One-pot synthesis of new 1,5-disubstituted tetrazoles bearing 2,2-bis(trimethylsilyl)ethenyl groups via the ugi four-component condensation reaction catalyzed by MgBr2·2Et2O

Article abstract of DOI:10.1002/jhet.1858

A simple one-pot Ugi four-component condensation reaction has been developed for the synthesis of tetrazoles bearing 2,2-bis(trimethylsilyl)ethenyl groups from the synthesized 4-[2,2-bis(trimethylsilyl) ethenyl]benzaldehyde (1), various amines, isocyanide

Full text of DOI:10.1002/jhet.1858

Month 2013 One-Pot Synthesis of New 1,5-Disubstituted Tetrazoles Bearing 2,2-Bis
(trimethylsilyl)ethenyl Groups via The Ugi Four-Component Condensation
Reaction Catalyzed by MgBr2Á2Et2O
*
Kazem D. Safa, Tohid Shokri, Hassan Abbasi, and Reza Teimuri-Mofrad
Organosilicon Research Laboratory, Faculty of Chemistry, University of Tabriz, 5166616471 Tabriz, Iran
*
E-mail: dsafa@tabrizu.ac.ir
Received June 11, 2012
DOI 10.1002/jhet.1858
Published online 00 Month 2013 in Wiley Online Library (wileyonlinelibrary.com).
A simple one-pot Ugi four-component condensation reaction has been developed for the synthesis of
tetrazoles bearing 2,2-bis(trimethylsilyl)ethenyl groups from the synthesized 4-[2,2-bis(trimethylsilyl) ethenyl]
benzaldehyde (1), various amines, isocyanides, and trimethylsilylazide at room temperature, without solvent,
and in the presence of catalytic amounts of MgBr2Á2Et2O as catalyst.
J. Heterocyclic Chem., 00, 00 (2013).
INTRODUCTION
In recent years, it is found that magnesium bromide
ethyl etherate (MgBr2Á2Et2O) has many applications as a
mild Lewis acid because of its ease of preparation, oxophilic
nature, and coordinating ability for bidentate chelation that
makes various chelation-controlled organic transformations
easier [16]. These results prompted us to use this catalyst in
the synthesis of new tetrazoles via multicomponent reaction.
Although multicomponent reaction based on isocyanide has
been applied to the synthesis of 1,5-disubstituted tetrazoles
[17,18], our literature survey revealed that this synthetic
strategy had not been applied to the synthesis of tetrazoles
containing 2,2-bis (trimethylsilyl)ethenyl moiety.
Tetrazoles are an important class of heterocycles with
wide-ranging applications in medicinal and synthetic
chemistry. The nitrogen-rich ring system is used in
propellants [1], trigger explosives, components of mixed
propellants, gas-generating mixtures [2,3], information
recording systems [4], and pharmaceuticals [5]. Tetrazoles
are also used as monodentate or bidentate ligands in
coordination chemistry [6].
The synthesis of monocyclic tetrazoles was originally
reported in 1961 [7,8]. It is by use of a variation of classical
Ugi reaction that condensation of an aldehyde or ketone
with a primary or secondary amine, an isocyanide, and an
azide affords the desired tetrazole [9]. Also, synthesis of
tetrazoles from a cycloaddition reaction between a nitrile
and an azide is well documented [10]. Organosilicon
reagents and compounds are valuable in organic synthesis
[11]. Because C(sp2)–Si bonds in organosilicon compounds
undergo numerous transformations [12, 11c], 2,2-bis
(trimethylsilyl)ethenyl compounds are used as precursors
for the preparation of ketones and isoxazoline derivatives,
as well as a variety of important organosilicon intermediates,
such as acylsilanes, epoxysilanes, and silanols [13,14]. We
have recently reported new organosilicon compounds
containing 2,2-bis(trimethylsilyl)ethenyl groups and their
conversion into amines [15].
