Three-step pathway towards bis(1,2,3-triazolyl-γ-propylsilatranes) as Cu2+ fluorescent sensor, via 'Click Silylation'

Article abstract of DOI:10.1016/j.tetlet.2014.03.043

A series of substituted aniline derivatized bis(1,2,3-triazolyl-γ- propylsilatranes) 3a-3f were designed in good yield from their triethoxysilane analogues via Cu(I) 'Click Silylation'. All the silatranes 3a-3f were characterized by IR, NMR (¹H, ¹³C) and HRMS studies. All these compounds were explored for their thermal stability by thermogravimetric analysis (TGA)/differential thermal analysis (DTA)/differential scanning calorimetry (DSC) study and electronic properties by UV-vis spectroscopy and fluorescence study. The binding of silatranes 3a-3f to Cu²⁺ ion proves them to be good chemosensor. These silatranes were subjected to time dependent hydrolysis under normal atmospheric conditions. IR spectroscopic data support hydrolytic instability of 3a, 3c and 3e.

Full text of DOI:10.1016/j.tetlet.2014.03.043

Tetrahedron Letters 55 (2014) 2551–2558
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Three-step pathway towards bis(1,2,3-triazolyl-c-propylsilatranes)
as Cu2+ fluorescent sensor, via ‘Click Silylation’
⇑
Gurjaspreet Singh , Jandeep Singh, Satinderpal Singh Mangat, Aanchal Arora
Department of Chemistry and Centre of Advanced Studies, Panjab University, Chandigarh 160014, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of substituted aniline derivatized bis(1,2,3-triazolyl-c-propylsilatranes) 3a–3f were designed in
Received 10 February 2014
Revised 6 March 2014
Accepted 7 March 2014
Available online 17 March 2014
good yield from their triethoxysilane analogues via Cu(I) ‘Click Silylation’. All the silatranes 3a–3f were
characterized by IR, NMR (1H, 13C) and HRMS studies. All these compounds were explored for their ther-
mal stability by thermogravimetric analysis (TGA)/differential thermal analysis (DTA)/differential scan-
ning calorimetry (DSC) study and electronic properties by UV–vis spectroscopy and fluorescence study.
The binding of silatranes 3a–3f to Cu2+ ion proves them to be good chemosensor. These silatranes were
subjected to time dependent hydrolysis under normal atmospheric conditions. IR spectroscopic data sup-
port hydrolytic instability of 3a, 3c and 3e.
Keywords:
Bis-silatrane
Click Silylation
[Cu(PPh3)3Br]
Fluorescence
Cu2+ sensing
Hydrolysis study
Ó 2014 Elsevier Ltd. All rights reserved.
Silatranes have always been of great interest due to the spatial
arrangement of atoms,1 particularly nitrogen lone pair donation
generating hyper-coordination at silicon centre.2 Silatranes are sil-
icon caged cyclic ethers packed in trigonal bipyramidal geometry
and synthesized by transetherification reaction of ‘water-sensitive’
organotriethoxysilanes.1,3 The variation of axial substituents con-
siderably affects the properties of silatranes and enhances their
use in various bio-medical applications.4 Silicon once embedded
in this position becomes unavailable for ‘water molecules’ to dis-
rupt the structure and hence finds more practical applications than
their precursor organotriethoxysilanes.5 The constant appreciation
received by organosilatranes has attracted the interest of modern
chemists to modify exocyclic fragment6 with differently substi-
tuted aromatic and alkyl chain linkers. But so far to the best of
our knowledge, no silatrane with 1,2,3-triazole bound aromatic
linkage has been reported in the literature. So, we herein report
material chemistry.12 The chemoselective coupling accompanied
by the versatile functional group tolerance for alkyne–azide entities
has made it a modular synthetic reaction. We have applied this
approach for the synthesis of silatranes by cycloaddition reaction
of substituted aromatic amine based terminal alkynes13 with
c
-azidopropyltriethoxysilane.14,15 This combination of different
synthetic moieties results into hybrid materials that can merge to-
gether the advantages of standard synthetic polymers to advanced
biological applications; for example the ratiometric fluorescent
sensing of Cu2+ by using the synthesized triazolyl silatranes.
Fluorescent chemosensors monitor electronic changes upon
binding of the compound to a specific guest.16 The essentiality of
copper among heavy metals for organisms makes it a vital element
to play a major role in biological processes.17 However, prolonged
exposure to high concentrations of copper has been known to
cause major physiological disorders in organisms and increases
toxicity in environment.18 In the past few years, the approach to
develop highly sensitive fluorescent probes towards different hea-
vy metal ions has received considerable attention.19 The general
affinity of amine ligands20 for transition metal ions encouraged
us to synthesize aniline based 1,2,3-triazolyl silatranes as metal
first bis(1,2,3-triazolyl-c-propylsilatranes) linked to primary aro-
matic functionalities via copper(I) catalysed alkyne–azide cycload-
dition (CuAAC).
