2-Halo-2-organyl-4H-benzo[d][1,3,2]dioxasilin-4-ones

Article abstract of DOI:10.1007/s10593-015-1698-1

[Figure not available: see fulltext.] Original method has been developed for the preparation of previously unknown cyclic organosilicon esters of salicylic acid, containing halogen-silicon bonds. This method is based on the reaction of trimethylsilyl ester of 2-(trimethylsiloxy)benzoic acid with organylhalosilanes RR¹SiXY under mild conditions, where R, R¹ = Cl, Me, CH=CH₂, Ph; X, Y = Cl, F.

Full text of DOI:10.1007/s10593-015-1698-1

DOI 10.1007/s10593-015-1698-1
Chemistry of Heterocyclic Compounds 2015, 51(3), 295–298
2-Halo-2-organyl-4H-benzo[d][1,3,2]dioxasilin-4-ones
Sergey V. Basenko1*, Lev E. Zelenkov1
1A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences,
1 Favorsky St., Irkutsk 664033, Russia; е-mail: sv_basenko@irioch.irk.ru
Translated from Khimiya Geterotsiklicheskikh Soedinenii,
2015, 51(3), 295–298
Submitted December 10, 2014
Acccepted January 24, 2015
O
O
O
SiMe3
RR1SiX2–nYn
R= Me, CH=CH2, Ph; R1 = X = Cl; n = 0;
R= Me; R1 = CH=CH2; X = Cl; n = 0;
R= Ph; R1 = F; X = F; Y = Cl; n = 0–2
O
O
SiMe3
rt, 8–24 h
85–98%
Si R
R1
O
Original method has been developed for the preparation of previously unknown cyclic organosilicon esters of salicylic acid, containing
halogen–silicon bonds. This method is based on the reaction of trimethylsilyl ester of 2-(trimethylsiloxy)benzoic acid with organylhalo-
silanes RR1SiXY under mild conditions, where R, R1 = Cl, Me, CH=CH2, Ph; X, Y = Cl, F.
Keywords: 4H-benzo[d][1,3,2]dioxasilin-4-ones, cyclic esters, organosilicon esters, organylfluorosilanes, organylchlorosilanes, salicylic
acid.
silthiane,14 refluxing of salicylic acid and diorganyl-
Salicylic acid, its esters and other derivatives are of
dichlorosilanes in the presence of triethylamine,17
great theoretical and practical interest due to their high
biological activity and widespread medicinal use as anti-
pyridine12,15,36,37 or N-methylmorpholine,7,9,29 treatment of
salicylic acid with alkoxysilanes or chlorosilanes,5,13,16,18
inflammatory, antipyretic, analgesic, antimicrobial, anti-
interaction of silyl hydride reagents with salicylic acid,24,26
as well as the reaction of salicylic acid with divinyloxy-
diorganylsilanes10 or diorganyldicyanosilanes.8 None of
these methods allowed to successfully prepare 2-halo-
2-organyl-4H-benzo[d][1,3,2]dioxasilin-4-ones.
septic, keratolytic, and antituberculosis drugs.1–4
Organosilicon derivatives of salicylic acid, in particular
cyclic esters, 4H-benzo[d][1,3,2]dioxasilin-4-ones, have
previously attracted the interest of researchers5–18 and remain
a current topic of study.19–31 This interest is linked with the
above-mentioned useful properties of salicylic acid and its
effects modified due to organosilicon substituents. Indeed,
many applications have been proposed for such modified
4H-benzo[d][1,3,2]dioxasilin-4-ones, which are used in
medicine as active components of hygiene products,
cosmetics, and polymeric medical devices for external use
with anti-inflammatory, antimicrobial, regenerating, and
moisturizing effects.27,28,32,33 Other uses include charge
control devices in electronics,19 electrolyte components
increasing the life of rechargable batteries,21 the main
components for porous membranes in electrochemical
cells,22 ingredients of electrostatic inks,34,35 components of
olefin polymerization catalysts in chemical technology,20
composite materials (including nanocomposites),23 etc.
At the same time, cyclic organosilicon esters of salicylic
acid containing silicon–halogen bonds remain unknown,
even though the presence of halogen as a good leaving
group would offer opportunities for the functionalization of
these esters.
In the current work, we have developed a method for the
synthesis of the aforementioned compounds in 93–95%
yields by a reaction of organyltrichlorosilane with tri-
methylsilyl 2-(trimethylsiloxy)benzoate (1) (1:1 molar ratio,
20–25°С) (Scheme 1). The obtained cyclic esters 2a–c
were colorless oils or amorphous materials, soluble in the
majority of organic solvents and readily hydrolyzed under
ambient conditions.
