Synthesis and structure of novel Si-substituted silylpropyl derivatives of 2-mercaptobenzoxazole and 2-mercaptobenzothiazole

Article abstract of DOI:10.1007/s10593-019-02532-3

[Figure not available: see fulltext.] A previously unknown carbofunctional (trimethoxysilyl)propyl derivative of the 2-mercaptobenzoxazole, C₆H₄NOCS(CH₂)₃Si(OMe)₃, containing a tetracoordinated silicon atom was synthesized by nucleophilic substitution of the chlorine atom in the (3-chloropropyl)-trimethoxysilane with the benzoxazol-2-ylsulfanyl group. The reaction of 2-[(trimethoxysilyl)propylsulfanyl]benzoxazole or –benzothiazole with boron trifluoride etherate led to a previously unknown hydrolytically unstable Si-fluoropropyl derivatives of 2-mercaptobenzoxazole or 2-mercaptobenzothiazole, C₆H₄N(Y)CS(CH₂)₃SiF₃ (Y = O, S). By transesterification of 2-[(trimethoxysilyl)-propylsulfanyl]benzoxazole by tris(2-hydroxyethyl)amine, a new silatranylpropyl derivative of 2-mercaptobenzoxazole containing an intramolecular coordination bond N→Si and a pentacoordinated silicon atom, C₆H₄NOCS(CH₂)₃Si(OCH₂CH₂)₃N, was obtained.

Full text of DOI:10.1007/s10593-019-02532-3

DOI 10.1007/s10593-019-02532-3
Chemistry of Heterocyclic Compounds 2019, 55(8), 762–767
Synthesis and structure of novel
Si-substituted silylpropyl derivatives
of 2-mercaptobenzoxazole and 2-mercaptobenzothiazole
Ekaterina А. Grebneva1, Yuliya I. Bolgova1, Olga M. Trofimova1*,
Aleksander I. Albanov1, Tat'yana N. Borodina1
1 Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences,
1 Favorsky St., Irkutsk 664033, Russia; e-mail: omtrof@irioch.irk.ru
Translated from Khimiya Geterotsiklicheskikh Soedinenii,
2019, 55(8), 762–767
Submitted February 6, 2019
Accepted after revision April 3, 2019
A previously unknown carbofunctional (trimethoxysilyl)propyl derivative of the 2-mercaptobenzoxazole, C6H4NOCS(CH2)3Si(OMe)3,
containing a tetracoordinated silicon atom was synthesized by nucleophilic substitution of the chlorine atom in the (3-chloropropyl)-
trimethoxysilane with the benzoxazol-2-ylsulfanyl group. The reaction of 2-[(trimethoxysilyl)propylsulfanyl]benzoxazole or -benzo-
thiazole with boron trifluoride etherate led to a previously unknown hydrolytically unstable Si-fluoropropyl derivatives of
2-mercaptobenzoxazole or 2-mercaptobenzothiazole, C6H4N(Y)CS(CH2)3SiF3 (Y = O, S). By transesterification of 2-[(trimethoxysilyl)-
propylsulfanyl]benzoxazole by tris(2-hydroxyethyl)amine, a new silatranylpropyl derivative of 2-mercaptobenzoxazole containing an
intramolecular coordination bond N→Si and a pentacoordinated silicon atom, C6H4NOCS(CH2)3Si(OCH2CH2)3N, was obtained.
Keywords: (3-chloropropyl)trimethoxysilane, 2-mercaptobenzoxazole, 2-mercaptobenzotriazole, silatrane, trifluorosilane.
Interest in nitrogen-containing heterocycles is owed to
their widespread use in industry, agriculture, and medicine.