The modification of Huisgen 1,3-dipolar reaction by Sharpless7
and Meldal8 using Cu(I) salts has promoted its use in selective, effi-
cient and versatile chemical reactions. The irreversible ligation9 of
two reactive molecular fragments to exceptionally stable 1,2,3-tri-
azole10 widens the scope of this methodology to medicine11 and
ion chemosensors. For this study, we used chloride salts of Cu2+
Ni2+, Ag+ and Ru+ to evaluate metal ion binding at concentration
,
of 100 lM. The competitive studies indicate our system to be fit
for Cu2+ sensing.
Silatranes 3a–3f were synthesized by a three-step route involv-
ing ‘Click Silylation’14b as azide–alkyne fragment linker. To begin
⇑
Corresponding author. Tel.: +91 0172 2534428.
E-mail address: gjpsingh@pu.ac.in (G. Singh).
http://dx.doi.org/10.1016/j.tetlet.2014.03.043
0040-4039/Ó 2014 Elsevier Ltd. All rights reserved.

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G. Singh et al. / Tetrahedron Letters 55 (2014) 2551–2558
with, the synthesis of terminal alkynes 1a–1f was carried out by
nucleophilic substitution reaction of substituted aromatic amines
with 30% excess mole of 80% propargyl bromide solution, followed
by the use of [Cu(PPh3)3Br] in THF/TEA [1:1] reaction system to
both o- and p-isomers was negligible on aliphatic protons while
minimal shifting of triazole-H singlet was observed. In case of
13C NMR spectra, the major shift was observed for C4 carbon of
1,2,3-triazole as it appeared in the region of d ꢀ 130.9–
128.4 ppm. The methylene carbon of propyl chain attached to sili-
con atom appeared as the most shielded carbon atom, which was
identified around d ꢀ 7.0–6.0 ppm for triethoxysilanes and
d ꢀ 13.0–12.0 ppm for silatranes. This downfield shift of methylene
carbon clearly indicates the hypervalency at silicon atom. Other
peaks due to –CH2CH2N3 were observed in the region d ꢀ 25.1–
24.7 ppm and d ꢀ 43.6–41.8 ppm, respectively. No significant ef-
fect of positional isomers was evident.
stitch alkynes 1a–1f with
c-azidopropyltriethoxysilane (AzPTES)
resulting into substituted 1,2,3-triazolyl triethoxysilanes 2a–2f.
The final step of atrane ring formation was proceeded by azeotro-
pic refluxing of 1:2 solution of 2a–2f and triethanolamine in tolu-
ene using catalytic amounts of KOH, yielding dull white powdered
solid compounds 3a–3f.21 These silatranes 3a–3f were found to be
stable towards hydrolysis under atmospheric conditions with the
exception of 3c and 3e which are highly moisture sensitive there-
fore requiring inert conditions for handling.
Vibrational spectroscopic data for silatranes 3a–3f were re-
corded as neat spectra in the range 4000–400 cmÀ1. The sharp
absorption bands at 2960–2800 and 1650–1450 cmÀ1 were due
to aromatic conjugation in the aniline ring and the 1,2,3-triazole
ring. The flat region between 2300 and 2100 cmÀ1 proved com-
plete conversion of triple bonded moieties to the 1,2,3-triazole
ring, thereby proving high yield of the reaction. The transannular
N ? Si bond was marked by the presence of sharp peak for all
silatranes 3a–3f in the region 760–740 cmÀ1. Upon examination
of the effects of various positional isomers on silatrane cage, it
was evident that asymmetric shifts corresponding to OASi and
N ? Si bonds increase in case of p-isomeric substituents while
the absorption frequency lowers down substantially for o-isomer
to cope with the expected change.
Photophysical properties
Aromatic compounds are among the most absorbing chro-
mophores due to low lying p-orbitals thus giving rise to rapid elec-
tronic transitions. The isomeric substituents strongly affect these
transitions which were clearly observed upon irradiation of com-
pounds 3a–3f with electromagnetic radiations in UV–vis region
and recording the absorption spectra in CHCl3 as shown in Fig. 1.
Considering 3a, an unsubstituted aniline based 1,2,3-triazolylsila-
tranyl moiety, with kmax at 298 nm, the absorption spectra for
silatranes 3b–3f were compared. The substitution of the aniline
ring with various electronegative groups at p-position such as –F
(3c), –Cl (3d) was found to have red shift of 20 nm with kmax value
at 308 nm; whereas –OMe at o-position (3e) absorbed at kmax of
279 nm showing blue shift of 19 nm while its p-isomer (3f) ab-
sorbed at kmax of 316 nm. The compound 3b was absorbed at kmax
of 252 nm which was exceptionally lower in comparison to that for
3a. This remarkable activating and deactivating properties of dif-
ferent groups regulate fundamental properties of silatranes at elec-
tronic level.
NMR (1H, 13C) spectra recorded for compounds 3a–3f in CDCl3
and DMSO-d6 at 25 °C were found to be well in agreement with
the synthesized products. The successful azide–alkyne cycloaddi-
tion reaction in 1H NMR was marked by the appearance of sharp
singlet in the region d ꢀ 7.6–7.2 ppm and complete disappearance
of peak that may arise from terminal alkyne moiety. Moreover, a
major shift of –N3CH2 triplet from d ꢀ 4.2–3.2 ppm is attributed
to 1,2,3-triazole formation. The close inspection of 1H NMR spectra
of silatranes reveals that protons on the carbon nearest to the sil-
icon atom are displayed as a multiplet with upfield shift and meth-
ylene protons linked with nitrogen appeared as a triplet with
relative downfield shift. The effect of different substituents having
The photonic properties of newly synthesized silatranes were
explored for fluorescence activity, as it is one of the most impor-
tant properties of substituted aromatic functionalities. For a prac-
tical approach, the effect of concentration change in fluorescence
emission spectra was recorded using MeOH as solvent media.
