Reactions of phosphines with aluminum carbenoids

Full text of DOI:10.1134/S1070428011020229

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 2, pp. 295297. Pleiades Publishing, Ltd., 2011.
Original Russian Text  I.R. Ramazanov, A.V. Yaroslavova, U.M. Dzhemilev, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 2, pp. 300302.
SHORT
COMMUNICATIONS
Reactions of Phosphines with Aluminum Carbenoids
I. R. Ramazanov, A. V. Yaroslavova, and U. M. Dzhemilev
Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, Ufa, 450075 Russia
e-mail: iramazan@inbox.ru
Received March 18, 2010
DOI: 10.1134/S1070428011020229
Metal carbenoids are known as highly reactive com-
pounds that are often used as intermediates in the organic
synthesis [1, 2]. We formerly studied the reactions with
acetylenes of various structures of aluminum carbenoids
obtained in situ from CH2I2 and trialkylalanes [3–5]. It
was established that the structure of compounds obtained
and the mechanism of their formation essentially de-
pended on the nature of the substituent at the acetylene
bond. In order to elucidate the role of the nature of the
substituent at the acetylene bond we studied the transfor-
mation of organophosphorus acetylenes under the action
of the aluminum carbenoids.
The structure of the compound obtained was confirmed
by an authentic synthesis of hex-1-yn-1-yl(diphenyl)
phosphonium iodide (IIa) by the reaction of hex-1-yn-
1-yl(diphenyl)phosphine with 1 equiv of MeI without
solvent The C and H NMR spectra of thus prepared
phosphonium salt and the hydrolysis product of the reac-
tion mixture were identical.
In the 13C NMR spectrum of compound Ia a doublet of
triplets was observed at δ 14.00 ppm due to the coupling
of carbon atom with phosphorus and deuterium nuclei.
13
1
Thus it was established that the reaction of (hex-1-
yn-1-yl)diphenylphosphine with aluminum carbenoid
Et2AlCH2I led to the formation of a phosphonium salt,
and the acetylene bond was not involved into the reaction.
In this case the C–I bond in the aluminum carbenoid was
more reactive than the metal–carbon bond. Besides the
The reaction of hex-1-yn-1-yl(diphenyl)phosphine
with the obtained in situ diethyl(iodomethyl)aluminum
Et2AlCH2I [6] after treating the mixture with deu-
terium oxide afforded 1-hexynyl-(deuteromethyl)
diphenylphosphonium iodide (Iа) in a quantitative yield.
CH2I2 + R3Al
R2AlCH2I + RI
CH2Cl2, 20°C
+
_
_
2 equiv R2AlCH2I
D2O
_Al(OD)3, _RD
Ph2P
AlR2
[Ph2PCH2D]+ I
I
Ph2PX
CH2Cl2, 20°C, 30 min
X
X
Ia_Ic
(1) 2 equiv R2AlCH2I
(2) H2O
+
n-Bu
PPh2
I _
n-Bu
PPh2
Me
_Al(OH)3, _RH
IIa
1 equiv MeI
X = hex-1-yn-1-yl (а), Ph (b), n-Bu (c); R = Et, i-Bu.
295

RAMAZANOV et al.
296
phosphonium substituent evidently reduced the reactivity
of the acetylene bond by decreasing its nucleophilicity.
atmosphere of dry argon was charged 5 ml of CH2Cl2,
2 mmol of trialkylalane [Et3Al or (i-Bu)3Al], and 0.16 ml
(2 mmol) of CH2I2, and the mixture was stirred for 1 h
at 20°С. To the formed solution of the aluminum car-
benoid 2 mmol of an appropriate phosphine was added,
the reaction mixture was stirred for 30 min, then it was
hydrolyzed with 5 ml of water, and filtered. The water
layer was extracted with ethyl ether, the extract was
combined with the organic layer, dried with CaCl2, the
solvents were distilled off in a vacuum. Phosphonium salt
Ia was isolated by column chromatography on silica gel,
eluent ethyl acetate–ethanol, 2:1 v/v. Compounds Ib, Ic
were recrystallized from ethanol.