Scheme 1
O
O
O
SiMe3
RSiCl3
O
O
Si R
Cl
SiMe3
rt, 8–24 h
93–95%
O
2a–c
1
a R = Me, b = CH=CH2, c = Ph
Our proposed method is also convenient for the
preparation of 2,2-diorganyl-4H-benzo[d][1,3,2]dioxasilin-
4-ones. Thus, the reaction of silyl ester 1 with dichloro-
methylvinylsilane (1:1 molar ratio, 20–25°С) gave
2-methyl-2-vinyl-4H-benzo[d][1,3,2]dioxasilin-4-one (3) in
96% yield (Scheme 2).
The synthesis of 4H-benzo[d][1,3,2]dioxasilin-4-ones
with alkyl, alkoxy, or aryl substituents at the silicon atom
was previously accomplished by the following methods:
treatment of salicylic acid with hexamethylcyclotri-
0009-3122/15/5103-0295©2015 Springer Science+Business Media New York
295

Chemistry of Heterocyclic Compounds 2015, 51(3), 295–298
Scheme 2
chlorofluorophenylsilane along with traces of benzoyloxy-
O
O
fluorophenylsilane. The yield of the latter was substantially
higher when the reaction duration was longer and the molar
ratio of reactants was modified.41
Cl
Cl
rt, 10–24 h
96%
O
Si
CH2
1
+
Si
H2C
Me
Even though we were unable to detect the acyclic
intermediate of the studied reaction, there is no doubt that
the reaction of silyl ester 1 begins from intermolecular
interaction of organyltrihalosilane with the carbonyl
oxygen atom of the ester moiety,40 with the formation of
organyldihalosilyl-2-(trimethylsiloxy) benzoate, which
undergoes further intramolecular interaction with the
oxygen atom of the trimethylsiloxy group, leading to the
cyclic product.
The attempts to stop the aforementioned reactions at the
stage of acyclic intermediate were not successful, nor could
these intermediates be detected by 13C, 19F, or 29Si NMR
spectroscopy. According to NMR spectroscopy data, it is
clear that only cyclic products were formed, namely, 2 halo-
2-organyl-4H-benzo[d][1,3,2]dioxasilin-4-ones.
Me
3
The reaction of the silyl ester 1 with dichlorofluoro-
phenylsilane (1:1 molar ratio, 20–25°С) after 8 h gave a
96% yield of 2-fluoro-2-phenyl-4H-benzo[d][1,3,2]dioxa-
silin-4-one (4). The formation of compound 4 under
analogous conditions was observed also with chloro-
difluorophenylsilane (reaction time 24 h, yield 98%) and,
quite remarkably, with trifluorophenylsilane (~50% yield
after 24 h and 87% yield after 126 h) (Scheme 3).
Scheme 3
We should note that the reaction of compound 1 with
tetrachlorosilane also did not stop at the stage of 2,2-di-
chloro-4H-benzo[d][1,3,2]dioxasilin-4-one: regardless of the
stoichiometry of reactants (1:1 or 1:2), the bis-product 5
was formed after 10 h at 20–25°С (Scheme 4).
Apparently, the interaction of chlorodifluorophenyl-
silanes and trifluorophenylsilanes with the the silyl ester 1
in these cases involves the participation of functional
groups of the latter, which leads to the observed products.
This assumption is supported by the very low reactivity of
trifluorophenylsilane towards trimethylsilyl esters of
carboxylic acids: no reaction products were detected after
refluxing for 7–14 h,38 while after maintaining for several
weeks the reaction mixture contained no more than 5-8%
of acyloxydifluorophenylsilane, according to 19F NMR data.
Thus, substitution of fluorine atoms with carboxyl group
was quite slow and involved only one fluorine atom.
The NMR monitoring of reaction mixtures indicated that
the reaction rates followed the order: PhSiFCl2 > PhSiF2Cl >
> SiCl4 > PhSiCl3 ≈ (CH=CH2)SiCl3 > Me(CH=CH2)SiCl2 ≈
≈ MeSiCl3 > PhSiF3. The reaction rates were apparently
dependent on the electronic effects of substituents at the
silicon atom of the starting silane (thus, the effective charge
at the silicon atom) and the nature of halogen (the Si–Hal
bond strength and polarizability).
O
Scheme 4
O
Si
O
SiCl4
O
O
1
O
rt, 10 h
90%
5
Thus, we have developed an effective approach to the
preparation of previosly known 2,2-diorganyl-4H-benzo[d]-
[1,3,2]dioxasilin-4-ones, as well as new 2-halo-2-organyl-
4H-benzo[d][1,3,2]dioxasilin-4-ones. This method allows
to obtain the indicated compounds under mild conditions in
practically quantitative preparative yields without using
any solvents or catalysts.
