Reactions of trimethylsilyl isocyanate with alcohols and phenols

Article abstract of DOI:10.1023/A:1012388413957

Mono-and diphenols add to trimethyl isocyanate on heating to give the corresponding aryl urethanes. Ethanol reacts with trimethylsilyl isocyanate to give ethyl urethane and ethyl allophanate in a ratio determined by reaction conditions.

Full text of DOI:10.1023/A:1012388413957

Russian Journal of General Chemistry, Vol. 71, No. 3, 2001, pp. 325 326. Translated from Zhurnal Obshchei Khimii, Vol. 71, No. 3, 2001,
pp. 358 359.
Original Russian Text Copyright
2001 by M. Pudovik, Krepysheva, Kharitonov, A. Pudovik.
Reactions of Trimethylsilyl Isocyanate
with Alcohols and Phenols
M. A. Pudovik, N. E. Krepysheva, D. I. Kharitonov, and A. N. Pudovik
Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center,
Russian Academy of Sciences, Kazan, Tatarstan, Russia
Received December 21, 1999
Abstract Mono- and diphenols add to trimethyl isocyanate on heating to give the corresponding aryl
urethanes. Ethanol reacts with trimethylsilyl isocyanate to give ethyl urethane and ethyl allophanate in a ratio
determined by reaction conditions.
Reactions of phosphorylated isocyanates with
protic nucleophiles have been studied in detail, and
the results are summarized in [1]. These reactions are
widely and successfully used for preparation of various
organophosphorus derivatives. However, the organo-
silicon analog, trimethylsilyl isocyanate I, practically
was not involved in such reactions. It is known only
that amines add to trimethylsilyl isocyanate I to form
silylated ureas [2, 3]. At the same time, reactions of
tri- and tetraisocyanatosilanes with alcohols result in
substitution of isocyanato groups by alkoxy groups,
instead of addition [4]. Trimethylsilyl isocyanate can
be relatively simply prepared from cheap reagents
product, silylated urethane II, which under the action
of phenol transforms into the final product III. The
highest yield is attained at the ratio isocyanate : phen-
ol = 1 : 2. The reaction of isocyanate I with resorcinol
gives compound VI with two urethane fragments. In
this case the reaction probably also involves inter-
mediate formation of addition product V which is
desilylated under the action of resorcinol.
OH
OC(O)NHSiMe3
2
I + 2
OH
OC(O)NHSiMe3
[5, 6], and it shows promise for organic synthesis.
IV
V
OC(O)NH2
OSiMe3
In this work we studied the reactions of isocyanate
IV
I with phenol, resorcinol, and ethanol. Reaction of I
with phenol was performed both in a solvent and
without a solvent. In both cases the final product is
phenyl urethane III, but in the latter case its yield is
higher.
+
OC(O)NH2
OSiMe3
VI
VII
In contrast to phenols, alcohols add to isocyanate I
to give two products, alkyl urethanes and alkyl allo-
phanates, in the ratio depending on the reaction condi-
tions. Isocyanate I reacts with ethanol in toluene on
heating for several hours to give ethyl urethane IX
and ethyl allophanate XI in yields of 54 and 27%,
respectively. When the same reaction was performed
without a solvent, the yield of XI increased to 44%,
and that of IX decreased to 39%.
Me SiNCO + PhOH
[Me SiNHC(O)OPh]
3
3
I
II
PhOH
PhOSiMe3
H NC(O)OPh.
2
III
Apparently, the reaction initially yields the addition
EtOH
1
H NC(O)OEt
2
I + EtOH
[Me SiNHC(O)OEt]
IX
[Me SiNHC(O)N(SiMe )C(O)OEt]
3
I
2
2EtOH
VIII
3
3
H NC(O)NHC(O)OEt.
2
X
XI
1
070-3632/01/7103-0325$25.00 2001 MAIK Nauka/Interperiodica