There was substantial variation in emission maxima peak for
2.0
1.6
1.2
0.8
0.4
0.0
3f: 316nm
3e: 279nm
3d: 308nm
3c: 308nm
3b: 252nm
3a: 298nm
200 225 250 275 300 325 350 375 400 425 450 475 500 525
Wavelength (nm)
Figure 1. UV–vis spectra of synthesized silatranes 3a–3f.

G. Singh et al. / Tetrahedron Letters 55 (2014) 2551–2558
2553
500
450
b
600
550
500
450
400
350
300
250
200
150
100
50
a
400
350
300
Concentration increase
Concentration increase
250
200
150
100
50
0
0
-50
-50
325 350 375 400 425 450 475 500 525 550 575 600
300 325 350 375 400 425 450 475 500 525 550 575
Wavelength (nm)
Wavelength (nm)
900
800
700
600
500
400
300
200
100
0
600
c
d
500
400
300
200
100
0
Concentration Increase
Concentration Increase
-100
300
325
350
375
400
425
450
475
500
525
550
300 325 350 375 400 425 450 475 500 525 550 575 600
Wavelength (nm)
Wavelength (nm)
500
450
400
350
300
250
200
150
100
50
900
800
700
600
500
400
300
200
100
0
e
f
Concentration Increase
Concentration Increase
0
300 325 350 375 400 425 450 475 500 525 550 575 600
350 375 400 425 450 475 500 525 550 575 600
Wavelength (nm)
Wavelength (nm)
Figure 2. Fluorescence spectra of bis(1,2,3-triazolyl-c-propylsilatranes) 3a–3f carried out in MeOH at concentration of 100 lM with kex = 310 nm for 3a, 3b, 3d and 3f,
kex = 300 nm for 3c and kex = 330 nm for 3e.
different silatranes that resulted from the substituent’s positional
isomerization, that is 3a at 343 nm, 3b at 405 nm, 3c and 3d at
358 nm, 3e at 435 nm and 3f at 365 nm (Fig. 2). The increased
intensity and red shift in wavelength were clearly evident on
the substitution of 3a with –F, –Cl, –OMe (-o and -p isomer),
depending upon a decrease in electronic movement due to differ-
ent electron withdrawing groups attached. The red shift of 15 nm
both in case of 3c (–F) and 3d (–Cl) compared to 3a was observed.
The fluorescence yield increased with an increase in concentra-
tion till saturation, after which the intensity began to decrease

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G. Singh et al. / Tetrahedron Letters 55 (2014) 2551–2558
400
350
300
250
200
150
100
50
500
a
b
400
Increase in
Cu2+ concentration
Increase in
Cu2+ concentration
300
200
100
0
0
-100
-50
325
350
375
400
425
450
475
500
525
550
575
250 275 300 325 350 375 400 425 450 475 500 525 550
Wavelength (nm)
Wavelength (nm)
600
500
400
300
200
100
0
700
600
500
400
300
200
100
0
d
c
Increase in
Cu2+ concentration
Increase in
Cu2+ concentration
-100
325 350 375 400 425 450 475 500 525 550 575 600
300 325 350 375 400 425 450 475 500 525 550
Wavelength (nm)
Wavelength (nm)
500
450
400
350
300
250
200
150
100
50
800
700
600
500
400
300
200
100
0
e
f
Increase in
Increase in
Cu2+ concentration
Cu2+ concentration
0
-50
-100
-100
300 325 350 375 400 425 450 475 500 525 550 575 600
350 375 400 425 450 475 500 525 550 575 600
Wavelength (nm)
Wavelength (nm)
Figure 3. Quenching spectral response of silatranes 3a–3f towards Cu2+ with red shift of 2–3 nm on addition of 5 equiv of CuCl soln. in MeOH.
gradually with a further increase in concentration. This decrease
can be attributed to self quenching phenomenon in high concen-
trations of silatranes resulting from aggregation of the molecules.
Further investigation of silatranes 3a–3f to act as metal ion
chemosensors was explored for Cu2+, Ni2+, Ag+ and Ru+ using their
chloride salts and found to have remarkable sensing towards
pounds 3a–3f in MeOH with 5 equiv of Cu2+ (Fig. 3). On addition
of CuCl2, a strong and efficient quenching resulted into red shift
of 2–3 nm for all silatranes 3a–3f. The quenching in fluorescence
spectra was due to the binding of Cu2+ with –N– of aniline and
the triazole ring.22 This unique behaviour of all silatranes 3a–3f
makes them different in the class of fluorescent Cu2+
chemosensors.
