Magnesium triflate [Mg(OTf)2] a highly stable, non-hygroscopic and a recyclable catalyst for the high yielding preparation of diethyl α-trimethylsilyloxyphosphonates from diethyl α-hydroxyphosphonates by HMDS under solventless conditions

Article abstract of DOI:10.1016/j.jorganchem.2004.07.009

A broad, adaptable, high yielding and convenient procedure for the easy conversion of various α-hydroxyphosphonates to α-trimethylsilyloxyphosphonates under mild conditions with HMDS in the presence of a catalytic amount of magnesium triflate as a highly stable and a non-hygroscopic recyclable catalyst in neat conditions is described. In order to show the general applicability of this method, we have also applied this procedure successfully for the silylation of ordinary alcohols and phenols.

Full text of DOI:10.1016/j.jorganchem.2004.07.009

Journal of Organometallic Chemistry 689 (2004) 3197–3202
www.elsevier.com/locate/jorganchem
Magnesium triflate [Mg(OTf) ] a highly stable, non-hygroscopic
2
and a recyclable catalyst for the high yielding preparation of diethyl
a-trimethylsilyloxyphosphonates from diethyl
a-hydroxyphosphonates by HMDS under solventless conditions
*
*
Habib Firouzabadi , Nasser Iranpoor , Sara Sobhani, Soheila Ghassamipour
Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454, Iran
Received 18 April 2004; accepted 3 July 2004
Available online 6 August 2004
Abstract
A broad, adaptable, high yielding and convenient procedure for the easy conversion of various a-hydroxyphosphonates to a-tri-
methylsilyloxyphosphonates under mild conditions with HMDS in the presence of a catalytic amount of magnesium triflate as a
highly stable and a non-hygroscopic recyclable catalyst in neat conditions is described. In order to show the general applicability
of this method, we have also applied this procedure successfully for the silylation of ordinary alcohols and phenols.
ꢀ
2004 Published by Elsevier B.V.
Keywords: Magnesium triflate; Phosphonates; Alcohols; Silylation; Solvent-free; Hexamethyl disilazane
1
. Introduction
carbon–carbon bond forming reactions. They react with
various ketones to produce the corresponding a-trimeth-
ylsilyloxy ketones [6]. Unsymmetrical ketones, b,c-un-
saturated ketones and carboxylic acids can be
produced by the reaction of a-lithiated a-trimethylsilyl-
oxyphosphonates with alkylating agents followed by hy-
drolysis of C–P and Si–O bonds [5,7,8]. a-Lithiated
a-trimethylsilyloxyphosphonates can also undergo easy
acylation with varieties of acylating agents producing
the corresponding a-acylated products. These com-
pounds in turn, are easily converted to a-hydroxy ke-
tones by the cleavage of Si–O bond and elimination of
dialkyl phosphite in alkaline media [4].
The common methods for the preparation of a-tri-
methylsilyloxyphosphonates include reaction of alde-
hydes with diethyl trimethylsilyloxyphosphite [5,7,8]
or with the mixture of triethylphosphite and trimethyl-
silyl chloride [2,3]. The reported procedures need harsh
reaction conditions accompanied with rather long reac-
tion times. The other method used for this purpose is
a-Trimethylsilyloxyphosphonates are interesting
compounds from different views. They are attractive in
biology, industry and organic chemistry [1–3]. The inter-
est on the preparation of a-trimethylsilyloxyphospho-
nates arises on one hand from the existence of an
a-acidic hydrogen in these compounds which can be
metalated by lithium diisopropylamide to produce rela-
tively stable a-carbanionic species [4]. On the other
hand, the C–P and Si–O bonds of a-trimethylsilyloxy-
phosphonates are easily hydrolyzed in alkaline and
acidic conditions [5]. Therefore, a-lithiated a-trimethyl-
silyloxyphosphonates have become important synthons
of masked acyl anions and have been widely used for
*
Corresponding authors. Tel.: +98 711 2284822; fax: +98 711
2
280926.
E-mail addresses: Firouzabadi@susc.ac.ir (H. Firouzabadi), ian-
poor@chem.susc.ac.ir (N. Iranpoor).
0
022-328X/$ - see front matter ꢀ 2004 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2004.07.009

3198
H. Firouzabadi et al. / Journal of Organometallic Chemistry 689 (2004) 3197–3202
the reaction of trialkyl phosphate with silyl phenyl ke-
tone, which requires a long reaction time (12 h) and al-
so proceeded at a high temperature (80 ꢁC) [9].
Trimethylsilyl chloride has also been used for the prep-
aration of diethyl a-trimethylsilyloxybenzylphosphonate
from sodium salt of diethylphosphite and benzaldehyde
in moderate yield (67%) [7]. Procedures for the direct
silylation of a-hydroxyphosphonates [10–12] to their
a-trimethylsilyloxyphosphonates are rare in the litera-
ture and to the best of our knowledge there is only
one report available for this purpose. In that report,
hexamethylsilathiane has been used as a silylating agent
at 50–70 ꢁC to produce the desired products in moder-
ate yields (55–78%) [13].
