PPh3/DDQ as a neutral system for the facile preparation of diethyl α-bromo, α-iodo and α-azidophosphonates from diethyl α-hydroxyphosphonates

Article abstract of DOI:10.1016/j.tet.2003.10.058

The mixture of triphenylphosphine (PPh₃) and 2,3-dichloro-5,6-dicyanobenzquinone (DDQ) as a neutral system has been used for the preparation of various types of diethyl α-bromo, α-iodo and α-azidophosphonates from their corresponding diethyl α-

Full text of DOI:10.1016/j.tet.2003.10.058

Tetrahedron 60 (2004) 203–210
PPh3/DDQ as a neutral system for the facile preparation of
diethyl a-bromo, a-iodo and a-azidophosphonates from
diethyl a-hydroxyphosphonates
*
Habib Firouzabadi, Nasser Iranpoor and Sara Sobhani
*
Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454, Iran
Received 5 May 2003; revised 22 September 2003; accepted 16 October 2003
Abstract—The mixture of triphenylphosphine (PPh3) and 2,3-dichloro-5,6-dicyanobenzquinone (DDQ) as a neutral system has been used
for the preparation of various types of diethyl a-bromo, a-iodo and a-azidophosphonates from their corresponding diethyl
a-hydroxyphosphonates in the presence of n-Bu4NBr, n-Bu4NI and NaN3 in good to high yields.
q 2003 Elsevier Ltd. All rights reserved.
1. Introduction
drawbacks; such as low yields of the products, use of
toxic reagents or requiring rather high temperatures. PPh3/
CBr4 in refluxing benzene and PPh3/Br2/Py in CH3CN at
room temperature are the reported procedures that have
been used for the preparation of diethyl a-bromophos-
phonates in low yields (42–67%).6a Toxic SOBr2 is the
other reported brominating agent that has been applied for
this purpose.6b In this report, iodination of diethyl
a-hydroxyphosphonates has also been tried in the presence
of phosphorus triiodide (PI3).6b However, attempts to obtain
a-iodophosphonates in reasonable yields failed and the
desired products were obtained in poor yields (,10%).6b
Allyl bromide/carbonyl diimidazole (CDI) and MeI/CDI
have been successfully applied for the preparation of diethyl
a-bromo and a-iodophosphonates, respectively from
diethyl a-hydroxyphosphonates.6c These procedures suffer
from requiring a high temperature (150 8C).
a-Functionalized phosphonates are fascinating organophos-
phorus compounds in biology, pharmacology and organic
chemistry.1 The main interest in the preparation of these
compounds arises from their common applications in the
Horner–Wadsworth–Emmons (HWE) olefination reaction
to produce a-functionalized olefins and acetylenes.2
a-Hydroxyphosphonates,3 which are easily prepared from
commercially available materials, are useful precursors for
the preparation of various types of a-functionalized
phosphonates. Although a wide range of procedures exists
in the literature for the conversion of ordinary hydroxyl
functional groups into other functional groups, these
methods are not readily applicable to a-hydroxyphospho-
nates.4 Therefore, introduction of new and suitable methods
for the preparation of a-functionalized phosphonates by the
replacement of hydroxyl functional groups has received
wide spread attention from organic chemists.3a,5
a-Azidophosphonates are important precursors for the
preparation of heterocyclic compounds via 1,3-cycloaddi-
tion reactions7 and also for the preparation of their primary
amines.5e,8 In this view, a-amino phosphonates, which are
phosphorus analogues of the corresponding a-aminoacids,
are successfully obtained by catalytic hydrogenation of
a-azidophosphonates,5e or by the Staudinger reaction of the
azido compounds with PPh3.8a,b Methods for the direct
preparation of diethyl a-azido-phosphonates from diethyl
a-hydroxy phosphonates are limited to Mitsunobu reaction
using PPh3/diethyl azodicarboxylate (DEAD) and HN3 as a
source of the azide anion. This reaction requires long
reaction times.5h Azidation of diethyl a-chloromethylphos-
phonates9 and a-tosylatedbenzylphosphonates10 by means
of sodium azide in dimethylformamide (DMF) or dimethyl-
sulfoxide (DMSO), respectively are the other reported
Preparation of biologically active diethyl a-halogenated
phosphonates, which are also good precursors for the
preparation of heavily substituted olefines via HWE
olefination reaction, is an interesting reaction in organic
chemistry.1g,2a,d–g A literature survey indicates that in
contrast to the existing methods for the conversion of
alcohols to their bromides and iodides, few methods are
known for the preparation of diethyl a-bromo and
a-iodophosphonates from their corresponding diethyl
a-hydroxyphosphonates.6 However, the reported pro-
cedures suffered from at least one of the following
*
Corresponding authors. Tel.: þ98-711-2284822; fax: þ98-711-2280926
(H.B.); (N.I.); e-mail address: firouzabadi@susc.ac.ir
0040–4020/$ - see front matter q 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2003.10.058

204
H. Firouzabadi et al. / Tetrahedron 60 (2004) 203–210
methods for this purpose. Azidation of triethylphosphono-
acetate with trifluromethanesulfonyl azide in the presence of
Et3N is the other reported procedure that has been used for
the preparation of a-azidophosphonates.11
the hydroxyl functional group of 1a by PPh3/DDQ/NaN3
with the ratio of 2:2:2 equiv. with respect to 1a in refluxing
CH3CN progressed well in good to high yields (Table 3).
The absorption peak of the a-CH group of the products in
their 1H NMR and also the absorption peak of the N3 group
in their IR spectra are tabulated in Table 3.
The interaction of quinones as electron-acceptors with
derivatives of group VB elements in their trivalent state as
electron-donors has been extensively investigated.12
A
According to our recent proposed mechanism for the
conversion of alcohols, thiols and selenols to their
corresponding halides by PPh3/DDQ/R4NX (X¼Cl, Br,
I),14 we now suggest a similar pathway for the bromination,
iodination and azidation of diethyl a-hydroxyphosphonates
with n-Bu4NBr, n-Bu4NI and NaN3 in the presence of PPh3/
DDQ. In the presented method, diethyl a-hydroxyphos-
phonates react with the adduct formed from the reaction of
PPh3 and DDQ (5) to give (6). Reaction of 6 with the
nucleophile produces the desired products (Scheme 2).
number of investigations have dealt more specifically with
the structure of the products formed between quinones and
tertiary amines, phosphites and phosphines.13 Although
some investigations have been carried out on the reaction of
tertiary phosphines with quinones and on their product
structures,12,13 the application of these mixed materials, as
reagents in organic synthesis have not been described.