In particular, 2-mercapto-1,3-benzoxazole (MBO) and its
derivatives are used to protect metals from the corrosive
effects of the environment,1–4 as chelating agents in
analytical chemistry for the determination of metal ions,1
and as collectors for the selective flotation of sulfide ores in
metalurgy.5 2-Mercapto-1,3-benzothiazole (MBT) and its
derivatives are an important class of rubber vulcanization
accelerators.6,7 The MBT exhibits a high degree of
corrosion inhibition of metals and is used to protect lead,
copper, and its alloys from contact with various media.8,9
MBT is used to modify multilayered carbon nanotubes
used as a sorbent for simultaneous magnetic solid-phase
microextraction of trace amounts of copper, cadmium, and
lead ions.10,11 MBT and some of its derivatives exhibit
potential biological activity, including anti-inflammatory,
analgesic, and antibacterial.12–17
Organosilicon compounds are valuable reagents and
building blocks for other more complex structures in
organic synthesis and also occupy an important place in
polymer chemistry and materials science.18 Introducing an
organosilicon substituent containing biogenic elements into
the MBO or MBT molecule can give new properties to the
compounds interesting from the scientific and practical
point of view. We previously synthesized organosilicon
derivatives of MBO, MBT, and 2-mercaptobenzimidazole,
A–C, in which the heterocyclic fragment is linked to the
silicon atom by the methylene bridge, C6H4NYCSCH2SiR3
(Y = O, S, NH; R = OMe, F, 1/3 (OCH2CH2)3N).19 (Fig. 1).
2-(1-Silatranylmethyl)thiobenzoxazole, -benzothiazole,
and -benzimidazole have a pronounced insecticidal effect
0009-3122/19/55(8)-0762©2019 Springer Science+Business Media, LLC
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Chemistry of Heterocyclic Compounds 2019, 55(8), 762–767
2-[(trimethoxysilyl)propylsulfanyl]benzoxazole (1a) and
2-[(trimethoxysilyl)propylsulfanyl]benzothiazole (2a)21 with
BF3·Et2O leads to previously unknown Si-fluoropropyl
derivatives of MBO (compound 1b) and MBT (compound
2b) (Scheme 2).
Scheme 2
Figure 1. Organosilicon derivatives of MBO, MBT, and
2-mercaptobenzimidazole А–С.
The reaction proceeds in 1 h with the release of diethyl
ether and trimethoxyborate. By distillation under reduced
pressure, liquids 1b and 2b, which hydrolyze in air, were
isolated in 69 and 57% yields, respectively. The presence
of highly electronegative fluorine atoms at the silicon atom
in trifluorosilanes 1b and 2b indicates the possibility of the
existence of an intramolecular coordination bond N→Si,
which closes the seven-membered NCSCCCSi ring.
on rice weevil beetles (100% insect death) and houseflies
(35–45% death rate). Silatranylmethyl derivatives of MBO
and benzimidazole have a high nematocidal activity,
causing the death of 65–100% of nematodes.20
Carbofunctional MBO organosilicon derivatives and
MBT trifluoro derivative in which the heterocyclic moiety
is linked to the organosilicon substituent by a hydrocarbon
bridge (CH2)3 are little studied.
The purpose of this work is the synthesis and study of the
structure and properties of organosilicon derivatives of MBO
and MBT with the general formula C6H4NYCS(CH2)3SiR3
(Y = O, S; R = OMe, F, 1/3 (OCH2CH2)3N) containing a
tetra- or pentacoordinated silicon atom linked to sulfanyl-
benzazole with a propyl bridge (CH2)3.
A previously unknown 2-{[3-(trimethoxysilyl)propyl]-
sulfanyl}-1,3-benzoxazole (1a) containing a tetracoordinated
silicon atom was synthesized by nucleophilic substitution
of the chlorine atom of (3-chloropropyl)trimethoxysilane
by the benzoxazol-2-ylsulfanyl group (Scheme 1).
Scheme 1
It was previously shown that 2-[(trifluorosilylmethyl)-
sulfanyl]benzoxazole and 2-[(trifluorosilylmethyl)sulfanyl]-
benzothiazole (Fig. 1, structures B) are neutral penta-
coordinated silicon complexes with a five-membered
NCSCSi ring and an intramolecular N→Si coordination
bond.22
Thus,
X-ray
structural
analysis
of
C6H4NOCSCH2SiF3 (3) and C6H4NSCSCH2SiF3 (4)
molecules showed that the coordination polyhedron of the
silicon atom in the molecules is a distorted trigonal
bipyramid, in which the N–Si bond length is 1.967 Å
(compound 3) and 1.988 Å (compound 4), indicating strong
N→Si interaction. This interaction is also retained in the
CDCl3 solution, which is confirmed by chemical shifts in
the 29Si NMR spectra of compounds 3 (–105.7 ppm) and
4 (–99.1 ppm) and corresponds to the shifts of the
pentacoordinated silicon atom in the spectra of typical
related compounds.23,24 In this regard, compounds 3 and 4
can be used as reference models.
