Synthesis of β-ketophosphonates via AgNO3-catalyzed hydration of alkynylphosphonates: A rate-enhancement effect of methanol

Article abstract of DOI:10.1016/j.tet.2014.12.001

β-Ketophosphonates were prepared via AgNO₃-catalyzed hydration of alkynylphosphonates with a dramatic rate-enhancement effect of methanol. This benign aqueous-methanol method catalyzed by a low-cost catalyst has simple, atom-economical procedure, and was used effectively with a wide range of substrates.

Full text of DOI:10.1016/j.tet.2014.12.001

Tetrahedron 71 (2015) 694e699
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis of
b-ketophosphonates via AgNO3-catalyzed hydration of
alkynylphosphonates: a rate-enhancement effect of methanol
*
Jiannan Xiang, Niannian Yi, Ruijia Wang, Linghui Lu, Huaxu Zou, Yuan Pan, Weimin He
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082,
PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 4 August 2014
Received in revised form 25 November 2014
Accepted 1 December 2014
Available online 5 December 2014
b
-Ketophosphonates were prepared via AgNO3-catalyzed hydration of alkynylphosphonates with a dra-
matic rate-enhancement effect of methanol. This benign aqueous-methanol method catalyzed by a low-
cost catalyst has simple, atom-economical procedure, and was used effectively with a wide range of
substrates.
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
Silver
Hydration
b-Ketophosphonates
Homogeneous catalysis
Alkynylphosphonates
1. Introduction
perspective of its applications in commercial syntheses because of
the high cost. Surprisingly, silver salts, inexpensive compared to
b
-Ketophosphonates represent an important class of carbonyl
palladium salts and gold(I) complexes, are seldom applied to cat-
compounds that are found in a variety of biologically active mole-
cules such as antiinflammatory agents1 and protein inhibitors.2
They also act as key building blocks in organic synthesis,3 espe-
alytic hydration of heterosubstituted alkynes.12 Owing to our con-
tinuous interest in the synthesis of
a-functionalized carbonyl
compounds,11,13 herein we describe an efficient synthesis of
b
-
cially as intermediates for the synthesis of
a
,
b
-unsaturated carbonyl
ketophosphonates via AgNO3-catalyzed hydration of alkynyl-
phosphonates, which can be easily prepared in one step from
commercially readily available terminal alkynes.14
compounds,4 chiral -amino5 and -hydroxy phosphonic acids.6
b
b
Furthermore, they are prime ligands in organometallic chemistry
to control most transition metal catalyzed reactions due to their
excellent metal ligation properties.7
2. Results and discussion
Due to such wide interest, several
have already been developed and any novel efficient access to
provide -ketophosphonates with good functional group compat-
b-ketophosphonate syntheses
Diethyl phenylethynylphosphonate (1a) was first chosen as the
model substrate to investigate our synthetic approach to b-keto-
b
ibility in high yields would be extraordinarily valuable.8 Among
these developed methods, hydration9 of alkynylphosphonates
catalyzed by transition metals is particularly interesting owning to
100% atom economy and environmental benignity.10 Mercury salts
are originally proposed for such transformation, but high toxicity is
a dramatic barrier for applications in both academic and industrial
utilization.8a,8c,8eeg Palladium salts8m and gold(I) complexes11 are
recently explored as catalysts for the reaction. However, these
methods suffer from several shortcomings, particularly from the
phosphonates. In the presence of 10 mol % of AgCl, the hydration
reaction of 1a was conducted in methanol/water (10/1) mixtur-
e9f,12b,15 at 120 ꢀC. Pleasingly, about 80% GC conversion of 1a was
observed after 24 h (Table 1, entry 1). Attempts to increase the
reaction efficiency by varying the silver salts (entries 2e7) revealed
that inexpensive AgNO3 was a superior catalyst with a 94% isolated
yield (entry 7). Encouraged by the impressive result, we sub-
sequently focused on determining the appropriate solvent (entries
8e17). Only a trace amount of substrate was converted into the
corresponding product when the reactions were carried out in
water, 1,2-Dichloroethane/H2O (10/1), CH3CN/H2O (10/1) and DMF/
H2O (10/1) (entries 8e11). Switching the solvent to EtOH/H2O (10/
1), iPrOH/H2O (10/1), Ethylene Glycol/H2O (10/1), 1,3-Propanediol/
* Corresponding author. Tel.: þ86 731 88222753; fax: þ86 731 88222754; e-mail
address: wmhe@hnu.edu.cn (W. He).
http://dx.doi.org/10.1016/j.tet.2014.12.001
0040-4020/Ó 2014 Elsevier Ltd. All rights reserved.

J. Xiang et al. / Tetrahedron 71 (2015) 694e699
695
Table 2
The reaction scope of alkynylphosphonatesa,b
Table 1
Screening optimal conditionsa
Entry
Catalyst
Reaction condition
Conv.%b
1
4
2
3
1
2
3
4
5
6
7
8
AgCl
AgBF4
AgOTf
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
H2O, 120 ꢀC
1,2-Dichloroethane/H2O(10/1), 120 ꢀC
CH3CN/H2O(10/1), 120 ꢀC
DMF/H2O(10/1), 120 ꢀC
EtOH/H2O(10/1), 120 ꢀC
iPrOH/H2O(10/1), 120 ꢀC
Ethylene Glycol/H2O(10/1), 120 ꢀC
1,3-Propanediol/H2O(10/1), 120 ꢀC
THF/H2O(10/1), 120 ꢀC
Dioxane/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 100 ꢀC
CH3OH/H2O(10/1), 80 ꢀC
CH3OH/H2O(10/1), 60 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
CH3OH/H2O(10/1), 120 ꢀC
83
87
92
85
83
86
97(94)
7
AgSbF6
Ag2SO4
AgOAc
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
Cu(NO3)2
Fe(NO3)3
HNO3
2b, 91%
2e, 93%
2c, 90%
2f, 91%
2d, 90%
2g, 80%
5
6
9
12
9
10
11
12
13
14
15
16
17
18c
19d
20
21
22
23
24
25
11
48
27
56
42
23
34
60
98
89
72
50
0
7
8
9c
2h, 92%
2k, 92%
2i, 90%
2l, 84%
2j, 70%
10
13
11
14
12
15
0
0
2m, 93%
a
Conditions: 1a (0.5 mmol), catalyst (10 mol %), solvent (0.5 mL) and water
(0.05 mL) in sealed tube at 120 ꢀC for 24 h.
b
GC conversions are average of at least two runs and the number in parentheses
2n, 85%
2q, 76%
2o, 77%
2r, 77%
2p, 82%
2s, 70%
is isolated yield.
