Michael addition of phosphorus derivatives on tetraethyl ethylidenediphosphonate

Article abstract of DOI:10.1016/j.tet.2005.04.045

Nucleophilic phosphorus add to tetraethyl ethylidene diphosphonate in protic solvent to yield the product of the Michael reaction. This reaction appeared to be reversible at a temperature upper than 160°C. To avoid this reverse reaction, alkylation in α position of the two phosphonate functions by activated elecrophile is reported.

Full text of DOI:10.1016/j.tet.2005.04.045

Tetrahedron 61 (2005) 6602–6609
Michael addition of phosphorus derivatives on tetraethyl
ethylidenediphosphonate
Lise Delain-Bioton,a Adele Turner,b Nicolas Lejeune,a Didier Villemin,a Gary B. Hixb
a,
*
`
and Paul-Alain Jaffres
a
´ ´ ´
Laboratoire de Chimie Moleculaire et Thioorganique, UMR CNRS 6507, Ecole Nationale Superieure d’Ingenieur de Caen,
´
´
Universite de Caen, ENSICAEN, 6 Bd du Marechal Juin, F-14050 Caen, France
bDepartment of chemistry, De Montfort University, The Gateway, Leicester LE1 9BH, UK
Received 10 December 2004; revised 1 April 2005; accepted 21 April 2005
Available online 24 May 2005
Abstract—Nucleophilic phosphorus add to tetraethyl ethylidene diphosphonate in protic solvent to yield the product of the Michael reaction.
This reaction appeared to be reversible at a temperature upper than 160 8C. To avoid this reverse reaction, alkylation in a position of the two
phosphonate functions by activated elecrophile is reported.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
are coordinated to the metal atoms constituting the
inorganic network, leading to limitate the chemical
reactivity of these functions. A first example of a zinc-
phosphonate material possessing functional groups that are
not co-ordinated to the metal atoms (‘free function’), was
reported by Sevov8 who used a phosphonated a-amino-acid
as the organic precursor. Recently we have also reported a
cobalt-phosphonate structure possessing a free amine
function located inside a microporous material.9 From
these results, it appears that the use poly-functional organic
precursors are good candidates to synthesise porous
materials possessing free functions. In order to synthesise
polyfunctional building blocks for the construction of metal
phosphonate materials the functionalisation of tetraethyl
ethylidenediphosphonate A by conjugate addition of a
nucleophile was very promising.
Metal-phosphonate materials are obtained by the reaction of
a phosphonic acid1 or a phosphonate2 with a metallic salt
(Al, Co, Zr.) in aqueous media or in polar organic
solvent.3 This class of materials possesses a well defined
structure typically formed by a layered4 or a three
dimensional organisation.5 Unfortunately, in many cases,
the accessibility of the interlayer space is reduced due to
overcrowding. Many applications such as the use of these
materials as heterogeneous catalysts, ion exchangers or ion
transporters depend upon the ability to control both the
porosity of these materials and the location of vacant
functional groups inside the pore. A first strategy, used to
improve the accessibility to the reactive functions, consists
of using two types of phosphonic acids (one bearing the
function group and the second acting as a spacer) in the
course of the synthesis of materials.6 The drawback of this
strategy is that the materials are poorly crystalline and size
of the pore is irregular. The second possibility, which is also
useful to introduce other functional groups into hybrid
materials, consists in using a phosphonic acid bearing others
functions (e.g., phosphonic acid, carboxylate, amine.).
According to this strategy, porous materials possessing
well-defined structures were obtained.7 Unfortunately, most
of the time all the functions present on the organic precursor
The functionalisation of compound A by Michael addition
of nucleophilic carbon,10,11 sulfur or amine12,13 can be
obtained according to the reported methods. More recently
the addition of heterocycle has been reported.14 It is worth
mentioning that in the case of amine, the reverse Michael
addition was frequently observed. The addition of nucleo-
philic phosphorus species has scarcely been studied. Indeed,
only two NMR studies of the conjugate addition of
dialkylphosphite12 or spirophosphorane13 to compound A
(the Michael addition occurred only with the presence of
1 equiv of diisopropylamine as a base) has been reported.
Keywords: Phosphonate; Michael addition.
*
Corresponding author. Tel.: C33 2 31452841; fax: C33 2 31452877;
e-mail: jaffres@ensicaen.fr
A limitation to the use of the Michael addition can arise
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.04.045

L. Delain-Bioton et al. / Tetrahedron 61 (2005) 6602–6609
6603
either from the existence of an equilibrated reaction or from
the fragility of the products that can lead to the reverse
Michael addition (elimination reaction).15
THF) and compound 1; 3—the formation of triethylphos-
phate has been observed by 31P NMR in the course of an
experiment carried out in a NMR tube. The intermediate II
eliminates the sodium salt of diethylphosphite to produce
the vinylphosphonate III that reacts with sodium ethoxide to
yield, after protonation of the intermediate IV, compound 3.
In this paper, we report the conjugate addition of
nucleophilic phosphorus across the carbon–carbon double
bond of tetraethyl ethylidenediphosphonate A. The alkyl-
ation of the anionic intermediate, thus yielding a product
that can not be decomposed by retro-Michael reaction, is
also reported.
The conditions of reaction used for the addition of
diethylphosphite on the tetraethyl ethylidenediphosphonate
A were used for the addition of other phosphorus
derivatives. The use of dimethylphosphite as a nucleophile
in the presence of a stoechiometric amount of sodium
ethoxide did not give the expected product but yield
compound 1 due to a complete transesterification reaction
(entry 4). By using sodium methoxide in methanol instead
of ethoxide the addition of dimethylphosphite is observed
(entry 5). The addition of ethylphenylphosphonite on
compound A in similar conditions (entry 6) yields
compounds 4 in good yield. Diethylthiophosphite (entry
7), which possess two potentially nucleophilic atoms
(phosphorus and sulfur), adds to the vinylidene A by a
phosphorus attack leading to the formation of the thiophos-
phonate 5. Unfortunately, a thermal degradation of
compound 5 was observed in the course of its purification
by distillation. Nevertheless the purity of the crude product
estimated by 1H NMR is good (O90%). Finally, the
methodology was applied to the addition of diphenylphos-
phine (entry 8) and its borane complex (entry 9). In both
cases, the addition takes place thus producing molecules 6
and 7 that could be used as ligand for homogeneous or
heterogenous catalysis. It worth noting, that the phosphine-
diphosphonate 6 is air sensitive, and during the workup its
oxidation to a phosphine oxide is not fully avoided (30% of
phosphine oxide is observed).