The chemical shifts in the 29Si NMR spectra of com-
pounds 1b and 2b are shifted upfield (by 46.4 and 39.9 ppm,
respectively), compared with the spectra of compounds 3
and 4 containing a pentacoordinated silicon atom. In the
19F NMR spectra of compounds 1b and 2b, chemical shifts
of 19F atoms are shifted downfield by ~ 12 ppm in
comparison with the spectra of compounds 3 and 4. The
same pattern is observed for the values of the spin-spin
coupling constants JSi–F. In the spectra of compounds 1b
and 2b, an increase in the coupling constant values is
observed (by 69 and 59 Hz, respectively) compared with
the spectra of compounds 3 and 4, which contain an
intramolecular coordination bond N→Si. That is, the
values of the chemical shifts in the spectra of compounds
1b and 2b fall within the range of chemical shifts
characteristic of tetrahedral carbofunctional silanes with the
SiF3 group, which indicates a lack of coordination of the
nitrogen atom with the silicon atom in CDCl3 solution. The
observed chemical shifts in the 29Si NMR spectra of
compounds 1b and 2b are similar to the observed chemical
shifts in the spectrum of the acyclic (3-chloropropyl)
The reaction of 2-sulfanylbenzoxazole (1) proceeds by
heating in a polar solvent (DMF) in the presence of a
dibenzo-24-crown-8 ether catalyst at 70°C for 1.5 h. The
composition and structure of the synthesized silane 1a are
confirmed by elemental analysis, IR and NMR
spectroscopy, as well as mass spectrometry. The IR
spectrum of compound 1a contains characteristic
absorption bands of the Si(OMe)3 group, as well as the
absorption bands of the corresponding heterocyclic
fragment. A chemical shift of –43.3 ppm in the 29Si NMR
spectrum of compound 1a indicates the presence of a
tetracoordinated silicon atom. The mass spectrum of
compound 1a is characterized by a low intensity molecular
ion peak with m/z 313 (3%); the peak of the [Si(OMe)3]+
ion with m/z 121 has the highest intensity (100%).
Compound 1a is the starting compound in the synthesis
of novel Si-fluoropropyl (compound 1b) and silatranyl-
propyl (compound 1c) derivatives of MBO. The reaction of
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Chemistry of Heterocyclic Compounds 2019, 55(8), 762–767
trifluorosilane Cl(CH2)3SiF3 (–59.0 ppm).25 Moreover, the
coupling constant values JSi–F in the spectra of compounds
1b and 2b are close to the value of coupling constant JSi–F
in the spectrum of the model compound (281 Hz). Thus,
trifluorosilanes 1b and 2b are compounds with
a
tetracoordinated silicon atom. In the mass spectra of
compounds 1b and 2b, there are peaks of molecular ions
with m/z of 277 (19%) and 293 (14%), respectively. In the
mass spectrum of compound 1b, the peak of the ion
[C6H4NOCSH]+ with m/z 151 has the highest intensity
(100%), the same intensity (100%) as the peak of the ion
[C6H4NSCSH]+ with m/z 167 in the mass spectrum of
compound 2b.
Figure 2. Molecular structure of compound 1c with atoms
represented as thermal vibration ellipsoids with 50% probability.
