Acyl iodides in organic synthesis: X. Reactions with triorganylsilanes and triphenylgermane

Article abstract of DOI:10.1134/S1070428007120019

Reaction of acyl iodides RCOI (R = Me, Ph) with triorganylsilanes R′₂R″SiH in toluene gives 50-60% of the corresponding triorganyliodosilanes R′₂R″SiI. Triethylsilane reacts with the same acyl iodides under solvent-free conditions to afford the corresponding aldehyde and triethyliodosilane as primary products. Triethyliodosilane undergoes subsequent transformations into hexaethyldisiloxane and triethyl(acyloxy)silane Et₃SiOCOR (R = Me, Ph). Reactions of acyl iodides RCOI (R = Me, Ph) with triphenylgermane in the absence of a solvent lead to formation of iodo(triphenyl)germane in more than 90% yield.

Full text of DOI:10.1134/S1070428007120019

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 12, pp. 1751–1753. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © M.G. Voronkov, A.A. Trukhina, L.I. Belousova, I.P. Tsyrendorzhieva, N.N. Vlasova, 2007, published in Zhurnal Organicheskoi
Khimii, 2007, Vol. 43, No. 12, pp. 1751–1753.
Acyl Iodides in Organic Synthesis: X.* Reactions
with Triorganylsilanes and Triphenylgermane
M. G. Voronkov, A. A. Trukhina, L. I. Belousova, I. P. Tsyrendorzhieva, and N. N. Vlasova
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: voronkov@irioch.irk.ru
Received May 10, 2006
Abstract—Reaction of acyl iodides RCOI (R = Me, Ph) with triorganylsilanes R′R″SiH in toluene gives
2
50–60% of the corresponding triorganyliodosilanes R′R″SiI. Triethylsilane reacts with the same acyl iodides
2
under solvent-free conditions to afford the corresponding aldehyde and triethyliodosilane as primary products.
Triethyliodosilane undergoes subsequent transformations into hexaethyldisiloxane and triethyl(acyloxy)silane
Et3SiOCOR (R = Me, Ph). Reactions of acyl iodides RCOI (R = Me, Ph) with triphenylgermane in the absence
of a solvent lead to formation of iodo(triphenyl)germane in more than 90% yield.
DOI: 10.1134/S1070428007120019
Methods have been reported previously for the syn-
thesis of trialkyliodosilanes via reactions of hexaalkyl-
disiloxanes with AlI3 [2] or with iodine and aluminum
[3], as well as by iodination of trialkylsilanes with
iodine or hydrogen iodide [4] and iodobenzene in the
presence of nickel colloid generated in situ [5]. With
a view to reveal general relations holding in reactions
of triorganylsilanes with the above iodinating agents
and acyl iodides, we examined reactions of acetyl and
benzoyl iodide with organosilicon and organogerma-
nium hydrides, Et3SiH (I), Ph3SiH (II), Me2PhSiH
(III), and Ph3GeH (IV).
triorganyliodosilanes Et3SiI (V), Me2PhSiI (VI), and
Ph3SiI (VII) in 55–65% yield (Scheme 1).
When the reaction of acetyl iodide with triethyl-
silane (I) was performed under solvent-free conditions
at 50–60°C (reaction time 14 h), we obtained a mixture
of acetaldehyde, triethylsilyl acetate, and hexaethyldi-
siloxane. The formation of acetaldehyde indicates that
the reaction shown in Scheme 1 occurs in the first
stage. However, in this case we failed to isolate tri-
ethyliodosilane (V). Its trace amount was detected in
the reaction mixture by 1H NMR spectroscopy [δ, ppm:
1.00 s (3H, CH3CH2SiI)]. The major part of Et3SiI is
converted into hexaethyldisiloxane via reaction with
water which is usually adsorbed on glass walls of the
reaction vessel (Scheme 2). The formation of hexa-
alkyldisiloxanes from trialkyliodosilanes in glass ves-
sels in the absence of moisture was observed previ-
ously by us [14] and other authors [15]. Hydrogen
iodide liberated as a result of hydrolysis was identified
using an aqueous solution of AgNO3 (as AgI).
It is known that aliphatic and aromatic carboxylic
acid chlorides react with triorganylsilanes to give tri-
organylchlorosilanes and the corresponding aldehydes
and esters and that these reactions require the presence
of a catalyst, such as AlCl3 [6, 7], palladium [8, 9] or
rhodium complexes [10], or Cr, Mo, Fe, Ni, or Co
acetylacetonate [11–13]. Unlike acyl chlorides, acetyl
iodide and benzoyl iodide were found to readily react
with triorganylsilanes R3SiH in the absence of a cata-
lyst. The reactions of acetyl iodide with silanes I–III
in toluene at 100°C in 6 h gave the corresponding
Hexaethyldisiloxane then reacts with initial acetyl
iodide to give triethylsilyl acetate and triethyliodo-
silane, as we reported previously [1] (Scheme 3).
Scheme 2.
Scheme 1.
2 Et3SiH
+
H2O
Et3SiOSiEt3 + 2 HI
R2R'SiH
+
MeCOI
R2R'SiI + MeCHO
I–III
V–VII
Scheme 3.
* For communication IX, see [1].
Et3SiOSiEt3
+
MeCOI
Et3SiOCOMe + Et3SiI
1751

