(162 MHz, CDCl3): δ −8.59. HRMS m/z (ESI): calcd for C14H19O3P
[M + Na]+ 289.0970, found 289.0964.
1
Compound). Oil; 132 mg, 89% yield. H NMR (CDCl3, 400 MHz):
δ 8.01−7.99 (d, J = 8.5 Hz, 2H), 7.60−7.58 (d, J = 8.0 Hz, 2H), 4.24−
4.16 (m, 4H), 3.89 (s, 3H), 1.39−1.35 (t, J = 7.1 Hz, 6H). 13C{1H}
NMR (100 MHz, CDCl3): δ 165.9, 132.5 (d, JC−P = 2.4 Hz), 131.8,
129.6, 123.9 (d, JC−P = 5.4 Hz), 97.4 (d, JC−P = 53.7 Hz), 81.0(d, JC−P
= 295.1 Hz), 63.4(d, JC−P = 5.4 Hz), 52.4, 16.1 (d, JC−P = 6.9 Hz). 31
P
NMR (162 MHz, CDCl3): δ −6.79. HRMS m/z (ESI): calcd for
C14H17O5P [M + Na]+ 319.0711, found 319.0709.
Diethyl ((5-Methylfuran-2-yl)ethynyl)phosphonate (3n) (CAS No.
Diphenyl (Phenylethynyl)phosphine Oxide (3v) (CAS No. 7608-
18-6). 101 mg, 67% yield. 1H NMR (CDCl3, 400 MHz): δ 7.91−7.86
(m, 4H), 7.57−7.38 (m, 9H), 7.35−7.30 (m, 2H). 13C{1H} NMR
1
947504-11-2). 87 mg, 72% yield. H NMR (CDCl3, 400 MHz): δ
6.76−6.75 (d, J = 3.3 Hz, 1H), 6.01−6.00 (m, 1H), 4.21−4.13 (m,
4H), 2.29 (m, 3H), 1.37−1.33 (t, J = 7.1 Hz, 6H). 13C{1H} NMR (100
MHz, CDCl3): δ 156.4, 132.8 (d, JC−P = 6.7 Hz), 121.6, 107.7, 89.4 (d,
JC−P = 53.8 Hz), 83.3 (d, JC−P = 296.4 Hz), 63.3 (d, JC−P = 5.6 Hz),
16.1 (d, JC−P = 7.0 Hz), 13.9. 31P NMR (162 MHz, CDCl3): δ −6.25.
HRMS m/z (ESI): calcd for C11H15O4P [M + Na]+ 265.0606, found
265.0604.
(100 MHz, CDCl3): δ 133.7, 132.5 (d, JC−P = 1.6 Hz), 132.2 (d, JC−P
=
2.6 Hz), 130.9 (d, JC−P = 11.1 Hz), 130.7, 128.7, 128.6, 119.9 (d, JC−P
= 4.1 Hz), 105.5 (d, JC−P = 30.2 Hz), 83.0 (d, JC−P = 168.8 Hz). 31P
NMR (162 MHz, CDCl3): δ 8.18. HRMS m/z (ESI): calcd for
C20H15OP [M + Na]+ 325.0758, found 325.0760.
4-((Diphenylphosphoryl)ethynyl)benzonitrile (3w) (CAS No.
Diethyl (Thiophene-2-ylethynyl)phosphonate (3o) (CAS No.
1
1
58971-88-3). 123 mg, 75% yield. H NMR (CDCl3, 400 MHz): δ
80034-76-0). 117 mg, 96% yield. H NMR (CDCl3, 400 MHz): δ
7.90−7.85 (m, 4H), 7.70−7.65 (m, 4H), 7.60−7.56 (m, 2H), 7.53−
7.42−7.40 (m, 2H), 7.01−6.99 (m, 1H), 4.22−4.15 (m, 4H), 1.38−
1.35 (t, J = 7.0 Hz, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ 135.9
(d, JC−P = 2.2 Hz), 130.6, 127.4, 119.2 (d, JC−P = 6.6 Hz), 92.4 (d, JC−P
= 54.0 Hz), 82.5 (d, JC−P = 300.3 Hz), 63.3 (d, JC−P = 5.6 Hz), 16.1 (d,
JC−P = 7.0 Hz). 31P NMR (162 MHz, CDCl3): δ −6.31. HRMS m/z
(ESI): calcd for C10H13SO3P [M + Na]+ 267.0221, found 267.0225.