18d
21
c
5 mol % AgNO3 was used and the reaction was run for 48 h.
15 mol % AgNO3 was used and the reaction was finished in 10 h.
16
19
17
20
d
H2O (10/1), THF/H2O (10/1) and 1,4-Dioxane/H2O (10/1), the cata-
lytic system provided modest GC conversions (48%, 27%, 56%, 42%,
23% and 34%, respectively, entries 12e17). These results suggested
that methanol was essential to dramatically increase of the hy-
dration rates.15 Less amount of catalyst (5 mol %) took longer time
to afford the higher conversion whereas increased amount of cat-
alyst (15 mol %) did not improve the yield (entries 18, 19). Mean-
while, the temperature influenced the reaction significantly. The
reaction did become sluggish when the temperature decreased
from 120 ꢀC to 60 ꢀC (entries 20e22). The blank experiments
showed that the presence of the silver catalyst was necessary in our
protocol (entries 23e25).
With the optimal conditions in hand (Table 1, entry 7), we
embarked on the evaluation of the substrate scope for this trans-
formation. The results were summarized in Table 2. For most cases,
the conversions were more than 90%. A variety of aromatic alky-
nylphosphonates were initially tested. Both electron-donating
groups and electron-withdrawing groups at para and meta posi-
tions were all tolerated under the reaction conditions, and excellent
yields of the corresponding hydration products were obtained
(2be2i). These bromide groups were the useful entities amenable
to further manipulations by the transition metal-catalyzed cross-
coupling strategies. However, the conversion rate of 1j was slow
under the optimal conditions, and 24% of 1j was still recovered after
the reaction was allowed to run for 36 h, likely due to the steric
hindrance. Heterocycle-containing alkynylphosphonates (2k, 2l)
were also well compatible with this transformation. Moreover,
a series of aliphatic alkynylphosphonates were tested. Important
functional groups including alkyl (2m), phthalimide (PhthNH, 2n),
2t, 80%
2u, 92%
2v, 92%
22
23
24
2w, 91%
2x, 91%
2y, 90%
a
Conditions: alkynylphosphonates (0.5 mmol), AgNO3 (10 mol%) ,
CH3OH (0.5 mL) and H2O (0.05 mL) in sealed tube at 120 oC for 24 h.
b Isolated yield.
c Run for 36 h.
d Run for 48 h.
p-toluenesulfonamide (TsNH2, 2o), acetoxyl (2p), pivaloyloxy (PivO,
2q), phenoxy (2r) and cyano moieties (2s) were well tolerated
under these reaction conditions. However, 24% of substrate
remained unreacted even though the reaction time was extended
to 48 h in the cases of diethyl (5-cyano-2-oxopentyl)phosphonate
(2s). We used phosphorus-substituted propargyl alcohol (1t) as the
substrate and afforded the a-hydroxy product (2t) in 80% isolated
yield, which highlighted the inexpensive catalytic system and
large-scale applications of this product in organic synthesis. There
are rarely reported examples concerning on efficient hydration of
unprotected propargyl alcohol substrates up to present. Much to
our delight, bulky substituents such as cyclohexenyl (2u),

696
J. Xiang et al. / Tetrahedron 71 (2015) 694e699
cyclohexyl (2v) and cyclopropyl (2w) groups could proceed suc-
cessfully. This alkynylphosphonate hydration strategy could also be
the corresponding
termediates)15 by nucleophilic attack of the methoxy anion. Soon
afterwards, the silver complex B decomposed to -ketophospho-
s-complex B (enol ether or diketal in-
extended to access the corresponding
b
-ketophosphonates (2t, 2x,
b
2y) when we used other phosphonates as the substrates.
We also explored the reactivity of the AgNO3-catalyzed hydra-
tion system for larger-scale synthesis as shown in Scheme 1. The
reaction with 3 mmol of diethyl phenylethynylphosphonate pro-
duced excellent isolated yield (94%) within 24 h. In the case of
10 mmol scale reaction, 92% of isolated yield was obtained within
36 h. The hydration proceeded smoothly even with a further in-
creased amount of substrate (25 mmol), affording the product in
87% isolated yield. These excellent results showed the promise of
the catalytic system for large-scale synthesis in the process of
alkynylphosphonates hydration.
nate 2 by substitution of the silver atom with a proton in a certain
direction. Perhaps the phosphate unit had some stabilization action
to the silver, the product formed with high regio- and
stereoselectivity.18
3. Conclusion
In summary, we have developed a novel and practical method
for the synthesis of
b-ketophosphonates through AgNO3-cata-
lyzed hydration of alkynylphosphonates with a dramatic rate-
enhancement effect of methanol. Considering the readily avail-
able substrates and benign aqueous-methanol condition, the
inexpensive catalytic system combined with an operationally
simple procedure render it a powerful opponent to traditional
approaches for the large-scale synthesis of various
b-keto-
phosphonates. Further studies to clearly understand the reaction
mechanism and the synthetic applications are ongoing in our
laboratory.
4. Experimental section
Scheme 1. Large-scale hydration.
4.1. General methods and materials
Ethyl acetate (ACS grade), hexanes (ACS grade) were purchased
from J&K Scientific Ltd. and used without further purification.
Commercially available reagents were used without further puri-
fication. Reactions were monitored by TLC. Flash column chroma-
tography was performed over silica gel (200e300 mesh). 1H NMR
and 13C NMR spectra were recorded on a Brucker ARX 400 FT NMR
plus spectrometer. High-resolution mass spectra were performed
on a Q-TOF microspectrometer.