O
O
Mg(OTf) (0.1 equiv.)
2
R
P(OEt)2
R
P(OEt)2
HMDS (0.7 equiv.)
rt, neat
OH
OTMS
2a-o
1a-o
Scheme 1.
Table 1
Silylation of diethyl a-hydroxyphosphonates (1a–o) to diethyl
a-trimethylsyilyloxyphosphonates (2a–o) with HMDS in the presence
of Mg(OTf) in neat conditions at room temperature
2
Product
R– Mg(OTf)
2
2
Ref.
a
Yield (%)
Time (min)
In conjunction with our interest in the development
of synthetic methods for the preparation of phospho-
nate derivatives from a-hydroxyphosphonates we have
focused our attention to the preparation of a-trimethy-
silyloxy phosphonates by direct silylation of a-hydroxy-
phosphonates [14–23].
b
a [3,9]
b [30]
C
6
H
5
–
–
96
90
91
92
93
90
92
94
90
92
91
90
94
95
90
b
–
4-CH
4-CH
3
C
6
H
4
–
c
3
OC
6
H
4
–
40
45
d
2,4,6-(CH
3
)
3
C
6
H
2
–
b
e
2-ClC H –
6
6
6
4
4
4
–
b
f
g [31]
3-ClC
4-ClC
2,6-Cl
H
H
–
–
–
b
–
b
h
2
C
6
H
3
–
–
i
2-O
3-O
4-O
2
2
2
NC
NC
NC
6
H
6
H
6
H
4
–
70
2
. Results and discussion
j
k [31]
4
–
–
120
95
4
In connection with our ongoing work on the catalytic
properties of metal triflates [24–28], herein we report
l
2-Naphthyl
3-Pyridyl
35
b
–
m
n [7]
o [7]
a
PhCH‚CH–
MeCH‚CH–
45
80
Mg(OTf) [29] as a highly stable, non-hygroscopic and
2
a recyclable catalyst for the high yielding preparation
of diethyl a-trimethylsilyloxyphosphonates (2a–o) by
the direct reaction of diethyl a-hydroxyphosphonates
Yields refer to isolated products. The equivalent ratios of sub-
strate/HMDS/catalyst are 1/0.7/0.1.
b
Immediate reaction occurred.
(
1a–o) with 1,1,1,3,3,3-hexamethylsilazane (HMDS) at
room temperature in the absence of solvent (Scheme 1
and Table 1).
As shown in Table 1, various types of a-hydroxy-
phenylmethyl) phosphonates (1a–k) were cleanly con-
Ce(OTf) [33], Hg(OTf) [34], Cu(OTf) [35] and some
2
4
2
(
other Lewis acids such as ZnCl2 [36], Zn(bipy) Cl
3 2
verted into their corresponding a-trimethylsilyloxyphos-
phonates (2a–k) in excellent yields (90–96%).
a-Hydroxy-2-naphthyl-, 3-pyridyl-, alkyl- and aryl-b,c-
unsaturated phosphonates (1l–o) were also silylated
efficiently giving the corresponding a-trimethylsilyloxy-
phosphonates (2l–o) in 90–95% yields.
We have observed that cleavage of C–P and Si–O
bonds of a-trimethylsilyloxyphosphonates was not oc-
curred in the presence of this catalyst in the absence of
solvent. Therefore, the products of high purity were ob-
tained after work-up and further purification was not
required.
[37], FeCl , Fe(bipy)Cl [37], CuCl , MgCl , AlCl and
3 3 2 2 3
ZrOCl Æ 8H O for the silylation of diethyl a-hydroxy-
2
2
(phenylmethyl)-phosphonate (1a), as a model com-
pound, with HMDS in the absence of solvent at room
temperature (Table 2). We found that Mg(OTf) was
2
the most effective catalyst for this purpose and the im-
mediate conversion of 1a to the corresponding silylated
product 2a (100%, monitored by TLC) was observed.
In all reactions, we have studied, fast evolution of
ammonia gas was observed. We were also able to isolate
Mg(OTf) from the reaction mixture and reused it for
2
the similar reaction without observable loss of its cata-
lytic activity. With these observations we have proposed
a mechanism in which the generation of NH and the
The spectral data of the known products (2a, b, g, k,
n and o) are compared with those reported in the litera-
ture. The spectral data of the other known products (2c,
e, f, i and j) which their spectral data have not been re-
3
catalytic role of Mg(OTf) in a catalytic cycle are clari-
2
fied (Scheme 2).