RESULTS AND DISCUSSION
Various heterocyclic compounds have been obtained by the
Ugi reaction, either directly [19] or by the post-condensation
modification [20]. We used Ugi four-component condensation
(Ugi-4CC) to synthesize new tetrazoles bearing 2,2-bis
(trimethylsilyl)ethenyl groups from the reaction of bissili-
lated aldehyde (1), which was prepared by the reaction of
(Me3Si)3CLi with terephthalaldehyde in a Peterson
olefination [15] and primary aminese, trimethylsilylazide,
and isocyanides (Scheme 1).
To obtain the expected tetrazoles, the reactions were
carried out with excess amount of primary amines,
© 2013 HeteroCorporation

K. D. Safa, T. Shokri, H. Abbassi, and R. Teymuri-Mofrad
Vol 0000
Scheme 1. The preparation of 4-[2,2-bis(trimethylsilyl)ethenyl]benzalde-
hyde (1) via Peterson protocol.
Fortunately, desired products (6a–6n) were isolated in
excellent yields when the reaction was performed in the
solvent-free conditions in the presence of MgBr2Á2Et2O.
The optimum amount of catalyst was 5 mol% for aromatic
and hetrocyclic amines and 10 mol% for aliphatic amines
(Scheme 2).
We have not established a detailed mechanism for the
formation of 6; however, a reasonable possibility is shown
in Scheme 3 [22]. To prove the efficiency of the conditions,
we studied the Ugi-4CC reaction of aldehyde (1) and
trimethylsilylazide with different amines and isocyanides
under similar conditions. The results are presented in Table 2.
Primary aromatic amines with electron-donating groups such
as methoxy and methyl gave the tetrazole derivatives 6b
and 6d in slightly higher yield than amines with electron-
withdrawing groups such as nitro (6g), obtained after
80 min. Heterocyclic amines reacted slowly under these
conditions. 2-Aminopyridine gave only 42% yield (6j) after
5 h, and 2-aminopyrimidine gave no product even after
3 days. The best results (96% yield) were obtained with
para-fluoroaniline (6e) under the same conditions.
Using cyclohexylisocyanide (3b) instead of tert-butyl
isocyanide (3a) gave the similar products (6m and 6n), but
the reaction times increased. In continuation of our work,
we attempted to synthesize epoxide derivatives of 6a and
6n by the reaction of MCPBA in CH2Cl2 at room temperature
[13], but unfortunately, the 1H NMR of the products showed
that the expected epoxides have not been prepared.
trimethylsilylazide, and isocyanides (3a,b) under mild
conditions, without solvent, and at room temperature in
the presence of Lewis acid as a catalyst.
Although MgBr2Á2Et2O has recently been used as a
catalyst for the synthesis of various organic compounds
[21], we decided to examine its catalytic activity for the
synthesis of tetrazoles via Ugi-4CC. Initially, aldehyde
(1) was reacted with aniline, trimethylsilylazide, and
tert-butyl isocyanide (3a) in the absence of catalyst in
methanol as a solvent. In this condition, the reaction took
place smoothly to afford the expected adduct (6a) in 30%
yield at 24 h. MgBr2Á2Et2O catalyst has a significant
effect on the reaction rate and yield. In the presence of
MgBr2Á2Et2O in methanol as solvent, 65% yield was
obtained after 90 min. The reactions were conducted in
different solvents such as ethanol, acetonitrile, THF, or
CH2Cl2. As shown in Table 1, the best result (87% yield)
was obtained under solvent-free conditions.
Table 1
One-pot synthesis of the tetrazole 6a in various organic solvents in the
presence of MgBr2Á2Et2O.
Scheme 2. Synthesis of new tetrazoles (6).
Scheme 3. Proposed mechanism.
Entry
Solvent
Time (min)
Yield (%)
1
2
3
4
5
6
Methanol
THF
Ethanol
CH3CN
CH2Cl2
Neat
90
60
50
60
45
30
65
62
67
69
71
87
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2013
One-Pot Synthesis of New 1,5-Disubstituted Tetrazoles Bearing 2,2-Bis(trimethylsilyl)
Ethenyl Groups via the Ugi Four-Component Condensation Reaction
Table 2
The organic layer was washed with saturated NaCl solution and
dried over Na2SO4. The solvent was evaporated and the residue
purified by preparative TLC (n-hexane/ethyl acetate; 10:2) to give
the tetrazole.