This highly efficient synthesis of functionalized b-ketophosph-
onates permits rapid access to various important phosphonate
compounds. For instance, coupled with a subsequent methylena-
tion reaction upon simple workup, this reaction led to diethyl (3-
oxo-3-phenylprop-1-en-2-yl)phosphonate in 61% overall yield
(Scheme 2).16
4.2. General procedure for the synthesis of 2ae2y, 3a
Procedure for 2: To
a solution of alkynylphosphonate
Scheme 2. Synthesis of diethyl (3-oxo-3-phenylprop-1-en-2-yl)phosphonate.
(0.5 mmol) in CH3OH (0.5 mL) in sealed tube was added H2O
(0.05 mL) and AgNO3 (0.05 mmol, 8.5 mg), the reaction mixture
was stirred at 120 ꢀC and the reaction was monitored by TLC. The
reaction typically took 24 h. Upon completion, the mixture was
concentrated under reduced pressure. The residue was purified by
column chromatography on silica gel (eluent: hexanes/ethyl ace-
tate) to afford 2ae2y.
The possible mechanism was shown in Scheme 3 was proposed
on the basis of the previous reported mechanism9f,12b,17 and our
Procedure for 3a: In a screw capped vial containing freshly
distilled THF (3 mL), diethyl (2-oxo-2-phenylethyl)phosphonate
(2a) (0.3 mmol, 77 mg), p-formaldehyde (0.9 mmol, 27 mg) and
CF3COONH2iPr2 salt (0.3 mmol, 65 mg) were added. CF3COOH
(0.03 mmol, 4 mg) was added and the mixture was warmed to 60 ꢀC
and stirred overnight. Upon completion, the mixture was extracted
with AcOEt/water and the organic layer dried over Na2SO4. The
solvent was then removed under reduced pressure. The residue
was purified by column chromatography on silica gel (eluent:
hexanes/ethyl acetate) to afford 3a.
4.3. Larger-scale synthesis of 2a
To
a solution of Diethyl phenylethynylphosphonate (1a)
(25 mmol, 5.95 g) in CH3OH (25 mL) in sealed tube was added H2O
(2.5 mL) and AgNO3 (2.5 mmol, 425 mg), the reaction mixture was
stirred at 120 ꢀC for 36 h and the reaction was monitored by TLC.
Upon completion, the mixture was concentrated under reduced
pressure. The residue was purified by column chromatography on
silica gel (eluent: hexanes/ethyl acetate) to afford 2a.
Scheme 3. Proposed reaction mechanism.
reaction results. First, the silver cation attacked the triple bond of 1
and formed a
p-complex A, which was subsequently converted to

J. Xiang et al. / Tetrahedron 71 (2015) 694e699
697
4.4. Characterization of the compounds
2H), 7.70 (d, J¼8.0 Hz, 2H), 4.14e4.07 (m, 4H), 3.62 (d, JH-P¼23.2 Hz,
2H), 1.25 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3):
¼191.01 (d,
d
4.4.1. Diethyl (2-oxo-2-phenylethyl)phosphonate (2a).8l Colorless
oil (120 mg, 94%); IR(neat): 3065, 2983, 1679, 1598, 1252, 1026,
JC-P¼6.5 Hz), 138.97, 134.69 (q, JC-F¼32.8 Hz), 129.31, 125.54 (q, JC-
¼3.7 Hz), 122.03, 62.71 (d, JC-P¼6.5 Hz), 38.79 (d, JC-P¼128.3 Hz),
F
962 cmꢁ1; 1H NMR (400 MHz, CDCl3):
d
¼7.98 (d, J¼7.2 Hz, 2H), 7.56
16.09 (d, JC-P¼6.5 Hz); 31P NMR (162 MHz, CDCl3):
d
¼18.96; HRMS
(t, J¼7.2 Hz, 1H), 7.45 (t, J¼7.6 Hz, 2H), 4.12e4.08 (m, 4H), 3.60 (d, JH-
(EI): m/z [M]þ calcd for C13H16F3O4P: 324.0733, found: 324.0732.
¼22.8 Hz, 2H), 1.24 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3):
P
d
¼191.81 (d, JC-P¼6.5 Hz),136.31,133.52, 128.86, 128.44, 62.50 (d, JC-
4.4.8. Diethyl (2-oxo-2-(m-tolyl)ethyl)phosphonate (2h). Colorless
¼6.6 Hz), 38.24 (d, JC-P¼129.80 Hz), 16.05 (d, JC-P¼6.6 Hz); 31P NMR
oil (124 mg, 92%); IR (neat): 2958,1688,1605,1250,1024, 970 cmꢁ1
;
P
(162 MHz, CDCl3):
d
¼19.97; HRMS (EI): m/z [M]þ calcd for
1H NMR (400 MHz, CDCl3):
d
¼7.78e7.76 (m, 2H), 7.37e7.30 (m, 2H),
C
12H17O4P: 256.0859, found: 256.0861.
4.14e4.06 (m, 4H), 3.58 (d, JH-P¼22.8 Hz, 2H), 2.38 (s, 3H), 1.24 (t,
J¼7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3):
¼191.94 (d, JC-P¼6.5 Hz),
d
4.4.2. Diethyl (2-oxo-2-(p-tolyl)ethyl)phosphonate (2b).8i Colorless
oil (123 mg, 91%); IR (neat): 2956,1684, 1608,1256,1028, 986 cmꢁ1
1H NMR (400 MHz, CDCl3):
¼7.88 (d, J¼8.0 Hz, 2H), 7.24 (d,
138.23, 136.41, 134.26, 129.26, 128.30, 126.16, 62.46 (d, JC-P¼6.6 Hz),
;
38.24 (d, JC-P¼129.8 Hz), 21.10, 16.03 (d, JC-P¼6.6 Hz); 31P NMR
d
(162 MHz, CDCl3):
d
¼20.09; HRMS (EI): m/z [M]þ calcd for
J¼8.0 Hz, 2H), 4.14e4.07 (m, 4H), 3.58 (d, JH-P¼22.4 Hz, 2H), 2.38 (s,
C13H19O4P: 270.1015, found: 270.1010.