1
ported in the literature and also the spectral data ( H
In this mechanism, we have suggested that a Lewis
acid–base interaction between metal triflate and nitro-
gen in HMDS polarizes N–Si bond of HMDS to pro-
1
NMR, C NMR, IR and MS) of unknown products
3
(
2d, h, l, m) are presented in Section 3.
We have compared the catalytic activity of Mg(OTf)2
29] with other metal triflates including LiOTf [32],
+
2
duce a reactive silylating agent (3). Mg that is a
+4
+
+2
harder Lewis acid in comparison with Li , Cu , Ce
[

H. Firouzabadi et al. / Journal of Organometallic Chemistry 689 (2004) 3197–3202
3199
Table 2
Table 3
Silylation of alcohols and phenols to the corresponding trimethylsil-
Silylation of diethyl a-hydroxy-(phenylmethyl)-phosphonate (1a) with
HMDS in the presence of various Lewis acids in neat conditions at
room temperature
2
ylethers with HMDS in the presence of Mg(OTf) in neat conditions at
room temperature
a
Entry
Lewis acid
Time (h)
% Conversion based
1
on H NMR 2a
Entry
Substrate
Mg(OTf)
2
a
Yield (%)
Time (min)
b
2
3
4
5
6
7
8
9
Mg(OTf)
Cu(OTf)
2
–
100
60
b
1
2
3
4
5
6
7
8
9
C
6
H
5
CH
4-CH
4- CH
4-ClC
4-O NC
PhCH(C
Anthracene-9-methanol
(Ph) CHOH
PhCH CH OH
Ph(CH CH OH
2
OH
CH
CH
OH
CH OH
)OH
38
15
34
35
50
140
60
120
20
50
50
95
b
2
4.5
3
3
C
6
H
4
2
OH
OH
93
Ce(OTf)
Hg(OTf)
LiOTf
4
80
60
b
3
OC
6
H
4
2
93
b
2
10
1.5
1
6
H
4
CH
2
91
100
100
20
b
2
6
H
4
2
93
ZnCl
Zn(bipy)
FeCl
Fe(bipy)Cl
ZrOCl Æ 8H
AlCl
CuCl
MgCl
2
c
2
H
5
90
d
3
Cl
2
24
1.5
1.5
1.5
4.5
10
6.5
70
3
80
30
c
70
2
1
1
1
1
1
0
1
2
4
5
3
c
2
2
97
c
2
2
O
30
80
1
1
0
1
2
)
2
2
98
c
3
1-Octanol
95
2
20
c
98
1
2
OH
3 h
2
50
a
The equivalent ratios of substrate/HMDS/catalyst are 1/0.7/0.1.
Immediate reaction occurred.
c
97
b
13
2-Octanol
120
d,g
–
1
4
24 h
HMDS
HO
b
1
5
16
(CH
CH
1-Aadamantanol
3
)
2
CdbondHCH
2
OH
125
6.75 h
120
90
92
H
N
b
Mg(OTf)2
(CH CH(CH‚CH
)
5
)OH
84
3
2
2
+
c
1
1
1
2
2
2
7
8
9
0
1
2
92
NH3
SiMe3
SiMe3
c
5-CH
4-CH
3
-5-decanol
OH
92
-
Mg
c
90
3
C
6
H
4
35
c
C
6
H
5
OH
NC
4-AcetylC
60
70
d,f
–
3
4-O
2
6
H
4
OH
OH
24 h
24 h
R
OH
d,f
6
H
4
–
a
Isolated yields: the structures which were predicted for the prod-
[
H N-Mg(OTf) ]
+
NH2
1
ucts were confirmed by their spectral data ( H NMR, C NMR, IR
13
3
2
R
OTMS
b
and MS). The equivalent ratios of substrate/HMDS/catalyst are 1/0.5/
-
Mg(OTf)
c
0.01, 1/0.7/0.01 or 1/1/0.01. Immediate reaction occurred. No re-
d
e
f
2
Me Si
3
g
action was observed in neat conditions and in CH
reaction was observed in neat conditions.
2 2
Cl as solvent. No
R
OTMS
R
OH
Scheme 2.
+
2
and Hg interacts more strongly with the nitrogen
atom as a hard Lewis base in HMDS. Therefore, N–Si
bond polarization effected by Mg(OTf) is more pro-
Mg(OTf) (0.01equiv.)
2
2
R OH
R OTM
S
nounced than those generated by LiOTf, Cu(OTf)2,
Ce(OTf) and Hg(OTf) . This qualitative explanation
justifies the more catalytic activity of Mg(OTf) than
HMDS (0.5-1 equiv.)
rt, neat
4
2
2
Scheme 3.
the other triflates we have studied.
Mg(OTf) (0.01 equiv.)
2
HMDS (1 equiv.)
rt, CH Cl
TMSO
HO
2
2
Scheme 4.