Recently we have reported that a mixture of PPh3 and 2,3-
dichloro,5,6-dicanobenzoquinone (DDQ) affords a complex
which in the presence of R4NX (X¼CL, Br, I) converts
alcohols, selenols and thiols into their corresponding alkyl
halides in high yields.14
In recent years, we have started extensive studies on the
development of new methods for the preparation of diethyl
a-functionalized phosphonates from diethyl a-hydroxyphos-
phonates. Along this line, we have reported mild oxidation
and silylation procedures for the preparation of diethyl
a-keto and a-trimethylsilyloxyphosphonates in high yields.15
We now report that the PPh3/DDQ system has been
successfully applied for the preparation of various types of
diethyl a-bromo, a-iodo and a-azidophophonates from
their corresponding hydroxyl compounds using MX
(n-Bu4NBr, n-Bu4NI and NaN3) as nucleophilic sources
under mild reaction conditions in good to excellent yields
(Scheme 1).
Scheme 2.
In order to show the unique behavior of PPh3/DDQ system
for the preparation of a-functionalized phosphonates, we
studied the bromination and iodination of 1a as a model
compound with n-Bu4NBr and n-Bu4NI in the presence of
PPh3/DEAD. The results indicate that under this reaction
condition, besides the formation of the desired products 2a
in 41% yield and 3a in 33% yield, two other by-products 7
and 8 were also isolated. One of the by-products 7 was
identified as the alkylated hydrazine derivative and isolated
in 5–7% for the bromination and iodination reactions
(Scheme 3). The presence of a peak as a doublet for the
Scheme 1.
2. Results and discussion
Initially, the halogenation reaction of a variety of diethyl
a-hydroxyphosphonates (1) with PPh3/DDQ/n-Bu4NX
(X¼Br, I) (molar ratio¼2:2:2 with respect to 1) in CH2Cl2
at room temperature was studied. The results and the
absorption peak of the a-CH group of the products in their
1H NMR are tabulated in the Tables 1 and 2.
2
a-CH at 5.87 ppm with JPH¼13.6 Hz in its 1H NMR
spectra and also two peaks at 3250 and 1730 cm21 for N–H
and –C(O)OEt in its IR spectra confirmed the formation of
7. This type of product is quite familiar in Mitsunobu
As shown in Tables 1 and 2, various types of diethyl
a-bromophosphonates (2a–m) and diethyl a-iodophospho-
nates (3a, e–g, i–k) were obtained in good to excellent
yields (60–98%) under similar reaction conditions.
In the second part of our studies, we have applied the
PPh3/DDQ system for the azidation of diethyl a-hydroxy-
phosphonates. The azidation reaction for the replacement of
Scheme 3.

H. Firouzabadi et al. / Tetrahedron 60 (2004) 203–210
205
Table 1. Preparation of diethyl a-bromophosphonates (2a–n) from diethyl a-hydroxyphosphonates (1a–n) by PPh3/DDQ/n-Bu4NBr in CH2Cl2 at room
temperature
ProductRef
R–
Time (h)
Yielda (%)
1H NMR (CDCl3) daCH (2JPH
)
13C NMR (CDCl3) daCH (1JPC
)
2a6a,16
2b16
2c
2d
2e
C6H5–b
5
5.5
6
5.5
7
9
8.5
6
6.5
7
8.5
5
5.5
98
97
97
90
97
95
98
97
95
94
96
94
92
4.79 (12.5)
4.85 (12.8)
4.80 (12.7)
5.65 (14.8)
5.53 (13.8)
5.36 (13.6)
5.86 (13.8)
6.1 (13.9)
6.01 (14.8)
5.98 (14.6)
6.3 (14.8)
5.10 (13.9)
4.91 (13.5)
41.85 (159.2)
41.80 (159.1)
41.9 (162.0)
36.19 (163.2)
36.29 (161.6)
36.67 (161.5)
40.91 (159.5)
38.76 (158.0)
34.06 (158.2)
38.77 (158.0)
40.12 (157.2)
41.92 (159.7)
38.28 (159.5)
4-CH3C6H4–b
4-CH3OC6H4–
2,4,6-(CH3)3C6H2–
2-ClC6H4–
2f
3-ClC6H4–
2g16
2h
4-ClC6H4–b
2,6-Cl2C6H3–
2-O2NC6H4–
3-O2NC6H4–
4-O2NC6H4–b
2-Naphthyl
2i
2j
2k17
2l
2m
3-Pyridyl
a
Isolated yields.
Registry numbers for 2a, b, g and k: 23755-78-4, 222850-34-2, 74917-62-7 and 39082-34-3, respectively.
b
reactions.18 Therefore, using the PPh3/DDQ system is a
superior method for the high yielding preparation of
a-functionalized phosphonates without side product
formation.
run on a Shimadzu GC-Mass-QP 1000 EX at 70 eV. The IR
spectra were recorded on a Shimadzu Fourier Transform
Infrared Spectrophotometer (FT-IR-8300). The NMR spec-
tra were recorded on a Bruker advance DPX 250 MHz
spectrometer. The solvents were purified and dried before
use.
We have also tried the chlorination of diethyl a-hydroxy-
phosphonates in the presence of this system with
n-Bu4NCl·H2O and n-Hex4NCl. However, chlorination of
the phosphonates did not proceed well and the starting
materials were isolated intact.
4.1. Typical procedure for the preparation of diethyl
a-bromobenzylphosphonate (2a) from diethyl
a-hydroxybenzylphosphonate (1a)
n-Bu4NBr (2 mmol, 0.644 g) was added to a stirring mixture
of DDQ (2 mmol, 0.454 g) and PPh3 (2 mmol, 0.524 g) in
dry CH2Cl2 (10 mL) at room temperature. Then 1a
(1 mmol, 0.244 g) was added to the reaction mixture and
the progress of the reaction was monitored by TLC. After
5 h, the reaction mixture was washed with H2O (3£20 mL).
The organic layer was separated and dried over anhydrous
Na2SO4 and filtered. Evaporation of the solvent afforded a
crude product that was purified by preparative plate
chromatography (silica gel) eluted with CCl4/EtOAc (2:1)
to afford diethyl a-bromobenzylphosphonate (2a) in 98%
yield (0.3 g) as a yellow oily compound.
3. Conclusion
In conclusion, in this investigation we have demonstrated
the use of PPh3/DDQ/MX system as a superior and
convenient method for the preparation of varieties of diethyl
a-bromo-, a-iodo- and a-azidophosphonates from the easily
available corresponding diethyl a-hydroxyphosphonates.
The ease of handling of the system, mild and neutral
reaction conditions, the absence of the formation of the side
products and the good to excellent yields of the products are
the useful practical points of the presented method.
4.2. Typical procedure for the preparation of diethyl
a-iodobenzylphosphonate (3a) from diethyl
a-hydroxybenzylphosphonate (1a)
4. Experimental
Chemicals were either prepared in our laboratories or were
purchased from Fluka and Merck Chemical Companies.