By transesterification of silane 1a by 2,2',2"-nitrilo-
triethanol, a new silatrane was synthesized, 1-[3-(1,3-
benzoxazol-2-ylsulfanyl)propyl]-2,8,9-trioxa-5-aza-1-silabi-
cyclo[3.3.3]undecane (1c), containing the intramolecular
coordination N→Si bond and a pentacoordinated silicon
atom (Scheme 3).
equals 0.197 Å. The ΔSi value is related to the N→Si bond
length: the greater the deviation of the silicon atom from
the equatorial plane of the bipyramid, the longer the N→Si
distance. The same pattern is observed in the 1-(N-heteryl-
alkyl)silatranes synthesized by us earlier.20,27–30 In molecule
1c, the interatomic distance N···Si (2.155 Å) is significantly
less than the sum of the van der Waals radii of nitrogen and
silicon atoms (3.5 Å31), but longer than the usual N–Si
bond (1.7–1.8 Å), and falls within the range of values
typical of electron-acceptor substituents at the silicon atom.
In this case, the distance between Si(1)–C(16) atoms
(1.882 Å) in silatrane 1c is shorter than the N–Si distance
by 0.273 Å. The same short interatomic N···Si distance is
also observed in silatranes Het(CH2)nSi(OCH2CH2)3N
(2.100–2.154 Å).27–30 The deviation of the nitrogen atom
∆N from the plane of the three carbon atoms framing it,
C(4), C(5), and C(6), in molecule 1c is 0.387 Å. The axial
valence angle of N(1)–Si(1)–C(16) in molecule 1c is
almost linear (179.3°) and is close to the ideal value for the
TBP (180°). The length of all endocyclic bonds in the
silatrane backbone of molecule 1c (Si–O, O–C, C–C, and
C–N) is characteristic for silatranes.18 The length of the
C(14)–S(1) bond in molecule 1c (1.828 Å) is close to the
mean values of the C–S bond (1.80 Å31). The analysis of
interatomic contacts in the crystal structure of silatrane 1c
indicates the existence of shortened interatomic contacts
between the nitrogen atom of the benzoxazole ring and the
hydrogen atom of the silatranyl fragment of the
neighboring molecule N(2)···H(3A) (2.628 Å), which is
stronger than the usual van der Waals interactions.32 The
crystalline packing of silatrane 1c is also formed due to
short contacts between the carbon atoms of the benzox-
azole cycle and the hydrogen atom of the hydrocarbon chain
C(8)···H(14B) (2.807 Å) and C(9)···H(14B) (2.752 Å).
Synthesized compounds are potentially biologically
active substances. According to the PASS program,33
compounds 1a–c and 2b possess potential antitumor
activity and can also be used in the treatment of
autoimmune disorders, rheumatoid arthritis, and other
diseases and are promising for further study of their
biological properties.
Scheme 3
OMe
N
O
S
Si OMe
OMe
1a
rt
92%
(HOCH2CH2)3N
O
N
O
S
Si
N
O
O
1c
The reaction proceeds at room temperature in the
absence of a catalyst. The resulting colorless crystalline
product 1c is highly soluble in alcohols, CHCl3, Me2CO,
DMF, and DMSO, easily sublimates under reduced
pressure. The yield of silatrane 1c is 92%. The IR spectrum
of compound 1c exhibits intense absorption bands in the
581–1127 cm–1 region, which belong to the deformation
vibrations of the silatrane skeleton. Mass spectrometry was
also used to confirm the composition and structure of
compound 1c.
A specific feature of silatrane 1c
fragmentation is the presence of an unstable molecular ion
[M]+ with m/z 366 (1%) in the mass spectrum. The main
direction of fragmentation of compound 1c is associated
with breaking of the C–Si bond in the molecular ion with
the formation of a highly stable analog of the onium ions,
[N(CH2CH2O)3Si]+, with m/z 174 (100%). The molecular
structure of silatrane 1c (Fig. 2) was established by X-ray
structural analysis, which indicates
pentacoordination of the silicon atom.
a
pronounced
Silatrane 1c exists as the endo-isomer, in which the lone
electron pair of the nitrogen atom is oriented toward the
silicon atom. The coordination polyhedron of the silicon
atom in molecule 1c as in other silatranes is a distorted
trigonal bipyramid (TBP).26 Displacement of the silicon
atom ∆Si in molecule 1c from the equatorial plane of the
bipyramid formed by three oxygen atoms O(1), O(2), and
O(3) in the direction of the axially located carbon atom
To conclude, a series of new carbofunctional organo-
silicon derivatives of 2-mercaptobenzoxazole and 2-mercapto-
benzothiazole containing trimethoxysilyl, trifluorosilyl, or
silatranyl group, in which the silicon atom is connected to
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Chemistry of Heterocyclic Compounds 2019, 55(8), 762–767
the sulfur atom of the 2-mercaptobenzazole by the propyl
bridge (CH2)3, was obtained.