3200
H. Firouzabadi et al. / Journal of Organometallic Chemistry 689 (2004) 3197–3202
Silylation of alcohols are among the most frequently
3.1. Typical procedure for the preparation of 2a from 1a
catalyzed by Mg(OTf) in neat conditions
used processes in organic synthesis and provides cheap
and efficient means for the protection of hydroxyl
groups during oxidation, peptide coupling and halogen-
ation reactions [38–40].
In order to show the general applicability of this
catalyst, we have also tried silylation of hydroxyl func-
tional groups in alcohols and phenols with HMDS
2
Mg(OTf) (0.032 g, 0.1 mmol) was added to the stir-
2
ring mixture of 1a (0.244 g, 1 mmol,) and HMDS (0.113
g, 0.7 mmol) at room temperature. Immediate reaction
was occurred with complete conversion of the starting
material (TLC). CH Cl (10 mL) was added to the re-
2
2
(
Scheme 3). We have observed that the reactions pro-
sulting reaction mixture and then the organic layer
was washed with H O (3 · 10 mL), separated and dried
ceeded smoothly in similar reaction conditions from
good to excellent yields (70–98%). The results are sum-
marized in Table 3.
2
over anhydrous Na SO and filtered. Evaporation of the
2
4
solvent afforded the pure product (2a) as a known com-
pound in 96% yield.
As it is shown in Table 3, p-substituted benzylic al-
cohols containing electron-donating and electron-with-
drawing groups, primary and secondary aliphatic
alcohols were protected efficiently in short reaction
times (entries 1–13). Longer reaction times are re-
quired for complete conversion of allylic and tertiary
aliphatic alcohols to the corresponding silylated prod-
ucts (entries 15–18). p-Cresole was silylated faster and
with higher yield than phenol (entries 19, 20). While
even after 24 h stirring, conversion of phenols substi-
tuted at para positions with nitro and acetyl groups
was not observed under similar reaction conditions
3.2. Typical procedure for trimethylsilylation of benzyl
alcohol with HMDS using Mg(OTf) in neat conditions
2
Mg(OTf) (0.003 g, 0.01 mmol) was added to the
2
stirring mixture of benzyl alcohol (0.108 g, 1 mmol)
and HMDS (0.113 g, 0.7 mmol) at room temperature.
The progress of the reaction was monitored by TLC.
After complete conversion of the starting material
(38 min), CH Cl (10 mL) was added to the resulting
reaction mixture and then the organic layer was
2 2
(
entries 21, 22). We have also tried silylation of cho-
washed with H O (3 · 10 mL), separated and dried
2
lesterol under solvent-free conditions in the presence
of this catalyst with HMDS. Our observation shows
that this compound does not undergo silylation reac-
tion under such conditions and the starting material
was isolated intact after 24 h. However, we tried this
reaction at room temperature in solution using
CH Cl . The reaction proceeded well and the desired
over anhydrous Na SO . After evaporation of the sol-
vent, pure benzyl trimethylsilyl ether in 95% yields was
obtained.
2
4
3.3. Spectral data and the elemental analysis of unknown
diethyl a-trimethylsilyloxyphosphonates
2
2
compound was isolated in 95% yield after 65 min
(
Scheme 4).
Conclusively, we have found that Mg(OTf) can be
3.3.1. Diethyl a-trimethylsilyloxy-2,4,6-trimethylbenzyl
phosphonate (2d)
2
1
used as a reusable and efficient catalyst for the prepa-
ration of varieties of diethyl a-trimethylsilyloxyphos-
phonates by direct silylation of the corresponding
diethyl a-hydroxyphosphonates with HMDS in the ab-
sence of solvent without cleavage of C–P and Si–O
bonds. We have also applied this protocol for the effi-
cient silylation of ordinary alcohols and phenols with
success.