Products were purified by plate chromatography. The purity
determination of the products was accomplished by TLC on
silica gel polygram SIL G/UV 254 plates. Mass spectra were
n-Bu4NI (2 mmol, 0.738 g) was added to a stirring mixture
of DDQ (2 mmol, 0.454 g) and PPh3 (2 mmol, 0.524 g) in
dry CH2Cl2 (10 mL) at room temperature. Then 1a
(1 mmol, 0.244 g) was added to the reaction mixture and
Table 2. Preparation of diethyl a-iodophosphonates (3a, e–g, i–k) from diethyl a-hydroxyphosphonates (1a, e–g, i–k) by PPh3/DDQ/n-Bu4NI in CH2Cl2 at
room temperature
ProductRef
R–
C6H5–b
2-ClC6H4–
3-ClC6H4–
4-ClC6H4–
2-O2NC6H4–
3-O2NC6H4–
4-O2NC6H4–b
Time (h)
Yielda (%)
1H NMR (CDCl3) daCH (2JPH
)
13C NMR (CDCl3) daCH (1JPC
)
3a16
3e
3f
3g
3
5
84
68
69
65
63
60
61
4.98 (13.4)
4.63 (13.2)
4.92 (13.8)
4.87 (13.6)
6.16 (15.0)
6.05 (14.8)
5.80 (13.9)
15.41 (139.9)
9.97 (158.2)
9.96 (158.5)
14.28 (156.3)
7.00 (155.8)
13.0 (155.1)
12.98 (154.6)
4.5
3.5
5
4.5
5.5
3i
3j
3k17
a
Isolated yields.
Registry numbers for 3a and k: 222850-36-4 and 39082-35-4, respectively.
b

206
H. Firouzabadi et al. / Tetrahedron 60 (2004) 203–210
Table 3. Preparation of diethyl a-azidohosphonates (4a, e–g, i–k) from diethyl a-hydroxyphosphonates (1a, e–g, i–k) by PPh3/DDQ/NaN3 in refluxing
CH3CN
ProductRef
R–
C6H5–b
2-ClC6H4–
3-ClC6H4–
4-ClC6H4–
2-O2NC6H4–
3-O2NC6H4–
4-O2NC6H4–b
Time (h)
Yielda (%)
IR (neat) nN3/cm21
1H NMR (CDCl3) daCH (2JPH
)
13C NMR (CDCl3) daCH (1JPC
)
4a1h,8
4e
4f
4g
3
6
95
83
89
80
76
83
75
2100
2150
2123
2110
2125
2140
2134
4.74 (16.5)
5.29 (17.0)
5.02 (16.4)
4.65 (17.0)
4.73 (16.4)
4.90 (16.4)
4.83 (16.7)
61.96 (158.2)
56.35 (161.1)
47.86 (162.2)
61.28 (158.3)
56.46 (157.5)
61.10 (156.2)
61.36 (155.0)
7.5
7
8.5
7.5
5.5
4i
4j
4k17
a
Isolated yields.
Registry numbers for 4a and k: 131523-51-8 and 17986-31-1, respectively.
b
the progress of the reaction was monitored by TLC. After
3 h, the reaction mixture was washed with H2O (3£20 mL)
and the organic layer was separated and dried over
anhydrous Na2SO4 and filtered. Evaporation of the solvent
afforded a crude product that was purified by the preparative
plate chromatography (silica gel) eluted with CCl4/EtOAc
(2:1) to afford diethyl a-bromobenzylphosphonate (3a) in
84% yield (0.297 g) as a yellow brownish oily compound.
2-OCH2CH3), 4.01–4.10 (m, 1H, 2-OCH2CH3), 4.16–4.27
2
(m, 2H, 2-OCH2CH3), 4.85 (d, 1H, JPH¼12.8 Hz, –CH),
3
7.15 (d, 2H, JHH¼6.9 Hz, –C6H4), 7.45 (d, 2H,
3JHH¼6.3 Hz, –C6H4) ppm; 13C NMR (CDCl3, TMS,
3
62.9 MHz): 16.50 (d, JCP¼5.7 Hz, 2-OCH2CH3), 16.82
3
(d, JCP¼5.7 Hz, 2-OCH2CH3), 22.18 (4-CH3), 41.80 (d,
1JCP¼159.1 Hz,
–CH),
63.51
(d,
2JCP¼4.5 Hz,
2
2-OCH2CH3), 64.70 (d, JCP¼4.5 Hz, 2-OCH2CH3),
130.0–132.5, 136.4–138.9 (–C6H4) ppm; IR (neat): peak
of OH was absent.; MS (70 eV), m/e: Mþ¼321,
C12H18BrO3P
4.3. Typical procedure for the preparation of diethyl
a-azidobenzylphosphonate (4a) from diethyl
a-hydroxybenzylphosphonate (1a)
M2Br¼241,
2412P(O)(OEt)2¼104;
requires C, 44.86; H, 5.61%, found: C, 44.85; H, 5.60%.
NaN3 (2 mmol, 0.13 g) was added to a stirring mixture of
DDQ (2 mmol, 0.454 g) and PPh3 (2 mmol, 0.524 g) in dry
CH3CN (10 mL). Then 1a (1 mmol, 0.244 g) was added to
the reaction mixture and was refluxed for 3 h (progress of
the reaction was monitored by TLC). The resulting reaction
mixture was washed with H2O (3£20 mL), the organic layer
was separated and dried over anhydrous Na2SO4 and
filtered. Evaporation of the solvent afforded a crude product
that was purified by preparative plate chromatography
(silica gel) eluted with CCl4/EtOAc (2:1) to afford diethyl
a-azidobenzylphosphonate (4a) in 95% yield (0.255 g) as a
faint yellow oily compound.
4.4.3. Diethyl a-bromo-4-methoxybenzylphosphonate
1
(2c). H NMR (CDCl3, TMS, 250 MHz): d 1.09 (t, 3H,
3
3JHH¼7.0 Hz, 2-OCH2CH3), 1.27 (t, 3H, JHH¼7.0 Hz,
2-OCH2CH3), 3.74 (s, 3H, 4-OCH3), 3.79–3.85 (m, 1H,
2-OCH2CH3), 3.94–4.04 (m, 1H, 2-OCH2CH3), 4.10–4.21
2
(m, 2H, 2-OCH2CH3), 4.80 (d, 1H, JPH¼12.7 Hz, –CH),
3
6.80 (d, 2H, JHH¼8.6 Hz, –C6H4), 7.44 (d, 2H,
3JHH¼7.5 Hz, –C6H4) ppm; 13C NMR (CDCl3, TMS,
3
62.9 MHz): 16.63 (d, JCP¼5.8 Hz, 2-OCH2CH3), 16.80
3
1
(d, JCP¼5.8 Hz, 2-OCH2CH3), 41.9 (d, JCP¼162.0 Hz,
–CH), 55.69 (4-OCH3), 64.33 (d, 2JCP¼6.7 Hz,
2
2-OCH2CH3), 64.43 (d, JCP¼6.7 Hz, 2-OCH2CH3),
114.49, 126.95, 130.64–131.29, 160.45 (–C6H4) ppm; IR
(neat): peak of OH was absent.; MS (70 eV), m/e: Mþ¼337,
C12H18BrO4P
4.4. Spectral data and elemental analysis of diethyl
a-bromo, a-iodo and a-azidophosphonate are presented
bellow
M2Br¼257,
2572P(O)(OEt)2¼120;
requires C, 42.73; H, 5.34%, found: C, 42.71; H, 5.32%.