Cu2+. The titration was performed using 100
lM solution of com-

G. Singh et al. / Tetrahedron Letters 55 (2014) 2551–2558
2555
50
45
40
35
30
25
20
15
10
5
Time dependent hydrolysis
3f
3e
3d
3c
3b
3a
0
10
20
30
40
50
60
70
80
90
100
Time (min)
Figure 4. Rate of hydrolysis plotted as moisture absorbed in
sample at the beginning and W2 is final weight of sample.
l
mols for silatranes 3a–3f against time; mols of water absorbed = (W2ÀW1)/18; where W1 is initial weight of
300 min
Compound 3c
120 min
60 min
30 min
10 min
5 min
2 min
1 min
0 min
moisture
absorption
500
1000
1500
2000
2500
3000
3500
4000
-1
Wavenumber (cm )
Figure 5. Hydrolysis behaviour of hydrolysed silatrane 3c as monitored by IR spectroscopy with time.
silatranes 3a–3f. The onset for transition started at near 70–
Thermal behaviour
100 °C and then it varied randomly for different silatranes thereby
proving distinguished behaviour of silatranes with change in aro-
matic substituent moiety.
Compounds 3a–3f were subjected to elevated temperature for
response to thermal stability and investigation of temperature
dependent decomposition pattern. TGA/DTA/DSC curves follow a
vivid pattern for every different compound thereby indicating un-
ique behaviour of silatranes at the molecular level of packing. TGA/
DTA studies reveal a uniformity in pattern of decomposition in the
temperature range of 320–400 °C for all the silatranes synthesized
but the disintegration temperature varies for different silatranes.
The thermal transformations for compounds 3a–3f begins at lower
temperature and show major decomposition at near 400 °C. DSC
curves also followed the similar pathway for phase changes in all
Hydrolytic stability study
The hydrolytic stability of compounds 3a–3f was studied under
normal atmospheric conditions. It was found that 3c and 3e hydro-
lysed rapidly within few minutes on exposure to air, while 3a
gained moisture to a little extent and 3b, 3d and 3f resisted mois-
ture attack. This gain of water molecules from atmospheric air with
time was studied and plotted to observe the amount of water ab-

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G. Singh et al. / Tetrahedron Letters 55 (2014) 2551–2558
120 min
60 min
40 min
20 min
10 min
(Compound 3e)
5 min
2 min
1 min
0 min
moisture
absorption
500
1000
1500
2000
2500
3000
3500
4000
Wavenumber (cm-1)
Figure 6. Hydrolysis behaviour of hydrolysed silatrane 3e as monitored by IR spectroscopy with time.
(EtO)3Si
(EtO)3Si
Cl
q
NH2
aI
a II
X
X
q
N3
N
b
1a-1f
X
q
X
q
3a: q = 0, X = H
3b: q = 1, X = H
3c: q = 0, X = p-F
3d: q = 0, X = p-Cl
N
N
N
c
N
3e: q = 0, X = o-OCH3
3f: q = 0, X = p-OCH3
N
N
N
N
N
N
O
N
N
N
N
S
O
i
Si
Si(OEt)3
O
(EtO)3Si
O
O
O
N
N
2a-2f
3a-3f
Scheme 1. Synthesis of silatranes 3a–3f. Schematic synthetic elaborationa: aReagents and conditions: (aI) propargyl bromide (1.3 equiv/aniline derivative), K2CO3 (5 equiv/
aniline derivative), DMF, 16 h. (aII) ClPTES (1.0 equiv), sodium azide (5 equiv/ClPTES), DMF, 4 h, 80 °C; (b) AzPTES (2 equiv/1a–1f), Cu(PPh3)3Br (0.01 equiv), Et3N (3 equiv/1a–
1f), THF (3 equiv/1a–1f), 10 h, 60 °C; (c) triethanolamine (2 equiv/2a–2f), KOH (cat. amt.), toluene, 111 °C, 12 h.
sorbed. For this study, 2 mg of each compound 3a–3f was taken on
a dry aluminium lid under inert atmosphere, spread uniformly and
exposed under atmospheric conditions. It was observed that silatr-
IR spectra of hydrolysed silatranes 3c (Fig. 5) and 3e (Fig. 6) with
time provide additional information regarding stability of silatrane
cage towards hydrolysis by the core existence of transannular
N ? Si bond which is clearly marked by the sharp and intense
absorption bands in the region of 700–500 cmÀ1. Moreover, to
our surprise only 3c and 3e gained sufficient moisture to become
jelly like material and insoluble in all organic solvents. The plausi-
ble explanation for this observation can be the tendency of
compounds 3c and 3e to form extensive intermolecular hydrogen
bonding with –F and ortho –OCH3 on interaction with water
molecules while others lack this ability and hence are inert to these
conditions. Therefore, the presence of inert atmosphere was
anes 3a, 3c and 3e gained 10, 44 and 43
lmols of water as moisture
respectively. The plot of mols of water absorbed versus time be-
l
comes a constant curve after 100 min (Fig. 4). Further, it was evi-
dent from these studies that the percentage moisture gain was
dependent on surface area of sample exposed per given mass of
sample and relative humidity of air under which experiment was
carried out.
This fact was well proven and supported by the Infrared Spec-
troscopy technique which clearly indicated water gain with time.

