Synthesis and stimulation of seed germination of γ-aminopropyl silatrane derivatives

Article abstract of DOI:10.1016/j.phytol.2013.12.011

γ-Aminopropyl silatranes have generated wider interests due to their plant growth-regulating activity, safe and demonstrate potential to be plant growth regulators. Therefore, its N-substituted derivatives were synthesized and confirmed by IR, ¹H NMR, ESI-MS, and elemental analysis. The seed germination test showed that most compounds possessed better activities of regulating the roots growth on corn (monocotyledon) and radish (dicotyledon) than 1-chloromethylsilatrane (CMS). Moreover, the effect of these compounds was higher at around 10^-7 mol/l, while 10^-6 mol/l CMS was most efficient.

Full text of DOI:10.1016/j.phytol.2013.12.011

Phytochemistry Letters 8 (2014) 202–206
Contents lists available at ScienceDirect
Phytochemistry Letters
journal homepage: www.elsevier.com/locate/phytol
Synthesis and stimulation of seed germination of
silatrane derivatives
g-aminopropyl
Zi-xin Xie, Liang-fang Chen, Yue-wu Wang, Xiao-qing Song, Xiao-lu Qi,
*
Ping Guo, Fa-qing Ye
School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang 325035, PR China
A R T I C L E I N F O
A B S T R A C T
-Aminopropyl silatranes have generated wider interests due to their plant growth-regulating activity,
Article history:
g
Received 15 August 2013
safe and demonstrate potential to be plant growth regulators. Therefore, its N-substituted derivatives
were synthesized and confirmed by IR, 1H NMR, ESI-MS, and elemental analysis. The seed germination
test showed that most compounds possessed better activities of regulating the roots growth on corn
(monocotyledon) and radish (dicotyledon) than 1-chloromethylsilatrane (CMS). Moreover, the effect of
these compounds was higher at around 10ꢀ7 mol/l, while 10ꢀ6 mol/l CMS was most efficient.
ß 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
Received in revised form 2 December 2013
Accepted 18 December 2013
Available online 13 January 2014
Keywords:
Silatrane
Synthesis
Seed germination
Regulation
1. Introduction
The particular biological activities of silatrane derivatives, are
likely to be bonds the silicon atom forms with adjacent atoms and
Silatranes, hetero-tricyclic compounds having an intramolecu-
lar transannular dative Si N bond, are of high interest both from
their structural and applications point of view (Chuit et al., 1993;
Puri et al., 2011). Due to their demonstrated antiviral, anti-
inflammatory, anticancer and antitumor activities, as well as to
their seed germination effects and applications in agriculture,
silatranes were widely used in biological systems (Puri et al., 2011;
Voronkov and Baryshok, 2004; Lin et al., 2011). Broad-spectrum
plant growth regulators with silatranes as a main component have
been produced in batches as agricultural chemicals, and are well
known for their characteristics of high performance resulting in
increased production, low toxicity, easy biodegradation, and
environmental friendliness (Lin et al., 2011). A previous report
showed that, treatment of tomatoes at flowering time with
aqueous solution of 1-chloromethylsilatrane (CMS) considerably
increased the amount of fruits and shortened ripening time
(Voronkov, 1979). It was preliminarily confirmed that silatrane
derivatives resistant to indoleacetic acid (IAA) oxidase, the auxin-
inactivating system (Galston and Dalberg, 1954), were practically
as active as auxins themselves. The presence of the silatrane group
prolonged the effect or facilitated the auxin transport through the
biomembranes (Voronkov, 1979).
the presence of some functional groups (Loginov et al., 2011).
Moreover, the toxicity of silatranes varied greatly and was mainly
dependent on the nature of substitution at the silicon atom. Most
1-arylsilatranes, with high and specific physiological activity
(Voronkov, 1968), were almost twice as toxic as such well-known
poisons as strychnine and hydrocyanic acid (Voronkov, 1979).
However, 1-alkyl- and 1-alkoxy-silatranes were almost non-toxic
(Voronkov and Lukevics, 1969). In particular, CMS (belonging to 1-
alkyl-silatranes) first synthesized at Favorsky Irkutsk Institute of
Chemistry, was efficient, essentially nontoxic, and ecologically safe
stimulators of crop growth and productivity (Khankhodzhaeva and
Voronkov, 1993). Furthermore, the compound not only increased
seed germinability but also enhanced its germination at the
optimum concentration (10ꢀ7 M to 10ꢀ5 M) (Voronkov et al., 2005;
Burlakova et al., 1996). Nevertheless, organosilicon compounds
containing a nitrogen atom in the g- or d-position in relation to the
silicon atom may be of high physiological activity and lower
toxicity (Voronkov and Lukevics, 1969; Voronkov et al., 1968), such
as
g-aminopropyl silatrane (as shown in Fig. 1). Some of its
derivatives are known to possess various activities in biology,
physiology, pharmacology, medicine, etc. (Voronkov et al., 1982).