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
tetrazol-5-yl)methyl}aniline (6a). White solid, mp 143–145ꢀC;
FTIR (potassium bromide): 1251, 821, (Si–CH3), 1622, 1514
Reaction of aldehyde (1) with various amines, trimethylsilylazide, and
isocyanides in the presence of MgBr2Á2Et2O.
Entry
R1
R2 Yield (%)
Time
Product
1
2
3
4
5
6
7
8
C6H5
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
87
93
81
90
96
78
65
54
63
42
60
67
75
69
30 min
40 min
35 min
30 min
20 min
25 min
80 min
20 min
15 min
5 h
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
6m
6n
4-MeC6H4
4-ClC6H4
4-MeOC6H4
4-FC6H4
3-ClC6H4
4-NO2C6H4
2-ClC6H4
2-BrC6H4
2-Pyridyl
(ph), 3320 (NH) cmÀ1
;
1H NMR (400 MHz, CDCl3): d À0.11
(s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 1.68 (s, 9H, C(CH3)), 4.77
(d, 1H, J= 9.6 Hz, 1H, NH), 6.12 (d, J= 9.6 Hz, 1H, CH), 6.66
(d, J = 8 Hz, 2H, Ar), 6.76 (t, J = 7.6 Hz, 1H, Ar), 7.13–7.25
(m, 6H, Ar), 7.67 (s, 1H, HC═); 13C NMR (100 MHz, CDCl3):
d À0.56, 0.93 (SiMe3), 29.08 )C(CH3((, 53.67(CH), 61.7(C
(CH3((, 113.54, 118.35, 126.25, 127.6, 128.34, 135.76, 142.32,
144.78, 146.81, 152.57, (Ar, vinyl), 154.07 (tetrazole-C-5) ppm;
GC–MS, (EI): m/z, 477 (66%, [M]+), 421 (23%, [M À t-Bu]+), 352
(94%, [M À C5H9N4]+), 73 (100%, [SiMe3]+).
9
10
11
12
13
14
CH3(CH2)2CH2 3a
CH3(CH2)3CH2 3a
2h
70min
60min
90min
4-FC6H4
C6H5
3b
3b
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
tetrazol-5-yl)methyl}4-methylaniline (6b).
Light yellow solid,
mp 135–137ꢀC; FTIR (potassium bromide): 1250, 840, (Si–CH3),
1
1517 (C6H4), 3384 (NH) cmÀ1; H NMR (400 MHz, CDCl3): d
À0.11 (s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 1.66 (s, 9H, C(CH3) ),
2.2 (s, 3H, CH3), 4.66 (d, 1H, J= 9.6 Hz, 1H, NH), 6.08
(d, J= 9.6 Hz, 1H, CH), 6.59 (d, J= 8 Hz, 2H, Ar), 6.95 (d,
J= 8 Hz, 2H, Ar), 7.14 (d, J= 8.0 Hz, 2H, Ar), 7.22 (d, J=8.0Hz,
2H, Ar), 7.66 (s, 1H, HC═), ppm; 13C NMR (100 MHz, CDCl3): d
À0.5, 0.9 (SiMe3), 19.4 (Me), 28.6 (C(CH3)), 54.2 (CH), 60.6 )C
(CH3)(, 113.9, 114.2, 126.24, 127.5, 127.7, 128.8, 135.9, 142.2,
142.5, 152.6 (Ar, vinyl), 154.1 (tetrazole-C-5) ppm; GC–MS, (EI):
m/z, 491 (66%, [M]+), 435 (10% [M À t-Bu]+ ), 366 (76%,
[M À C5H9N4]+), 207 (100%, [C15H13N]+), 73 (90%, [SiMe3]+).
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
CONCLUSION
In summary, treatment of aldehyde (1) with amines,
trimethylsilylazide, and isocyanides gave a series of
new tetrazoles containing the 2,2-bis(trimethylsilyl)ethenyl
group. The use of MgBr2Á2Et2O as a catalyst decreased the
reaction times and increased the yields. We have described
a successful route for the convenient synthesis of new
tetrazoles bearing 2,2-bis(trimethylsilyl)ethenyl groups
via the Ugi-4CC reaction. The method offers several
advantages including operational simplicity, mild reaction
conditions, good yields, short time reaction, and easy
work-up.
tetrazol-5-yl)methyl}4-chloroaniline (6c).