Diethyl (Pyridin-4-ethynyl)phosphonate (3p) (New Compound).
Oil; 91 mg, 76% yield. 1H NMR (CDCl3, 400 MHz): δ 8.65−8.64 (d, J
= 5.5 Hz, 2H), 7.39−7.38 (d, J = 5.5 Hz, 2H), 4.26−4.18 (m, 4H),
1.41−1.37 (t, J = 7.1 Hz, 6H). 13C{1H} NMR (100 MHz, CDCl3) δ
150.1, 125.7 (d, JC−P = 5.3 Hz), 125.9, 94.9 (d, JC−P = 50.6 Hz), 82.8
(d, JC−P = 293.9 Hz), 63.6(d, JC−P = 5.5 Hz), 16.1 (d, JC−P = 7.0 Hz).
31P NMR (162 MHz, CDCl3): δ −7.52. HRMS m/z (ESI): calcd for
7.48 (m, 4H). 13C{1H} NMR (100 MHz, CDCl3): δ 133.0 (d, JC−P
=
1.5 Hz), 132.6 (d, JC−P = 2.7 Hz), 132.3 (d, JC−P = 122.2 Hz), 132.2,
131.0 (d, JC−P = 11.2 Hz), 128.8 (d, JC−P = 13.6 Hz),124.7 (d, JC−P
=
3.9 Hz), 117.8, 114.1, 102.3 (d, JC−P = 28.5 Hz), 87.1 (d, JC−P = 162.1
Hz). 31P NMR (162 MHz, CDCl3): δ 8.40. HRMS m/z (ESI): calcd
for C21H14ONP [M + Na]+ 350.0711, found 350.0706.
(Naphthalen-2-ylethynyl)diphenylphosphine (3x) (CAS No.
1
930807-33-3). 144 mg, 82% yield. H NMR (CDCl3, 400 MHz): δ
8.16 (s, 1H), 7.97−7.91 (m, 4H), 7.85−7.82 (m, 3H), 7.60−7.48 (m,
9H). 13C{1H} NMR (100 MHz, CDCl3): δ 133.9, 133.8, 133.7 (d,
JC−P = 2.0 Hz), 132.6, 132.5 (d, JC−P = 2.8 Hz), 131.0 (d, JC−P = 11.2
Hz), 128.7 (d, JC−P = 13.3 Hz), 128.4, 128.1, 128.0, 127.9, 127.8,
127.1, 117.1 (d, JC−P = 4.2 Hz), 105.9 (d, JC−P = 29.7 Hz), 83.1 (d,
JC−P = 169.4 Hz). 31P NMR (162 MHz, CDCl3): δ 6.44. HRMS m/z
(ESI): calcd for C24H17OP [M + Na]+ 375.0909, found 375.0903.
Ethyl Phenyl(phenylethynyl)phosphinate (3y) (CAS No. 225928-
24-5). 108 mg, 80% yield. 1H NMR (CDCl3, 400 MHz): δ 7.97−7.91
(m, 2H), 7.59−7.47 (m, 5H), 7.44−7.40 (m, 1H), 7.36−7.32 (m, 2H),
4,32−4.25 (m, 2H), 1.44−1.40 (t, J = 7.0 Hz, 3H). 13C{1H} NMR
(100 MHz, CDCl3): δ 132.8 (d, JC−P = 2.9 Hz), 132.6 (d, JC−P = 2.0
Hz), 131.2 (d, JC−P = 165.8 Hz), 131.1 (d, JC−P = 11.2 Hz), 130.6,
C11H14NO3P [M + Na]+ 262.0609, found 262.0604.