4.4.1. Diethyl a-bromobenzylphosphonate (2a).6a,16 1
H
4.4.4. Diethyl a-bromo-2,4,6-trimethylbenzylphospho-
1
NMR (CDCl3, TMS, 250 MHz):
d
1.08 (t, 3H,
nate (2d). H NMR (CDCl3, TMS, 250 MHz): d 0.98 (t,
3
3JHH¼7.1 Hz, 2-OCH2CH3), 1.26 (t, 3H, JHH¼7.1 Hz,
2-OCH2CH3), 3.79–3.82 (m, 1H, 2-OCH2CH3), 3.93–4.00
(m, 1H, 2-OCH2CH3), 4.03–4.17 (m, 2H, 2-OCH2CH3),
3H, 3JHH¼7.0 Hz, 2-OCH2CH3), 1.31 (t, 3H, 3JHH¼7.0 Hz,
2-OCH2CH3), 2.21 (s, 3H, –CH3), 2.29 (s, 3H, –CH3), 2.60
(s, 3H, –CH3), 3.61–3.64 (m, 1H, 2-OCH2CH3), 3.87–3.91
(m, 1H, 2-OCH2CH3), 4.13–4.21 (m, 2H, 2-OCH2CH3),
2
4.79 (d, 1H, JPH¼12.5 Hz, –CH), 7.25–7.28 (m, 3H,
–C6H5), 7.47–7.49 (m, 2H, –C6H5) ppm; 13C NMR
5.65 (d, 1H, JPH¼14.8 Hz, –CH), 6.75 (s, 1H, –C6H2),
2
3
(CDCl3, TMS, 62.9 MHz): 16.57 (d, JCP¼5.8 Hz,
6.81 (s, 1H, –C6H2) ppm; 13C NMR (CDCl3, TMS,
62.9 MHz): 15.00–15.39 (m, 2-OCH2CH3), 20.07 (–CH3),
3
2-OCH2CH3), 16.78 (d, JCP¼5.8 Hz, 2-OCH2CH3), 41.85
1
2
1
(d, JCP¼159.2 Hz, –CH), 64.46 (d, JCP¼4.2 Hz,
20.71 (–CH3), 28.68 (–CH3), 36.19 (d, JCP¼163.2 Hz,
2
2-OCH2CH3), 64.57 (d, JCP¼4.2 Hz, 2-OCH2CH3),
–CH), 62.88–63.36 (m, 2-OCH2CH3), 128.02, 130.56
(–C6H2) ppm; IR (neat): peak of OH was absent.;
129.05–129.95, 134.94, 134.99 (–C6H5) ppm; IR (neat):
peak of OH was absent.; MS (70 eV), m/e: Mþ¼307,
M2Br¼227, 2272P(O)(OEt)2¼90; C11H16BrO3P requires
C, 43.00; H, 5.21%, found: C, 43.02; H, 5.20%.
MS
(70 eV),
m/e:
Mþ¼349,
M2Br¼269,
2692P(O)(OEt)2¼132; C14H22BrO3P requires C, 48.14;
H, 6.30%, found: C, 48.12; H, 6.28%.
4.4.2. Diethyl a-bromo-4-methylbenzylphosphonate
(2b).16 1H NMR (CDCl3, TMS, 250 MHz): d 1.16 (t, 3H,
4.4.5. Diethyl a-bromo-2-chlorobenzylphosphonate (2e).
1H NMR (CDCl3, TMS, 250 MHz): d 1.18 (t, 3H,
3
3
3JHH¼7.0 Hz, 2-OCH2CH3), 1.34 (t, 3H, JHH¼7.0 Hz,
3JHH¼7.5 Hz, 2-OCH2CH3), 1.36 (t, 3H, JHH¼7.5 Hz,
2-OCH2CH3), 2.34 (s, 3H, 4-CH3), 3.85–3.92 (m, 1H,
2-OCH2CH3), 3.88–4.12 (m, 2H, 2-OCH2CH3), 4.22–4.31

H. Firouzabadi et al. / Tetrahedron 60 (2004) 203–210
207
2
3
3
(m, 2H, 2-OCH2CH3), 5.53 (d, 1H, JPH¼13.8 Hz, –CH),
(d, 1H, JHH¼7.9 Hz, –C6H4), 8.18 (d, 1H, JHH¼8.1 Hz,
3
7.25–7.37 (m, 3H, –C6H4), 7.99 (d, 1H, JHH¼7.4 Hz,
–C6H4) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz): 16.10
–C6H4) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz): 16.19
(d, JCP¼5.8 Hz, 2-OCH2CH3), 16.38 (d, JCP¼5.8 Hz,
3
3
3
3
1
(d, JCP¼5.8 Hz, 2-OCH2CH3), 16.43 (d, JCP¼5.8 Hz,
2-OCH2CH3), 34.06 (d, JCP¼158.2 Hz, –CH), 64.02 (d,
1
2
2-OCH2CH3), 36.29 (d, JCP¼161.6 Hz, –CH), 64.05 (d,
2JCP¼7.2 Hz, 2-OCH2CH3), 64.80 (d, JCP¼7.2 Hz,
2JCP¼6.9 Hz, 2-OCH2CH3), 64.37 (d, JCP¼6.9 Hz,
2-OCH2CH3), 124.76, 128.47–129.61, 132.07–132.22,
133.28–133.42 (–C6H4) ppm; IR (neat): peak of OH was
absent.; MS (70 eV), m/e: Mþ¼352, M2Br¼272,
2722P(O)(OEt)2¼135; C11H15BrNO5P requires C, 37.5;
H, 4.26%, found: C, 37.8; H, 4.28%.
2
2-OCH2CH3), 127.52–133.56 (–C6H4) ppm; IR (neat): peak
of OH was absent.; MS (70 eV), m/e: Mþ¼342, Mþ2¼344,
M2Br¼262, 2622P(O)(OEt)2¼125; C11H15BrClO3P
requires C, 38.60; H, 4.39%, found: C, 38.60; H, 4.36%.