Apart from these, they might be very promising in plant industry.
It was of interest to determine whether this type of silatranes
possess the fairly or higher stimulatory effect on seed germination
than CMS, under the same concentration (10ꢀ7 M to 10ꢀ5 M).
Additionally, this was a necessity for investigation of the effects of
*
Corresponding author. Tel.: +86 15088557352.
E-mail addresses: yfq415@163.com, yfq664340@163.com (F.-q. Ye).
1874-3900/$ – see front matter ß 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.phytol.2013.12.011

Z.-x. Xie et al. / Phytochemistry Letters 8 (2014) 202–206
203
10ꢀ7 mol/l, and their activity trends are presented in Fig. 3 (the
length of roots was converted into efficacy using an empirical
formula shown in this figure).
According to the above figure, at 10ꢀ7 mol/l, efficacy of 3f on corn
was best. Meanwhile, 4d performed the strongest stimulatory effect
on radish seedlings. In order to clarify the relationship between
concentration and bioactivity, compounds 3f and 4d were selected
as representatives in comparison to CMS as shown in Fig. 4.
These above figures showed that both 3f (10ꢀ7 mol/l) and 4d
(10ꢀ7 mol/l) increased seed germinability most efficiently, and
likewise with other aminopropyl derivatives, while the optimum
concentration of CMS was higher (10ꢀ6 mol/l). It was of interest
that the effect of these compounds did not show a dose-dependent
relationship but an optimum concentration, consistent with the
results reported in many literatures (Voronkov, 1979; Voronkov
et al., 2005). It might have been supposed that the aminopropyl
silatrane derivatives inhibit IAA-oxidase more efficient and at
lower concentration than CMS.
Fig. 1. The structure of g-aminopropyl silatrane.
its micromolar and appropriate concentration range. This knowl-
edge allowed us to synthesize a series of derivatives of
aminopropyl silatrane, and to conduct botanical experiments,
making it possible to obtain new compounds, efficient, practical
and safe for ecologically pure chemicals used in agriculture.
g
-
2. Results and discussion
In addition, most compounds possess higher activity than CMS,
especially at 10ꢀ7 mol/l. In generally, N-substituted derivatives
were more active than aminopropyl silatranes (1a–b). And the
compounds adorned with methyl groups (3a–f) had significant
loss of efficacy in comparison with the unadorned (4a–d). Besides
that, introduction of substitution such as chloro or methyl on the
phenyl connected with aminopropyl groups to form the com-
pounds 3b, 3e, 3f or 4b–d resulted in stronger efficacy compared to
the compound 3a or 4a, both of which had no substitution.
In conclusion, based on the discussion, the aminopropyl
silatrane derivatives containing nitrogen atom in 1-substitute
group worked on seed germination better than the common 1-
alkyl and 1-alkoxy silatranes. These derivatives could potentially
be used as plant growth regulators at appropriate concentrations.
Nevertheless, the mechanism of enhancement of seed germination
by these compounds still needs to be further investigated.
2.1. Chemistry
The structure and general synthesis of analogs designed are
illustrated and outlined in Fig. 2. Upon mixing of
g-aminopropyl
triethoxysilane, and triisopropanolamine or triethanolamine, this
mixture was stirred at 150 8C for 2 h for compounds 1a and 1b,
respectively. Thereafter, they were obtained by vacuum distillation
in high yields (1a: 74.96%; 1b: 76.83%). And the results were
consistent with the data in this literature (Dumitriu et al., 2012),
established by IR, 1H NMR as well as elemental analysis. The
synthesis of2was accomplished bysulfonylationreactionof1bwith
tosyl chloride in 53.7% yields. All these compounds (3a–f and 4a–d)
were obtained from N-acylation of 1a–b with different substituted
benzoyl chlorides (yields: 3a–f: 38.4–66.7%, 4a–d: 51.2–67.9%).