135–137ꢀC; FTIR (potassium bromide): 1249, 839 (Si–CH3),
1597, 1489 (C6H4), 3319 (NH) cmÀ1 1H NMR (400 MHz,
Yellow solid, mp
;
CDCl3): d À0.11 (s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 1.67
(s, 9H, C(CH3) ), 4.85 (d, 1H, J = 9.6 Hz, 1H, NH), 6.08 (d,
J = 9.6 Hz, 1H, CH), 6.58 (d, J = 8.8 Hz, 2H, Ar), 7.09
(d, J = 8.4 Hz, 1H, Ar), 7.15 (d, J = 8.0 Hz, 2H, Ar), 7.24 (d,
J = 8.0 Hz, 2H, Ar), 7.66 (s, 1H, HC═); 13C NMR (100 MHz,
CDCl3): d À0.58, 0.91, (SiMe3), 29.0 C(CH3), 53.8 (CH), 60.7
(C(CH3)), 114.7, 123.04, 126.23, 127.65, 128.2, 135.2, 142.4,
143.3, 146.9, 152.4 (Ar, vinyl), 153.7 (tetrazole-C-5) ppm;
GC–MS, (EI): m/z, 512 (7%, [M]+), 455 (7%, [M À t-Bu]+),
207 (100%, [C15H13N]+); 73 (35%, [SiMe3]+).
EXPERIMENTAL
Reactions involving organolithium reagents were carried out
under dry argon. Solvents were dried by standard methods.
Substrates for the preparation of 4-[2,2-bis(trimethylsilyl)ethe-
nyl]benzaldehyde (1) and also all amines used in the synthesis
of tetrazoles, via trimethylsilylazide, tert-butyl isocyanide, cyclo-
hexylisocyanide, and MgBr2Á2Et2O, were purchased from Merck
and Fluka and used without further purification. FTIR spectra
were recorded on a Bruker-Tensor 270 spectrometer. 1H and
13C NMR spectra were recorded with a Bruker FT-400 MHz
spectrometer at room temperature and with CDCl3 as solvent.
For 1H NMR, TMS served as internal standard. Mass spectra were
obtained with a GC-Mass Agilent quadrupole model 5973N
instrument, operating at 70 eV. Melting points were measured with
a Barnstead international capillary melting point apparatus.
General procedure for the synthesis of new tetrazole
containing 2,2-bis(trimethylsilyl)ethenyl groups (6a–6n).
4-[2,2-Bis(trimethylsilyl)ethenyl]benzaldehyde (0.36 mmol), amine
(0.43 mmol), and MgBr2Á2Et2O (mol%) were mixed, and
trimethylsilylazide (0.36 mmol) and isocyanide (0.36 mmol)
were added after 5 min. The mixture was stirred at room
temperature until the reaction was complete (as monitored by
TLC). When the reaction was complete, the mixture was poured
into water (20 mL) and extracted with dichloromethane (3 Â 5mL).
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
tetrazol-5-yl)methyl}4-methoxyaniline (6d). Yellow solid, mp
121–123ꢀC; FTIR (potassium bromide): 1245, 837 (Si–CH3),
1624, 1512 (C6H4), 3441 (NH) cmÀ1 1H NMR (400 MHz,
;
CDCl3): d À0.11 (s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 1.64
(s, 9H, C(CH3)), 3.7 (s, 3H, OCH3), 4.52 (d, J = 12 Hz, 1H,
NH), 5.99 (d, J = 12 Hz, 1H,CH), 6.67 (d, J = 12 Hz, 2H, Ar),
6.73 (d, J = 12 Hz, 2H, Ar), 7.14 (d, J = 8 Hz, 2H, Ar), 7.21
(d, J = 8 Hz, 2H, Ar), 7.6 (s, 1H, HC═); 13C NMR (100 MHz,
CDCl3): d À0.5, 0.9, (SiMe3), 29.0 (C(CH3)), 54.5(CH), 55.5
(OMe), 60.5 (C(CH3)), 113.7, 116.2, 126.3, 127.5, 135.9,
142.2, 146.7, 152.6 (Ar, vinyl), 154.1 (tetrazole-C-5) ppm; GC–
MS, (EI): m/z, 507 (8%, [M]+), 451 (5% [M À t-Bu]+), 73 (42%,
[SiMe3]+), 207 (100%, [C15H13N]+).