4.4.6. Diethyl a-bromo-3-chlorobenzylphosphonate (2f).
1H NMR (CDCl3, TMS, 250 MHz): d 1.08 (t, 3H,
4.4.10. Diethyl a-bromo-3-nitrobenzylphosphonate (2j).
1H NMR (CDCl3, TMS, 250 MHz): d 1.14 (t, 3H,
3
3
3JHH¼7.1 Hz, 2-OCH2CH3), 1.28 (t, 3H, JHH¼7.1 Hz,
3JHH¼7.0 Hz, 2-OCH2CH3), 1.28 (t, 3H, JHH¼7.0 Hz,
2-OCH2CH3), 3.78–4.01 (m, 2H, 2-OCH2CH3), 4.14–4.26
(m, 2H, 2-OCH2CH3), 5.36 (d, 1H, JPH¼13.6 Hz, –CH),
2-OCH2CH3), 3.92–4.24 (m, 4H, 2-OCH2CH3), 5.98 (d, 1H,
2
3
2JPH¼14.6 Hz, –CH), 7.49 (t, 1H, JHH¼8.0 Hz, –C6H4),
3
7.14–7.30 (m, 3H, –C6H4), 7.89–7.93 (m, 1H,
–C6H4) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz): 16.54
7.88 (d, 1H, JHH¼7.7 Hz, –C6H4), 8.13 (d, 1H,
3JHH¼7.8 Hz, –C6H4), 8.32 (s, 1H, –C6H4) ppm; 13C
3
3
3
(d, JCP¼5.8 Hz, 2-OCH2CH3), 16.78 (d, JCP¼5.8 Hz,
NMR (CDCl3, TMS, 62.9 MHz): 15.26 (d, JCP¼5.8 Hz,
1
3
2-OCH2CH3), 36.67 (d, JCP¼161.5 Hz, –CH), 64.40 (d,
2-OCH2CH3), 15.40 (d, JCP¼5.8 Hz, 2-OCH2CH3), 38.77
2JCP¼7.0 Hz, 2-OCH2CH3), 64.72 (d, JCP¼7.0 Hz,
(d, JCP¼158.0 Hz, –CH), 63.25 (d, JCP¼7.1 Hz,
2
1
2
2
2-OCH2CH3), 127.85–133.93 (–C6H4) ppm; IR (neat): peak
of OH was absent.; MS (70 eV), m/e: Mþ¼342, Mþ2¼344,
M2Br¼262, 2622P(O)(OEt)2¼125; C11H15BrClO3P
requires C, 38.60; H, 4.39%, found: C, 38.61; H, 4.41%.
2-OCH2CH3), 63.65 (d, JCP¼7.1 Hz, 2-OCH2CH3),
122.76–123.46, 128.74, 134.48–134.57 (–C6H4) ppm; IR
(neat): peak of OH was absent.; MS (70 eV), m/e: Mþ¼352,
M2Br¼272, 2722P(O)(OEt)2¼135; C11H15BrNO5P
requires C, 37.5; H, 4.26%, found: C, 37.6; H, 4.27%.
4.4.7. Diethyl a-bromo-4-chlorobenzylphosphonate
(2g).16 1H NMR (CDCl3, TMS, 250 MHz): d 1.11 (t, 3H,
4.4.11. Diethyl a-bromo-4-nitrobenzylphosphonate
(2k).17 1H NMR (CDCl3, TMS, 250 MHz): d 1.10–1.14
(m, 3H, 2-OCH2CH3), 1.27–1.30 (m, 3H, 2-OCH2CH3),
3.90–4.05 (m, 2H, 2-OCH2CH3), 4.12–4.21 (m, 2H,
3
3JHH¼7.0 Hz, 2-OCH2CH3), 1.26 (t, 3H, JHH¼7.0 Hz,
2-OCH2CH3), 3.79–3.90 (m, 1H, 2-OCH2CH3), 3.95–4.04
(m, 1H, 2-OCH2CH3), 4.10–4.21 (m, 2H, 2-OCH2CH3),
2
2
5.86 (d, 1H, JPH¼13.8 Hz, –CH), 7.24 (d, 2H,
2-OCH2CH3), 6.3 (d, 1H, JPH¼14.8 Hz, –CH), 7.66–7.69
3
3JHH¼8.4 Hz, –C6H4), 7.43 (d, 2H, JHH¼8.4 Hz,
(m, 2H, –C6H4), 8.12–8.15 (m, 2H, –C6H4) ppm; 13C NMR
–C6H4) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz): 16.62
(CDCl3, TMS, 62.9 MHz): 16.63 (d, JCP¼5.8 Hz,
3
3
3
3
(d, JCP¼5.8 Hz, 2-OCH2CH3), 16.79 (d, JCP¼5.8 Hz,
2-OCH2CH3), 16.78 (d, JCP¼5.8 Hz, 2-OCH2CH3), 40.12
1
1
2
2-OCH2CH3), 40.91 (d, JCP¼159.5 Hz, –CH), 64.43 (d,
(d, JCP¼157.2 Hz, –CH), 64.60 (d, JCP¼7.0 Hz,
2JCP¼7.0 Hz, 2-OCH2CH3), 64.67 (d, JCP¼7.0 Hz,
2-OCH2CH3), 65.05 (d, JCP¼7.0 Hz, 2-OCH2CH3),
2
2
2-OCH2CH3), 129.24–135.33 (–C6H4) ppm; IR (neat): peak
of OH was absent.; MS (70 eV), m/e: Mþ¼342, Mþ2¼344,
M2Br¼262, 2622P(O)(OEt)2¼125; C11H15BrClO3P
requires C, 38.60; H, 4.39%, found: C, 38.59; H, 4.38%.
124.09, 130.19–130.96, 142.34–142.40 (–C6H4) ppm; IR
(neat): peak of OH was absent.; MS (70 eV), m/e: Mþ¼352,
M2Br¼272, 2722P(O)(OEt)2¼135; C11H15BrNO5P
requires C, 37.5; H, 4.26%, found: C, 37.8; H, 4.29%.
4.4.8. Diethyl a-bromo-2,6-dichlorobenzylphosphonate
1
4.4.12. Diethyl a-bromo-2-naphthylphosphonate (2l). 1H
(2h). H NMR (CDCl3, TMS, 250 MHz): d 1.12–1.20 (m,
3H, 2-OCH2CH3), 1.33–1.40 (m, 3H, 2-OCH2CH3), 3.91–
4.06 (m, 2H, 2-OCH2CH3), 4.19–4.27 (m, 2H,
NMR (CDCl3, TMS, 250 MHz):
d
1.12 (t, 3H,
3
3JHH¼7.1 Hz, 2-OCH2CH3), 1.34 (t, 3H, JHH¼7.1 Hz,
2-OCH2CH3), 3.81–3.91 (m, 1H, 2-OCH2CH3), 4.00–4.10
(m, 1H, 2-OCH2CH3), 4.18–4.30 (m, 2H, 2-OCH2CH3),
2
2-OCH2CH3), 6.1 (d, 1H, JPH¼13.9 Hz, –CH), 7.16–7.35
(m, 3H, –C6H4) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz):
16.86 (d, 3JCP¼6.8 Hz, 2-OCH2CH3), 16.96 (d,
5.10 (d, 1H, JPH¼13.9 Hz, –CH), 7.46–7.50 (m, 2H,
2
–C10H7), 7.71–7.83 (m, 4H, –C10H7), 7.97 (s, 1H,
–C10H7) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz): 16.21
1
3JCP¼6.8 Hz, 2-OCH2CH3), 38.76 (d, JCP¼158.0 Hz,
2
3
3
–CH), 63.35 (d, JCP¼7.1 Hz, 2-OCH2CH3), 63.60 (d,
(d, JCP¼5.8 Hz, 2-OCH2CH3), 16.42 (d, JCP¼5.8 Hz,
2JCP¼7.1 Hz, 2-OCH2CH3), 128.60, 129.99, 131.31, 135.73,
136.87 (–C6H3) ppm; IR (neat): peak of OH was absent.; MS
(70 eV), m/e: Mþ¼376, Mþ2¼378, Mþ4¼381,
M2Br¼296, 2962P(O)(OEt)2¼159; C11H14BrClO3P
requires C, 35.11; H, 3.72%, found: C, 35.08; H, 3.69%.