VORONKOV et al.
1752
of triethyliodosilane, bp 85°C (22 mm), nD20 = 1.4948;
Benzoyl iodide reacted with triethylsilane (I) in the
1
published data [3]: bp 191°C, nD20 = 1.4948. H NMR
absence of a solvent in a similar way but under more
severe conditions (220°C, 3 h). The products were
benzaldehyde, hexaethyldisiloxane, and triethylsilyl
benzoate (Scheme 4).
spectrum: δ 0.99 ppm, s (3H, CH3CH2Si). 29Si NMR
spectrum: δSi 29.47 ppm.
b. A mixture of 3.6 g (0.02 mol) of acetyl iodide
and 2.5 g (0.02 mol) of triethylsilane was placed in
an ampule, the ampule was evacuated to a residual
pressure of 10–12 mm, and the mixture was heated for
Scheme 4.
[H2O]
2PhCOI
+
3Et3SiH
PhCHO + Et3SiOSiEt3
–2 HI
Et3SiOCOPh
1
14 h at 50–60°C. According to the H, 13C, and 29Si
+
NMR and IR spectra, the mixture contained acetalde-
hyde, triethylsilyl acetate, and hexaethyldisiloxane. IR
spectrum, ν, cm–1: 1745 (CHO), 1710 (CH3CO), 1050
By contrast, reactions of acyl iodides RCOI (R =
Me, Ph) with triphenylgermane (IV) in the absence of
a solvent at 100°C (R = Me) or 200–220°C (R = Ph)
afforded only iodotriphenylgermane (yield 91–98%)
and the corresponding aldehyde (Scheme 5).
1
(SiOSi). H NMR spectrum, δ, ppm: 0.51 q (2H,
CH2Si), 0.75 q (2H, CH2Si), 0.92 s (3H, CH3CH2Si),
1.0 s (3H, CH3CH2Si), 2.05 s (3H, CH3CO), 6.7 d (1H,
CHO). 13C NMR spectrum, δC, ppm: 4.2 (CH3CH2Si),
6.1 (CH3CH2Si), 6.2 (CH3CH2Si), 7.1 (CH3CH2Si).
29Si NMR spectrum, δSi, ppm: 8.99 (Et3SiOSiEt3),
25.36 (Et3SiOCOCH3).
Scheme 5.
RCOI
+
Ph3GeH
Ph3GeI + RCHO
R = Me, Ph.
By vacuum distillation we isolated hexaethyldi-
siloxane {bp 80–82°C (4 mm), nD20 = 1.4340; published
data [18]: bp 236.3°C (760 mm), nD20 = 1.4340. Found,
%: C 58.24; H 12.59; Si 22.53. C12H30Si2O. Calculat-
ed, %: C 58.46; H 12.27; Si 22.78} and triethylsilyl
acetate {bp 180–183°C, nD20 = 1.4180; published data
[19]: bp 173.4°C, nD20 = 1.4190}.
As with silicon hydrides, acetyl iodide reacted with
Ph3GeH more readily than did benzoyl iodide due to
positive inductive effect of the methyl group. This
reaction underlies a simple and convenient procedure
for the synthesis of iodo(triphenyl)germane. The only
previously known method for the preparation of this
compound was based on the reaction of germanium
diiodide with diphenylmercury [16] (Scheme 6).
Reaction of benzoyl iodide with triethylsilane.
A mixture of 6.0 g (0.03 mol) of benzoyl iodide and
3.0 g (0.03 mol) of triethylsilane was heated for 3 h at
Scheme 6.
1
220°C. According to the H, 13C, and 29Si NMR spec-
2 Ph2Hg
+
GeI2
Ph3GeI + PhHgI
tra, the mixture contained benzaldehyde, hexaethyldi-
siloxane, and triethylsilyl benzoate. H NMR spec-
1
The product structure was determined on the basis
1
of their elemental analyses and H, 13C, and 29Si NMR
trum, δ, ppm: 0.52 (2H, CH2Si), 0.93 s (3H, CH3CH2),
7.33–7.88 m (5H, C6H5), 8.23 q (1H, CHO). 13C NMR
spectrum, δC, ppm: 5.58 (CH3CH2), 6.74 (CH2Si),
128.73–135.51 (Carom). 29Si NMR spectrum, δSi, ppm:
8.90 (Et3SiOSiEt3), 29.82 (Et3SiOCO). Distillation
gave hexaethyldisiloxane and triethylsilyl benzoate
with bp 133–134°C (9 mm), nD20 = 1.4910; published
data [19]: bp 133°C (8 mm), nD20 = 1.4930.
and IR spectra.
EXPERIMENTAL
The IR spectra were recorded on a UR-20 spec-
1
trometer from thin films. The H, 13C, and 29Si NMR
spectra were measured on a Bruker DPX-400 spec-
trometer (400 MHz) from solutions in chloroform-d
using tetramethylsilane or hexamethyldisiloxane as
internal reference. Initial acyl iodides were prepared by
reaction of the corresponding acyl chlorides with anhy-
drous sodium iodide [17].
Reaction of acetyl iodide with dimethyl(phenyl)-
silane. A solution of 11.3 g (0.07 mol) of acetyl iodide
and 9.1 g (0.07 mol) of dimethyl(phenyl)silane in
10 ml of toluene was heated for 4 h at 90°C. The
solvent was distilled off, and the residue was distilled
under reduced pressure to isolate 5.09 g (56%) of
iodo(dimethyl)(phenyl)silane, bp 65°C (3 mm),
nD20 = 1.5656; published data [20]: bp 65°C (3 mm),
Reaction of acetyl iodide with triethylsilane.
a. Acetyl iodide, 11.8 g (0.07 mol), was added under
stirring to a solution of 8.08 g (0.07 mol) of triethyl-
silane in 10 ml of toluene, and the mixture was heated
for 6 h at 100°C. Vacuum distillation gave 9.6 g (58%)
1
nD20 = 1.5660. H NMR spectrum, δ, ppm: 0.99 s (3H,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 12 2007