(18 mg, 0.04 mmol). The reaction mixture was stirred
magnetically at 70°С for 1.5 h. The formed precipitate was
filtered, the filtrate was distilled under decreases pressure.
Yield 16.89 g (77%), light-yellow liquid, bp 165–168°С
Experimental
20
IR spectra were registered on a Varian 3100 FTIR
spectrometer in 4000–400 cm–1 range with the sample as a
(3 mmHg), nD 1.4700. IR spectrum (thin film), ν, cm–1:
811 (Si(OMe)3), 1003, 1088 (Si(OMe)3), 1126, 1238, 1305,
1453, 1500 (benzoxazole), 2841 (Si(OMe)3). 1H NMR spect-
rum, δ, ppm (J, Hz): 0.78–0.82 (2Н, m, SiCH2); 1.88–1.96
(2Н, m, CCH2C); 3.30 (2H, t, 3J = 7.2, SCH2); 3.55 (9H, s,
1
thin film or in KBr pellets. H, 13C, 15N, 19F, and 29Si NMR
spectra were acquired on a Bruker DRX-400 spectrometer
(400, 101, 41, 377, and 80 MHz, respectively) at 297 K in
1
3
3
CDCl3. For H NMR spectra, HMDSO (0.05 ppm) was
3OCH3); 7.18 (1Н, t, J5–6 ≈ J5–4 = 7.8, Н-5); 7.23 (1Н, t,
3
used as internal standard; in 13C NMR spectra, chemical
shifts were assigned relative to the residual signal of the
solvent CDCl3 (77.0 ppm), for 19F NMR spectra, CCl3F was
used as internal standard, for 15N NMR spectra, internal
standard was MeNO2. The 15N chemical shifts were
obtained using the 1H–15N HMBC-gp method of
heteronuclear inverse two-dimensional spectroscopy with a
gradient pulse, in ampoules with a 5 mm diameter at a
concentration of 0.6 mol/l. Assignments in the 13С NMR
spectra were made on the basis of literature data.34 Mass
spectra were recorded on a Shimadzu GCMS-QP5050A
mass spectrometer, injector temperature 200–250°С,
helium carrier gas, detector temperature 290°С, quadrupole
mass analyzer, EI ionization (70 eV). Chromatographic
separation of the studied compound samples was done on a
SPB-5 (60 m × 0.25 mm × 0.25 m) capillary column, helium
carrier gas, 0.7 ml/min flow, evaporator temperature 230°С,
280 kPa pressure, gradient from 60 to 250°С at 10°С/min.
Elemental analysis was performed on a Thermo Scientific
Flash 2000 CHNS-Analyzer. Fluorine content is
determined by the Schöniger titrimetric method, gravi-
metric determination of silicon content was carried out by
the literature method.35 Melting points were determined on
a Boetius heating bench.
3J6–5 ≈ J6–7 = 7.8, Н-6); 7.38 (1Н, d, 3J7–6 = 7.8, Н-7); 7.55
3
(1Н, d, J4–5 = 7.8, Н-4). 13C NMR spectrum, δ, ppm: 8.4
(SiCH2); 22.8 (CCH2C); 34.8 (SCH2); 50.3 (OCH3); 109.6
(С-7); 118.1 (С-4); 123.5 (С-6); 124.0 (С-5); 141.9 (С-3а);
151.6 (С-7а); 164.8 (С-2). 29Si NMR spectrum, δ, ppm:
–43.3. 15N NMR spectrum, δ, ppm: –145.9. Mass spectrum,
m/z (Irel, %): 313 [M]+ (3), 281 [M−S]+ (12), 266 [M–SCH2–H]+
(13), 238 [M–SCH2CH2CH2–H]+ (5), 234 [M–(OMe)2–O–H]+
(7), 208 [M–Si(OMe)2–Me] (5), 192 [M–Si(OMe)3]+ (2),
178 [M–CH2Si(OMe)3]+ (8), 165 [M–CH2CH2Si(OMe)3+H]+
(9), 151 [M–CH2CH2CH2Si(OMe)3+H]+ (51), 121 [Si(OMe)3]+
(100), 91 [Si(OMe)3–OMe+H]+ (53), 77 [Si(OMe)3–Me3+H]+
(8), 61 [Si(OMe)3–OMe–Me2+H]+ (15), 59 [Si(OMe)3–(OMe)2]+
(17). Found, %: С 49.65; Н 6.29; N 4.62; S 9.90; Si 9.35.