Diethyl (Naphthalen-2-ylethynyl)phosphonate (3q) (New Com-
pound). Oil; 119 mg, 83% yield. 1H NMR (CDCl3, 400 MHz): δ 8.10
(s, 1H), 7.82−7.79 (m, 3H), 7.55−7.49 (m, 3H), 4.29−4.21 (m, 4H),
1.43−1.39 (t, J = 7.2 Hz, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ
133.8, 132.5, 128.4, 128.1, 128.0, 127.9, 127.8, 127.1, 116.7 (d, JC−P
=
5.7 Hz), 99.5 (d, JC−P = 53.0 Hz), 78.5 (d, JC−P = 298.4 Hz), 63.3 (d,
JC−P = 5.5 Hz), 16.2 (d, JC−P = 7.1 Hz). 31P NMR (162 MHz, CDCl3):
δ −6.00. HRMS m/z (ESI): calcd for C16H17O3P [M + Na]+
311.0813, found 311.0811.
128.6 (d, JC−P = 14.9 Hz), 119.8 (d, JC−P = 4.2 Hz), 101.5 (d, JC−P
=
Diethyl (Anthracen-9-ylethynyl)phosphonate (3r) (New Com-
1
39.7 Hz), 81.8 (d, JC−P = 216.1 Hz), 62.3 (d, JC−P = 6.4 Hz), 16.4 (d,
JC−P = 7.0 Hz). 31P NMR (162 MHz, CDCl3): δ 9.93. HRMS m/z
(ESI): calcd for C16H15O2P [M + Na]+ 293.0707, found 293.0703.
Ethyl (Naphthalen-1-ylethynyl)(phenyl)phosphinate (3z) (CAS
No. 225928-24-5). 133 mg, 83% yield. 1H NMR (CDCl3, 400
MHz): δ 8.23−8.21 (d, J = 8.3 Hz, 1H), 8.06−8.00 (m, 2H), 7.91−
7.89 (d, J = 8.3 Hz, 1H), 7.85−7.83 (d, J = 7.6 Hz, 1H), 7.80−7.79 (d,
J = 7.0 Hz, 1H), 7.61−7.49 (m, 5H), 7.44−7.40 (t, J = 7.9 Hz, 1H),
4.41−4.33 (m, 2H), 1.48−1.44 (t, J = 7.1 Hz, 3H). 13C{1H} NMR
(100 MHz, CDCl3): δ 133.3, 132.9, 132.8 (d, JC−P = 2.7 Hz), 132.6 (d,
JC−P = 2.0 Hz), 131.4 (d, JC−P = 165.6 Hz), 131.3, 131.2 (d, JC−P = 11.7
Hz), 128.7, 128.6, 127.7, 126.9, 125.6, 125.0, 117.1 (d, JC−P = 4.4 Hz),
pound). Yellow solid; mp 101−102 °C; 149 mg, 88% yield. H NMR
(CDCl3, 400 MHz): δ 8.53 (s, 1H), 8.48−8.46 (d, J = 8.6 Hz, 2H),
8.03−8.01 (d, J = 8.5 Hz, 2H), 7.65−7.61 (m, 2H), 7.55−7.51 (d, J =
7.5 Hz, 2H), 4.41−4.32 (m, 4H), 1.50−1.47 (t, J = 7.0 Hz, 6H).
13C{1H} NMR (100 MHz, CDCl3): δ 133.8 (d, JC−P = 2.1 Hz), 130.8,
130.7, 129.0, 127.9, 126.0, 125.9, 112.8 (d, JC−P = 5.9 Hz), 96.5(d, JC−P
= 52.6 Hz), 89.2 (d, JC−P = 298.1 Hz), 63.4 (d, JC−P = 5.5 Hz), 16.3 (d,
JC−P = 7.0 Hz). 31P NMR (162 MHz, CDCl3): δ −5.76. HRMS m/z
(ESI): calcd for C20H19O3P [M + Na]+ 361.0970, found 361.0974.