3H), 1.25 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3):
¼191.34 (d,
d
JC-P¼6.5 Hz), 144.49, 133.89, 129.12, 129.02, 62.44 (d, JC-P¼6.5 Hz),
4.4.9. Diethyl
(2-(3-bromophenyl)-2-oxoethyl)phosphonate
38.16 (d, JC-P¼129.0 Hz), 21.51, 16.07 (d, JC-P¼6.5 Hz); 31P NMR
(2i). Colorless oil (150 mg, 90%); IR (neat): 2945, 1685, 1587, 1253,
(162 MHz, CDCl3):
d
¼20.23; HRMS (EI): m/z [M]þ calcd for
1028, 968 cmꢁ1 1H NMR (400 MHz, CDCl3):
;
d¼8.11 (t, J¼2.0 Hz,
C
13H19O4P: 270.1015, found: 270.1009.
1H), 7.93e7.90 (m, 1H), 7.70e7.67 (m, 1H), 7.34 (t, J¼8.0 Hz, 1H),
4.15e4.07 (m, 4H), 3.57 (d, JH-P¼22.4 Hz, 2H), 1.26 (t, J¼7.2 Hz, 6H);
4.4.3. Diethyl
(2-(4-(tert-butyl)phenyl)-2-oxoethyl)phosphonate
13C NMR (100 MHz, CDCl3):
d
¼190.61 (d, JC-P¼6.5 Hz), 138.14,
(2c). Colorless oil (140 mg, 90%); IR (neat): 2968, 1687, 1586, 1255,
136.42, 131.94, 130.15, 127.65, 122.87, 62.74 (d, JC-P¼6.5 Hz), 38.64
1022, 960 cmꢁ1 1H NMR (400 MHz, CDCl3):
;
d
¼7.90 (d, J¼8.4 Hz,
(d, JC-P¼128.3 Hz),16.17 (d, JC-P¼5.8 Hz); 31P NMR (162 MHz, CDCl3):
2H), 7.44 (d, J¼8.4 Hz, 2H), 4.11e4.05 (m, 4H), 3.57 (d, JH-P¼22.8 Hz,
d
¼19.13; HRMS (EI): m/z [M]þ calcd for C12H16BrO4P: 333.9964,
2H), 1.29 (s, 9H), 1.23 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3):
found: 333.9958.
d
¼191.27 (d, JC-P¼6.6 Hz), 157.26, 133.82, 128.82, 125.33, 62.39 (d, JC-
¼6.6 Hz), 38.15 (d, JC-P¼129.1 Hz), 34.92, 30.79 16.01 (d, JC-
4.4.10. Diethyl (2-oxo-2-(o-tolyl)ethyl)phosphonate (2j). Colorless
P
¼6.6 Hz); 31P NMR (162 MHz, CDCl3):
d
¼20.20; HRMS (EI): m/z
oil (95 mg, 70%); IR (neat): 3065, 2964, 1678, 1250, 1025, 975 cmꢁ1
;
P
[M]þ calcd for C16H25O4P: 312.1485, found: 312.1484.
1H NMR (400 MHz, CDCl3):
d
¼7.67 (d, J¼7.2 Hz, 1H), 7.31 (t,
J¼7.4 Hz, 1H), 7.22e7.16 (dd, J¼7.2 Hz, 7.6 Hz, 2H), 4.07e4.00 (m,
4.4.4. Diethyl
(2-(4-methoxyphenyl)-2-oxoethyl)phosphonate
4H), 3.52 (d, JH-P¼22.4 Hz, 2H), 2.44 (s, 3H),1.18 (t, J¼7.0 Hz, 6H); 13
C
(2d).8i Colorless oil (128 mg, 90%); IR (neat): 2962, 1680, 1594,
NMR (100 MHz, CDCl3):
d
¼194.95 (d, JC-P¼6.6 Hz), 138.82, 137.10,
1256, 1030, 968 cmꢁ1
;
1H NMR (400 MHz, CDCl3):
d
¼7.98 (d,
131.85, 131.80, 129.48, 125.56, 62.38 (d, JC-P¼5.9 Hz), 40.93 (d, JC-
J¼8.8 Hz, 2H), 6.93 (d, J¼8.8 Hz, 2H), 4.16e4.09 (m, 4H), 3.86 (s, 3H),
¼129.1 Hz), 21.18, 16.10 (d, JC-P¼6.6 Hz); 31P NMR (162 MHz,
P
3.57 (d, JH-P¼22.8 Hz, 2H), 1.27 (t, JC-P¼7.2 Hz, 6H); 13C NMR
CDCl3):
d
¼20.18; HRMS (EI): m/z [M]þ calcd for C13H19O4P:
(100 MHz, CDCl3):
d
¼190.11 (d, JC-P¼6.5 Hz), 163.88, 131.37, 129.51,
270.1015, found: 270.1016.
113.63, 62.52 (d, JC-P¼6.6 Hz), 55.37, 38.08 (d, JC-P¼129.1 Hz), 16.10
(d, JC-P¼6.6 Hz); 31P NMR (162 MHz, CDCl3):
d
¼20.51; HRMS (EI): m/
4.4.11. Diethyl (2-(benzo[d][1,3]dioxol-5-yl)-2-oxoethyl)phosphonate
(2k). Colorless oil (138 mg, 92%); IR (neat): 2932, 1685, 1255, 1026,
z [M]þ calcd for C13H19O5P: 286.0965, found: 286.0964.