2-OCH2CH3), 41.92 (d, JCP¼159.7 Hz, –CH), 64.11 (d,
1
2JCP¼7.4 Hz,
2-OCH2CH3),
64.22
(2JCP¼7.4 Hz,
2-OCH2CH3), 126.04–128.97, 131.90–133.31 (–C10H7)
ppm; IR (neat): peak of OH was absent.; MS (70 eV),
m/e: Mþ¼357, M2Br¼277, 2772P(O)(OEt)2¼140;
C15H18BrO3P requires C, 50.42; H, 5.04%, found: C, 50.4;
H, 5.0%.
4.4.9. Diethyl a-bromo-2-nitrobenzylphosphonate (2i).
1H NMR (CDCl3, TMS, 250 MHz): d 1.15 (t, 3H,
3
1
3JHH¼7.0 Hz, 2-OCH2CH3), 1.36 (t, 3H, JHH¼7.0 Hz,
4.4.13. Diethyl a-bromo-3-pyridylphosphonate (2m). H
1.20 (t, 3H,
2-OCH2CH3), 3.91–4.16 (m, 2H, 2-OCH2CH3), 4.22–4.34
(m, 2H, 2-OCH2CH3), 6.01 (d, 1H, JPH¼14.8 Hz, –CH),
NMR (CDCl3, TMS, 250 MHz):
d
2
3
3JHH¼7.1 Hz, 2-OCH2CH3), 1.35 (t, 3H, JHH¼7.1 Hz,
7.46–7.56 (m, 1H, –C6H4), 7.63–7.70 (m, 1H, –C6H4), 7.92
2-OCH2CH3), 3.93–4.15 (m, 2H, 2-OCH2CH3), 4.20–4.31

208
H. Firouzabadi et al. / Tetrahedron 60 (2004) 203–210
2
(m, 2H, 2-OCH2CH3), 4.91 (d, 1H, JPH¼13.5 Hz, –CH),
1H NMR (CDCl3, TMS, 250 MHz): d 1.10 (t, 3H,
3
3
7.31–7.36 (m, 1H, –C5H4N), 8.04 (d, 1H, JHH¼8.0 Hz,
3JHH¼7.0 Hz, 2-OCH2CH3), 1.27 (t, 3H, JHH¼7.0 Hz,
–C5H4N), 8.58 (d, 1H, 3JHH¼4.1 Hz, –C5H4N), 8.68 (s, 1H,
2-OCH2CH3), 3.78–4.17 (m, 4H, 2-OCH2CH3), 4.87 (d, 1H,
–C5H4N) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz): 16.25
2JPH¼13.6 Hz, –CH), 7.20 (d, 2H, JHH¼8.2 Hz, –C6H4),
3
3
3
(d, JCP¼5.8 Hz, 2-OCH2CH3), 16.42 (d, JCP¼5.8 Hz,
7.44 (d, 2H, 3JHH¼8.2 Hz, –C6H4) ppm; 13C NMR (CDCl3,
1
1
2-OCH2CH3), 38.28 (d, JCP¼159.5 Hz, –CH), 64.46 (d,
TMS, 62.9 MHz): 14.28 (d, JCP¼156.3 Hz, –CH), 16.62
2JCP¼7.1 Hz, 2-OCH2CH3), 64.80 (d, JCP¼7.1 Hz,
(d, JCP¼5.8 Hz, 2-OCH2CH3), 16.76 (d, JCP¼5.8 Hz,
2
3
3
2
2-OCH2CH3), 123.94, 128.70–128.89, 13.56–132.44,
137.64–137.72, 149.96–150.27 (–C5H4N) ppm; IR (neat):
peak of OH was absent.; MS (70 eV), m/e: Mþ¼308,
C10H15BrNO3P
2-OCH2CH3), 64.59 (d, JCP¼6.8 Hz, 2-OCH2CH3),
129.33, 131.19, 131.31, 134.78, 135.48 (–C6H4) ppm;
IR (neat): peak of OH was absent.; MS (70 eV), m/e:
Mþ¼389, Mþ2¼391, M2Br¼261, 2612P(O)(OEt)2¼125;
C11H15ClIO3P requires C, 33.93; H, 3.86%, found: C, 33.94;
H, 3.87%.
M2Br¼228,
2282P(O)(OEt)2¼91;
requires C, 38.96; H, 4.87%, found: C, 38.90; H, 4.80%.
4.4.14. Diethyl a-iodobenzylphosphonate (3a).16 1H NMR
3
(CDCl3, TMS, 250 MHz): d 1.13 (t, 3H, JHH¼7.0 Hz,
4.4.18. Diethyl a-iodo-2-nitrobenzylphosphonate (3i). 1H
3
2-OCH2CH3), 1.32 (t, 3H, JHH¼7.0 Hz, 2-OCH2CH3),
NMR (CDCl3, TMS, 250 MHz):
d
1.23 (t, 3H,
3
3.84–3.90 (m, 1H, 2-OCH2CH3), 3.99–3.08 (m, 1H,
2-OCH2CH3), 4.18–4.27 (m, 2H, 2-OCH2CH3), 4.98 (d,
3JHH¼7.0 Hz, 2-OCH2CH3), 1.34 (t, 3H, JHH¼7.0 Hz,
2-OCH2CH3), 4.00–4.31 (m, 4H, 2-OCH2CH3), 6.16 (d, 1H,
2JPH¼15.0 Hz, –CH), 7.48–7.54 (m, 1H, –C6H4), 7.66–
2
1H, JPH¼13.4 Hz, –CH), 7.28–7.31 (m, 3H, –C6H5),
7.56–7.59 (m, 2H, –C6H5) ppm; 13C NMR (CDCl3, TMS,
7.72 (m, 1H, –C6H4), 7.96 (d, 1H, JPH¼8.2 Hz, –C6H4),
2
1
62.9 MHz): 15.41 (d, JCP¼139.9 Hz, –CH), 16.57 (d,
8.09 (d, 1H, 2JPH¼8.0 Hz, –C6H4) ppm; 13C NMR (CDCl3,
3JCP¼5.9 Hz, 2-OCH2CH3), 16.7 (d, 3JCP¼5.9 Hz,
TMS, 62.9 MHz): 7.00 (d, 1JCP¼155.8 Hz, –CH), 16.50 (d,
2
3
2-OCH2CH3), 64.42 (d, JCP¼8.6 Hz, 2-OCH2CH3), 64.55
3JCP¼5.9 Hz, 2-OCH2CH3), 16.71 (d, JCP¼5.9 Hz,
2
(d,
(–C6H5) ppm; IR (neat): peak of OH was absent.;
2JCP¼8.6 Hz,
2-OCH2CH3),
128.95–130.04
2-OCH2CH3), 63.31 (d, JCP¼8.8 Hz, 2-OCH2CH3), 64.50
(d, 2JCP¼8.8 Hz, 2-OCH2CH3), 127.5–129.6 (–C6H4) ppm;
MS
(70 eV),
m/e:
Mþ¼354,
M2Br¼226,
IR (neat): peak of OH was absent.; MS (70 eV), m/e:
M2Br¼272,
2262P(O)(OEt)2¼89; C11H16IO3P requires C, 37.29; H,
Mþ¼399,
2612P(O)(OEt)2¼136;
4.52%, found: C, 37.2; H, 4.58%.