G. Singh et al. / Tetrahedron Letters 55 (2014) 2551–2558
2557
18. Alies, B.; Renaglia, E.; Rozga, M.; Bal, W.; Faller, P.; Hureau, C. Anal. Chem. 2013,
85, 1501–1508.
19. (a) Arduini, M.; Marcuz, S.; Montolli, M.; Rampazzo, E.; Mancin, F.; Gross, S.;
Armelao, L.; Tecilla, P.; Tonellato, U. Langmuir 2005, 21, 9314–9321; (b) He, X.;
Zhang, P.; Lin, J. B.; Huynh, H. V.; Munoz, S. E. N.; Ling, C. C.; Baumgartner, T.
Org. Lett. 2013, 15, 5322–5325.
20. (a) Andoa, M.; Swartb, C.; Pringsheimb, E.; Mirskyb, V. M.; Wolfbeis, O. S. Sens.
Actuators, B 2005, 108, 528–534; (b) Hicks, J. C.; Jones, C. W. Langmuir 2006, 22,
2676–2681.
mandatory to preserve the compounds 3a, 3c and 3e to explore its
further reactivity.23
We have successfully synthesized and characterized bis
(1,2,3-triazolyl-c-propylsilatranes) 3a–3f via CuAAC reaction. The
fluorescent activity and efficient ratiometric sensing of Cu2+ ions
by these bis-silatranes are reported for the first time, to the best
of our knowledge. On exploration for the sensitivity of silatranes
3a–3f towards moisture, 3b, 3d and 3f were found to be resistant
towards hydrolysis whereas 3b was moderately hydrolysed. The
effects of positional isomers and electronegative atoms on fluores-
cence quenching and hydrolytic ability proved the variability of
this reaction in diverse environments (Scheme 1).
21. General procedure for the synthesis of bis(1,2,3-triazolyl-
c-propylsilatranyl)
complexes (3a–3f): To uniformly stirred solution of triethanolamine
a
(2 equiv) and potassium hydroxide (cat. amt.) in toluene, was slowly added
di-substituted triethoxysilanes 2a–2f dropwise within 2 min. The mixture was
refluxed at 111 °C for 12 h and allowed to cool at room temperature. The
volume of solvent mixture was reduced to 2 ml by vacuum evaporation and on
addition of 10 ml of n-pentane, dull white coloured solid separated out. The
solid so obtained was stirred for 2 h, filtered and washed with 2 Â 5 ml n-
pentane to afford silatranes 3a–3f.
Acknowledgments
3a: N,N-Bis((1-(3-(2,8,9-trioxa-5-aza-1-silatranyl)propyl)-1H-1,2,3-triazol-4-
yl)methyl)benzenamine. A procedure as above was used. The quantities used
were as follows: 2a (1.0 g, 1.51 mmol), triethanolamine (0.45 g, 3.01 mmol)
and toluene (50 ml). Yield: 85% (0.88 g, 1.28 mmol). Mp = 156 °C. IR (neat):
2928, 2872, 1667, 1597, 1505, 1453, 1350, 1275, 1211, 1171, 1121, 1085, 1047,
We thank the University Grant Commission (U.G.C.) for the
financial support. We also thank Mr. Avtar Singh for the NMR
and Mr. Anoop Patyal for HRMS studies (SAIF, Panjab University,
Chandigarh).
1013, 909, 750, 691, 615, 580 cmÀ1 1H NMR (300 MHz, CDCl3, 25 °C): d = 7.35
.
(s, 2H), 7.10 (dd, J = 15.1, 7.8 Hz, 2H), 6.81 (d, J = 8.0 Hz, 2H), 6.62 (dd, J = 15.0,
7.8 Hz, 1H), 4.57 (s, 4H), 4.26–4.04 (m, 4H), 3.67 (t, J = 5.8 Hz, 12H), 2.74 (t,
J = 5.8 Hz, 12H), 1.91–1.80 (m, 4H), 0.38–0.17 (m, 4H). 13C NMR (75 MHz,
CDCl3, 25 °C): d = 147.25, 143.64, 128.18, 127.34, 121.10, 116.30, 112.43, 56.28,
52.11, 49.69, 45.38, 25.33, 12.16. Empirical formula: C30H47N9O6Si2: MS (EI) m/
z 710 (16), 709 (46), 708 (100), 686 (47), 475 (16), 371 (18), 362 (33), 172 (14),
150 (26), 132 (11), 105 (17). HRMS (ES+) Calcd for [M+Na]+ 708.3086; Found
708.3068. Anal. Calcd: C, 52.5; H, 6.9; N, 18.4; Found: C, 52.5; H, 7.0; N, 18.5.
3b: N,N-Bis((1-(3-(2,8,9-trioxa-5-aza-1-silatranyl)propyl)-1H-1,2,3-triazol-4-
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.tetlet.2014.03.
043.
yl)methyl)(phenyl)methanamine.