С13Н19NO4SSi. Calculated, %: С 49.81; Н 6.11; N 4.47;
S 10.23; Si 8.96.
2-{[3-(Trifluorosilyl)propyl]sulfanyl}-1,3-benzoxazole
(1b). BF3·Et2O (1.75 g, 12.3 mmol) was added dropwise to
2-{[3-(trimethoxysilyl)propyl]sulfanyl}-1,3-benzoxazole (1а)
(2.57 g, 8.2 mmol). The reaction mixture was stirred
magnetically at room temperature for 1 h. Distillation
under vacuum over dry KF afforded hydrolytically unstable
product 1b. Yield 1.57 g (69%), colorless liquid, bp 116–
118°С (3 mmHg). IR spectrum (thin film), ν, cm–1: 889,
948 (SiF3), 1133, 1239, 1313, 1453, 1500 (benzoxazole).
1H NMR spectrum, δ, ppm (J, Hz): 1.15–1.19 (2Н, m,
2-[(Trimethoxysilyl)propylsulfanyl]benzoxazole
(2a)
was obtained as described previously;21 its physico-
chemical characteristics mach those described in the
literature. 2-Mercaptobenzoxazole and 2-mercaptobenzo-
thiazole were commercially available (Aldrich). All
solvents were purified by standard procedures.
3
SiCH2); 2.03–2.11 (2Н, m, CCH2C); 3.31 (2H, t, J = 7.1,
SCH2); 7.19–7.23 (1Н, m, Н-5); 7.23–7.27 (1Н, m, Н-6);
3
7.40 (1Н, d, J7–6 = 7.8, Н-7); 7.57 (1Н, d, 3J4–5 = 7.6, Н-4).
13C NMR spectrum, δ, ppm: 6.0 (SiCH2); 21.3 (CCH2C);
34.0 (SCH2); 109.6 (С-7); 118.3 (С-4); 124.0 (С-6); 124.3
(С-5); 141.6 (С-3а); 151.8 (С-7а); 164.2 (С-2). 29Si NMR
spectrum, δ, ppm (J, Hz): –59.9 (1JSi–F = 278.0). 19F NMR
spectrum, δ, ppm: –136.50. 15N NMR spectrum, δ, ppm:
–145.4. Mass spectrum, m/z (Irel, %): 277 [M]+ (19), 230
[M–SCH2–H]+ (7), 165 [M–CH2CH2SiF3+H]+ (6), 151
[M–CH2CH2CH2SiF3+H]+ (100). Found, %: С 43.30; Н 3.64;
F 20.64; N 5.20; S 11.73; Si 9.83. С10Н10F3NOSSi. Calcu-
lated, %: С 43.31; Н 3.63; F 20.55; N 5.05; S 11.56; Si 10.13.