Experimental
IR spectra were recorded on a Specord IR 75
spectrometer in KBr (compound 5), or in thin layer (the
rest of the compounds). 1H, 13С, 19F, and 29Si NMR spectra
were acquired on a Bruker DPX 400 instrument (400, 100,
80, and 162 MHz, respectively) in CDCl3, the internal
The formation of cyclic products 2а–c in the reaction of
organyltrichlorosilanes with the silyl ester 1 was also
unexpected, because organylchlorosilanes, according to our
data* and a literature source,39 do not participate in
transsilylation reactions with trimethylsilyl derivatives of
alcohols and phenols at room temperature in the absence of
Lewis acid catalysts.
The transsilylation reactions of carboxylic acid
trimethylsilyl esters with organyltrihalosilanes are known,
although only a few examples have been described.40–42
Thus, the reaction of trimethylsilyl benzoate with
chlorodifluorophenyl silane (1:1 molar ratio, 20°С, 52 h)
gave benzoyloxydifluorophenylsilane in 90% yield, while
the reaction with dichlorofluorophenylsilane under the
same conditions after 2–3 h gave 36% of benzoyloxy-
1
standard was TMS for the H, 13С, and 29Si nuclei, and
CFCl3 for the 19F nuclei. Mass spectra were recorded on a
Shimadzu GCMS-QP5050A spectrometer, the injector
temperature was 200–250°С, the carrier gas was helium,
detector temperature 200°С, quadrupole mass analyzer, EI
ionization (70 eV). Elemental analysis (С, Н) was
performed on a FLASH EA 1112 Series instrument. The
content of halogens and silicon was analyzed according to
the method described by Gel'man.43 Melting points were
determined on a Kofler apparatus.
The reaction mixture monitoring by NMR was
1
performed by integrating the H NMR signal intensity for
*Maintaining PhOSiMe3 and PhSiCl3 in a sealed ampoule for one month
at 20–25°С.
Me3SiCl and silyl ester 1, as well as the 29Si NMR signals
296

Chemistry of Heterocyclic Compounds 2015, 51(3), 295–298
immediately after mixing, and then after every 0.5–1 h for
8–10 h.
Tetrachlorosilane, trichloromethylsilane, trichlorovinyl-
silane, trichlorophenylsilane, and dichloromethylvinylsilane
were purchased from commercial sources and purified by
2-Methyl-2-vinyl-4H-benzo[d][1,3,2]dioxasilin-4-one
(3) was obtained analogously from the silyl ester 1 and
dichloromethylvinylsilane. Reaction time 24 h. Yield 96%,
colorless oil, bp 114–116°С (2 mmHg) (bp 129–131°С
(4 mmHg)15). 1H NMR spectrum, δ, ppm: 0.44 (3H, s, CH3);
5.93–6.11 (3H, m, CH=CH2); 6.72–6.79 (1H, m, H-8); 6.88–
6.91 (1H, m, H-7); 7.25–7.35 (1H, m, H-6); 7.78–7.83 (1H,
m, H-5). 13C NMR spectrum, δ, ppm: –3.34; 117.4; 120.2;
122.4; 130.7; 132.3; 135.9; 139.2; 156.1; 159.4. 29Si NMR
spectrum, δ, ppm: –6.2.
distillation. Trifluorophenylsilane was obtained by
a
published method.44 The mixed chlorofluorophenylsilanes
PhSiF3–nCln with n = 1–2 were obtained by exchange
reaction between PhSiF3 and PhSiСl3.45 Trimethylsilyl
2-(trimethylsiloxy) benzoate (1) was synthesized according
to a published procedure.46
2-Fluoro-2-phenyl-4H-benzo[d][1,3,2]dioxasilin-4-one
(4) was obtained analogously from the silyl ester 1 and
dichlorofluorophenylsilane (method I, reaction time 8 h),
chlorodifluorophenylsilane (method II, reaction time 24 h),
or trifluorophenylsilane (method III, reaction time 126 h). Yield
96% (method I), 98% (method II), 87% (method III),
2-Chloro-2-methyl-4H-benzo[d][1,3,2]dioxasilin-4-one
(2a). A mixture of MeSiCl3 (1.49 g, 0.01 mol) and trimethyl-
silyl-2-(trimethylsiloxy) benzoate (1) (2.72 g, 0.01 mol) was
maintained at room temperature for 24 h. Distillation of the
obtained mixture gave a nearly quantitative yield of
Me3SiCl (bp 57°С), the residue (reaction product) was
purified by vacuum distillation. Yield 0.20 g (95%),
20
colorless oil, bp 143–144°С (2 mmHg), nD 1.5607. IR
spectrum, ν, cm–1: 1745 (C=O). 1H NMR spectrum, δ, ppm:
7.25–7.31 (1H, m, H-6); 7.32–7.39 (1H, m, H-8); 7.67–
7.98 (7H, m, H-5,7, H Ph). 13C NMR spectrum, δ, ppm:
117.2; 120.1; 123.4; 128.8; 132.5; 133.4; 134.5; 134.9;
136.3; 155.1; 157.4. 19F NMR spectrum, δ, ppm (J, Hz):
–130.7 (d, JFSi = 283.1). 29Si NMR spectrum, δ, ppm: –59.1.