The IR spectrum of substituted aminopropyl silatranes showed
that there was a peak between 570 and 580 cmꢀ1 corresponding to
the characteristic absorption of N!Si. And the shift of H-
a
in the
3. Experimental
HNMR was under 0.5 ppm, attributing to the electrophobic effect
of silicon atom. In addition, the fragment peaks of silatrane or
3,7,10-trimethyl silatrane can be observed normally in MS. The
above phenomena corresponded to prediction.
3.1. General comments
Uncorrected melting points (mp) were determined using an
XRC-1 micro-melting point apparatus. Thin-layer chromatography
(TLC, Rf values) was performed on F254 or silica gel plates F254
(0.2 mm thick), and all the synthesized compounds were visual-
ized under ultraviolet light. 1H NMR spectra were recorded on a
Brucker Avance-3600 Spectrometer (600 MHz). Samples were
dissolved in CDCl3 while TMS was used as internal standard.
2.2. Seed germination test results
All tested compounds (1a–b, 2, 3a–f and 4a–d) significantly
enhanced seed germination. The maximal effect of them on
germination of both corn and radish seeds was observed at
R
N
R
N
i
ii
H2N(CH2)3Si(OC2H5)3
R
R
R
R
Si
Si
O
C
O
O
O
O
O
O
1a:R=H
1b:R=CH3
CH2CH2CH2NH2
CH2CH2CH2NH
3a-f,4a-d
R1
2: R=CH3, R2=4-Me-C6H4
1a-b
3a:R=CH3,R1=C6H5
iii
3b:R=CH3,R1=4-Me-C6H4
3c:R=CH3, R1=4-MeO-C6H4
3d:R=CH3,R1=2-F-C6H4
3e:R=CH3,R1=3,4-Cl-C6H4
3f:R=CH3, R1=3,5-Cl-C6H4
4a:R=H, R1=C6H5
4b:R=H, R1=4-Me-C6H4
4c:R=H, R1=4-MeO-C6H4
4d:R=H, R1=2-F-C6H4
R
N
R
R
Si
O
O
O
O
CH2CH2CH2NH
S
R2
O
2
Fig. 2. Synthesis of
g-aminopropyl silatrane derivatives. Regents and conditions: (i) g-aminopropyl triethoxysilane, triisopropanolamine or triethanolamine; reflux, 2 h; (ii)
chloroform, different substituted benzoyl chlorides, triethylamine; 25 8C, 2 h; (iii) tosyl chloride, triethylamine, acetone; 25 8C, 2 h.

204
Z.-x. Xie et al. / Phytochemistry Letters 8 (2014) 202–206
(m, 9H, CH3-3,7,10), 1.54–1.75 (m, 2H, H-b), 2.15–2.35 (m, 2H, H-
g
), 2.39 (s, 3H, Ph–CH3), 2.67–3.20 (m, 6H, H-4,6,11), 3.77–4.15 (m,
3H, H-3,7,10), 5.84 (br, 1H, NH), 7.26 (d, 2H, J = 7.8 Hz, Ph–H), 7.72
(d, 2H, J = 7.8 Hz, Ph–H); ESI-MS m/z 429 [M+H]+; found: C, 53.44;
H, 7.82; N, 6.74; Si, 6.51. Calc. for C19H32N2O5SSi: C, 53.24; H, 7.53;
N, 6.54; Si, 6.55%.
3.3. General procedure for syntheses of the compounds 3a–f and 4a–d
To a mixture of
g-aminopropyl silatranes 1a–b (10 mmol) in
20 mL of chloroform and 2 mL of triethylamine was added
different substituted benzoyl chlorides (10 mmol) by dripping
slowly. The mixture was refluxed in a three-necked round
bottom flask fitted with a magnetic stirrer for 2 h. The crude
product was filtered to remove the precipitate. Finally, the
compounds 3a–f and 4a–d were purified as white solids by
column chromatography, using an eluent of petroleum ether and
ethyl acetate.
3.3.1.
mp: 143–144 8C. IR (KBr)
1H NMR (CDCl3, 600 MHz)
g-Benzamidepropyl-3,7,10-trimethyl silatrane (3a)
n
max: 576 (N!Si), 1627 (C55O) cmꢀ1
;
Fig. 3. Effect of all the compounds tested on corn and radish germination efficacy.