2-{[3-(Trifluorosilyl)propyl]sulfanyl}-1,3-benzothia-
zole (2b) was obtained by the same method as compound
1b from compound 2a (1.98 g, 0.006 mol) and BF3·Et2O
(1.14 g, 0.008 mol). Yield 1.00 g (57%), colorless liquid,
bp 138–139°С (3 mmHg). IR spectrum (thin film), ν, cm–1:
889, 950 (SiF3), 993, 1079, 1128, 1249, 1310, 1428, 1458
The starting (3-chloropropyl)trimethoxysilane was
produced by alkoxylation of (3-chloropropyl)trichlorosilane,
obtained according to a literature method.36 A mixture of
(3-chloropropyl)trichlorosilane (288.06 g, 1.36 mol) and
hexane (138.82 g, 1.61 mol) (1:1 volume ratio) was added
dropwise over 1 h to a solution of urea (244.76 g, 4.08 mol)
in anhydrous MeOH (130.63 g, 4.08 mol). The reaction
mixture was heated under reflux for 4 h. The upper layer
was separated and distilled. Yield 205.25 g (76%),
25
colorless liquid, bp 195°С, nD 1.4183 (bp 195°С,
nD25 1.418336).
2-{[3-(Trimethoxysilyl)propyl]sulfanyl}-1,3-benzoxa-
zole (1a). The reaction of MeONa, obtained by dissolving
Na (1.61 g, 0.07 mol) in MeOH (2.24 g, 0.07 mol), with
2-sulfanylbenzoxazole (1) (10.58 g, 0.07 mol) afforded
1,3-benzoxazole-2-thiol sodium salt (12.12 g, 0.07 mol).
(3-Chloropropyl)trimethoxysilane (13.91 g, 0.07 mol) was
added dropwise to a solution of the above sodium salt in
DMF (30 ml) in the presence of dibenzo-24-crown-8 ether
1
(benzothiazole). Н NMR spectrum, δ, ppm (J, Hz): 1.18–
1.22 (2Н, m, SiCH2); 2.05–2.12 (2Н, m, CCH2C); 3.40
(2H, t, 3J = 7.1, SCH2); 7.27–7.31 (1Н, m, Н-6); 7.40–7.44
3
(1Н, m, Н-5); 7.74 (1Н, d, J7–6 = 8.2, Н-7); 7.90 (1Н, d,
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Chemistry of Heterocyclic Compounds 2019, 55(8), 762–767
3J4–5 = 8.2, Н-4). 13C NMR spectrum, δ, ppm: 6.0 (SiCH2);
(С-6); 134.0 (С-7а); 144.2 (С-3а); 176.2 (С-2). 29Si NMR
spectrum, δ, ppm (J, Hz): –99.1 (1JSi–F = 222.0). 19F NMR
spectrum, δ, ppm: –124.12.
21.3 (CCH2C); 35.0 (SCH2); 120.9 (С-7); 121.5 (С-4);
124.3 (С-5); 126.0 (С-6); 135.1 (С-7а); 153.0 (С-3а); 165.9
(С-2). 29Si NMR spectrum, δ, ppm (J, Hz): –59.5 (1JSi–F = 280.8).
19F NMR spectrum, δ, ppm: –136.20. 15N NMR spectrum,
δ, ppm: –85.7. Mass spectrum, m/z (Irel, %): 293 [M]+ (14),
273 [M–F–H]+ (2), 260 [M−S–H]+ (2), 246 [M−SCH2–H]+
(7), 232 [M−SCH2CH2−H]+ (2), 194 [M–CH2SiF3]+ (20),
181 [M–CH2CH2SiF3+H] (15), 167 [M–CH2CH2CH2SiF3+H]+
(100), 136 [C6H4NSCSH–S+H]+ (8). Found, %: С 41.12;
Н 3.56; F 19.63; N 4.75; S 21.76; Si 9.94. С10Н10F3NS2Si.
Calculated, %: С 40.94; Н 3.44; F 19.43; N 4.77; S 21.86;
Si 9.57.