C11H15INO5P requires C, 33.08; H, 3.76%, found: C,
33.02; H, 3.71%.
4.4.15. Diethyl a-iodo-2-chlorobenzylphosphonate (3e).
1H NMR (CDCl3, TMS, 250 MHz): d 1.08 (t, 3H,
4.4.19. Diethyl a-iodo-3-nitrobenzylphosphonate (3j). 1H
3
3JHH¼7.0 Hz, 2-OCH2CH3), 1.28 (t, 3H, JHH¼7.0 Hz,
NMR (CDCl3, TMS, 250 MHz):
d
1.15 (t, 3H,
3
2-OCH2CH3), 3.81–4.02 (m, 2H, 2-OCH2CH3), 4.12–
4.24 (m, 2H, 2-OCH2CH3), 4.63 (d, 1H, JPH¼13.2 Hz,
3JHH¼7.0 Hz, 2-OCH2CH3), 1.28 (t, 3H, JHH¼7.0 Hz,
2
2-OCH2CH3), 3.90–4.23 (m, 4H, 2-OCH2CH3), 6.05 (d, 1H,
3
–CH), 7.10–7.25 (m, 3H, –C6H4), 7.97 (d, 1H,
3JHH¼7.9 Hz, –C6H4) ppm; 13C NMR (CDCl3, TMS,
2JPH¼14.8 Hz, –CH), 7.44 (t, 1H, JHH¼8.0 Hz, –C6H4),
3
7.89 (d, 1H, JHH¼7.7 Hz, –C6H4), 8.07 (d, 1H,
1
62.9 MHz): 9.97 (d, JCP¼158.2 Hz, –CH), 16.55 (d,
3JHH¼7.6 Hz, –C6H4), 8.31 (s, 1H, –C6H4) ppm; 13C
3
1
3JCP¼5.8 Hz, 2-OCH2CH3), 16.75 (d, JCP¼5.8 Hz,
NMR (CDCl3, TMS, 62.9 MHz): 13.0 (d, JCP¼155.1 Hz,
2
2-OCH2CH3), 64.45 (d, JCP¼7.0 Hz, 2-OCH2CH3),
–CH),
16.59–16.80
(2-OCH2CH3),
64.68–65.02
2
64.64 (d, JCP¼7.0 Hz, 2-OCH2CH3), 127.98, 128.01,
(2-OCH2CH3), 123.70–124.77, 130.24, 136.10, 136.20,
139.25 (–C6H4) ppm; IR (neat): peak of OH was absent.;
129.69–130.08, 132.84–133.06, 134.80 (–C6H4) ppm;
IR (neat): peak of OH was absent.; MS (70 eV), m/e:
Mþ¼389, Mþ2¼391, M2Br¼261, 2612P(O)(OEt)2¼
125; C11H15ClIO3P requires C, 33.93; H, 3.86%, found:
C, 33.90; H, 3.84%.
MS
(70 eV),
m/e:
Mþ¼399,
M2Br¼272,
2612P(O)(OEt)2¼136; C11H15INO5P requires C, 33.08;
H, 3.76%, found: C, 33.06; H, 3.74%.
4.4.20. Diethyl a-iodo-4-nitrobenzylphosphonate (3k).17
1H NMR (CDCl3, TMS, 250 MHz): d 1.04–1.18 (m, 3H,
2-OCH2CH3), 1.26–1.31 (m, 3H, 2-OCH2CH3), 3.85–4.07
(m, 2H, 2-OCH2CH3), 4.12–4.21 (m, 2H, 2-OCH2CH3),
4.4.16. Diethyl a-iodo-3-chlorobenzylphosphonate (3f).
1H NMR (CDCl3, TMS, 250 MHz): d 1.08 (t, 3H,
3
3JHH¼6.7 Hz, 2-OCH2CH3), 1.29 (t, 3H, JHH¼6.7 Hz,
2
2-OCH2CH3), 3.86–4.00 (m, 2H, 2-OCH2CH3), 4.16–4.22
(m, 2H, 2-OCH2CH3), 4.92 (d, 1H, JPH¼13.8 Hz, –CH),
5.80 (d, 1H, JPH¼13.9 Hz, –CH), 7.65–7.69 (m, 2H,
–C6H4), 8.08–8.18 (m, 2H, –C6H4) ppm; 13C NMR
2
1
7.17–7.23 (m, 3H, –C6H4), 7.96–7.99 (m, 1H,
–C6H4) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz): 9.96
(CDCl3, TMS, 62.9 MHz): 12.98 (d, JCP¼154.6 Hz,
–CH),
16.59–16.82
(2-OCH2CH3),
64.70–65.09
1
3
(d, JCP¼158.5 Hz, –CH), 16.50 (d, JCP¼5.8 Hz,
(OCH2CH3), 124.02, 124.27, 130.19, 130.90, 131.01
(–C6H4) ppm; IR (neat): peak of OH was absent.;
3
2-OCH2CH3), 16.75 (d, JCP¼5.8 Hz, 2-OCH2CH3), 64.51
2
2
(d, JCP¼7.1 Hz, 2-OCH2CH3), 64.70 (d, JCP¼7.1 Hz,
2-OCH2CH3), 128.03, 129.99–130.07, 132.89–132.95,
134.82 (–C6H4) ppm; IR (neat): peak of OH was absent.;
MS (70 eV), m/e: Mþ¼389, Mþ2¼391, M2Br¼261,
2612P(O)(OEt)2¼125; C11H15ClIO3P requires C, 33.93;
H, 3.86%, found: C, 33.91; H, 3.84%.