2. Results and discussion
The conditions, reported by Sturtz10 for the addition of
nucleophilic carbon on tetraethyl ethylidenediphosphonate
A (protic conditions), were first tested for the addition of
diethylphosphite as a nucleophilic phosphorus (Scheme 1).
A stoichiometric amount of sodium ethoxide was first used
yielding compound 1 in 82% yield after 15 min of reaction
(Table 1, entry 1). The competitive nucleophilic addition of
sodium ethoxide on ethylidenediphosphonate A was only
observed at a trace level. Therefore, the use of a more
hindered alkoxide was not needed. The use of a catalytic
amount of sodium ethoxide (respectively, 10 and 30%—
entries 2 and 3) yield also compound 1 in good yield
indicating that the anionic intermediate, formed by the
addition of the nucleophilic phosphorus, is protonated by
ethanol. These catalytic conditions (10 to 30% of sodium
ethoxide) were finally preferred compare to the use of a
stoechiometric amount of sodium ethoxide. Indeed, a longer
reaction time (more than 30 min) associated with the use of
a stoechiometric amount of sodium ethoxide produce
diethyl 2-ethoxyethylphosphonate 3 in high yield (recently,
we observed a similar reaction pathway by the addition of
other alcoolate). The mechanism proposed to explain the
formation of this unwanted product is reported in Scheme 1.
The purification of compound 1 has been successful by the
elimination of the side product by distillation at a pressure
of 10 mTorr at a temperature above 130 8C. Noteworthy a
higher temperature (160 8C) at the same pressure leads to
induce the retro-Michael reaction and the formation of small
amount of tetraethyl ethylidenediphosphonate A. In order to
get an accurate value of the temperature needed to induce
the retro-Michael reaction, a DSC analysis of compound 1
from 20 to 300 8C has been recorded. An exothermic
transition is observed between 180 to 240 8C followed by a
sharp endothermic transition (240 to 265 8C).
The first transition, which is attributed to the retro-Michael
reaction (molecular modelling calculation based on semi-
empiric method PM316 indicates that the retro-Michael
reaction is indeed exothermic), revels that compound 1
starts to be damaged at 180 8C under atmospheric pressure.
This lack of stability could be a problem for the use of this
tris-phosphonate molecule in the course of the synthesis of
hybrid materials according to hydrothermal synthesis that
usually use temperature included from 140 to 180 8C.17
In order to increase the stability of compound 1a towards
the retro-Michael degradation the alkylation on carbon in
a position of the two phosphonate functions has been
investigated. The second interest to trap the anionic
intermediate arises from the possibility to introduce another
functional group by using either a functionalised electro-
phile or an electrophile that can be subsequently
Scheme 1.
The nucleophilic addition of sodium ethoxide on compound
1 produce the intermediate I that loose triethylphosphate to
generate the stabilised anionic intermediate II. This part of
the proposed mechanism was corroborated by the following
experiences: 1—the addition of sodium ethoxide (1 equiv)
on compound 1 produce compound 3 (conversion: 100%;
1
yield: O90% according to H NMR); 2—no reaction was
observed between the sodium salt of diethylphosphite (in

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L. Delain-Bioton et al. / Tetrahedron 61 (2005) 6602–6609
Table 1. Michael addition of nucleophilic phosphorus on vinylidenediphosphonate I
Entry
Nucleophile II
Base
Product
Yield %
1
2
3
4b
5
6
7
8
9
IIa
IIa
IIa
IIb
IIb
IIc
IId
IIe
IIf
HPO(OEt)2
HPO(OEt)2
HPO(OEt)2
HPO(OMe)2
HPO(OMe)2
HPO(OEt)Ph
HPS(OEt)2
HPPh2
RZEt 1 equiv
RZEt 0.1 equiv
RZEt 0.3 equiv
RZEt 1 equiv
RZMe 0.3 equiv
RZEt 0.3 equiv
RZEt
1
1
82a
78a
93a
82a
89a
67a
75c
77d
74a
1
1b
2
4
5
6
7
RZEt
RZEt
HPPh2–BH3
a Isolated yields.
b Dimethylphosphite was used but transesterification takes place yielding compound 1.
c Crude product.
d Presence of 30% of phosphine oxide.
functionalised. Two strategies has been tested to introduce a
methyl fragment on the carbon bearing the two phosphonate
functions (Scheme 2): The one pot procedure, that starts
from the ethylidenediphosphonate A in aprotic solvent (path
a, Scheme 2), produces the expected product 8 in modest
yield. Indeed, the presence of small amount of un-alkylated
molecules in the crude product has reduced the yield due to
difficulties in the purification step. The two steps process
(path b, Scheme 2), which consists to deprotonate the tri-
phosphonate 1 by NaH followed by the addition of methyl
iodide, was finally more efficient. It is worth noting that,
despite steric hindrance, the alkylation step is carried out in
good yield (90%). The DSC analysis of compound 8 from
20 to 300 8C indicates a thermal stability up to 240 8C. The
higher stability of this alkylated tris-phosphonate 8 will
allow its use to synthesise hybrid materials by using the
hydrothermal conditions.
around the nucleophilic carbon that induces the elimination
reaction versus the substitution one. Therefore, only the
addition of activated electrophiles, in which elimination
reaction is not possible, were successful. Indeed, good yield
are obtained in the course of the addition of allyl bromide
(entry 2) propargyl bromide (entry 3) and with benzyl
bromide (entry 4). On the other hand the use of more
hindered electrophile like diethylchlorophosphate, ethyl
bromoacetate or diethylcarbonate, were unsuccessful (!5%
1
conversion determined by H NMR).
As the addition of ethyl bromoacetate on the anionic form of
compound 1 was unsuccessful, compound 12 was finally
obtained (87% yield) in two steps18 from compound 9
(Scheme 3).
Scheme 3.