H NMR (CDCl ): d À0.04 [s, 9H, –Si(CH ) ], 1.02
3
3 3
2
(t, 3H,
2
J = 7 Hz, 2-OCH CH ), 1.22 (t, 3H,
HH 2 3
JHH = 7 Hz, 2-OCH CH ), 2.12 (s, 3H, –CH ), 2.25
2
3
3
(s, 3H, –CH ), 2.51 (s, 3H, CH ), 3.58–3.68 (m, 1H, 2-
3
3
OCH CH ), 3.81–3.90 (m, 1H, 2-OCH CH ), 3.98–
2
2
3
3
1
4.10 (m, 2H, 2-OCH CH ), 5.28 (d, 1H, J = 18.3
2
3
PH
Hz, CH), 6.66 (s, 1H, C H ), 6.72 (s, 1H, –C H ) ppm;
2
6
2
6
1
3
C NMR (CDCl3): 0.00 [–Si(CH ) ], 16.56 (d,
3 3
JCP = 5.9 Hz, 2-OCH CH ), 16.87 (d, J = 5.9 Hz,
3
3
2
3
CP
2
-OCH CH ), 21.16, 21.67, 21.69 (–CH ), 62.70 (d,
2 3 3
2
2
JCP = 7.1 Hz, 2-OCH CH ), 62.92 (d, J = 7.1 Hz,
2
3
CP
1
3
. Experimental
2-OCH CH ), 69.60 (d, J = 177.2 Hz, –CH) 129.05
2 3 CP
(d, JCP = 2 Hz, –C H ), 130.25 (–C H ), 131.57 (d,
6 2 6 2
Chemicals were purchased from Merck and Fluka
JCP = 3.3 Hz, –C H ), 136.08 (d, JCP = 8.1 Hz,
6 2
Chemical Companies. IR spectra were run on a Shim-
adzu model 8300 FT-IR spectrophotometer. NMR spec-
tra were recorded on a Bruker Avance DPX-250. Mass
spectra were recorded on a Shimadzu GCMS-QP 1000
EX. The purity of the products and the progress of
the reactions were accomplished by TLC on silica-gel
polygram SILG/UV254 plates.
–C H ), 137.41 (d, J = 3.4 Hz, –C H ), 139.88 (d,
6 2 CP 6 2
JCP = 4.2 Hz, –C H ) ppm; IR (neat): OH peak was
6
2
absent; MS (70 eV), m/e (relative intensity %): 431
+
[M + Si(CH ) , 19.3], 358 (M , 3.2), 221 [M À
3
3
P(O)(OEt) , 100], 147 [221-Si(CH ) , 12], 73 [Si(CH ) ,
2
3 3
3 3
44.3]; C H O PSi requires C, 56.98; H, 8.66, found:
31
1
7
4
C, 56.90; H, 8.70%.

H. Firouzabadi et al. / Journal of Organometallic Chemistry 689 (2004) 3197–3202
3201
3
phonate (2h)
.3.2. Diethyl a-trimethylsilyloxy-26-dichlorobenzylphos-
(d, JCP = 6.7 Hz, –C H N), 149.43 (d, J = 3.3 Hz,
5 4 CP
–C H N) ppm; IR (neat): OH peak was absent; MS
5
4
1
H NMR (CDCl ): d 0.00 [s, 9H, –Si(CH ) ], 1.07–
(70 eV), m/e (relative intensity %): 390 [M + Si(CH ) ,
3 3
3
3 3
+
1
OCH CH ), 5.81 (d, 1H, J = 19.3 Hz, –CH), 7.03–
.24 (m, 6H, 2-OCH CH ), 3.89–4.15 (m, 4H, 2-
1
62.1], 317 (M , 1.2), 180 [M À P(O)(OEt) , 86.2], 108
2
3
2
[180-Si(CH ) , 48.8], 73 [Si(CH ) , 100]; C H NO P-
13 24
2
3
PH
3 3
3 3
4
7
.10 (m, 1H, –C H ), 7.20–7.25 (m, 1H, –C H ), ppm;
6
Si requires C, 49.21; H, 7.57, found: C, 49.18 H,
7.51%.
3
6
3
1
3
C
JCP = 6.8 Hz, 2-OCH CH ), 16.96 (d, J = 6.8 Hz,
NMR (CDCl3): 0.00 [–Si(CH ) ], 16.86 (d,
3 3
3
3
2
3
CP
2
2
6
-OCH CH ), 63.35 (d, J = 7.1 Hz, 2-OCH CH ),
2 3 CP 2 3
3.4. Spectral data of known a-trimethylsilyloxyphospho-
2
3.60 (d, JCP = 7.1 Hz, 2-OCH CH ), 70.02 (d,
2 3
nates which are not reported in the literature
1
JCP = 179.8 Hz, –CH), 128.60 (d, JCP = 2.0 Hz,
C H ), 129.99 (d, J = 2.9 Hz, –C H ), 131.31 (d,
JCP = 2.8 Hz, –C H ), 135.73 (d, JCP = 8.2 Hz,
–
6
3
CP
6
3
3.4.1. Diethyl a-trimethylsilyloxy-4-methoxybenzylphos-
6
3
phonate (2c)
1
–
C H ), 136.87 (d, J = 4.9 Hz, –C H ) ppm; IR (neat):
3
6
3
CP
6
H NMR (CDCl ): d 0.00 [s, 9H, –Si(CH ) ], 1.11–
3
3 3
OH peak was absent; MS (70 eV), m/e (relative intensity
): 457 [M + Si(CH ) , 100], 389 (M + 4, 2.3), 387
1
.19 (m, 6H, 2-OCH CH ), 3.71 (s, 3H, 4-OCH ),
2 3 3
%
3
3
3
.81–3.99 (m, 4H, 2-OCH CH ), 4.83 (d, 1H,
2 3
+
(
M + 2, 10.8), 385 (M , 14), 247 [M À P(O)(OEt) ,
1
2
JPH = 13.4 Hz, –CH), 7.79 (d, JHH = 8.4 Hz, 2H,
2
5
C H Cl O PSi requires C, 43.64; H, 5.97, found: C,
2.2], 173 [247-Si(CH ) , 2.4], 73 [Si(CH ) , 93.5];
2
C H ), 7.30 (d, J = 6.9 Hz, 2H, –C H ) ppm;
13
3
3
3 3
–
C
NMR (CDCl ): 0.00 [–Si(CH ) ], 16.38–16.59 (2-
6
4
HH
6
4
1
4
23
2
4
3
3 3
4
3.60; H, 5.91%.