A procedure as above was used. The
quantities used were as follows: 2b (1.0 g, 1.48 mmol), triethanolamine
(0.44 g, 2.95 mmol) and toluene (50 ml). Yield: 82% (0.85 g, 1.21 mmol). Mp
>200 °C. IR (neat): 2966, 2926, 2868, 1654, 1599, 1493, 1452, 1373, 1343, 1152,
References and notes
1107, 1048, 963, 879, 741, 698, 544 cmÀ1 1H NMR (300 MHz, CDCl3, 25 °C):
.
1. (a) Puri, J. K.; Singh, R.; Chahal, V. K. Chem. Soc. Rev. 2011, 40, 1791–1840; (b)
Corey, J. Y. Chem. Rev. 2011, 111, 863–1071; (c) Sidorkin, V. F.; Pestunovich, V.
A. Organometallics 2001, 20, 927–931.
2. Kovacs, I.; Matern, E.; Sattler, E.; Anson, C. E.; Parkanyi, L. J. Organomet. Chem.
2009, 694, 14–20.
d = 7.52 (s, 2H), 7.27 (dd, J = 15.9, 8.0 Hz, 4H), 7.17–7.12 (m, 1H), 4.29–4.15 (m,
4H), 3.72–3.64 (m, 12H), 3.63–3.47 (m, 6H), 2.74 (t, J = 5.8 Hz, 12H), 1.99–1.79
(m, 4H), 0.42–0.26 (m, 4H). 13C NMR (75 MHz, CDCl3, 25 °C): d = 144.11,
139.21, 129.02, 128.23, 126.85, 122.93, 59.21, 57.43, 56.79, 53.14, 50.85, 47.52,
26.28, 13.05. Empirical formula: C31H49N9O6Si2: MS (EI) m/z 722 (22), 701 (38),
700 (76), 475 (20), 443 (24), 442 (100), 301 (31), 279 (14), 102 (5). HRMS (ES+)
Calcd for [M+H]+ 700.3422; Found 722.3404. Anal. Calcd: C, 53.2; H, 7.1; N,
18.0; Found: C, 53.3; H, 7.0; N, 18.1.
3. Dumitriu, A. M. C.; Cazacu, M.; Shova, S.; Turta, C.; Simionescu, B. C. Polyhedron
2012, 33, 119–126.
4. (a) Pukhalskaya, V. G.; Kramarova, E. P.; Kozaeva, L. P.; Korlyukov, A. A.; Shipov,
A. G.; Bylikin, S. Y.; Negrebetsky, V. V.; Poryadin, G. V.; Baukov, Y. I. Appl.
Organomet. Chem. 2010, 24, 162–168; (b) Kransnoslobodtsev, A. V.;
Shlyakhtenko, L. S.; Ukraintsev, E.; Zaikova, T. O.; Keana, J. F. W.;
Lyubchenko, Y. L. Nanomed. Nanotechnol. Biol. Med. 2005, 1, 300–305; (c)
Han, A.; Li, L.; Qing, K.; Qi, X.; Hou, L.; Luo, X.; Shi, S.; Ye, F. Bioorg. Med. Chem.
Lett. 2013, 23, 1310–1314.
5. (a) Belogolova, E. F.; Sidorkin, V. F. J. Phys. Chem. A 2013, 117, 5365–5376; (b)
Senapati, S.; Manna, S.; Lindsay, S.; Zhang, P. Langmuir 2013, 29, 14622–14630.
6. (a) Singh, G.; Saroa, A.; Garg, M.; Sharma, R. P.; Gubanov, A. I.; Smolentsev, A. I.
J. Organomet. Chem. 2012, 719, 21–25; (b) Singh, G.; Mangat, S. S.; Singh, J.;
Arora, A.; Sharma, R. K. Tetrahedron Lett. 2014, 55, 903–909.
7. Kolb, H. C.; Finn, M. G.; Sharpless, K. B. Angew. Chem., Int. Ed. 2001, 40, 2004–
2021.
8. (a) Tornoe, C. W.; Christensen, C.; Meldal, M. J. Org. Chem. 2002, 67, 3057–3064;
(b) Meldal, M.; Tornoe, C. W. Chem. Rev. 2008, 108, 2952–3015.
9. Rodionov, V. O.; Fokin, V. V.; Finn, M. G. Angew. Chem., Int. Ed. 2005, 44, 2210–
2215.
3c: N,N-Bis((1-(3-(2,8,9-trioxa-5-aza-1-silatranyl)propyl)-1H-1,2,3-triazol-4-
yl)methyl)(4-fluorophenyl)methanamine.
A procedure as above was used.
The quantities used were as follows: 2c (1.0 g, 1.47 mmol), triethanolamine
(0.44 g, 2.94 mmol) and toluene (50 ml). Yield: 89% (0.92 g, 1.31 mmol).
Mp = 182 °C. IR (neat): 2946, 2871, 2799, 1670, 1603, 1509, 1442, 1352,
1227, 1096, 983, 904, 766, 683, 542 cmÀ1 1H NMR (300 MHz, CDCl3, 25 °C)
.
d = 7.26 (s, 2H), 6.85–6.71 (m, 4H), 4.50 (s, 4H), 4.18 (t, J = 7.5 Hz, 4H), 3.64 (t,
J = 5.8 Hz, 12H), 2.71 (t, J = 7.7 Hz, 12H), 1.93–1.70 (m, 4H), 0.34–0.14 (m, 4H).