968 cmꢁ1; 1H NMR (400 MHz, CDCl3):
d
¼7.60 (d, J¼8.4 Hz, 1H), 7.44
4.4.5. Diethyl
(2-(4-fluorophenyl)-2-oxoethyl)phosphonate
(s, 1H), 6.83 (d, J¼8.4 Hz, 1H), 6.02 (s, 2H), 4.15e4.07 (m, 4H), 3.53
(2e). Colorless oil (127 mg, 93%); IR (neat): 2984, 1682, 1603, 1266,
(d, JH-P¼22.8 Hz, 2H), 1.26 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz,
1022, 955 cmꢁ1
;
1H NMR (400 MHz, CDCl3):
d
¼8.02 (dd, J¼8.4 Hz,
CDCl3):
d
¼189.68 (d, JC-P¼6.6 Hz), 152.22, 148.12, 131.26, 125.91,
5.6 Hz, 2H), 7.11 (t, J¼8.4 Hz, 2H), 4.14e4.06 (m, 4H), 3.57 (d, JH-
108.30, 107.69, 101.87, 62.52 (d, JC-P¼6.6 Hz), 38.20 (d, JC-
¼22.8 Hz, 2H), 1.25 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3):
¼129.8 Hz), 16.10 (d, JC-P¼6.6 Hz); 31P NMR (162 MHz, CDCl3):
P
d
P
d
¼190.18 (d, JC-P¼6.6 Hz), 165.91 (d, JC-F¼254.4 Hz), 132.77, 131.70
¼20.21; HRMS (EI): m/z [M]þ calcd for C13H17O6P: 300.0757,
(d, JC-F¼9.5 Hz),115.57 (d, JC-F¼21.9 Hz), 62.53 (d, JC-P¼6.6 Hz), 38.45
found: 300.0759.
(d, JC-P¼128.4 Hz), 16.07 (d, JC-P¼5.8 Hz); 31P NMR (162 MHz,
CDCl3):
274.0765, found: 274.0764.
d
¼19.58; HRMS (EI): m/z [M]þ calcd for C12H16FO4P:
4.4.12. Diethyl
(2-oxo-2-(thiophen-3-yl)ethyl)phosphonate
(2l). Colorless oil (110 mg, 84%); IR (neat): 2960, 1678, 1588, 1246,
1028, 958 cmꢁ1 1H NMR (400 MHz, CDCl3):
;
d
¼8.15 (d, J¼2.0 Hz,
4.4.6. Diethyl
(2-(4-bromophenyl)-2-oxoethyl)phosphonate
1H), 7.51 (d, J¼6.0 Hz, 1H), 7.25e7.23 (m, 1H), 4.10e4.03 (m, 4H),
(2f). Colorless oil (152 mg, 91%); IR (neat): 2958, 1692, 1586, 1253,
3.46 (d, JH-P¼22.8 Hz, 2H), 1.22 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz,
1024, 962 cmꢁ1
;
1H NMR (400 MHz, CDCl3):
d
¼7.87 (dd, J¼8.4 Hz,
CDCl3):
d
¼185.44 (d, JC-P¼6.6 Hz), 141.72, 134.20, 127.12, 126.26,
1.2 Hz, 2H), 7.61 (dd, J¼8.4 Hz, 1.2 Hz, 2H), 4.14e4.10 (m, 4H), 3.58
62.54 (d, JC-P¼6.5 Hz), 39.83 (d, JC-P¼128.4 Hz), 16.06 (d, JC-
(d, JH-P¼22.4 Hz, 2H), 1.28 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz,
¼6.6 Hz); 31P NMR (162 MHz, CDCl3):
¼19.89; HRMS (EI): m/z
d
P
CDCl3):
d
¼190.83 (d, JC-P¼6.6 Hz), 135.14, 131.83, 130.47, 128.95,
[M]þ calcd for C10H15O4PS: 262.0423, found: 262.0420.
62.66 (d, JC-P¼6.6 Hz), 38.51 (d, JC-P¼128.3 Hz), 16.13 (d, JC-
¼6.6 Hz); 31P NMR (162 MHz, CDCl3):
d¼19.37; HRMS (EI): m/z
4.4.13. Diethyl (2-oxopentyl)phosphonate (2m). Colorless oil
P
[M]þ calcd for C12H16BrO4P: 333.9964, found: 333.9963.
(135 mg, 93%); IR (neat): 2968, 1715, 1258, 1026, 968 cmꢁ1; 1H NMR
(400 MHz, CDCl3):
d
¼4.16e4.08 (m, 4H), 3.04 (d, JH-P¼22.4 Hz, 2H),
4.4.7. Diethyl (2-oxo-2-(4-(trifluoromethyl)phenyl)ethyl)phospho-
nate (2g). Colorless oil (130 mg, 80%); IR (neat): 2964, 1682, 1253,
2.59 (t, J¼7.2 Hz, 2H), 1.55 (t, J¼7.2 Hz, 2H), 1.33e1.24 (m, 16H), 0.85
(t, J¼7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3):
¼202.20 (d, JC-
d
1028, 982 cmꢁ1
;
1H NMR (400 MHz, CDCl3):
d
¼8.10 (d, J¼8.0 Hz,
¼5.9 Hz), 62.42 (d, JC-P¼6.5 Hz), 44.03, 42.25 (d, JC-P¼126.1 Hz),
P

698
J. Xiang et al. / Tetrahedron 71 (2015) 694e699
31.71, 29.24, 29.02, 28.88, 23.34, 22.54, 16.22 (d, JC-P¼6.6 Hz), 13.99;
CDCl3):
247.0968, found: 247.0957.
d
¼19.40; HRMS (EI): m/z [M]þ calcd for C10H18NO4P:
31P NMR (162 MHz, CDCl3):
d
¼20.07; HRMS (EI): m/z [M]þ calcd for
C
14H29O4P: 292.1798, found: 292.1789.