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
tetrazol-5-yl)methyl}4-flouroaniline (6e).
Yellow solid, mp
120–123ꢀC; FTIR (potassium bromide): 1249, 836 (Si–CH3),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

K. D. Safa, T. Shokri, H. Abbassi, and R. Teymuri-Mofrad
Vol 0000
1605, 1504 (C6H4), 3322 (NH) cmÀ1
;
1H NMR (400 MHz,
1H, CH), 6.55 (d, J = 8 Hz, 1H, Ar), 6.59–6.63 (m, 1H, Ar),
7.07 (t, J = 8.0 Hz, 1H, Ar), 7.16 (d, J = 8.0 Hz, 2H, Ar), 7.28
(d, J = 8.0 Hz, 2H, Ar), 7.43 (dd, J = 8.0, 1.2 Hz, 1H, Ar), 7.6
(s, 1H, HC═); 13C NMR (100 MHz, CDCl3): d À0.5, 0.9
(SiMe3), 0.89, 29.0 (C(CH3)3), 53.0 (CH), 60.8 (C(CH3)),
111.8, 118.7, 126.12, 127.2, 127.6, 131.8, 135.05, 141.6,
142.43, 146.81, 152.49 (Ar, vinyl), 153.6 (tetrazole-C-5) ppm;
GC–MS, (EI); m/z, 555 (7%, [M]+), 432 (12%, [M À C5H9N4]+),
207 (100%, [C15H13N]+), 73 (38%, [SiMe3]+).
CDCl3): d À0.11 (s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 1.65
(s, 9H, C(CH3) ), 4.71 (d, 1H, J = 8.4 Hz, 1H, NH), 6.03
(d, J = 8.4 Hz,1H, CH), 6.64–6.61 (m, 2H, Ar), 6.82–6.87
(m, 2H, Ar), 7.15 (d, J = 8.0 Hz, 2H, Ar), 7.21 (d, J = 8.0 Hz,
2H, Ar), 7.6 (s, 1H, HC═); 13C NMR (100 MHz, CDCl3):
d À0.57, 0.92, (SiMe3), 29.0 (C(CH3)), 54.8 (CH), 60.6 (C
(CH3)), 114.7, 114.9, 126.2, 127.6, 135.5, 141.1, 142.4, 146.9,
152.4, 153.9 (Ar, vinyl), 154.0 (tetrazole-C-5) ppm; GC–MS,
(EI): m/z, 495 (20%, [M]+), 439 (10% [M À t-Bu]+), 370
(35%, [M À C5H9N4]+), 207 (100%, [C15H13N]+), 73 (62%,
[SiMe3]+).
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
tetrazol-5-yl)methyl}pyridin-2-amine (6j).
Yellow viscous
liquid; FTIR (potassium bromide): 837.9, 1257.9 (Si–CH3),
1
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
1559.8, 1603.4 (Ph), 3423.1 (N–H) cmÀ1; H NMR (400 MHz,
tetrazol-5-yl)methyl}3-chloroaniline (6f).