13C NMR (75 MHz, CDCl3, 25 °C): d = 128.38, 122.03, 115.68, 115.59, 77.12,
57.55, 52.96, 51.13, 26.08, 12.61. Empirical formula: C30H46N9O6Si2F: MS (EI)
m/z 742 (22), 727 (45), 726 (100), 704 (37), 701 (16), 475 (31), 380 (12), 371
(22), 360 (10), 301 (17), 172 (9), 150 (76), 105 (29). HRMS (ES+) Calcd for
[M+Na]+ 726.2991; Found 726.3004. Anal. Calcd: C, 51.2; H, 6.6; N, 17.9;
Found: C, 51.1; H, 6.7; N, 18.0.
3d: N,N-Bis((1-(3-(2,8,9-trioxa-5-aza-1-silatranyl)propyl)-1H-1,2,3-triazol-4-
yl)methyl)(4-chlorophenyl)methanamine.
A procedure as above was used.
The quantities used were as follows: 2d (1.0 g, 1.43 mmol), triethanolamine
(0.43 g, 2.87 mmol) and toluene (50 ml). Yield: 86% (0.89 g, 1.23 mmol). Mp
>230 °C. IR (neat): 3130, 2923, 2873, 1596, 1498, 1453, 1352, 1276, 1213, 1121,
10. Ackermann, L.; Potukuchi, H. K. Org. Biomol. Chem. 2010, 8, 4503–4513.
11. (a) Moses, J. E.; Moorhouse, A. D. Chem. Soc. Rev. 2007, 36, 1249–1262; (b) Kolb,
H. C.; Sharpless, K. B. Drug Discovery Today 2003, 8, 1128–1137; (c) Hein, C. D.;
Liu, X. M.; Wang, D. Pharm. Res. 2008, 25, 2216–2230.
1095, 1048, 1014, 909, 876, 762, 681, 615, 580, 542 cmÀ1 1H NMR (400 MHz,
.
DMSO-d6, 25 °C): d = 7.99 (s, 2H), 7.27–7.21 (m, 2H), 7.05 (d, J = 9.0 Hz, 2H),
4.75 (s, 4H), 4.33 (t, J = 7.3 Hz, 4H), 3.77 (t, J = 5.8 Hz, 12H), 2.95 (t, J = 5.7 Hz,
12H), 1.98–1.89 (m, 4H), 0.33–0.24 (m, 4H). 13C NMR (101 MHz, DMSO-d6,
25 °C): d = 147.18, 146.65, 143.65, 128.17, 122.55, 114.24, 113.57, 56.63, 52.64,
49.96, 45.69, 26.54, 18.07, 13.85. Empirical formula: C30H46N9O6Si2Cl: MS (EI)
m/z 745 (14), 743 (43), 742 (100), 731 (37), 720 (34), 709 (10), 462 (22), 446
(62), 444 (33), 424 (25), 379 (31), 360 (12), 301 (15), 192 (12), 174 (21), 172
(3), 105 (15). HRMS (ES+) Calcd for [M+Na]+ 742.2696; Found 742.2669. Anal.
Calcd: C, 50.2; H, 6.4; N, 17.5; Found: C, 50.2; H, 6.4; N, 17.3.
12. Fournier, D.; Hoogenboom, R.; Schubert, U. S. Chem. Soc. Rev. 2007, 36, 1369–
1380.
13. (a) Basu, B.; Paul, S.; Nanda, A. K. Green Chem. 2009, 11, 1115–1120; (b) Alfonsi,
M.; Arcadi, A.; Chiarini, M.; Marinelli, F. Tetrahedron Lett. 2011, 52, 5145–5148;
(c) Guo, Z.; Lei, A.; Liang, X.; Xub, Q. Chem. Commun. 2006, 4512–4514; (d)
Nakazawa, J.; Stack, T. D. P. J. Am. Chem. Soc. 2008, 130, 14360–14361.
14. (a) Burglova, K.; Moitra, N.; Hodacova, J.; Cattoen, X.; Man, M. W. C. J. Org.
Chem. 2011, 76, 7326–7333; (b) Moitra, N.; Moreau, J. J. E.; Cattoen, X.; Man, M.
W. C. Chem. Commun. 2010, 8416–8418.
15. (a) Jirawutthiwongchai, J.; Krause, A.; Draeger, G.; Chirachanchai, S. Macro Lett.
2013, 2, 177–180; (b) Jin, Z.; Zhang, X. B.; Xie, D. X.; Gong, Y. J.; Zhang, J.; Chen,
X.; Shen, G. L.; Yu, R. Q. Anal. Chem. 2010, 82, 6343–6346; (c) Nakazawa, J.;
Smith, B. J.; Stack, T. D. P. J. Am. Chem. Soc. 2012, 134, 2750–2759.
16. (a) Jung, H. S.; Kwon, P. S.; Lee, J. W.; Kim, J. I.; Hong, C. S.; Kim, J. W.; Yan, S.;
Lee, J. Y.; Lee, J. H.; Joo, T.; Kim, J. S. J. Am. Chem. Soc. 2009, 131, 2008–2012; (b)
Zhang, X.; Shiraishi, Y.; Hirai, T. Org. Lett. 2007, 9, 5039–5042; (c) Renault, R.