OCH CH ), 55.20 (4-OCH ), 62.65–63.21 (2-CH CH ),
2
2
3
3
3
1
1.50 (d, JCP = 173.7 Hz, –CH), 113.58–113.62,
7
128.49–129.30, 159.47–159.51 (–C H ) ppm; IR (neat):
OH peak was absent.
6
4
3
.3.3. Diethyl a-trimethylsilyloxy-2-naphthylphosphonate
2l)
(
1
H NMR (CDCl ): d 0.00 [s, 9H, –Si(CH ) ], 1.10 (t,
3
3 3
2
H, J = 7.1 Hz, 2-OCH CH ), 3.79–3.99 (m, 4H, 2-
6
OCH CH ), 5.03 (d, 1H, J = 14.5 Hz, –CH), 7.33–
7
7
0
3.4.2. Diethyl a-trimethylsilyloxy-2-chlorobenzylphospho-
nate (2e)
HH
2
3
1
2
3
PH
1
.37 (m, 2H, –C H ), 7.49–7.52 (m, 1H, –C H ),
7
H NMR (CDCl ): d 0.00 [s, 9H, –Si(CH ) ], 1.08–
1
0
7
10
3
3 3
1
.69–7.84 (m, 4H, –C H ) ppm; C NMR (CDCl3):
3
1.24 (m, 6H, 2-OCH CH ), 3.79–4.10 (m, 4H, 2-
2 3
1
0
7
3
.00 [–Si(CH ) ], 16.39 (d, J = 5.6 Hz, 2-OCH CH ),
1
OCH CH ), 5.50 (d, 1H, J = 12.3 Hz, –CH), 7.11–
2 3 PH
3
3
CP
2
3
3
6.48 (d, JCP = 5.6 Hz, 2-OCH CH ), 62.77 (d,
1
7.27 (m, 3H, –C H ), 7.65–7.73 (m, 1H, –C H ) ppm;
6 4 6 4
2
3
2
2
JCP = 7.3 Hz, 2-OCH CH ), 63.22 (d, J = 7.3 Hz,
13
C NMR (CDCl ): 0.47 [–Si(CH ) ], 16.47–16.73 (2-
3 3 3
2
3
CP
1
-OCH CH ), 72.13 (d, JCP = 174.4 Hz, –CH),
2
1
1
OCH CH ), 63.20–63.69 (2-CH CH ), 67.89 (d,
2
2
3
3
2
3
1
25.23–126.44, 127.61–128.06, 133.07–133.21, 134.94–
35.48 (–C H ) ppm; IR (neat): OH peak was absent;
JCP = 175.8 Hz, –CH), 127.08–135.80 (–C H ) ppm;
6 4
IR (neat): OH peak was absent.
1
0
7
MS (70 eV), m/e (relative intensity %): 439
229
+
(M ,
[
M + Si(CH ) ,
3
16.2],
366
4.8),
3
3
.4.3. Diethyl a-trimethylsilyloxy-3-chlorobenzylphospho-
[
[
M À P(O)(OEt) , 100], 155 [229-Si(CH ) , 18.8], 73
2
3 3
nate (2f)
1
Si(CH ) , 87.5]; C H O PSi requires C, 59.02; H,
3
3
18 27
4
H NMR (CDCl ): d 0.00 [s, 9H, –Si(CH ) ], 1.09–
3
3 3
7
.38, found: C, 59.04; H, 7.35%.
1.17 (m, 6H, 2-OCH CH ), 3.90–4.01 (m, 4H, 2-
OCH CH ), 4.83 (d, 1H, J = 14.5 Hz, –CH), 7.14–
2 3
1
2
3
PH
1
3
7.41 (m, 4H, –C H ) ppm; C NMR (CDCl ): 0.47
6 4 3
3
.3.4. Diethyl a-trimethylsilyloxy-3-pyridylphosphonate
2m)
[
–Si(CH ) ], 16.44–16.59 (2-OCH CH ), 62.94–63.50
3 3 2 3
(
1
(2-CH CH ), 71.43 (d, J = 171.6 Hz, –CH), 125.47–
1
2 3 CP
H NMR (CDCl ): d 0.00 [s, 9H, –Si(CH ) ], 1.13
3
3 3
1
39.73 (–C H ) ppm; IR (neat): OH peak was absent.