The synthesis of the phosphonic acid from the correspond-
ing phosphonate has been realised on two compounds.
First on the tris(diethylphosphonate) 1 which is converted
to the corresponding tris-phosphonic acid 13 by refluxing
into concentrated hydrochloric solution in quantitative
yield without any sign of retro-Michael reaction. The
phosphine-diphosphonate
6
is converted to the
phosphine-diphosphonic 14 acid according to a softer method
(Me3SiBr followed by methanolysis).19 The phosphine
function is observed, by 31P NMR in deuteriated water or
deuteriated methanol, as a broad peak, respectively, at 7.67
and K3.21 ppm. Both the presence of such an unusual
chemical shift for a diphenylalkylphosphine and the shape of
the peak indicate the existence of a hydrogen bond or the
presence of a zwitterion that could arise from a proton
exchange from one phosphonic function to the phosphine one.
It might be postulated that the exchange is certainly dynamic
Scheme 2.
The addition of other electrophiles on compound 1 was
carried out according to the path b presented on Scheme 2.
The results of these reactions are summarised in Table 2.
The addition of alkyl halide was limited to methyl iodide.
Indeed the addition of ethyl iodide produces the alkylated
compound in poor yield (5% determined by 1H NMR). This
lack of reactivity could be explained by steric congestion

L. Delain-Bioton et al. / Tetrahedron 61 (2005) 6602–6609
6605
Table 2.
Entry
Electrophile
E
Product
Yield %a
1
2
3
4
MeI
Me
8
9
10
11
65
71
95
66
H2C]CH–CH2–Br
HC^C–CH2–Br
Ph–CH2–Br
H2C]CH–CH2
HC^C–CH2
Ph–CH2
a Isolated yield.
as only one signal is observed for the phosphonic acid function
indicating the equivalence at the NMR time scale of the two
phosphonic function (see Scheme 4). This hydrogen bond or
this zwitterion is broken by the addition of sodium hydroxide
in the NMR tube. Indeed, after its addition, the peak
attributed to the phosphine function is sharp (as expected a
triplet is observed) and the chemical shift is now observed at
K14.50 ppm. The presence of the hydrogen bond or a
zwitterions in water indicate that this bond might be present
also at the solid state thus protecting the phosphine to its
oxidation to a phosphine oxide function. This kind of unusual
stability of phosphine toward oxidation has been also reported
by Katti and co-workers.20 This hydrogen bond or the
existence of a zwitterion would explain the greater stability
ofcompound 14versusits analogous diphosphonate 6 towards
oxidation.
In order to increase the thermal stability of the Michael
addition product, the deprotonation of the tri-phosphonate 1
followed by its alkylation is reported. Furthermore the
alkylation with activated halide (allyl, propargyl), offers
molecules that could be use to introduce new functionalities
into hybrid materials or on the surface of inorganic sup-
port.21 These possibilities are currently under investigation.
4. Experimental
1H, 13C and 31P NMR spectra (liquid-state) were recorded
on a Bruker AC 250 or a Bruker Avance 400 spectrometer.
Elemental analyses were recorded on a CE Instrument NA
2500. Mass spectrum were recorded on a QTOF Micro
(waters), ionisation electrospray positive (ESI), lockspray
PEG, infusion introduction (5 mL/min), source temperature
80 8C, desolvatation temperature 120 8C.
4.1. General procedure for the addition of
dialkylphosphite on compound A
To absolute alcohol (ethanol or methanol) placed in a two
necks round bottom flask fitted with a refluxed condenser
bearing on its top a drying guard, sodium (0.3 equiv) is
added. The solution is stirred at room temperature until all
the sodium as reacted. A solution of diethylphosphite in
alcohol (1 mL) is then added. After 5 min, a solution of
tetraethyl vinylidenediphosphonate A (1 equiv) in alcohol
(1 mL) is added. The solution is stirred for further 20 min at
room temperature and then a saturated ammonium chloride
solution (8 mL) is added. The aqueous–organic solution is
partially evaporated in vacuo to remove alcohol and then
water (8 mL) and dichloromethane (20 mL) are added. The
aqueous phase is further extracted with dichloromethane
(2!20 mL). The organic phases are assembled and dried
over MgSO4. The solution is filtrated and concentrated in
vacuo to yield the crude product. The impurities are
removed by Kugelrohr distillation (10 mTorr; up to 150 8C).
Scheme 4.
3. Conclusion
The Michael addition of nucleophilic phosphorus on
tetraethyl ethylidenediphosphonate A is reported. The
reactions take place in protic solvent with a catalytic
amount of sodium alkoxide. The Thermal stabilities of these
Michael addition products are moderate. Therefore, their
use to elaborate hybrid materials would be investigated with
care. Nevertheless, the retro-Michael reaction was not
observed when diphenylphosphine has been added to
tetraethyl ethylidenediphosphonate A to produce compound
6. This molecule will be use in due time for the design of
hybrid materials. Furthermore, the phosphine-diphosphonic
acid 14 obtained from the corresponding diphosphonate 6 is
a good candidate to be use as a ligand in biphasic catalysis.
4.1.1. Hexaethyl ethan-1,1,2-tris(phosphonate)(1). Ethanol
(20 mL); sodium (0.045 g, 6.66 mmol); diethylphosphite
(0.92 g, 6.66 mmol), tetraethyl vinylidenediphosphonate A
(2.0 g, 6.66 mmol); Pure compound 1 is isolated in 93%
yield (2.71 g) after removing all the volatiles and impurities
by distillation (10 mTorr K120 8C); 1H NMR (CDCl3):
1.30–1.36 (m, 18H, 6!CH3–CH2–O), 2.2–2.5 (m, 2H,
3
2
3
CH2–P), 2.7 (dtt, 1H, JHHZ5.5 Hz, JHPZ25 Hz, JHP
25 Hz, P–CH–P), 4.07–4.27 (m, 12H, 6!CH3–CH2–O);
Z

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L. Delain-Bioton et al. / Tetrahedron 61 (2005) 6602–6609
3
13C NMR (CDCl3): 16.5 (d, JCPZ6 Hz, CH3–CH2–O),
81 (7%); HRMS (ES-TOF): calcd for C8H19O4PNa MCNa
233.0919, found 233.1044.