Efficacy = (the average length of sample roots ꢀ the average length of blank roots)/
the average length of blank roots ꢁ 100%. (A) Efficacy in corn (%) at 10ꢀ7 mol/l. (B)
Efficacy in radish (%) at 10ꢀ7 mol/l. Values are mean ꢂ S.D. n = 3, p < 0.05, ANOVA,
Duncan’s multiple-range test.
d
: 0.25–0.48 (m, 2H, H-
a
), 1.08–1.49 (m,
9H, CH3-3,7,10), 1.56–1.78 (m, 2H, H-
b
), 2.05–2.35 (m, 2H, H-g),
2.61–3.29 (m, 6H, H-4,6,11), 3.79–4.20 (m, 3H, H-3,7,10), 6.55 (br,
1H, NH), 7.21–7.78 (m, 5H, Ph–H); ESI-MS m/z 379 [M+H]+; Found:
C, 60.40; H, 7.87; N, 7.32; Si, 7.69. Calc. for C19H30N2O4Si: C, 60.29;
H, 7.99; N, 7.40; Si, 7.42%.
Chemical shifts were recorded in (ppm) values relative to TMS and
J values are expressed in Hertz. MS were recorded using an Agilent-
1100 LC–MS Spectrometer. IR spectra (KBr) were recorded on a
Bruker Vector 22 spectrometer. All reagents were of analytical-
reagent grade and were used without further purification.
3.3.2.
White solid; mp: 139–140 8C. IR (KBr)
1633 (C55O) cmꢀ1 1H NMR (CDCl3, 600 MHz)
(m, 2H, H- ), 1.05–1.50 (m, 9H, CH3-3,7,10), 1.51–1.82 (m,
2H, H- ), 2.02–2.33 (m, 2H, H- ), 2.35 (s, 3H, Ph–CH3), 2.62–
g
-(4-Methybenzamide) propyl-3,7,10-trimethyl silatrane (3b)
max: 569 (N!Si),
: 0.22–0.49
n
;
d
a
3.2. General procedure for syntheses of the compound 2
b
g
3.28 (m, 6H, H-4,6,11), 3.85–4.20 (m, 3H, H-3,7,10), 6.69
(br, 1H, NH), 7.32 (d, 2H, J = 8.4 Hz, Ph–H), 7.84 (d, 2H,
J = 8.4 Hz, Ph–H); ESI-MS m/z 393 [M+H]+; found: C, 61.08; H,
8.21; N, 7.15; Si, 7.19. C20H32N2O4Si: C, 61.19; H, 8.22; N, 7.14;
Si, 7.15%.
The compound 1b (0.35 mmol) and a catalytic amount of
triethylamine were dissolved in 7 ml of acetone. At room
temperature, in a period of 20–30 min, the equimolar tosyl
chloride was added dropwise with stirring. The reaction mixture
was stirred at room temperature for 2 h, and then the precipitate
(triethylamine hydrochloride) formed was discarded. The filtrate,
concentrated under reduced pressure, was poured into diethyl
ether, and a yellow precipitate formed. The target product was
purified by column chromatography on silica gel using petroleum
ether and ethyl acetate as eluent.
3.3.3.
g-(4-Methoxybenzamide) propyl-3,7,10-trimethyl silatrane
(3c)
mp: 140–141 8C. IR (KBr)
1H NMR (CDCl3, 600 MHz)
n
max: 572 (N!Si), 1685 (C55O) cmꢀ1
;
d
: 0.28–0.53 (m, 2H, H-
a
), 1.07–1.49 (m,
9H, CH3-3,7,10), 1.53–1.83 (m, 2H, H-
b
), 2.05–2.38 (m, 2H, H-g),
2.65–3.42 (m, 6H, H-4,6,11), 3.82 (s, 3H, –OCH3), 3.85–4.13 (m, 3H,
H-3,7,10), 6.71 (br, 1H, NH), 6.87 (d, 2H, J = 8.4 Hz, Ph–H), 7.73 (d,
2H, J = 8.4 Hz, Ph–H); ESI-MS m/z 409 [M+H]+; found: C, 59.12; H,
8.20; N, 7.24; Si, 6.93. Calc. for C20H32N2O5Si: C, 58.79; H, 7.89, N,
6.86; Si, 6.87%.
3.2.1.
silatrane (2)
mp: 125–126 8C. IR (KBr)
1H NMR (CDCl3, 600 MHz)
g-(4-Methybenzenesulfonamide) propyl-3,7,10-trimethyl
n
max: 584 (N!Si), 1325 (–SO2ꢀ) cmꢀ1
;
d
: 0.23–0.40 (m, 2H, H-a), 1.09–1.42
Fig. 4. Effect of compounds 3f, 4d and CMS on corn and radish germination efficacy. (A) Efficacy in corn (%) at 10ꢀ7 mol/l. (B) Efficacy in radish (%) at 10ꢀ7 mol/l. Values
p < 0.01, significantly different with Student’s t-test.