ACYL IODIDES IN ORGANIC SYNTHESIS: X.
1753
CH3), 7.33–7.60 m (5H, C6H5). 29Si NMR spectrum:
δSi 0.214 ppm.
4. Voronkov, M.G. and Khudobin, Yu.I., Izv. Akad. Nauk
SSSR, Ser. Khim., 1956, no. 7, p. 805.
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Reaction of acetyl iodide with triphenylsilane.
A solution of 3.9 g (0.02 mol) of acetyl iodide and
4.0 g (0.02 mol) of triphenylsilane in 5 ml of toluene
was heated for 6 h at 100°C. The solvent was distilled
off, the residue was recrystallized from anhydrous
hexane, and the product was evacuated at a residual
pressure of 2 mm. Yield of iodo(triphenyl)silane 3.6 g
(63%), mp 154–156°C; published data [21]: mp 154–
156°C. 29Si NMR spectrum, δSi 8.78 ppm.
Reaction of acetyl iodide with triphenylgermane.
A mixture of 3.4 g (0.02 mol) of acetyl iodide and
6.1 g (0.02 mol) of triphenylgermane was heated for
4 h at 100–105°C. The precipitate was filtered off and
recrystallized from heptane. Yield of iodo(triphenyl)-
germane 8.4 g (98%), mp 156–157°C; published data
[16]: mp 157°C. Found, %: C 50.51; H 3.63; Ge 17.09;
I 29.00. C18H15GeI. Calculated, %: C 50.18; H 3.51;
Ge 16.85; I 29.46.
11. Voronkov, M.G., Pukhnarevich, V.B., Tkach, V.S., Usha-
kova, N.I., Burnashova, T.D., Tsykhanskaya, I.I., and
Rossinskaya, E.S., Zh. Obshch. Khim., 1986, vol. 56,
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skaya, I.I., Zh. Obshch. Khim., 1989, vol. 59, p. 2391.
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va, L.I., Zh. Obshch. Khim., 1990, vol. 60, p. 1584.
Reaction of benzoyl iodide with triphenyl-
germane. A mixture of 2.3 g (0.01 mol) of benzoyl
iodide and 3.0 g (0.01 mol) of triphenylgermane was
heated for 6 h at 220°C. From the reaction mixture we
isolated 3.9 g (91%) of iodotriphenylgermane and
0.8 g (76%) of benzaldehyde with bp 177–178°C, nD20 =
1.5455.
14. Voronkov, M.G., Tsyrendorzhieva, I.P., Albanov, A.I.,
Shergina, N.I., Klyba, L.V., and Dubinskaya, E.I., Russ.
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This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 05-03-32096a).
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