(E)-Diethyl (4-Phenylbut-3-en-1-yn-1-yl)phosphonate (3s) (New
Compound). Oil; 108 mg, 82% yield. 1H NMR (CDCl3, 400 MHz): δ
7.38−7.29 (m, 5H), 7.19−7.15 (d, J = 16.3 Hz, 1H), 6.16−6.11 (dd, J
= 16.4 Hz, 3.7 Hz, 1H), 4.20−4.12 (m, 4H), 1.37−1.33 (t, J = 7.0 Hz,
6H). 13C{1H} NMR (100 MHz, CDCl3): δ 147.3 (d, JC−P = 3.7 Hz),
100.1 (d, JC−P = 39.5 Hz), 86.5 (d, JC−P = 214.0 Hz), 62.4 (d, JC−P
=
6.4 Hz), 16.5 (d, JC−P = 6.9 Hz). 31P NMR (162 MHz, CDCl3): δ 9.67.
HRMS m/z (ESI): calcd for C20H17O2P [M + Na]+ 343.0864, found
343.0856.
134.9, 130.0, 128.9, 126.8, 104.5 (d, JC−P = 6.5 Hz), 98.7 (d, JC−P
=
52.7 Hz), 80.0 (d, JC−P = 298.8 Hz), 63.1 (d, JC−P = 5.6 Hz), 16.1 (d,
JC−P = 7.0 Hz). 31P NMR (162 MHz, CDCl3): δ −5.97. HRMS m/z
(ESI): calcd for C14H17O3P [M + Na]+ 287.0813, found 287.0814.
Tetraethyl (1,4-Phenylenebis(ethyne-2,1-diyl))bis(phosphonate)
ASSOCIATED CONTENT
■
1
(3t) (CAS No. 945083-55-1). 179 mg, 90% yield. H NMR (CDCl3,
S
* Supporting Information
400 MHz): δ 7.51 (s, 4H), 4.21−4.13 (m, 4H), 1.37−1.33 (t, J = 7.1
1
Copies of H NMR, 31P NMR, and 13C NMR spectra. This
Hz, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ 132.6 (d, JC−P = 2.3
material is available free of charge via the Internet at http://
pubs.acs.org.
Hz), 121.7 (d, JC−P = 5.7 Hz), 97.1 (d, JC−P = 52.5 Hz), 81.3 (d, JC−P
=
296.0 Hz), 63.4 (d, JC−P = 5.6 Hz), 16.1 (d, JC−P = 7.1 Hz). 31P NMR
3682
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The Journal of Organic Chemistry
Note
(13) (a) Hirao, T.; Masunaga, T.; Ohshiro, Y.; Agawa, T. J. Org.
Chem. 1981, 46, 3745−3747. (b) Abbas, S.; Hayes, C. J.; Worden, S.
Tetrahedron Lett. 2000, 41, 3215−3219. (c) Kuang, C.; Senboku, H.;
Tokuda, M. Tetrahedron 2002, 58, 1491−1496.
AUTHOR INFORMATION
Corresponding Authors
*E-mail: gaoxingchem@xmu.edu.cn.
*E-mail: stacyliu@xmu.edu.cn.
Notes
■
(14) (a) Zhang, X. H.; Liu, H. Z.; Hu, X. M.; Tang, G.; Zhu, J.; Zhao,
Y. F. Org. Lett. 2011, 13, 3478−3481. (b) Zhao, Z. X.; Xue, W. H.;
Gao, Y. X.; Tang, G.; Zhao, Y. F. Chem.Asian J. 2013, 8, 713−716.
(c) Hu, G. B.; Chen, W. Z.; Fu, T. T.; Peng, Z. M.; Qiao, H. W.; Gao,
Y. X.; Zhao, Y. F. Org. Lett. 2013, 15, 5362−5365.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
(15) Some selected publications: (a) Buchwald, S.; Bolm, C. Angew.
Chem., Int. Ed. 2009, 48, 5586−5587. (b) Crabtree, R. H. Chem. Rev.
This work was supported by the Chinese National Natural
Science Foundation (21202135), the Natural Science Founda-
tion of Fujian Province of China (Nos. 2013J05031 and
2012J01053), and the National Basic Research Program of
China (2012CB821600).
́
2012, 112, 1536−1554. (c) Thome, I.; Nijs, A.; Bolm, C. Chem. Soc.
Rev. 2012, 41, 979−987. (d) Bhunia, A.; Yetra, S. R.; Biju, A. T. Chem.
Soc. Rev. 2012, 41, 3140−3152.
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