M.; Herault, A.; Vachon, J. J.; Pansu, R. B.; Gerbier, S. A.; Larpent, C. Photochem.
Photobiol. Sci. 2006, 5, 300–310; (d) Qian, X. X.; Cui, J. Org. Lett. 2005, 7, 3029–
3032.
3e: N,N-Bis((1-(3-(2,8,9-trioxa-5-aza-1-silatranyl)propyl)-1H-1,2,3-triazol-4-
yl)methyl)-2-methoxybenzenamine.
A procedure as above was used. The
quantities used were as follows: 2e (1.0 g, 1.44 mmol), triethanolamine (0.43 g,
2.88 mmol) and toluene (50 ml). Yield: 83% (0.86 g, 1.20 mmol). Mp = 163 °C.
IR (neat): 2941, 2872, 2799, 1592, 1499, 1437, 1351, 1239, 1177, 1096, 984,
909, 745, 617, 583, 540 cmÀ1 1H NMR (400 MHz, CDCl3, 25 °C) d = 7.63–7.53
.
(m, 2H), 7.43–7.36 (m, 2H), 7.33 (s, 2H), 4.28 (s, 4H), 4.17 (t, J = 9.1 Hz, 4H), 3.82
(s, 3H), 3.66 (t, J = 5.8 Hz, 12H), 2.71 (t, J = 5.8 Hz, 12H), 1.92–1.75 (m, 4H),
0.39–0.15 (m, 4H). 13C NMR (101 MHz, DMSO-d6, 25 °C): d = 142.78, 130.81,
127.81, 122.40, 58.38, 56.45, 56.10, 51.90, 49.47, 38.97, 25.89, 12.93. Empirical
formula: C31H49N9O7Si2: MS (EI) m/z 754 (19), 739 (46), 738 (100), 716 (34),
17. Royzen, M.; Dai, Z.; Canary, J. W. J. Am. Chem. Soc. 2005, 127, 1612–1613.

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701 (13), 496 (14), 480 (32), 458 (25), 386 (13), 301 (36), 279 (17), 172 (33),
(75 MHz, CDCl3, 25 °C): d = 142.78, 130.81, 127.81, 127.44, 122.27, 58.38,
56.45, 56.10, 49.47, 26.92, 17.68, 12.85. Empirical formula: C31H49N9O7Si2: MS
(EI) m/z 740 (16), 739 (44), 738 (100), 716 (61), 701 (13), 475 (24), 386 (20),
378 (25), 377 (51), 370 (36), 360 (11), 301 (7), 192 (8), 175 (13), 105 (28).
HRMS (ES+) Calcd for [M+Na]+ 738.3191; Found 738.3207. Anal. Calcd: C, 52.0;
H, 6.9; N, 17.6; Found: C, 52.0; H, 7.0; N, 17.7.
150 (76), 132 (30), 105 (26). HRMS (ES+) Calcd for [M+Na]+ 738.3191; Found
738.3178. Anal. Calcd: C, 52.0; H, 6.9; N, 17.6; Found: C, 51.9; H, 7.0; N, 17.5.
3f: N,N-Bis((1-(3-(2,8,9-trioxa-5-aza-1-silatranyl)propyl)-1H-1,2,3-triazol-4-
yl)methyl)-4-methoxybenzenamine.
A procedure as above was used. The
quantities used were as follows: 2f (1.0 g, 1.44 mmol), triethanolamine (0.43 g,
2.88 mmol) and toluene (50 ml). Yield: 78% (0.80 g, 1.13 mmol). Mp = 109 °C.
IR (neat): 2923, 2873, 1654, 1511, 1481, 1454, 1352, 1240, 1121, 1093, 1049,
22. (a) Xu, Z.; Xiao, Y.; Qian, X.; Cui, J.; Cui, D. Org. Lett. 2005, 7, 889–892; (b) Liu, Z.
C.; Yang, Z. Y.; Li, T. R.; Wang, B. D.; Li, Y.; Qin, D. D.; Wang, M. F.; Yan, M. H.
Dalton Trans. 2011, 40, 9370–9373.
1015, 937, 909, 877, 759, 616, 580 cmÀ1 1H NMR (300 MHz, CDCl3, 25 °C):
.
d = 7.19 (s, 2H), 7.05 (d, J = 7.5 Hz, 2H), 6.74 (d, J = 9.0 Hz, 1H), 6.52 (d,
J = 8.8 Hz, 1H), 4.56 (s, 4H), 4.25–4.13 (m, 4H), 3.70 (s, 3H), 3.67 (t, J = 5.8 Hz,
12H), 2.73 (t, J = 4.2 Hz, 12H), 1.92–1.80 (m, 4H), 0.38–0.17 (m, 4H). 13C NMR
23. (a) Sathupunyaa, M.; Gularib, E.; Wongkasemjita, S. J. Eur. Ceram. Soc. 2003, 23,
1293–1303; (b) Sathupunyaa, M.; Gularib, E.; Wongkasemjita, S. J. Eur. Ceram.
Soc. 2002, 22, 2305–2314.