1
2
1
22.6 (dt, JCPZ139 Hz, JCPZ5 Hz, CH), 31.1 (td, JCP
Z
Z
2
2
134 Hz, JCPZ5 Hz, CH2–P(O)(OEt2)), 62.5 (d, JCP
6.4 Hz, CH2–O–P), 63–63.5(w2d, 2JCPZ6.8 Hz, CH2–O–P),
4.1.4. Tetraethyl 2-(ethoxyphenylphosphinyl)ethan-1,1-
bis(phosphonate) (4). Ethanol (10 mL); sodium (12 mg,
0.16 mmol); tetraethylvinylidene diphosphonate (0.5 g;
1.66 mmol), ethyl phenylphosphonite (0.282 g; 1.66 mmol).
Pure compound 4 is isolated in 67% yield (0.52 g) after
removing all the volatiles and impurities by distillation
(10 mTorr K120 8C); 1H NMR (CDCl3) 1.16–1.38 (m,
15H, O–CH2–CH3), 2.40–2.72 (m, 2H, CH2–P), 2.75–3.13
(m, 1H, CH(PO)2), 3.77–4.27 (m, 10H, O–CH2), 7.43–7.60
(m, 3H, CHAr), 7.75–7.85 (m, 2H, CHAr2); 13C NMR
(CDCl3): 16.4–16.8 (m, CH3), 25.48 (dt, JCPZ5.1 Hz,
31P NMR (CDCl3): 23.45 (d, JPPZ27.3 Hz, P–CH–P),
3
3
29.22 (t, JPPZ27.3 Hz, P–CH2); DSC (10 8C/min): 180–
240 8C (exothermic transition); 240–265 (endothermic
transition); IR (NaCl): 1253 (nP]O); 1050 and 968 (nP–O);
m/z: 439 (MC%C1; 13%); 438 (MC%; 12%); 393 (100%);
365 (56%); 337 (44%); 302 (67%); 274 (70%); 245 (51%);
217 (23%); 189 (33%); 137 (15%); 109 (40%); HRMS
(ES-TOF): calcd for C14H34O9P3 MCH 439.1416, found
439.1342.
1JCPZ100.1 Hz, CH2–PO), 30.21 (dt, 2JCPZ4.0 Hz, 1JCP
Z
4.1.2. Tetraethyl 2-(dimethoxyphosphonyl)ethan-1,1-
bis(phosphonate) (2). Methanol (8 mL); sodium (10 mg;
0.13 mmol); tetraethyl vinylidenediphosphonate A (0.4 g;
1.33 mmol); dimethylphosphite (0.16 g; 1.46 mmol); pure
compound 2 is isolated in 89% yield (0.48 g) after removing
all the volatiles and impurities by distillation (10 mTorr
2
134.3 Hz, CH–(PO)2), 61.23 (d, JCPZ6.3 Hz, CH2–O–P),
62.85 (d, 2JCPZ6.7 Hz, CH2–O–P), 63.16 (d, 2JCPZ6.7 Hz,
2
CH2–O–P), 63.34 (d, JCPZ6.4 Hz, CH2–O–P), 63.37 (d,
3
2JCPZ6.4 Hz, CH2–O–P), 128.81 (d, JCPZ12.8 Hz, CAr),
131.20 (d, 3JCPZ128.4 Hz, CAr), 131.99 (d, 2JCPZ10.0 Hz,
4
CAr), 132.61 (d, JCPZ2.7 Hz, CAr); 31P NMR (CDCl3):
1
3
K120 8C); H NMR (CDCl3): 1.35 (t, JHHZ7.1 Hz, 12H,
23.21 and 23.25 (2d, 3JPPZ21, 25 Hz, 2* PO(OEt)2), 41.54
3
CH3–CH2–O), 2.39 (m, 2H, CH2–P), 2.81 (tq, 1H, JHH
Z
Z
3
(dd, JPPZ21, 3JPPZ25 Hz, PO(OEt)Ph).
5.4 Hz, JHPZ3JHPZ23 Hz, P–CH–P), 3.76 (d, JHP
2
3
10.9 Hz, 6H, P–O–CH3) 4.20 (m, 8H, CH3–CH2–O); 13C
4.1.5. Tetraethyl 2-(diethoxythiophosphonyl)-ethan-1,1-
bis(phosphonate) (5). THF (7 mL); sodium hydroxide
(5 mg, 2 mmol); Tetraethylvinylidene diphosphonate
(0.6 g; 2 mmol), diethylthiophosphonate (0.300 g; 2 mmol).
Pure compound 5 is isolated in 75% yield (0.68 g) after
removing all the volatiles and impurities by distillation
(10 mTorr K120 8C); TLC (CH2Cl2/MeOH; 90/100) RfZ
0.6; 1H NMR (CDCl3): 1.30–1.36 (m, 18H, 6!CH3–CH2–
O), 2.54 (m, 2H, CH2–P), 3.05 (m, 1H, P–CH–P), 4.15 (m,
3
NMR (CDCl3): 15.33 and 15.35 (2d, JCPZ6.3 Hz, CH3–
1
2
CH2–O), 19.41 (dt, JCPZ144.1 Hz, JCPZ5.1 Hz, CH),
29.83 (td, 1JCPZ134.4 Hz, 2JCPZ5.3 Hz, CH2–P(O)), 51.70
2
2
(d, JCPZ6.5 Hz, P–O–CH3), 61.88 and 62.18 (2d, JCP
Z
6.7 Hz, CH2–O–P); 31P NMR (CDCl3): 23.31 (d, JPPZ
3
3
27.4 Hz, P–CH–P), 32.04 (t, JPPZ27.4 Hz, P–CH2);
HRMS (ES-TOF): calcd for C12H30O9P3Na MCNa
434.1000, found 434.0957.
12H, 6!CH3–CH2–O); 13C NMR (CDCl3): 16.4 (d, 3JCP
Z
7 Hz, CH3–CH2–O–P]S), 16.7 (d, 3JCPZ6 Hz, CH3–CH2–
4.1.3. Diethyl 2-ethoxyethylphosphonate (3). To 20 mL of
absolute ethanol placed in a two necks round bottom flask
fitted with a refluxed condenser bearing on its top a drying
guard, 100 mg of sodium (1.3 equiv) are added. The
solution is stirred at room temperature until all the sodium
as reacted. A solution of 1 g of tetraethyl vinylidenediphos-
phonate 1 (3.33 mmol, 1 equiv) in ethanol (1 mL) is added.
