Regio- and stereospecific hydrophosphorylation of phenylacetylene

Article abstract of DOI:10.1070/MC2005v015n04ABEH002132

The interaction of diethyl phosphite with phenylacetylene within the coordination sphere of the trialkynemonocarbonyl-molybdenum(0) complex produces diethyl (Z)-2-phenylvinylphosphonate.

Full text of DOI:10.1070/MC2005v015n04ABEH002132

, 2005, 15(4), 155–156
Regio- and stereospecific hydrophosphorylation of phenylacetylene
Arcady I. Kuramshin,* Andrey A. Nikolaev and Rafael A. Cherkasov
A. M. Butlerov Chemical Institute, Kazan State University, 420008 Kazan, Russian Federation.
Fax: +7 8432 31 5416; e-mail: arcady.kuramshin@ksu.ru
DOI: 10.1070/MC2005v015n04ABEH002132
The interaction of diethyl phosphite with phenylacetylene within the coordination sphere of the trialkynemonocarbonyl-
molybdenum(0) complex produces diethyl (Z)-2-phenylvinylphosphonate.
The attractiveness of the catalytic phosphorylation1 and phos-
phination2 of alkenes and alkynes can be described not only by
an acceleration of the formation of target organophosphorus
OEt
O
Mo(CO)6
P
OEt
C
CH + (EtO)2P(O)H
compounds but also by the fact that the use of homogeneous
catalysis with transition metals can produce organophosphorus
compounds that cannot be obtained under conditions of classic
organoelement synthesis. We reported the addition of dialkyl
phosphites to alkenes in the presence of chromium-group metal
carbonyl complexes3 and the dehalophosphorylation of chloro-
and bromobenzene in the coordination sphere of the aryltri-
carbonyl complexes of the above metals.4
H
H
1
In order to explain the regio- and stereospecificity of phenyl-
acetylene hydrophosphorylation, the structure of the catalytically
active intermediate of the addition reaction was studied. The
fractional recrystallization of the reaction mixture allowed us to
isolate organometallic compound 2, which is characterised as
monocarbonyltri(phenylacetylene)molybdenum(0) using elemental
analysis, IR‡ and 1H NMR spectroscopy.
Here we describe the addition of diethylphosphite to phenyl-
acetylene in the presence of hexacarbonylmolybdenum(0). The
hydrophosphorylation of the alkyne proceeds under the refluxing
of a reaction mixture containing stoichiometric quantities of
phenylacetylene and diethyl phosphite in the presence of 10 mol%
Mo(CO)6 as a catalyst in an atmosphere of dry argon. The
addition of dialkylphosphites proceeds as a regio- and stereo-
specific process with the quantitative formation of a single
organophosphorus product – an internal vinylphosphonate with
the cis-disposition of hydrogen atoms relatively to the double
bond – O,O-diethyl-(Z)-2-phenylvinylphosphonate 1.
In the 1H NMR spectra of compound 2, the acetylenic hydrogen
atom displays the singlet upfield chemical shift (1.64 ppm in
For 1: 1H NMR, d: 7.95 (d, 1H, PhCH=, 3JHH-cis 8.35 Hz), 6.50 (dd, 1H,
†
2
3
=CHP, JHP 29.5 Hz, JHH-cis 8.35 Hz), 7.00–7.65 (m, 5H, Ph), 3.74 (q,
4H, 2OCH2Me), 1.27 (t, 6H, 2OCH2Me). 31P NMR, d: 2.56 (s). IR (n/cm–1):
1210 (P=O), 1650 (Ph), 1700 (C=C). MS, m/z: 240.1 (M+). Found (%):
C, 60.05; H, 7.15; P, 12.75. Calc. for C12H17O3P (%): C, 59.99; H, 7.13;
P, 12.89.
The composition and structure of phosphonate 1 were studied
1
by mass spectrometry, elemental analysis, and IR, H and 31P
For 2: IR (n/cm–1): 2036 (C=O). Found (%): C, 70.33; H, 4.15. Calc.
‡
NMR spectroscopy.†
for C25H18MoO (%): C, 69.77; H, 4.22.
Mendeleev Commun. 2005 155

, 2005, 15(4), 155–156
bond with the metal core and to phosphonate dissociation from
the coordination sphere. The coordinatively unsaturated organo-
metallics can be bound with another phenylacetylene molecule,
closing a catalytic cycle. The stereospecificity of the P–H frag-
ment addition can be caused by the template effect of transition
metal atoms.
The proposed mechanism can be proved both by the regio-
chemistry of the reaction and by the absence of bis(phos-
phonates) – the products of the addition of dialkylphosphites to
vinylphosphonates in the final reaction mixture. The previously
reported examples of dialkylphosphites towards alkynes, pro-
ceeding through the interaction of organophosphorus compounds
with transition metal complexes either proceed according to
the Markovnikoff rule7 or do not stop on the formation of the
monophosphonate, producing bis(phosphonates) independently
from the alkyne:diethylphosphite ratio.8
EtO
EtO
O
P
H
H
Mo0
Ph
HC
C
EtO
EtO
HC
Ph
O
P
C
Mo
C
Mo0
C
Ph
CH
Mo0
O
2
The above regio- and stereospecific addition of dialkyl phos-
phite to phenylacetylene in the coordination sphere of molyb-
denum(0) opens up new opportunities to the use of chromium-
group organometallic compounds in the directed synthesis of
organophosphorus compounds.
EtO
O
OEt
P
H
compound 2, 3.06 ppm in non-coordinated phenylacetylene).
The spectral characteristics of organometallic compound 2 are
in good agreement with previously reported data on an analogous
triphenylacetylene tungsten complex.5 Note that the monocar-
bonyl complexes of zero-valent chromium-group metals having
three molecules of phenyl- and diphenylacetylene earlier were
produced only from tricarbonyltrinitrile or benzyltricarbonyl
molybdenum and tungsten complexes.6 Thus, we observed the
first example of the formation of the (alkyne)3Mo(CO) complex
via the direct interaction of an alkyne with hexacarbonyl-
molydenum(0).
This work was supported by the Ministry of Education and
Sciences of the Russian Federation (grant no. ur.05.01.081),
CRDF (grant no. REC-007) and by the Academy of Sciences of
Tatarstan (grant no. 03-12).
References
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3 A. I. Kuramshin, E. S. Kuramshina and R. A. Cherkasov, Zh. Obshch.
Khim., 2001, 71, 387 (Russ. J. Gen. Chem., 2001, 71, 354).
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Sulfur Silicon Relat. Elem., 2002, 177, 1989.
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Organometallic compound 2 is an intermediate in the catalytic
hydrophosphorylation of phenylacetylene to form O,O-diethyl-
(Z)-2-phenylvinylphosphonate.
The entrance of phenylacetylene to the molybdenum coor-
dination sphere reduces the electronic density on the triple
bond. This facilitates a nucleophilic attack of the hydrophos-
phoryl compound. The primary attack of the P-nucleophile is
directed towards the terminal carbon atom of the triple bond.
It is caused by the steric hindrance of the triple bond carbon
atom connected with the phenyl ring. The terminal carbon atom
of the phenylacetylene triple bond is most electrophilic.
The addition of a phosphoryl group probably leads to the
weakening of the O,O-diethyl-(Z)-2-phenylvinylphosphonate
Received: 28th January 2005; Com. 05/2455
156 Mendeleev Commun. 2005