Z.-x. Xie et al. / Phytochemistry Letters 8 (2014) 202–206
205
3.3.4.
White solid; mp: 152–153 8C. IR (KBr)
(C55O) cmꢀ1; 1H NMR (CDCl3, 600 MHz)
: 0.20–0.55 (m, 2H, H-
1.00–1.55 (m, 9H, CH3-3,7,10), 1.60–1.87 (m, 2H, H- ), 2.23–2.55
(m, 2H, H- ), 2.75–3.45 (m, 6H, H-4,6,11), 3.85–4.19 (m, 3H, H-
3,7,10), 7.04 (br, 1H, NH), 7.47–7.86 (m, 4H, Ph–H); ESI-MS m/z 397
[M+H]+; found: C, 56.99; H, 7.35; N, 7.01; Si, 6.98. C19H29N2O4SiF:
C, 57.55; H, 7.37; N, 7.06; Si, 7.06%.
g
-(2-Fluorobenzamide) propyl-3,7,10-trimethyl silatrane (3d)
max: 578 (N!Si), 1640
),
3.4. Germination test
n
d
a
The experiment was carried out according to the standard
operation procedure of bioassay established by Ministry of
Efficacy of National Pesticide Research & Development South
Center (Shanghai) (Li et al., 2007). Corn and radish seeds produced
in 2011 were purchased from Shandong Academy of Agricultural
Sciences (their germinability was evaluated before sowing). Both
kinds of seeds were respectively sterilized with 1% KMnO4 and
kept in water for 12 h, which is a common agricultural practice.
Each treatment was performed with 30 seeds. Then the seeds were
placed in large Petri dishes on several layers of filter papers
moistened with distilled water (blank control) or aqueous
solutions of compounds tested, prepared by successive tenfold
dilution from 10ꢀ8 to 10ꢀ5 mol/l for the compounds synthesized
or CMS (positive control). And the seeds were left at 25 8C and dim
light during the day time in an artificial climate chamber
(Climacell RXZ-0450) for 7 days. The filter papers were daily
wetted with the above solutions. Preliminary experiments
demonstrated that such procedures were optimal, and there
were no signs of fermentation during seed soaking (Voronkov
et al., 2005). The length of roots was measured on the 7th day in
comparison with the no dose group. All experiments were
repeated three times.
b
g
3.3.5.
g-(3,4-Dichlorobenzamide) propyl-3,7,10-trimethyl silatrane
(3e)
mp: 116–118 8C. IR (KBr)
1H NMR (CDCl3, 600 MHz)
n
max: 570 (N!Si), 1637 (C55O) cmꢀ1
;
d
: 0.26–0.53 (m, 2H, H-
a
), 1.08–1.48 (m,
9H, CH3-3,7,10), 1.64–1.84 (m, 2H, H-
b
), 2.18–2.48 (m, 2H, H-g),
2.58–3.09 (m, 6H, H-4,6,11), 3.79–4.20 (m, 3H, H-3,7,10), 7.04 (br,
1H, NH), 7.47–7.86 (m, 3H, Ph–H); ESI-MS m/z 447 [M+H]+; found:
C, 51.20; H, 6.51; N, 6.25; Si, 6.31. Calc. for C19H28N2O4SiCl2: C,
51.00; H, 6.31; N, 6.26; Si, 6.28%.
3.3.6.
g-(3,5-Dichlorobenzamide) propyl-3,7,10-trimethyl silatrane
(3f)
mp: 130–132 8C. IR (KBr)
1H NMR (CDCl3, 600 MHz)
n
max: 579 (N!Si), 1627 (C55O) cmꢀ1
;
d
: 0.27–0.55 (m, 2H, H-
a
), 1.10–1.45 (m,
9H, CH3-3,7,10), 1.66–1.87 (m, 2 H, H-
b
), 2.20–2.42 (m, 2H, H-g),
2.75–3.45 (m, 6H, H-4,6,11), 3.85–4.19 (m, 3H, H-3,7,10), 7.13 (br,
1H, NH) 7.56–7.78 (m, 3H, Ph–H); ESI-MS m/z 447 [M+H]+; found:
C, 51.21; H, 6.51; N, 6.06; Si, 6.39. Calc. for C19H28N2O4SiCl2: C,
51.00; H, 6.31; N, 6.26; Si, 6.28%.