4.4.20. Diisopropyl
(3-hydroxy-2-oxopropyl)phosphonate
4.4.14. Diethyl
(4-(1,3-dioxoisoindolin-2-yl)-2-oxobutyl)phospho-
(2t). Colorless oil (95 mg, 80%); IR (neat): 3375, 2980, 1710, 1235,
1108, 981 cmꢁ1
;
1H NMR (400 MHz, CDCl3):
d
¼4.77e4.69 (m, 2H),
nate (2n). Colorless oil (162 mg, 85%); IR (neat): 2978, 1712, 1485,
1256, 1032, 962 cmꢁ1 1H NMR (400 MHz, CDCl3):
;
d¼7.82 (dd,
4.33 (s, 2H), 3.16 (d, JH-P¼23.2 Hz, 2H), 1.34 (d, J¼6.0 Hz, 12H); 13C
J¼5.6 Hz, 2.8 Hz, 2H), 7.70 (dd, J¼5.6 Hz, 2.8 Hz, 2H), 4.18e4.08 (m,
4H), 3.68 (t, J¼6.8 Hz, 2H), 3.06 (d, JH-P¼22.8 Hz, 2H), 2.67 (t,
J¼7.2 Hz, 2H), 1.72e1.59 (m, 4H), 1.32 (t, J¼7.2 Hz, 6H); 13C NMR
NMR (100 MHz, CDCl3):
d
¼202.73(d, JC-P¼5.9 Hz), 72.08 (d, JC-
¼6.6 Hz), 69.04, 40.28 (d, JC-P¼126.1 Hz), 23.89 (d, JC-P¼3.7 Hz),
P
23.77 (d, JC-P¼5.1 Hz); 31P NMR (162 MHz, CDCl3):
¼17.03; HRMS
d
(EI): m/z [M]þ calcd for C9H19O5P: 238.0965, found: 238.0970.
(100 MHz, CDCl3):
d
¼201.34 (d, JC-P¼5.8 Hz), 168.28, 133.81, 131.99,
123.10, 62.50 (d, JC-P¼6.5 Hz), 43.10, 42.33 (d, JC-P¼126.1 Hz), 37.37,
27.63, 20.38, 16.19 (d, JC-P¼5.8 Hz); 31P NMR (162 MHz, CDCl3):
4.4.21. Diethyl
(2u). Colorless oil (120 mg, 92%); IR (neat): 2976, 1667, 1260, 1028,
976 cmꢁ1; 1H NMR (400 MHz, CDCl3):
¼7.01 (s, 1H), 4.16e4.09 (m,
(2-(cyclohex-1-en-1-yl)-2-oxoethyl)phosphonate
d
¼19.89; HRMS (EI): m/z [M]þ calcd for C18H24NO6P: 381.1336,
d
found: 381.1323.
4H), 3.31 (d, JH-P¼22.8 Hz, 2H), 2.30e2.23 (m, 4H), 1.64e1.59 (m,
4H), 1.31 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3):
¼192.50 (d,
d
4.4.15. Diethyl (4-(4-methylphenylsulfonamido)-2-oxobutyl) phos-
JC-P¼5.9 Hz), 143.73, 139.22, 62.45 (d, JC-P¼6.6 Hz), 36.84 (d, JC-
phonate (2o). Colorless oil (145 mg, 77%); IR (neat): 3318, 2946,
¼130.5 Hz), 26.26, 23.00, 21.70, 21.27, 16.22 (d, JC-P¼6.5 Hz); 31P
1710, 1600, 1258, 1028, 956 cmꢁ1 1H NMR (400 MHz, CDCl3):
;
P
NMR (162 MHz, CDCl3):
d
¼21.19; HRMS (EI): m/z [M]þ calcd for
d
¼7.73 (d, J¼8.0 Hz, 2H), 7.30 (d, J¼8.4 Hz, 2H), 5.41 (t, J¼6.4 Hz,
C12H21O4P: 260.1172, found: 260.1173.
1H), 4.17e4.09 (m, 4H), 3.14 (q, J¼6.0 Hz, 2H), 3.06 (d, JH-P¼22.8 Hz,
2H), 2.87 (t, J¼5.8 Hz, 2H), 2.42 (s, 3H),1.32 (t, J¼7.0 Hz, 6H); 13C
4.4.22. Diethyl
(2-cyclohexyl-2-oxoethyl)phosphonate
NMR (100 MHz, CDCl3):
d¼201.26 (d, JC-P¼6.6 Hz), 143.37, 136.84,
(2v). Colorless oil (120 mg, 92%); IR (neat): 2966, 1715, 1258, 1026,
129.70, 126.99, 62.81 (d, JC-P¼6.6 Hz), 43.52, 42.55 (d, JC-
968 cmꢁ1; 1H NMR (400 MHz, CDCl3):
d
¼4.13e4.06 (m, 4H), 3.07 (d,
¼126.1 Hz), 37.90, 21.46, 16.24 (d, JC-P¼5.8 Hz); 31P NMR (162 MHz,
P
¼19.18; HRMS (EI): m/z [M]þ calcd for C15H24NO6PS:
JH-P¼22.4 Hz, 2H), 2.57e2.51 (m, 1H), 1.85e1.83 (m, 2H), 1.75e1.72
CDCl3):
d
(m, 2H), 1.64e1.60 (m, 1H), 1.30e1.18 (m, 11H); 13C NMR (100 MHz,
377.1062, found: 377.1055.
CDCl3):
d
¼205.22 (d, JC-P¼5.8 Hz), 62.30 (d, JC-P¼6.6 Hz), 51.24,
40.06 (d, JC-P¼127.0 Hz), 28.02, 25.55, 25.30, 16.13 (d, JC-P¼6.6 Hz);
4.4.16. 4-(Diethoxyphosphoryl)-3-oxobutyl acetate (2p). Colorless
31P NMR (162 MHz, CDCl3):
d
¼20.44; HRMS (EI): m/z [M]þ calcd for
oil (120 mg, 82%); IR (neat): 2952, 1718, 1255, 1019, 963 cmꢁ1; 1H
C12H23O4P: 262.1328, found: 262.1330.