MS
(70 eV),
m/e:
Mþ¼399,
M2Br¼272,
2612P(O)(OEt)2¼136; C11H15INO5P requires C, 33.08;
H, 3.76%, found: C, 33.02; H, 3.71%.
4.4.21. Diethyl a-azidobenzylphosphonate (4a).1h,8 1H
NMR (CDCl3, TMS, 250 MHz): d 1.21–1.31 (m, 6H,
2-OCH2CH3), 3.94–4.14 (m, 4H, 2-OCH2CH3), 4.74 (d, 1H,
4.4.17. Diethyl a-iodo-4-chlorobenzylphosphonate (3g).
2JPH¼16.5 Hz, –CH), 7.38–7.45 (m, 5H, –C6H5) ppm; 13
C

H. Firouzabadi et al. / Tetrahedron 60 (2004) 203–210
209
3
NMR (CDCl3, TMS, 62.9 MHz): 16.80 (d, JCP¼6.0 Hz,
4.4.26. Diethyl a-azido-3-nitrobenzylphosphonate (4j).
1H NMR (CDCl3, TMS, 250 MHz): d 1.26–1.37 (m, 6H,
2-OCH2CH3), 4.06–4.26 (m, 4H, 2-OCH2CH3), 4.90 (d, 1H,
2JPH¼16.4 Hz, –CH), 7.55–7.62 (m, 1H, –C6H4), 7.80–
7.83 (m, 1H, –C6H4), 8.21–8.39 (m, 2H, –C6H4) ppm; 13
C
1
2-OCH2CH3), 61.96 (d, JCP¼158.2 Hz, –CH), 63.91 (d,
2JCP¼8.6 Hz, 2-OCH2CH3), 128.61–129.28 (–C6H4) ppm;
IR (neat): n 2100 (N3) cm21, Peak of OH was absent.;
MS
(70 eV),
m/e:
Mþ¼269,
M2N3¼227,
3
2272P(O)(OEt)2¼90; C11H16N3O3P requires C, 49.07; H,
NMR (CDCl3, TMS, 62.9 MHz): 16.75 (d, JCP¼5.9 Hz,
1
5.95%, found: C, 49.10; H, 5.90%.
2-OCH2CH3), 61.10 (d, JCP¼156.2 Hz, –CH), 63.1 (d,
2JCP¼8.2 Hz, 2-OCH2CH3), 123.33–123.94, 128.83–
130.06, 132.44–132.60, 134.31 (–C6H4) ppm; IR (neat):
n 2140 (N3) cm21, Peak of OH was absent.; MS (70 eV),
m/e: Mþ¼314, M2N3¼272, 2722P(O)(OEt)2¼135;
C11H15N4O5P requires C, 42.04; H, 4.78%, found: C,
42.02; H, 4.70%.
4.4.22. Diethyl a-azido-2-chlorobenzylphosphonate (4e).
1H NMR (CDCl3, TMS, 250 MHz): d 1.15 (t, 3H,
3
3JHH¼7.0 Hz, 2-OCH2CH3), 1.29 (t, 3H, JHH¼7.0 Hz,
2-OCH2CH3), 3.85–4.20 (m, 4H, 2-OCH2CH3), 5.29 (d, 1H,
2JPH¼17.0 Hz, –CH), 7.19–7.37 (m, 3H, –C6H4), 7.61–
7.64 (m, 1H, –C6H4) ppm; 13C NMR (CDCl3, TMS,
62.9 MHz): 15.13–15.46 (2-OCH2CH3), 56.35 (d,
1JCP¼161.1 Hz, –CH), 62.90–63.32 (2-OCH2CH3),
126.31, 128.67–129.17 (–C6H4) ppm; IR (neat): n 2150
(N3) cm21, Peak of OH was absent.; MS (70 eV), m/e:
Mþ¼304, Mþ2¼306, M2N3¼261, 2612P(O)(OEt)2¼
125; C11H15ClN3O3P requires C, 43.42; H, 4.93%, found:
C, 43.45; H, 4.95%.
4.4.27. Diethyl a-azido-4-nitrobenzylphosphonate (4k).17
1H NMR (CDCl3, TMS, 250 MHz): d 1.18–1.27 (m, 6H,
2-OCH2CH3), 3.99–4.14 (m, 4H, 2-OCH2CH3), 4.83 (d, 1H,
2JPH¼16.7 Hz, –CH), 7.57 (m, 2H, –C6H4), 8.18 (d, 2H,
–C6H4) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz): 16.80
3
1
(d, JCP¼5.5 Hz, 2-OCH2CH3), 61.36 (d, JCP¼155.0 Hz,
–CH), 64.35 (2-OCH2CH3), 124.12–124.30, 129.00–
129.33, 131.51 (–C6H4) ppm; IR (neat):
n
2134
4.4.23. Diethyl a-azido-3-chlorobenzylphosphonate (4f).
1H NMR (CDCl3, TMS, 250 MHz): d 1.13 (t, 3H,
(N3) cm21, Peak of OH was absent.; MS (70 eV),
m/e: Mþ¼314, M2N3¼272, 2722P(O)(OEt)2¼135;
C11H15N4O5P requires C, 42.04; H, 4.78%, found: C,
42.01; H, 4.72%.
3
3JHH¼7.0 Hz, 2-OCH2CH3), 1.29 (t, 3H, JHH¼7.0 Hz,
2-OCH2CH3), 3.85–4.01 (m, 2H, 2-OCH2CH3), 4.11–4.22
(m, 2H, 2-OCH2CH3), 5.02 (d, 1H, JPH¼16.4 Hz, –CH),
2
7.20–7.33 (m, 3H, –C6H4), 7.80–7.85 (m, 1H,
–C6H4) ppm; 13C NMR (CDCl3, TMS, 62.9 MHz):
Acknowledgements
1
15.13–15.46 (2-OCH2CH3), 47.86 (d, JCP¼162.2 Hz,
–CH), 62.89–63.32 (2-OCH2CH3), 126.30–126.41,
128.31–129.08, 130.30, 130.36 (–C6H4) ppm; IR (neat):
n 2123 (N3) cm21, Peak of OH was absent.; MS (70 eV),
We are thankful to the Shiraz University Research Council
for the partial support of this work.
m/e:
2612P(O)(OEt)2¼125; C11H15ClN3O3P requires C,
Mþ¼304,
Mþ2¼306,
M2N3¼261,
43.42; H, 4.93%, found: C, 43.40; H, 4.90%.
References and notes
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2-OCH2CH3), 3.90–4.13 (m, 4H, 2-OCH2CH3), 4.65 (d, 1H,
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1
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2JPH¼16.4 Hz, –CH), 7.44 (t, 1H, JHH¼7.5 Hz, –C6H4),
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3JHH¼7.7 Hz, –C6H4), 7.92 (d, 1H, JHH¼8.2 Hz,
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16.56–16.76 (2-OCH2CH3), 56.46 (d, JCP¼157.5 Hz,
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