ADDITION OF DIALKYL HYDROGEN PHOSPHITES TO ALKENES
357
2
cyclohexylphosphonate (yield 80%), which was iden-
2-(cyclohexene)pentacarbonylmolybdenum(0),
-
tified by the H and 31P NMR spectra ( 27 ppm;
(cyclohexene)tetracarbonyliron(0), 2-(1-hexene)pen-
1
P
1.22 ppm, JPH 16.8 Hz, methine proton). The most
probable pathway of phosphonate formation is inser-
tion of the alkene double bond into the P M bond
(similarly to [3]).
tacarbonylchromium(0), 2-(1-hexene)pentacarbonyl-
molybdenum(0),
2-(1-hexene)tetracarbonyliron(0),
and 2-(1-hexene)pentacarbonyltungsten(0) were pre-
pared similarly. The complexes of Cr, Mo, and W can
be prepared not only by UV irradiation of reaction
mixtures for 5 h, but also by their refluxing for 3 4 h.
IIIb
II.
Reaction of dialkyl hydrogen phosphites with
2-(cyclohexene)pentacarbonyltungsten(0). To
a
It should be noted, however, that, when addition of
dialkyl hydrogen phosphites to alkenes is performed
in the presence of homoligand carbonyl complexes of
transition metals, the addition mechanism can be
different. Thus, the signals of IIIa and IIIb are not
observed in the 13P NMR spectra of the reaction mix-
solution of 0.5 g of 2-(cyclohexene)pentacarbonyl-
tungsten(0) in 8 ml of cyclohexene we added 0.15 ml
of dimethyl hydrogen phosphite. The mixture was al-
lowed to stand at room temperature for several days
or refluxed for 30 45 min, after which it was con-
centrated in a water-jet-pump vacuum. The crystals
that formed were filtered off, and the filtrate was con-
centrated to constant volume ( 0.08 ml). The residue,
a viscous liquid (dimethyl cyclohexylphosphonate, I),
was vacuum-distilled; bp 190 210 C (10 mm Hg). IR
tures
2-(alkene)M(CO)x (RO)2P(O)H NEt3 and
M(CO)x alkene (RO)2P(O)H NEt3.
In our opinion, the procedure involving preliminary
activation of dialkyl hydrogen phosphite by reaction
with the metal (formation of the M P bond) followed
by reaction of the alkene with the M P bond is pre-
ferable.
1
spectrum, , cm : 1250 (P=O), 1025 narrow, s
1
(P O CH3). H NMR spectrum, , ppm: 1.17 d (JHP
17.4 Hz, methine group in the cyclohexyl ring, bound
to phosphorus), 3.50 m (JHP 11.7 Hz, O-methyl
groups bound to phosphorus); low-field signals char-
acteristic of hydrogen atoms at the C=C bond are
absent. 31P NMR spectrum, P, ppm: 32 s (typical for
phosphorus atoms in alkylphosphonates). Found P, %:
16.3. C8H17O3P. Calculated P, %: 16.1.
EXPERIMENTAL
The IR spectra were taken on a Specord M-80
spectrophotometer (mulls in mineral oil). The 1H
NMR spectra were recorded on Varian Unity-300
(298.4 MHz), Bruker-100 (100 MHz), and Bruker
Gemini-200 (199.827 MHz) spectrometers at 25 C;
the chemical shift was determined relative to the sig-
nals of the residual protons of the solvents (C6D6,
CDCl3, CD3OD); the solution concentration was
0.7 1.5 wt %. The 31P NMR spectra were recorded
on Varian Unity-300 (121.4 MHz) and RYa-2303
(8 MHz) spectrometers, with 85% H3PO4 as external
reference.
The reactions with the other combinations of di-
alkyl hydrogen phosphites and cyclohexene
com-
plexes of transition metals were performed similarly.
Catalytic reaction of diethyl hydrogen phosphite
with cyclohexene in the presence of W(CO)6. A mix-
ture of 0.42 g of W(CO)6, 10 ml of cyclohexene, and
1 2 drops of triethylamine was refluxed for 1 h, 1.0
1.5 ml of diethyl hydrogen phosphite was added, and
the mixture was refluxed for an additional 3 5 h.
Then the mixture was concentrated in a water-jet-
pump vacuum. The crystalline products were filtered
off, and the filtrate was distilled in a water-jet-pump
vacuum or high vacuum. Certain amount of un-
changed diethyl hydrogen phosphite was recovered,
and diethyl cyclohexylphosphonate II, bp 195 220 C
All manipulations were performed under argon.
2-(Cyclohexene)pentacarbonyltungsten(0).
A solution of 0.5 g of W(CO)6 in a mixture of 4 ml of
THF and 4 ml of cyclohexene was irradiated with UV
light from a high-pressure mercury lamp for 5 6 h
with continuous stirring. After irradiation completion,
the mixture was concentrated by removing the solvent
in a water-jet-pump vacuum to a volume of 1.5
2.0 ml, and the precipitate was filtered off. A finely
crystalline light yellow powder was obtained, yield
46%, decomposition point 78 82 C. IR spectrum, ,
(8 mm), was isolated. IR spectrum (thin film),
,
1
1
cm : 1230 (P=O), 1040 narrow, s (P O CH2). H
NMR spectrum, , ppm: 1.23 d (JHP 17.1 Hz, methine
group in the cyclohexyl ring bound to phosphorus),
3.80 m (JHP 12.0 Hz, O-methylene groups bound to
phosphorus); low-field signals characteristic of hydro-
gen atoms at C=C bond are absent. 31P NMR spec-
trum, P, ppm: 27.8 s. Found P, %: 14.15. C10H21O3P.
Calculated P, %: 14.06.
1
cm : 1510 (coordinated C=C bond); 1990, 1970,
1
1940, 1920, 1900 (coordinated CO ligands). H NMR
spectrum, , ppm: 4.1 m, 3.8 m (coordinated CH=CH
bond).
2-(Cyclohexene)pentacarbonylchromium(0),
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 3 2001