NMR (400 MHz, CDCl3):
d
¼4.09e4.05 (m, 4H), 4.00e3.97 (m, 2H),
3.01 (d, JH-P¼23.3 Hz, 2H), 2.60 (t, J¼6.4 Hz, 2H), 1.96 (s, 3H),
1.58e1.56 (m, 4H), 1.26 (t, J¼7.2 Hz, 6H); 13C NMR (100 MHz,
4.4.23. Diethyl
(2-cyclopropyl-2-oxoethyl)phosphonate
(2w). Colorless oil (100 mg, 91%); IR (neat): 2962, 1718, 1252, 1027,
CDCl3):
d
¼201.29 (d, JC-P¼6.6 Hz), 170.87, 63.77, 62.35 (d, JC-
960 cmꢁ1; 1H NMR (400 MHz, CDCl3):
d
¼4.12e4.05 (m, 4H), 3.14 (d,
¼6.6 Hz), 43.12, 42.25 (d, JC-P¼126.8 Hz), 27.58, 20.69, 19.58,
P
16.06 (d, JC-P¼5.8 Hz); 31P NMR (162 MHz, CDCl3):
d
¼19.85;
JH-P¼22.4 Hz, 2H), 2.16e2.09 (m, 1H), 1.27 (t, J¼7.2 Hz, 6H),
1.06e1.02 (m, 2H), 0.93e0.88 (m, 2H); 13C NMR (100 MHz, CDCl3):
HRMS (EI): m/z [M]þ calcd for C12H23O6P: 294.1227, found:
d
¼201.94 (d, JC-P¼5.9 Hz), 62.29 (d, JC-P¼5.8 Hz), 43.04 (d, JC-
294.1219.
¼126.9 Hz), 21.49, 16.09 (d, JC-P¼6.5 Hz), 11.87; 31P NMR (162 MHz,
P
CDCl3):
221.0937, found: 221.0936.
d
¼20.12; HRMS (EI): m/z [MþH]þ calcd for C9H18O4P:
4.4.17. 3-(Diethoxyphosphoryl)-2-oxopropyl pivalate (2q). Colorless
oil (113 mg, 76%); IR (neat): 2976, 1715, 1252, 1025, 956 cmꢁ1 1H
;
NMR (400 MHz, CDCl3):
d
¼4.77 (s, 2H), 4.18e4.10 (m, 4H), 3.09
(d, JH-P¼22.8 Hz, 2H), 1.33 (t, J¼7.2 Hz, 6H), 1.24 (s, 9H); 13C NMR
4.4.24. Diisopropyl
(2-oxo-2-phenylethyl)phosphonate
(2x).8m Colorless oil (129 mg, 91%); IR (neat): 2978, 1677, 1598,
(100 MHz, CDCl3):
d
¼195.22 (d, JC-P¼6.6 Hz), 177.62, 68.08,
1250, 1102, 975 cmꢁ1
;
1H NMR (400 MHz, CDCl3):
d¼7.99 (d,
62.83 (d, JC-P¼5.9 Hz), 39.05 (d, JC-P¼128.3 Hz), 38.63, 27.05,
16.22 (d, JC-P¼6.6 Hz); 31P NMR (162 MHz, CDCl3):
d
¼18.54;
J¼7.6 Hz, 2H), 7.56 (t, J¼7.2 Hz, 1H), 7.45 (t, J¼7.6 Hz, 2H), 4.74e4.66
(m, 2H), 3.57 (d, JH-P¼22.8 Hz, 2H), 1.26e1.24 (m, 12H); 13C NMR
HRMS (EI): m/z [M]þ calcd for C12H23O6P: 294.1227, found:
(100 MHz, CDCl3):
d
¼191.99 (d, JC-P¼6.6 Hz), 136.60, 133.39, 129.02,
294.1220.
128.38, 71.42 (d, JC-P¼6.5 Hz), 39.60 (d, JC-P¼129.8 Hz), 23.83 (d, JC-
¼3.6 Hz), 23.62 (d, JC-P¼5.3 Hz); 31P NMR (162 MHz, CDCl3):
4.4.18. Diethyl (2-oxo-3-phenoxypropyl)phosphonate (2r). Colorless
P
d
¼17.71; HRMS (EI): m/z [M]þ calcd for C14H21O4P: 284.1172, found:
oil (110 mg, 77%); IR (neat): 2982, 1712, 1248, 1020, 968 cmꢁ1 1H
;
284.1168.
NMR (400 MHz, CDCl3):
d
¼7.24e7.20 (m, 2H), 6.92 (t, J¼7.4 Hz, 1H),
6.84 (d, J¼7.6 Hz, 2H), 4.64 (s, 2H), 4.11e4.05 (m, 4H), 3.21 (d, JH-
4.4.25. Dibutyl (2-oxo-2-phenylethyl)phosphonate (2y).8m Colorless
¼22.4 Hz, 2H), 1.25 (t, J¼7.0 Hz, 6H); 13C NMR (100 MHz, CDCl3):
P
d
oil (140 mg, 90%); IR (neat): 2965, 1683, 1596, 1269, 1028,
¼198.63 (d, JC-P¼6.6 Hz),157.45,129.61,121.80,114.52, 72.63, 62.81
1008 cmꢁ1
;
1H NMR (400 MHz, CDCl3):
d¼7.98 (d, J¼8.4 Hz, 2H),
(d, JC-P¼6.6 Hz), 38.53 (d, JC-P¼127.6 Hz), 16.20 (d, JC-P¼5.9 Hz); 31
P
¼18.83; HRMS (EI): m/z [M]þ calcd for
7.55 (t, J¼7.6 Hz, 1H), 7.44 (t, J¼7.6 Hz, 2H), 4.05e4.01 (m, 4H), 3.61
NMR (162 MHz, CDCl3):
d
(d, JH-P¼22.8 Hz, 2H), 1.59e1.52 (m, 4H), 1.34e1.22 (m, 4H), 0.85 (t,
C
13H19O5P: 286.0965, found: 286.0962.
J¼7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3):
¼191.75 (d, JC-P¼6.6 Hz),
d
136.37, 133.45, 128.87, 128.41, 66.13 (d, JC-P¼6.6 Hz), 38.14 (d, JC-
4.4.19. Diethyl (5-cyano-2-oxopentyl)phosphonate (2s). Colorless
oil (86 mg, 70%); IR (neat): 2980, 1715, 1252, 1036, 975 cmꢁ1 1H
NMR (400 MHz, CDCl3):
¼4.15e4.07 (m, 4H), 3.06 (d, JH-P¼22.4 Hz,
¼128.3 Hz), 32.18 (d, JC-P¼6.5 Hz), 18.43, 13.37; 31P NMR (162 MHz,
;
P
CDCl3):
d
¼19.86; HRMS (EI): m/z [M]þ calcd for C16H25O4P:
d
312.1485, found: 312.1483.