The solution is stirred for further 1 h at room temperature
and then a saturated ammonium chloride solution (8 mL) is
added. The aqueous–organic solution is partially evaporated
in vacuum to remove ethanol and then water (8 mL) and
dichloromethane (20 mL) are added. The aqueous phase is
further extracted with dichloromethane (2!20 mL). The
organic phases are assembled and dried over MgSO4. The
solution is filtrated and concentrated in vacuo to yield
680 mg of crude product (colorless oil). The product is
purified by Kugelrohr distillation (10 mTorr; at 80 8C)
1
2
O–P]O), 29.0 (dt, JCPZ112 Hz, JCPZ5 Hz, CH2–
1
2
P(O)(OEt2)), 32.1 (dt, JCPZ136 Hz, JCPZ4 Hz, CH),
62.6 (d, 2JCPZ6 Hz, CH2–O–P), 63.8 (d, 2JCPZ7 Hz, CH2–
3
O–P]S); 31P NMR (CDCl3): 23.2 (d, JPPZ27.6 Hz, P–
3
CH–P), 98.36 (t, JPPZ27.7 Hz, P]S); m/z: 477 (MCNa,
100), 455 (MC%C1, 19%), 439 (19),369 (7), 323 (9), 301
(4), 204 (6); HRMS (ES-TOF): calcd for C14H33NaO9P3S
MCH 477.1007, found 477.0970.
4.1.6. Tetraethyl 2-(diphenylphosphinyl)-ethan-1,1-
bis(phosphonate) (6). Diphenylphosphine (0.31 g,
1.66 mmol) is added to a solution of sodium ethoxide
(2 mmol) in ethanol (solution prepared by the addition of
48 mg of sodium metal in 8 mL of ethanol) placed in a
round bottom flask placed under argon. Tetraethylvinilyde-
nediphosphonate A (0.5 g; 1.66 mmol) in degassed ethanol
(1 mL) is added. The solution is stirred at room temperature
for 25 min. After the addition of a concentrated solution of
ammonium chloride, the solution was evaporated to dryness
in vacuo. 8 mL of degassed water were added and the
solution was extracted with dichloromethane (2!25 mL).
The organic phase is dried on MgSO4, filtered and
concentrated to produce 740 mg of crude product. The
impurities were eliminated by distillation (150 8C,
15 mTorr) to produce 590 mg of very viscous oil (yield:
74%). Compound isolated with 33% of phosphine oxide. 31P
NMR (CDCl3): K12.64 (t, 3JPPZ18.2 Hz, PPh2), 23.84 (d,
3JPPZ18.2 Hz, P–CH–P), phosphine oxide as impurity:
1
offering compound 3 in 97% yield; H NMR (CDCl3): 1.2
2
2
(t, 3H, JHHZ7.0 Hz, CH3–CH2–O), 1.3 (t, 6H, JHH
Z
Z
7.0 Hz, CH3–CH2–O–P), 2.1 (dt, 2H, 3JHHZ7.4 Hz, 2JHP
3
18 Hz, CH2–P), 3.5 (q, 2H, JHHZ7.0 Hz, CH3–CH2–O),
3
3
3.7 (dt, 2H, JHHZ7.5 Hz, JHPZ12.5 Hz, O–CH2–CH2–
P), 4.1 (m, 4H, CH3–CH2–O–P); 13C NMR (CDCl3): 15.1
3
(s, CH3), 16.4 (d, JCPZ6 Hz, CH3–CH2–O), 27.1 (d,
1JCPZ139 Hz, CH2–P), 61.6 (d, JCPZ6.3 Hz, CH2–O–P),
2
64.3 (s, CH3–CH2–O), 66.2 (s, CH3–CH2–O–P); 31P NMR
(CDCl3): 29.72 (s, P); IR (NaCl): 1247 (nP]O); 1163
(nC-O).1027 and 962 (nP–O); m/z: 211 (MC%C1; 100%); 210
(MC%; 2%); 181 (18%); 153 (15%); 125 (29%); 111 (22%);

L. Delain-Bioton et al. / Tetrahedron 61 (2005) 6602–6609
6607
3
3
29.61 (t, JPPZ24 Hz, phosphine oxide), 23.44 (d, JPPZ
24 Hz, P–CH–P).
135 8C). The undistilled product (1.04 g; 69%) is formed by
compounds 8 and 1 in the ratio 90/10.
Method b. THF (8 mL); sodium hydride (60% in oil; 51 mg;
1.27 mmol); hexaethyl ethan-1,1,2-tris(phosphonate) 1
(0.4 g, 0.91 mmol); methyl iodide (0.30 g; 3.24 mmol).
Purification by Kugelrohr distillation (159 8C K10 mTorr);
4.1.7. Tetraethyl 2-(diphenylphosphinylborane)-ethan-
1,1-bis(phosphonate) (7). Ethanol (10 mL); sodium (5 mg,
1.66 mmol); Tetraethylvinylidene diphosphonate (0.5 g;
1.66 mmol), diphenylphosphineborane (0.373 g; 1.66 mmol).