3.5. Statistical analysis
Results were mean ꢂ S.D. of three parallel measurements. All
statistical comparisons were determined by Student’s t-test and
one-way ANOVA followed by Duncan’s multiple-range test, p-
values < 0.05 were regarded as statistically significant.
3.3.7.
mp: 177–178 8C. IR (KBr) nmax
(C55O) cmꢀ1 1H NMR (CDCl3, 600 MHz)
H- ), 1.54–1.76 (m, 2H, H- ), 2.13–2.36 (m, 2H, H-g
g-Benzamidepropyl silatrane (4a)
:
572 (N!Si), 1685
: 0.22–0.42 (m, 2H,
), 2.61–3.26
;
d
a
b
Acknowledgments
(m, 6H, H-4,6,11), 3.80–4.19 (m, 6H, H-3,7,10), 5.28 (br, 1H, NH),
7.28–7.80 (m, 5H, Ph–H); ESI-MS m/z 337 [M+H]+; found: C,
57.30; H, 6.89; N, 8.03; Si, 8.33. Calc. for C16H24N2O4Si: C, 57.12;
H, 7.19; N, 8.33; Si, 8.35%.
This work was financially supported by the Natural Science
Foundation of Zhejiang Province of China (Y2080697) and
Wenzhou Science and Technology Projects (Y2009250 and
S20090043). The NMR, elemental analysis, and MS spectra were
recorded by the Instrumental Analysis Center of Wenzhou Medical
University.
3.3.8.
White solid; mp: 168–169 8C. IR (KBr)
(C55O) cmꢀ1; 1H NMR (CDCl3, 600 MHz)
: 0.23–0.45 (m, 2H, H-
1.65–1.85 (m, 2H, H- ), 2.47–2.69 (m, 2H, H- ), 2.52 (s, 3H,
g
-(4-Methybenzamide) propyl silatrane (4b)
max: 570 (N!Si), 1637
),
n
d
a
Appendix A. Supplementary data
b
g
PhCH3), 2.65–3.40 (m, 6H, H-4,6,11), 3.75–4.13 (m, 6H, H-3,7,10),
6.71 (br, 1H, NH), 7.30 (d, 2H, J = 8.4 Hz, Ph–H), 7.82 (d, 2H,
J = 8.4 Hz, Ph–H); ESI-MS m/z 351 [M+H]+; found: C, 58.11; H,
7.50; N, 7.81; Si, 7.80. C17H26N2O4Si: C, 58.26; H, 7.48; N, 7.99; Si,
8.01%.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.phytol.2013.12.011.
References
3.3.9.
mp: 161–162 8C. IR (KBr) nmax
(C55O) cmꢀ1 1H NMR (CDCl3, 600 MHz)
H- ), 1.60–1.89 (m, 2H, H- ), 2.08–2.41 (m, 2H, H-g
(m, 6H, H-4,6,11), 3.77 (s, 3H, –OCH3), 3.75–3.81 (m, 6H, H-
3,7,10), 6.81 (br, 1H, NH), 7.02 (d, 2H, J = 8.12 Hz, Ph–H), 7.82 (d,
2H, J = 8.32 Hz, Ph–H); ESI-MS m/z 367 [M+H]+; found C, 55.23;
H, 7.23; N, 7.69; Si, 7.71. Calc. for C17H26N2O5Si: C, 55.71; H,
7.15; N, 7.64; Si, 7.66%.
g
-(4-Methoxybenzamide) propyl silatrane (4c)
578 (N!Si), 1627
: 0.21–0.45 (m, 2H,
), 2.65–3.40
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:
;
d
a
b
3.3.10.
White solid; mp: 170–171 8C. IR (KBr)
(C55O) cmꢀ1 1H NMR (CDCl3, 600 MHz)
), 1.45–1.87 (m, 2H, H- ), 2.52–2.65 (m, 2H, H-g
g
-(2-Fluorobenzoyl)-aminopropyl silatrane (4d)
max: 581 (N!Si), 1642
: 0.23–0.50 (m, 2H, H-
), 2.65–3.38
n
d
;
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7.30–7.76 (m, 4H, Ph–H); ESI-MS m/z 355 [M+H]+; found: C,
54.89; H, 6.77; N, 7.80; Si, 7.50. C16H23N2O4SiF: C, 54.22; H, 6.54;
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