2H), 2.78 (t, J¼6.8 Hz, 2H), 2.37 (t, J¼7.0 Hz, 2H), 1.93e1.86 (m, 2H),
1.30 (t, J¼7.0 Hz, 6H); 13C NMR (100 MHz, CDCl3):
¼200.18 (d, JC-
d
4.4.26. Diethyl
(3-oxo-3-phenylprop-1-en-2-yl)phosphonate
¼5.9 Hz), 119.01, 62.59 (d, JC-P¼6.5 Hz), 42.31 (d, JC-P¼126.1 Hz),
P
(3a).16 Colorless oil (52 mg, 65%); 1H NMR (400 MHz, CDCl3):
41.49, 19.03, 16.09 (d, JC-P¼5.8 Hz), 16.02; 31P NMR (162 MHz,

J. Xiang et al. / Tetrahedron 71 (2015) 694e699
699
ꢀ
Asymmetry 1999, 10, 1471; (d) Koprowski, M.; Szymanska, D.; Bodzioch, A.;
d
¼7.86 (d, J¼6.8 Hz, 2H), 7.61e7.57 (m, 1H), 7.49e7.45 (m, 2H), 6.82
ꢀ_
Marciniak, B.; Rozycka-Soko1owska, E.; Ba1czewski, P. Tetrahedron 2009, 65,
(d, JH-P¼24.0 Hz, 1H), 6.29 (d, JH-P¼44.8 Hz, 1H), 4.22e4.15 (m, 4H),
4017.
1.31 (t, J¼7.0 Hz, 6H); 13C NMR (100 MHz, CDCl3):
¼193.90 (d, JC-
d
8. (a) Sturtz, G.; Charrier, C.; Normant, H. Bull. Soc. Chim. Fr. 1966, 1707; (b)
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P. Can. J. Chem. 1974, 52, 2894; (d) Calogeropoulou, T.; Hammond, G. B.; Wiemer,
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4810; (f) Corey, E. J.; Virgil, S. C. J. Am. Chem. Soc. 1990, 112, 6429; (g) Guile, S. D.;
Saxton, J. E.; Thornton-Pett, M. J. Chem. Soc., Perkin Trans. 11992, 1763; (h) Baker,
T. J.; Wiemer, D. F. J. Org. Chem. 1998, 63, 2613; (i) Luke, G. P.; Seekamp, C. K.;
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Tedrow, J.; Larsen, R.; Faul, M. Tetrahedron Lett. 2009, 50, 870; (l) Wei, W.; Ji, J.-X.
Angew. Chem., Int. Ed. 2011, 50, 9097; (m) Li, X.; Hu, G.; Luo, P.; Tang, G.; Gao, Y.;
Xu, P.; Zhao, Y. Adv. Synth. Catal. 2012, 354, 2427.
9. (a) Fukuda, Y.; Utimoto, K. J. Org. Chem. 1991, 56, 3729; (b) Baidossi, W.; Lahav,
M.; Blum, J. J. Org. Chem. 1997, 62, 669; (c) Suzuki, T.; Tokunaga, M.; Wakatsuki,
Y. Org. Lett. 2001, 3, 735; (d) Tokunaga, M.; Suzuki, T.; Koga, N.; Fukushima, T.;
Horiuchi, A.; Wakatsuki, Y. J. Am. Chem. Soc. 2001, 123, 11917; (e) Nishizawa, M.;
Skwarczynski, M.; Imagawa, H.; Sugihara, T. Chem. Lett. 2002, 31, 12; (f) Miz-
ushima, E.; Sato, K.; Hayashi, T.; Tanaka, M. Angew. Chem., Int. Ed. 2002, 41,
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S.; Jones, L. A.; Mohr, F.; Laguna, M. Organometallics 2007, 26, 952; (i) Acker-
¼9.5 Hz), 139.63, 138.47 (d, JC-P¼3.6 Hz), 136.13 (d, JC-P¼5.1 Hz),
P
133.58, 129.91, 128.58, 62.91 (d, JC-P¼5.8 Hz), 16.27 (d, JC-P¼6.6 Hz);
31P NMR (162 MHz, CDCl3):
d¼12.33.
Acknowledgements
This work was supported byNational Natural Science Founda-
tion of China (21302048), Specialized Research Fund for the Doc-
toral Program of Higher Education (20130161120035), China
Postdoctoral Science Foundation (2013M540625), Hunan Pro-
vincial Natural Science Foundation of China (14JJ7028) and the
Fundamental Research Funds for the Central Universities (Hunan
University).
Supplementary data
ꢀ
mann, L.; Kaspar, L. T. J. Org. Chem. 2007, 72, 6149; (j) Marion, N.; Ramon, R. n.
S.; Nolan, S. P. J. Am. Chem. Soc. 2009, 131, 448; (k) Wu, X.-F.; Bezier, D.; Darcel, C.
ꢀ
Adv. Synth. Catal. 2009, 351, 367; (l) Nun, P.; Ramon, R. S.; Gaillard, S.; Nolan, S. P.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.tet.2014.12.001.
J. Organomet. Chem. 2011, 696, 7; (m) Nun, P.; Dupuy, S.; Gaillard, S.; Poater, A.;
Cavallo, L.; Nolan, S. P. Catal. Sci. Technol. 2011, 1, 58; (n) Wong, W.-L.; Ho, K.-P.;
Lee, L. Y. S.; Lam, K.-M.; Zhou, Z.-Y.; Chan, T. H.; Wong, K.-Y. ACS Catal. 2011, 1,
ꢀ ꢀ
116; (o) Mukherjee, A.; Liu, R.-S. Org. Lett. 2011, 13, 660; (p) Czegeni, C. E.; Papp,
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