6 4
2
(
t, 6H, JHH = 7.0 Hz, 2-OCH CH ), 3.91–3.99 (m,
2 3
1
4
H, 2-OCH CH ), 4.89 (d, 1H, JPH = 14.5 Hz,
2 3
–
JPH = 7.3 Hz, –C H N), 8.43 (d, 1H, J = 4.1 Hz,
CH), 7.15–7.21 (m, 1H, –C H N), 7.74 (d, 1H,
3.4.4. Diethyl a-trimethylsilyloxy-2-nitrobenzylphospho-
nate (2i)
5
4
5
4
PH
1
C H N), 8.54 (s, 1H, –C H N) ppm; C NMR
3
1
–
H NMR (CDCl ): d 0.00 [s, 9H, –Si(CH ) ], 1.01–
5
4
5
4
3
3 3
3
CDCl ): 0.00 [–Si(CH ) ], 16.51 (d, J = 5.1 Hz, 2-
(
OCH CH ), 16.58 (d, JCP = 5.1 Hz, 2-OCH CH ),
1.11 (m, 6H, 2-OCH CH ), 3.83–3.97 (m, 4H, 2-
2 3
3
3 3
3
CP
1
OCH CH ), 6.02 (d, 1H, J = 15.9 Hz, –CH), 7.28
2 3 PH
2
3
2
3
2
3.06 (d, JCP = 7.3 Hz, 2-OCH CH ), 63.43 (d,
2
2
6
(t, 1H, J = 7.3 Hz, –C H ), 7.48 (t, 1H, J = 7.3
HH 6 4 HH
2
3
2
1
JCP = 7.3 Hz, 2-OCH CH ), 69.88 (d, JCP = 175.8
13
Hz, –C H ), 7.72–7.80 (m, 2H, –C H ) ppm;
4
C
2
3
6
4
6
Hz, –CH), 123.31 (d, JCP = 2.6 Hz, –C H N), 133.53
5
NMR (CDCl ): 0.46 [–Si(CH ) ], 16.41–16.60 (2-
3 3 3
4
(
–C H N), 135.14 (d, J = 4.9 Hz, –C H N), 148.69
CP
OCH CH ), 63.26–63.62 (2-CH CH ), 66.40 (d,
2 3 2 3
5
4
5
4

3
1
202
H. Firouzabadi et al. / Journal of Organometallic Chemistry 689 (2004) 3197–3202
JCP = 172.0 Hz, –CH), 124.70–134.02, 147.94–148.04
–C H ) ppm; IR (neat): OH peak was absent.
[12] A.R. Sardarian, B. Kaboudin, Synth. Commun. 27 (1997) 543.
[
[
[
13] E.P. Lebedev, M.D. Mizhiritskii, V.A. Baburina, V.F. Mironov,
E.N. Ofitserov, Zh. Obshch. Khim. 49 (1979) 1731.
(
6
4
14] H. Firouzabadi, N. Iranpoor, S. Sobhani, A.R. Sardarian,
Tetrahedron Lett. 42 (2001) 4369.
15] H. Firouzabadi, N. Iranpoor, S. Sobhani, Tetrahedron Lett. 43
3.4.5. Diethyl a-trimethylsilyloxy-3-nitrobenzylphospho-
nate (2j)
(
2002) 477.
1
H NMR (CDCl ): d 0.00 [s, 9H, –Si(CH ) ], 1.08–
3
3 3
[16] H. Firouzabadi, N. Iranpoor, S. Sobhani, Tetrahedron Lett. 43
(2002) 3653.
1
OCH CH ), 4.96 (d, 1H, J = 14.8 Hz, –CH), 7.41
.17 (m, 6H, 2-OCH CH ), 3.91–3.99 (m, 4H, 2-
2 3
1
[17] H. Firouzabadi, N. Iranpoor, S. Sobhani, S. Ghassamipour, Z.
Amoozgar, Tetrahedron Lett. 44 (2003) 891.
[18] H. Firouzabadi, N. Iranpoor, S. Sobhani, Tetrahedron 60 (2004)
2
3
PH
2
2
(t, 1H, J = 7.8 Hz, –C H ), 7.70 (d, 1H, J = 7.4
HH 6 4 HH
Hz, –C H ), 8.01 (d, 1H, J = 7.9 Hz, –C H ), 8.19
2
6
4
HH
6
4
2
03.
1
3
(
s, 1H, –C H ) ppm;
6
C NMR (CDCl ): 0.47
3
4
[19] H. Firouzabadi, N. Iranpoor, S. Sobhani, Z. Amoozgar, Synthesis
(2004) 295.