Pure compound 7 is isolated in 74% yield (0.61 g) after
removing all the volatiles and impurities by distillation
1
colorless oil; yield 65% (0.27 g); H NMR (CDCl3): 1.32–
Z
3
1.37 (m, 18H, 6!CH3–CH2–O), 1.72 (t, 3H, JHP
1
16.4 Hz, CH3–C), 2.39–2.45 (m,2H, C–CH2–P), 4.05–4.26
(m, 12H, 6!CH3–CH2–O); 13C NMR (CDCl3): 16.23 (s
broad, CH3), 16.49 (s broad, O–CH2–CH3), 28.19 (dm,
1JCPZ138.6 Hz, CH2–P), 38.81 (m, CH3–C), 61.75 (d,
2JCPZ6.3 Hz, O–CH2), 63.03 at 63.03 (2 m, O–CH2); 31P
(10 mTorr K120 8C); H NMR (CDCl3): 1.19 and 1.24,
1.34 (t, JZ7 Hz, 4!CH3–CH2–O), 2.95 (m, 2H, CH2–P),
3.25 (m, 1H, P–CH–P), 4.15 (m, 4!CH3–CH2–O), 7.46 (m,
6H, Harom), 7.77 (m, 4H, Harom); 13C NMR (CDCl3): 16.6
1
2
(m, CH3–CH2–O–P), 25.0 (dt, JCPZ69 Hz, JCPZ5 Hz,
3
1
NMR (CDCl3): 26.28 (d, sys AB, JPPZ45 Hz, C–PO),
CH2–P(O)(OEt2)), 31.5 (t, JCPZ136 Hz, CH), 62.9 (d,
26.36 (d, syst AB, 3JPPZ31 Hz, C–PO), 27.368 (sys AA0B,
2
2JCPZ6 Hz, CH2–O–P), 63.6 (d, JCPZ7 Hz, CH2–O–P–
3
3
BH3), 128.9 (d, 2JCP2Z11 Hz, Cortho), 131.2 (d, 2JCPZ9 Hz,
0
PA and PA JPPZ33.8 Hz, JPPZ44 Hz, CH2–PO); m/z
(intensity %): 453 (MC1, 2%), 407(11%), 379 (8%), 315
(100%), 288 (18%), 259 (11%), 231 (6%); HRMS (ES-TOF):
calcd for C15H36O9P3 MCH 453.1572, found 453.1586;
DSC (10 8C/min): 240 8C K270 (exothermic transition),
285 (endothermic transition).
2
Cmeta), 132.0 (d, JCPZ3 Hz, Cpara), 133.1 (d, JCP
Z
145 Hz, Cquat); 31P NMR (CDCl3): 21.86 (s large, P–BH3),
3
23.13 (d, JPPZ21.36 Hz, P–CH–P); m/z: 525 (MCNaC
2H, 86.8%), 503 (MC%C3, 29.4%), 457 (9%), 439 (11%),
326 (16%), 325 (100%), 303 (16%); HRMS (ES-TOF):
calcd for C22H38BNaO9P3 MCNaC2H 525.1872, found
525.1271.
4.2.2. Hexaethyl pent-4-en-1,2,2-tris(phosphonate) (9).
Method b, THF (15 mL); hexaethyl ethan-1,1,2-tris(phos-
phonate) 1 (2.0 g; 4.56 mmol); allyl bromide (1.65 g;
13.68 mmol). The impurities are removed by Kugelrohr
distillation (10 mTorr; 160 8C). The crude product was
purified by flash chromatography. (Eluent dichloromethane/
methanol (85/15), RfZ0.5) to afford compound 9, colorless
4.2. Alkylation of hexaethyl ethan-1,1,2-
tris(phosphonate) 1
Method a—one pot synthesis Under argon atmosphere,
10 mL of freshly distilled THF are placed in a dry 50 mL
round bottom flask fitted with a reflux condenser. Diethyl-
phosphite (1.1 equiv) and sodium (3 equiv) are added. After
9 h at room temperature, the excess of sodium is removed
from the round bottom flask. Ethan-1,1,2-tris(phosphonate)
1 (1 equiv) and THF (1 mL) are added. The solution is
stirred at 20 8C for 30 min before the addition of the
electrophile (1.3 equiv) and THF (1 mL). The solution is
stirred for further 30 min and then hydrolysed by the
addition of water (3 mL). The solvents are partially removed
in vacuo. The residue (a water solution) is extracted with
dichloromethane (3!10 mL). The organic phase is dried on
MgSO4, filtered and concentrated in vacuo. The impurities
are removed by Kugelrohr distillation.
oil; YieldZ71% (1.54 g). 1H NMR (CDCl3): 1.29–1.36 (m,
3
18H, CH3), 2.38 (m, 2H, CH2–P), 2.98 (ddd, 2H, JHH
Z
3
2.7 Hz, JHPZ14 Hz, CH2–C]CH), 4.09 (m, 4H, CH3–
CH2–O–P), 4.19 (m, 4H, CH3–CH2–O–P), 5.12 (dd, 1H,
2JHHZ.0.8 Hz, 3JHHZ6.4 Hz, CH]CHHcis), 5.28 (dd, 1H,
2JHHZ.0.8 Hz, 3JHHZ10.5 Hz, CH]CHHcis), 5.99 (m, 1H,
CH2]CH); 13C NMR (CDCl3): 16.31–16.48 (m, CH3),
1
1
25.55 (dd, JCPZ149 Hz, JCCZ38 Hz, CH2–P), 34.28
2
1
(m, CH2CH]CH2), 43.74 (dt, JCPZ3.2 Hz, JCP
Z
2
130 Hz, P–C–P), 61.75 (d, 2C, JCPZ6.5 Hz, CH3–CH2–
O–P), 62.82–63.21 (m, 4C, CH3–CH2–O–P), 118.85
(s, CH]CH2), 133.22 (t, JCPZ8 Hz, CH]CH2); 31P
3
3
NMR (CDCl3): 23.45 (d, JPPZ46.8 Hz, C–PO), 23.46 (d,
3
3
2P, JPPZ43.5 Hz, C–PO), 26.22 (dd, JPPZ43.5 Hz,
3JPPZ46.8 Hz, P–CH2); IR: 3078 (nC-HC]C), 1638
(nC]C), 1248 (nP]O), 1050 and 966 (nP–O); m/z: 479
(MC%C1; 59%); 478 (MC%; 4%); 433 (15%); 405 (11%);
342 (86%); 341 (100%); 314 (17%); 285 (8%); HRMS
(ES-TOF): calcd for C17H37O9NaP3 MCNa 501.1514,
found 501.1519.
Method b—from hexaethyl ethan-1,1,2-tris(phosphonate) 1.
THF is added to sodium hydride (60% in oil; 1.4 equiv)
placed under azote and previously washed with pentane
(2 mL). The solution is cooled by an ice bath. A solution of
compound 1 (1 equiv) in THF (4 mL) is added dropwise.