Found, %: С 60.41; H 3.29; F 7.64; Si 10.99. C13H9FO3Si.
Calculated, %: С 59.99; H 3.49; F 7.30; Si 10.79 .
20
colorless oil, bp 104–105°С (2 mmHg), nD 1.5304. IR
spectrum, ν, cm–1: 1743 (C=O). 1H NMR spectrum, δ, ppm:
0.86 (3H, s, CH3); 6.86–7.01 (1H, m, H-8); 7.02–7.13 (1H,
m, H-7); 7.40–7.57 (1H, m, H-6); 7.85–8.00 (1H, m, H-5).
13C NMR spectrum, δ, ppm: 0.2; 116.9; 120.3; 123.6;
132.4; 136.7; 154.8; 158.6. 29Si NMR spectrum, δ, ppm: –
17.0. Mass spectrum, m/z (Irel, %): 214 [M]+ (100), 199 [M
–CH3]+ (3), 186 [M–CO]+ (5), 170 [M–COO]+ (48), 155
[M–Me–COO]+ (45), 134 (17), 120 [C6H4COO]+ (8), 92
[C6H4O]+ (28). Found, %: С 45.00; H 3.64; Cl 16.02; Si
13.16. C8H7ClO3Si. Calculated, %: С 44.76; H 3.29; Cl
16.51; Si 13.08.
4H,4'H-2,2'-Spirobis[benzo[d][1,3,2]dioxasilin]-4,4'-
dione (5) was obtained analogously from the silyl ester 1
and SiCl4. Reaction time 10 h, the product was purified by
washing with pentane, followed by drying under vacuum.
Yield 90%, colorless amorphous powder, mp 248–250°С.
1
2-Chloro-2-vinyl-4H-benzo[d][1,3,2]dioxasilin-4-one
(2b) was obtained analogously from the silyl ester 1 and
trichlorovinylsilane. Reaction time 24 h. Yield 0.21 g
(93%), colorless oil, bp 117–118°С (2 mmHg), nD20 1.5468.
IR spectrum, ν, cm–1: 1746 (C=O). H NMR spectrum, δ,
ppm: 6.98–7.04 (1H, m, H-8); 7.22–7.31 (1H, m, H-7);
7.54–7.63 (1H, m, H-6); 7.91–8.03 (1H, m, H-5). 13C NMR
spectrum, δ, ppm: 117.9; 119.3; 127.5; 131.0; 136.5; 162.6;
174.1. 29Si NMR spectrum, δ, ppm: –93.5. Found, %:
С 55.72; H 2.86; Si 9.68. C14H8O6Si. Calculated, %:
С 56.00; H 2.69; Si 9.35.
1
IR spectrum, ν, cm–1: 1745 (C=O). H NMR spectrum, δ,
3
3
ppm (J, Hz): 6.35 (1H, dd, Jcis = 14.6, Jtrans = 20.4,
2
3
SiCH=CH2); 6.65 (1H, dd, Jgem = 5.3, Jtrans = 14.1) and
2
3
6.58 (1H, dd, Jgem = 5.3, Jtrans = 20.3, SiCH=CH2); 7.16–
7.29 (4H, m, H Ar). 13C NMR spectrum, δ, ppm: 117.0;
120.2; 123.5; 125.9; 132.4; 136.4; 143.1; 154.7; 157.3.
29Si NMR spectrum, δ, ppm: –34.0. Mass spectrum, m/z
(Irel, %): 226 [M]+ (53), 198 [M–CO]+ (5), 182 [M–COO]+
(82), 181 (100), 155 [M–CH=CH2–COO]+ (24), 134 (5),
120 [C6H4COO]+ (6), 92 [C6H4O]+ (39). Found, %:
С 48.07; H 3.07; Cl 15.43; Si 12.38. C9H7ClO3Si.
Calculated, %: С 47.69; H 3.11; Cl 15.64; Si 12.39.
This work received financial support from the Grants
Council of the President of the Russian Federation (grant
NSh-3649.2014.3). The main results were obtained by
using the instruments at the Baikal Analytical Collective
Use Center of the Siberian Branch of the Russian Academy
of Sciences.
The autors would like to acknowledge the assistance by
I. A. Gebel' and D. A. Shabalin in performing this work.
2-Chloro-2-phenyl-4H-benzo[d][1,3,2]dioxasilin-4-one
(2с) was obtained analogously from the silyl ester 1 and
trichlorophenylsilane. Reaction time 24 h. Yield 0.26 g
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