[20] H. Firouzabadi, N. Iranpoor, S. Sobhani, Synthesis (2004)
[
(
–Si(CH ) ], 16.50–16.63 (2-OCH CH ), 63.20–63.75
3 3 2 3
1
2-CH CH ), 71.16 (d, J = 171.5 Hz, –CH), 122.11–
2
3
CP
2
90.
1
1
23.07, 129.12–129.33, 133.32–133.40, 140.23, 148.28–
48.33 (–C H ) ppm; IR (neat): OH peak was absent.
[
[
[
[
21] H. Firouzabadi, N. Iranpoor, S. Sobhani, Phosphorus Sulfur
Silicon (in print).
22] H. Firouzabadi, N. Iranpoor, S. Sobhani, Synthetic Commun.
6
4
(
2004) 1463.
23] H. Firouzabadi, N. Iranpoor, S. Sobhani, Z. Amoozgar, Synthesis
2004) 1771.
Acknowledgements
(
We are thankful to Iran TWAS Chapter Based at
ISMO and Shiraz University Research Council for the
support of this work.
24] N. Iranpoor, M. Shekarriz, Bull. Chem. Soc. Jpn. 72 (1999)
455.
[25] N. Iranpoor, H. Firouzabadi, A. Safavi, M. Shekarriz, Synth.
Commun. 33 (2003) 165.
[
26] H. Firouzabadi, B. Karimi, Sh. Eslami, Tetrahedron Lett. 40
1999) 4055.
References
(
[27] H. Firouzabadi, Sh. Eslami, B. Karimi, Bull. Chem. Soc. Jpn. 74
(2001) 2401.
[
1] M.M. Kabachnik, E.V. Synatkova, Z.S. Novikova, G.L. Abra-
mova, N.G. Rozhkova, E.I. Andreeva, Vesthn. Mosk. Univ., Ser.
[28] H. Firouzabadi, N. Iranpoor, G. Kohmareh, Synth. Commun. 33
(2003) 165.
2: Khim 31 (1990) 384.
[
2] G.H. Birum, G.A. Richardson, US Patent 3, 113, 139 (to
Monsanto Chem. Co.), December, 3 (1963), Chem. Abst. 60
[29] E.J. Corey, K. Shimoji, Tetrahedron Lett. 24 (1983) 169.
[30] A. Ernst, H. Karola, M. Hermann, Synthesis (1990) 323.
[31] L. Zhonghua, Z. Chuanfang, Main Group Met. Chem. 18 (1995)
669.
(1964) 5551d.
[
[
3] G.A. Olah, A.-H. Wu, J. Org. Chem. 56 (1991) 902.
4] M. Sekine, M. Nakajima, T. Hata, Bull. Chem. Soc. Jpn. 54
[32] J. Auge, F. Leory, Tetrahedron Lett. 37 (1996) 7715.
[33] T. Imamoto, Y. Koide, S. Hiyama, Chem. Lett. (1990) 1445.
[34] M. Nishizawa, H. Takenaka, H. Nishide, Y. Hayashi, Tetrahe-
dron Lett. 24 (1983) 2581.
(1982) 218.
[
5] T. Hata, A. Hashizume, M. Nakajima, M. Sekine, Tetrahedron
Lett. 4 (1978) 363.
[
[
6] R.E. Koenigkramer, H. Zimmer, Tetrahedron Lett. 21 (1980) 1017.
7] M. Sekine, M. Nakajima, A. Kume, A. Hashizume, Bull. Chem.
Soc. Jpn. 55 (1982) 224.
[35] C.L. Jenkins, J.K. Kochi, J. Am. Chem. Soc. 94 (1972) 843.
[36] H. Firouzabadi, B. Karimi, Synth. Commun. 23 (1993)
1633.
[
[
8] D.A. Evans, K.M. Hurst, L.K. Truesdale, J.M. Takacs, Tetrahe-
dron Lett. 29 (1977) 2495.
9] A. Sekiguchi, M. Ikeno, W. Ando, Bull. Chem. Soc. Jpn. 51
[37] H. Firouzabadi, A.R. Sardarian, Z. Khayat, B. Karimi, Sh.
Tangestaninejad, Synth. Commun. 27 (1997) 2709.
[38] T.W. Green, P.G.M. Wuts, Protective Groups in Organic
Synthesis, third ed., Wiley, New York, 1999.
(1978) 337.
[
[
10] F. Texier-Boullet, A. Foucaud, Synthesis (1982) 916.
11] P.G. Baraldi, M. Guarneri, F. Moroder, G.P. Polloni, D. Simoni,
Synthesis (1982) 653.
[39] G. Stork, T. Takahashi, I. Kawamoto, T. Suzuki, J. Am. Chem.
Soc. 100 (1978) 8272.
[40] N. Azizi, M.R. Saidi, J. Orgmet. Chem. (2004) 1457.