The solution is stirred at room temperature for 30 min. The
electrophile is added. The solution is stirred at room
temperature for 16 h. The solution is evaporated to dryness
in vacuo and a concentrated aqueous solution of ammonium
chloride is added (10 mL). The solution is extracted with
dichloromethane. The organic phase is dried over MgSO4,
filtered, concentrated and purified by Kugelrohr distillation
or by chromatography on silica gel.
4.2.3. Hexaethyl pent-4-yn-1,2,2-tris(phosphonate) (10).
Method b, THF (15 mL); hexaethyl ethan-1,1,2-tris(phos-
phonate) 1 (5.9 g; 13.5 mmol); propargyl bromide (6.02 g;
40.5 mmol). The impurities are removed by Kugelrohr
distillation (10 mTorr; 160 8C). The crude product was
purified by flash chromatography. (Eluent dichloromethane/
methanol (85/15), RfZ0.6) to afford compound 10; color-
1
4.2.1. Hexaethyl propan-1,2,2-tris(phosphonate) (8).
Method a. Diethylphosphite (0.51 g; 3.66 mmol); sodium
(0.23 g; 9.99 mmol); hexaethyl ethan-1,1,2-tris(phosphon-
ate) 1 (1.00 g ; 3.33 mmol); methyl iodide (0.165 g). The
impurities are removed by Kugelrohr distillation (12 mTorr;
less oil; YieldZ95% (6.12 g). H NMR (CDCl3): 1.31 (t,
3
3
6H, JHHZ7 Hz, CH3), 1.33 (t, 12H, JHHZ7 Hz, CH3),
2.10 (t, 1H, 4JHHZ2.7 Hz, CC–H), 2.44–2.63 (m, 2H, CH2–
3
3
P), 3.17 (dt, 2H, JHHZ2.7 Hz, JHPZ14 Hz, CH2–CC),
4.06–4.26 (m, 12H, CH3–CH2–O–P); NMR 13C (CDCl3):

6608
L. Delain-Bioton et al. / Tetrahedron 61 (2005) 6602–6609
1
2
15.00–15.5 (m, CH3), 19.80–20.01 (m, CH2–CC), 25.55 (d,
C1 and C8), 25.13 (dd, JCPZ141.5 Hz, JCPZ5.8 Hz, C4),
40.79 (dd, 2JCPZ3.2 Hz, 1JCPZ129.8 Hz, C5), 61.80–62.76
(m, C2), 63.43–64.01 (m, C7), 49.32 (s, C9), 170.53 (t,
2
1
1JCPZ140 Hz, CH2–P), 41.60 (dt, JCPZ2.2 Hz, JCP
Z
133 Hz, P–C–P), 60.93 (d, 2C, 2JCPZ6.5 Hz, CH3–CH2–O–
P), 62.17–62.56 (m, 4C, CH3–CH2–O–P), 71.0 (s, CC–H),
78.24 (t, 3JCPZ11.4 Hz, CC–H); 31P NMR (CDCl3): 23.45
3JCPZ11. Hz, C10); 31P NMR (CDCl3): 22.34 (d, JPPZ
42.7 Hz, C–PO), 28.14 (t, JPPZ42.8 Hz, P–CH2); IR
(NaCl): 3449 (nO-H), 2114 (nCC), 1728 (nC]O), 1249
(nP]O), 1028 and 969 (nP–O); m/z: 519(MC%CNa; 100),
497 (MCH, 21); 496 (MC, 2), 461 (52), 451 (15), 393 (13),
325 (21), 303 (5), 204 (11); HRMS (ES-TOF): calcd for
C16H35O11NaP3 MCNa 519.1290, found 519.1272.
2
3
3
3
(d, JPPZ46.8 Hz, C–PO), 23.46 (d, 2P, JPPZ40.5 Hz,
3
3
C–PO), 26.22 (dd, JPPZ40.5 Hz, JPPZ46.8 Hz, P–CH2);
IR (NaCl): 3220 (nC-HCC), 2114 (nCC), 1251 (nP]O), 1035
and 963 (nP–O); m/z: 477 (MC%C1; 79%); 476 (MC%; 1%);
340 (100%); 301 (51%); 273 (18%); 147 (10%); HRMS
(ES-TOF): calcd for C17H35O9NaP3 MCNa 499.1392,
found 499.1315.
4.4. Hydrolysis of phosphonate to phosphonic acid
4.2.4. Hexaethyl prop-3-phenyl-1,2,2-tris(phosphonate)
(11). Method b. THF (15 mL); hexaethyl ethan-1,1,2-
tris(phosphonate) 1 (0.5 g; 1.14 mmol); benzyl bromide
(0.58 g; 3.42 mmol). The impurities are removed by
Kugelrohr distillation (10 mTorr; 160 8C). The crude
product was purified by flash chromatography. (Eluent
dichloromethane/methanol (90/10), RfZ0.5) to afford
compound 11; colorless oil; yieldZ66% (0.40 g). NMR
4.4.1. Ethan-1,1,2-tris(phosphonic acid) (13). Concen-
trated HCl (60 mL, 37% in water) is added to 2.12 g
(4.84 mmol) of hexaethyl ethan-1,1,2-tris(phosphonate) 1.