X-ray structural analysis of compound 1c for a single
crystal with linear dimensions of 0.16 × 0.13 × 0.12 mm,
grown by slow evaporation of a CHCl3 solution, was
performed on a Bruker D8 Venture diffractometer with a
Photon 100 CMOS detector (MoKα radiation, λ 0.71073 Å,
φ- and ω-scanning) at 100 K. The structure was solved with
the direct method using the Bruker SAINT software and
refined by the least-squares technique in the full-matrix
anisotropic approximation using the Bruker SHELXTL
program set for all non-hydrogen atoms.37 Absorption
correction was performed by using SADABS software.38
The positions of hydrogen atoms were calculated geo-
metrically and refined isotropically in the rigid body approxi-
mation. Main crystallographic parameters and structure
refinement results: the crystal is monoclinic, Р21/c spatial
symmetry group; a 6.613(4), b 9.914(6), c 26.189(15) Å;
α 90, β 94.69(2), γ 90°; V 1711.1(18) Å3; for a compound
with empirical formula C16H22N2О4SSi, Z 4; µ 0.283 mm–1;
a total of 35258 reflections were collected (θmax 28.0°), of
which 4125 were independent (Rint 0.0675). R1 0.0827,
wR2 0.2161 for reflections with I > 2σ(I), R1 0.0999,
wR2 0.2338 over all reflections, the quality factor at
F2 1.045, ∆ρmax / ∆ρmin 3.16/–1.02 e/Å3. The full set of
X-ray structural data for compound 1c was deposited at the
Cambridge Crystallographic Data Center (deposit ССDС
1473736).
1-[3-(1,3-Benzoxazol-2-ylsulfanyl)propyl]-2,8,9-trioxa-
5-aza-1-silabicyclo[3.3.3]undecane (1c). 2,2',2''-Nitrilo-
triethanol (0.60 g, 0.004 mol) was added with stirring to
compound 1a (1.25 g, 0.004 mol). The formed precipitate
was recrystallized from CHCl3. Yield 1.35 g (92%), white
crystals, mp 125–126°С. IR spectrum (KBr), ν, cm–1: 581,
617, 765, 909, 934, 1093, 1127 (Si(OCH2CH2)3N), 1123,
1
1452, 1498 (C–O). H NMR spectrum, δ, ppm (J, Hz):
0.56–0.60 (2Н, m, SiCH2); 1.88–1.92 (2Н, m, CCH2C);
3
3
3.31 (2H, t, J = 7.2, SCH2); 3.74 (6Н, t, J = 5.8, 3OCH2),
3
3
3
7.18 (1Н, t, J5–4  J5–6 = 7.6, Н-5), 7.23 (1Н, t, J6–7

 3J6–5 = 7.6, Н-6); 7.39 (1Н, d, J7–6 = 7.6, Н-7); 7.56 (1Н,
3
d, J4–5 = 7.8, Н-4); 2.78 (6H, t, 3J = 5.8, 3NCH2).
3
13C NMR spectrum, δ, ppm: 16.0 (SiCH2); 25.4 (CCH2C);
35.8 (SCH2); 50.9 (NCH2); 57.5 (ОCH2); 109.6 (С-7);
118.1 (С_4); 123.4 (С-6); 124.0 (С-5); 142.1 (С-3а); 151.6
(С-7а); 166.0 (С-2). 29Si NMR spectrum, δ, ppm: –68.3.
15N NMR spectrum, δ, ppm: –145.3 (N benzoxazole); –358.4
(N silatrane). Mass spectrum, m/z (Irel, %): 366 [M]+ (1), 319
[M–SCH2−H]+ (6), 281 [M−OCH2CH2–CH2CH2–CH2+H]+
(13), 266 [M−OCH2CH2–CH2CH2–CH2CH2]+ (5), 234
[M–C6H4NOC–CH2] (3), 174 [M–C6H4NOCSCH2CH2CH2]+
(100), 175 [M–C6H4NOCSCH2CH2CH2+H]+ (12), 165
The main results were obtained using the material and
technical base of the Baikal Analytical Center for
Collective Use of the Siberian Branch of the Russian
Academy of Sciences.
References
[M–CH2CH2Si(OCH2CH2)3N+H]+
[M–CH2CH2CH2Si(OCH2CH2)3N+H]+
[Si(OCH2CH2)3N–OCH2CH2]+
(3),
(16),
(3),
151
130
118
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7.44 (1Н, t, J6–5
≈
3J6–7 = 7.8, Н-6); 7.56 (1Н, t,
3J5–6 ≈ 3J5–4 = 7.8, Н-5); 7.75 (1Н, d, 3J7–6 = 7.8, Н-7); 8.05
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(SiCH2S); 119.3 (С-7); 122.0 (С-4); 126.0 (С-5); 127.7
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