Inasmuch as the reaction with the aluminum carbenoids
proceeded exclusively at the phosphine center we studied
the behavior in this reaction of a series of phosphines
like Ph3P, Ph2PBu-n. In all events phosphonium salts
formed in the reaction with large yields independent of
the nature of the trialkylalane [Et3Al, (i-Bu)3Al] used for
the generation of the aluminum carbenoid.
Notwithstanding the presence in the reaction mixture
of iodoethane forming in the reaction of CH2I2 with R3Al
(R = Et, i-Bu) the phosphine reacted exclusively with the
aluminum carbenoid R2AlCH2I. We believe that it results
from the greater stabilization of the iodide anion in struc-
ture А that we assume to form as a result of the reaction
(Fig. 1). Actually, the quantum-chemical calculations
of structures А–D (to simplify the calculations methyl
groups were used as alkyl substituents at the aluminum)
in the basis 3-21+G* showed the energetical preference
of the iodide anion coordination at the aluminum atom.
Hex-1-yn-1-yl(deuteromethyl)diphenylphosphon-
ium iodide (Iа). Yield 94%. Viscous oily yellow fluid,
Rf 0.4 (eluent ethyl acetate–ethanol, 4 : 1 v/v). 1H NMR
spectrum, δ, ppm (Fig. 2): 0.84 t (3Н, СH3, J 7.2 Hz),
1.3–1.4 m (2H, C10H2), 1.55–1.65 m (2H, C9H2),
2.6–2.7 m (2H, C8H2), 2.89 d (2Н, СH2DP, J 14.0 Hz),
7.5–8.2 m (10Н, Ph). 13
С NMR spectrum, δ, ppm: 13.40
(C11), 14.00 d.t (C1, J 20.5, J 62.4 Hz), 20.64 (C8), 22.05
(C10), 28.94 (C9), 61.70 d (C6, 1JCP 182.3 Hz), 119.40 d
(C2, 1JCP 98.5 Hz), 123.65 d (C7, 1JCP 30.6 Hz), 130.40 d
(C4, 1JCP 14.2 Hz), 132.24 d (C3, 1JCP 12.6 Hz), 135.26 d
(C5, 1JCP 2.4 Hz). Found, %: C 55.43; I 29.11. C19H21DIP.
Calculated, %: C 55.76; I 31.01.
Thus we established that organophosphorus disubsti-
tuted acetylenes in contrast to their organosilicon analogs
under the action of the aluminum carbenoids were not
converted into compounds of cyclopropane series, but
formed phosphonium salts.
Reaction of phosphines with aluminum carbenoids.
(Deuteromethyl)triphenylphosphonium iodide
General procedure. Into a reactor cooled to 0°С under the
I _
I _
Me
_ Me
I
Al
I _
Et
P+
P+
P+
P+
Al
Me
Me
Me
D
A
B
C
Δ(Δ2r98Go)
0
38.7
42.4
40.9 kcal mol–1
Fig. 1. Calculated relative free Gibbs energy of the reaction of Ph3P with Me2AlCH2I, EtI, and MeI (3-21+G*).
11
9
11
10
3
4
3
4
9
3
4
7
9
3
4
10
8
7
6
7
6
2
2
2
2
P+
5
P+
5
P+
P+
1
5
5
8
6
8
I_
1
1
1
I_
I_
I_
D
Ic
D
Ib
D
Ia
IIa
Fig. 2. Numeration of atoms in the 1Н and 13С NMR spectra.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011

REACTIONS OF PHOSPHINES WITH ALUMINUM CARBENOIDS
297
combustion [7]. 1Н and 13С NMR spectra were registered
on a spectrometer BrukerAvance 400 (operating frequen-
cies 400 and 100 MHz respectively), internal references
TMS and CDCl3. TLC was carried out on Silufol UV-
254 plates, eluent ethyl acetate–ethanol, 4:1 v/v. The
quantum-chemical calculations were performed with
complete geometry optimization by RHF method in the
basis 3-21+G* using GAMESS software [8].