The solution is refluxed for 2 h 30 min. The excess of HCl
and water are removed in vacuo to produce a very viscous
1
oil (1.35 g; 100%Ctraces of water); H NMR (D2O): 2.02
3
2
(dq, JHHZ6.24 Hz; JHPZ3JHPZ16.7 Hz; 2H, CH2–P),
2.35 (m, 1H, P–CH–P); 13C NMR (D2O): 22.71 (dt, 1JCP
Z
3
2
1
1H (CDCl3): 1.19 (t, JHHZ7.5 Hz, 6H, CH3), 1.26 (t,
133.0 Hz, JCPZ3.9 Hz, CH2–P), 32.78 (dt, JCPZ126.2,
3
3JHHZ7.5 Hz, 6H, CH3), 1.36 (t, JHHZ7.5 Hz, 6H, CH3),
2JCPZ3.9 Hz, P–CH–P); 31P NMR (D2O): 20.14 (d, 3JPPZ
3
3
2.41 (m, 2H, CH2P), 3.56 (dd, JHPZ11.5 Hz, JHP
Z
31 Hz, P–CH2), 25.98 (t, 3JPPZ31 Hz, P–CH–P); NMR 31
P
16.8 Hz, 2H, P–CH2–Ph), 4.05–4.26 (m, 12H, CH2–O–P),
7.25 (m, 3Harom), 7.60 (dd, JHHZ1.8 Hz, JHHZ8.1 Hz);
NMR 13C (CDCl3): 16.6–16.8 (m, 6C, CH3), 27.38 (dd,
2JCPZ2.2 Hz, 1JCPZ143 Hz, CH2P), 33.43 (s, C–Ph), 46.4
(t, 1JCPZ130 Hz, P-C-P), 62.85 (d, 2C, 2JCPZ6.9 Hz, CH3–
CH2–O–P), 63.8 (m, 4C, CH3–CH2–O–P), 126.9 (s, 1C,
Caromtrans), 127.93 (s, 2C, Carom), 132.1 (s, 2C, Carom), 137.4
(s, 1C, Cquatarom); 31P NMR (CDCl3): 23.9 (d, 2JPPZ49 Hz,
C-PO), 23.9 (d, 2JPPZ42 Hz, C-PO), 26.8 (dd, 3JPPZ42 Hz,
3JPPZ49 Hz, P-CH2); m/z: 529 (MC%C1; 5%); 528
(MC%; 2); 454 (12); 391 (100); 363 (10); 317 (38); 289
(15); 261 (28); IR (NaCl): 1237 (nP]O), 1016 and 952
(nP–O), 665 and 704 (narom); m/z: 529 (MC%C1; 5%); 528
(MC%; 2%); 454 (12%); 391 (100%); 363 (10%); 317
(38%); 289 (15%); 261 (28%); HRMS (ES-TOF): calcd for
C21H39O9NaP3 MCNa 551.1705, found 551.1633.
(D2OCNaOH): 22.96 (d, 3JPPZ21.7 Hz, P–CH2), 24.34 (t,
3JPPZ21.7 Hz, P–CH–P).
4.4.2. Tetraethyl 2-(diphenylphosphinyl)-ethan-1,1-
bis(phosphonate) (14). Tetraethyl 2-(diphenylphosphinyl)-
ethan-1,1-bis(phosphonate) 6 (0.59 g, pure as 66%) was
dissolved under argon in dichloromethane (5 mL). Bromo-
trimethylsilane (1.5 mL) is added and the solution was
stirred at 20 8C for 15 h. The volatiles were removed in
vacuo to produce a viscous oil. 8 mL of methanol were
added. The solution was stirred at room temperature for 3 h
30 min and evaporated to dryness to produce a white solid
(530 mg) of compound 14 (66%) accompanied with the
phosphine oxide derivative (33%). 1H NMR (D2O): 1.70 (m,
1H, CH), 2.46 (m, 2H, CH2), 7.2–7.6 (m; 10H, HAr), 33% of
phosphine oxide: 2.08 (m, 1H, CH), 2.89 (m, 2H, CH2), 7.0–
7.4 (m; 10H, HAr); 31P NMR (D2O): 7.67 (m broad, PPh2),
3
4.3. Catalytic oxidation of compound 10
19.43 (d, JPPZ20 Hz, P–CH–P), (phosphine oxide impur-
ity (33%): 17.35 (d, 3JPPZ23 Hz, P–CH–P), 41.41 (t, 3JPPZ
23 Hz, phosphine oxide); 31P NMR (D2OCNaOH): K14.5
4.3.1. 3,3,4-Tris(diethylphosphonyl) butanoic acid (12).
A two necked round bottom flask equipped with a condenser
is charged with a magnetic stirrer, 4 mL of carbon
tetrachloride, 4 mL of acetonitrile, 6 mL of water, 1.18 g
of compound 10 (2.5 mmol, 1 equiv) and 2.70 g of sodium
metaperiodate (10.1 mmol, 4.1 equiv). To this biphasic
solution 20 mg (2.2 mol%) of ruthenium trichloride hydrate
was added and the mixture was stirred vigorously for 2 h at
room temperature. After the addition of CH2Cl2 (20 mL),
the phases were separated. The aqueous layer was extracted
further with CH2Cl2 (3!15 mL). The combined organic
extracts were dried over MgSO4 and concentrated. The
residue was diluted with 50 mL of diethylether, filtered
through a Celite pad and concentrated. The crude product
was purified by flash chromatography. (Eluent ethanol/
methanol (85/15), RfZ0.5) to afford 1.08 g of compound 12
3
3
(t, JPPZ20 Hz, PPh2), 22.98 (d, JPPZ20 Hz, P–CH–P)
3
(phosphine oxide impurity (33%)): 21.62 (d, JPPZ24 Hz,
3
P–CH–P), 45.39 (t, JPPZ24 Hz, phosphine oxide); NMR
31P (CD3OD): K3.21 (m broad, PPh2), 19.88 (d, JPPZ
22.1 Hz, P–CH–P) (phosphine oxide impurity (33%)): 19.02
3
3
3
(d, JPPZ25.6 Hz, P–CH–P), 40.33 (t, JPPZ25.6 Hz,
phosphine oxide)).
Acknowledgements
We gratefully acknowledge the ‘PunchOrga’ Network
ˆ
(Pole Universitaire Normand de Chimie Organique), the
‘Ministere de la Recherche et des Nouvelles Technologies’,
`
CNRS (Centre National de la Recherche Scientifique), the
´
1
as a yellow oil (87%). H NMR (CDCl3): 1.30–1.38 (m,
Z
‘Region Basse-Normandie’ and the European Union
3
18H, H13and H8), 2.65–2.78 (m, 2H, H4), 3.24 (dt, JHH
(FEDER funding) for financial support. The travel costs
were supported by both EGIDE and the British Council
(Alliance program).
2.2 Hz, JHPZ14.9 Hz, 2H, H9), 4.09–4.20 (m, 4H, H2),
4.23–4.29 (m, 8H, H7); 13C NMR (CDCl3): 16.23–16.42 (m,

L. Delain-Bioton et al. / Tetrahedron 61 (2005) 6602–6609
6609
11. Lolli, M. L.; Lazzarato, L.; Di Stilo, A.; Fruttero, R.; Gasco, A.
J. Organomet. Chem. 2002, 650, 77.
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