3
26
PUDOVIK et al.
The first reaction stage involves addition of alcohol
Reaction of trimethylsilyl isocyanate with
ethanol. a. A mixture of 2.12 g of anhydrous ethanol
and 3.52 g of trimethylsilyl isocyanate was heated for
5 h at 100 C. The resulting crystals of XI were fil-
tered off and washed with benzene. Yield of XI 0.9 g
to the isocyanato group of I to form silylated urethane
VIII. The latter contains a labile Si N bond which is
readily cleaved under the action of excess alcohol to
form urethane IX (pathway 1). Concurrently, silyl
urethane VIII reacts with the initial isocyanate I (path- (44%), mp 189 191 C [10]. IR spectrum (KBr), ,
1
1
way 2) to give silicon-containing allophanate X. The
latter under the action of ethanol readily transforms
into allophanate XI by cleavage of the Si N bond.
These reactions can be considered as a new conveni-
ent method for generation of the urethane fragment
from hydroxyl-containing compounds. Trimethylsilyl
isocyanate does not react with acetic acid on heating
for several hours.
cm : 1695, 1740 (C=O). H NMR spectrum (DMSO-
d ), , ppm: 7.38 s (2H, NH ); 9.95 s (1H, NH). From
6
2
the mother liquor, after removal of volatiles, 0.61 g
(39%) of ethyl urethane IX was isolated, mp 48 50 C
[11].
b. A solution of 2.33 g of ethanol and 3.89 g of I
in 15 ml of toluene was heated for 7 h. The resulting
crystals of XI were filtered off and washed with ben-
zene. Yield of XI 0.61 g (27%), mp 188 190 C. From
the mother liquor, after removal of volatiles, 1.23 g
(54%) of ethyl urethane was isolated, mp 48 50 C.
EXPERIMENTAL
1
The H NMR spectra were taken on a Varian T-60
spectrometer, internal reference TMS.
REFERENCES
Phenyl urethane III. a. A mixture of 2.12 g of
phenol and 3.52 g of isocyanate I was heated for
1
2
. Shokol, V.A. and Kozhushko, B.N., Izotsianaty fos-
fora (Phosphorus Isocyanates), Kiev: Naukova Dumka,
5
h at 100 C. The resulting crystals were separated,
washed with benzene, and recrystallized from ethan-
1
992, p. 52.
ol benzene. Yield of III 1.8 g (71%), mp 149 C [7].
1
. Goubean, J. and Heubach, E., Chem. Ber., 1960,
vol. 93, no. 5, pp. 1117 1125.
IR spectrum (KBr), , cm : 1700 (C=O); 3180, 3270,
3
1
1
330, 3410 (NH ). Found, %: C 61.47; H 5.16; N
2
0.48. C H NO . Calculated, %: C 61.20; H 5.10; N
3. Neville, R.G. and McGree, J.J., Can. J. Chem., 1963,
7
7
2
0.20.
vol. 41, no. 9, pp. 2123 2129.
b. A solution of 3.36 g of phenol and 2.74 g of
4. Abe, Y., Motoyama, K., Kobayashi, T., Iwasaki, S.,
and Gunji, T., J. Chem. Soc. Jpn., 1996, vol. 69,
no. 11, pp. 969 974.
isocyanate I in 20 ml of toluene was refluxed for 7 h.
The crystals were filtered off and washed with ben-
zene. Yield of III 1.38 g (56%), mp 149 C.
5
. Voronkov, M.G., Roman, V.K., and Maletina, E.L.,
Zh. Obshch. Khim., 1979, vol. 49, no. 7, p. 1673.
m-Phenylene diurethane VI. A mixture of 2.2 g
of resorcinol and 2.3 g of trimethylsilyl isocyanate
was heated for 8 h at 110 C. The crystals that formed
on cooling were washed with ether and alcohol. Yield
6. Kozyukov, V.P., Dobrovinskaya, E.K., and Miro-
nov, V.F., Zh. Obshch. Khim., 1974, vol. 46, no. 7,
pp. 1531 1536.
of VI 0.62 g (31%), mp 188 190 C [8]. IR spectrum
7
. Scholl, R. and Kacer, F., Chem. Ber., 1900, vol. 33,
pp. 51 54.
1
(
KBr), , cm : 1690 1720 (C=O), 3180 3410 (NH ).
2
Found, %: C 48.57; H 4.08; N 14.47. C H N O .
8
8
2
4
8
9
. Gattermann, J., Lieb. Ann., 1888, vol. 244, pp. 42 48.
Calculated, %: C 49.02; H 4.08; N 14.28. Vacuum
fractionation of the mother liquor gave 0.72 g of a
mixture consisting of 1,2-bis(trimethylsiloxy)benzene
VII and an impurity of resorcinol, bp 124 127 C
. Lebedev, E.P., Baburina, V.A., and Reikhsfel’d, V.O.,
Zh. Obshch. Khim., 1975, vol. 45, no. 2, pp. 348 351.
1
0. Schroeter, G. and Lewinski, M., Chem. Ber., 1893,
10 mm), n2 1.4767 [9]. H NMR spectrum
0
1
vol. 26, pp. 2171 2174.
(
(
(
D
CHCl ), , ppm: 0.15 s (18H, SiMe ); 6.95 7.33 m
11. Schmidt, O., Chem. Ber., 1903, vol. 36, pp. 2459
3
3
4H, C H ).
2482.
6
4
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 3 2001