(Ib). Yield 92%. White crystals, mp 183.5–184°С.
1H NMR spectrum, δ, ppm (Fig. 2): 3.10 d (2Н, СH2DP,
J 12.8 Hz), 7.60–7.85 m (15Н, Ph). 13С NMR spectrum,
δ, ppm: 11.46 d.t (C1, J 20.0, J 57.0 Hz), 118.79 d (C2,
1JCP 88.0 Hz), 130.56 d (C4, 1JCP 12.8 Hz), 133.29 d (C3,
1JCP 10.6 Hz), 135.30 (C5). Found, %: C 56.12; I 29.70.
C19H17DIP. Calculated, %: C 56.31; I 31.32.
Butyl(deuteromethyl)diphenylphosphonium
iodide (Ic). Yield 95%. White crystals, mp 157.5–
158°С. 1H NMR spectrum, δ, ppm (Fig. 2): 0.84 t (3Н,
С9H3, J 6.0 Hz), 1.4–1.6 m (4H, C7,8H2), 2.74 d (3Н,
СH2DP, J 13.2 Hz), 3.1–3.25 m (2H, C6H2), 7.55–8.0)
m (10Н, Ph). 13С NMR spectrum, δ, ppm: 8.74 d.t (C1,
J 20.6, J 55.0 Hz), 13.61 (C9), 23.04 d (C6, 1JCP 50.6 Hz),
ACKNOWLEDGMENTS
The study was carried out under the financial support
of the Ministry of Science and Education of the Russian
Federation (grant NSh-4105.2010.3) and of the Depart-
ment of Chemistry and Material Science of the Russian
Academy of Sciences (Program no.1).
1
1
23.55 d (C7, JCP 16.7 Hz), 24.08 d (C8, JCP 4.2 Hz),
119.21 d (C2, 1JCP 84.5 Hz), 130.35 d (C4, 1JCP 12.4 Hz),
132.59 d (C3, 1JCP 10.0 Hz), 134.81 d (C5, 1JCP 3.0 Hz).
Found, %: C 53.43; I 30.24. C17H21DIP. Calculated, %:
C 53.00; I 32.94.
REFERENCES
1. Kobrich, G., Angew. Chem., Int. Ed., 1972, vol. 11, p. 473.
Hex-1-yn-1-yl(methyl)diphenylphosphonium
iodide (IIa) was obtained from 1 mmol of hex-1-yn-1-
yl(diphenyl)-phosphine and 0.14 g (1 mmol) of MeI at
20°С. Yield 97%, mp 158–158.5°С (ethanol). 13С NMR
spectrum, δ, ppm (Fig. 2): 13.41 (C11), 14.31 d (C1,
1JCP 61.2 Hz), 20.69 (C8), 22.03 (C10), 28.91 (C9),
61.81 d (C6, 1JCP 182.3 Hz), 119.42 d (C2, 1JCP 98.5 Hz),
123.68 d (C7, 1JCP 30.6 Hz), 130.44 d (C4, 1JCP 14.2 Hz),
132.25 d (C3, 1JCP 12.6 Hz), 135.33 d (C5, 1JCP 2.4 Hz).
Found, %: C 55.84; H 5.32. C19H22IP. Calculated, %:
C 55.90; H 5.43.
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Ph2PCl with the appropriate organomagnesium com-
pounds in THF. Dichloromethane before use was distilled
over P2O5. The reaction products were subjected to liquid
chromatography on a Hewlett Packard 1050 instrument
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rate 1 ml/min, UV detection at wavelength 254 nm).
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011