144–146ꢀC; FTIR (potassium bromide): 1249, 848 (Si–CH3),
1600,1497 (C6H4), 3448 (NH) cmÀ1 1H NMR (400 MHz,
CDCl3): d À0.11 (s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 1.68
(s, 9H, C(CH3) ), 4.9 (d, 1H, J = 9.2 Hz, 1H, NH), 6.07 (d,
J = 9.2 Hz, 1H, CH), 6.52 (dd, J = 1.6, 9.1 Hz, 1H, Ar), 6.61
(t, J = 1.6 Hz, 1H, Ar), 6.71 (dd, J = 1.6, 9.1 Hz, 1H, Ar), 7.04
(t, J = 9.2 Hz, 1H, Ar), 7.16 (d, J = 8 Hz, 2H, Ar), 7.23
(d, J = 8 Hz, 1H, Ar), 7.6 (s, 1H, HC═); 13C NMR (100 MHz,
Yellow solid, mp
CDCl3): d À0.10 (s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 1.71
(s, 9H, C(CH3) ), 4.47 (d, J = 9.2 Hz, 1H, NH), 6.49 (d,
J = 8.4 Hz, 1H, CH), 6.59 (t, J = 6.8 Hz, 1H, Ar), 7.06
(d, J = 9.2 Hz, 1H, Ar), 7.14 (d, J = 8.0 Hz, 2H, Ar), 7.22 (d,
J = 8.0 Hz, 2H, Ar), 7.35–7.39 (m, 1H, Ar), 7.67 (s, 1H, HC═),
8.0 (d, J = 4.3 Hz, 1H, Ar); 13C NMR (100 MHz, CDCl3):
d À0.55, 0.93 (SiMe3), 28.8(C(CH3)3), 49.55 (CH), 60.61 (C
(CH3)), 108.86, 113.29, 126.61, 127.48, 136.13, 136.3, 142.1,
146.3, 146.6, 152.7, 154.7 (Ar, vinyl), 155.7 (tetrazole-C-5) ppm;
GC–MS, (EI): m/z, 478 (52%, [M]+), 422 (36% [M À t-Bu]+), 207
(100%, [C15H13N]+), 73 (85%, [SiMe3]+).
;
CDCl3):
d
À0.570, 0.91, (SiMe3), 28.06 (C(CH3)), 53.3
(CH), 60.8 (C(CH3)), 111.7, 113.01, 118.1, 126.2, 127.6, 129.3,
134.0, 135.1, 142.5, 145.8, 147.03, 152.4 (Ar, vinyl), 153.7
(tetrazole-C-5) ppm; GC–MS, (EI): m/z, 511( 15%, [M]+), 386
(25%, [M À C5H9N4]+), 207 (100%, [C15H13N]+), 73 (70%,
[SiMe3]+).
N-{[4-(2,2-Bis(trimethylsilyl)ethenylphenyl](1-tert-butyl-1H-
tetrazol-5-yl)methyl}butan-1-amine (6k).
FTIR (potassium bromide); 1250, 840 (Si–CH3), 1597, 1489
(C6H4), 3325 (NH) cmÀ1 1H NMR (400 MHz, CDCl3):
mp 126–130ꢀC;
;
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
d À0.11 (s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 0.84–0.87 (t,
J = 8 Hz, 3H, CH3), 1.24–1.35 (m, 4H, CH2), 1.61 (s, 9H, C
(CH3)), 1.83 (s, 1H, NH), 2.47–2.53 (m, 2H, CH2), 5.2 (s, 1H,
(CH)), 7.12–7.20 (m, 4H, Ar), 7.67 (s, 1H, HC═); 13C NMR
(100 MHz, CDCl3): d À0.56, 0.92 (SiMe3), 12.8 (CH3), 19.32
(CH2), 28.95 (C(CH3)3), 29.89 (CH2), 46.69 (CH2), 57.86
(CH2), 60.26 (C(CH3)), 126.47, 127.3, 136.4, 141.8, 146.4,
152.7 (Ar, vinyl), 154.65 (tetrazole-C-5) ppm; GC–MS, (EI):
m/z, 457 (25%, [M]+), 401 (20%, M À t-Bu]+), 429 (95%), 207
(100%, [C15H13N]+), 386 (20%), 73 (35%, [SiMe3]+).
tetrazol-5-yl)methyl}4-nitroaniline (6g).
Yellow solid, mp
70–71ꢀC; FTIR (potassium bromide): 1256, 842 (Si–CH3),
1643, 1592, 1510 (C6H4), 3394 (NH) cmÀ1; H NMR (400 MHz,
1
CDCl3): d À0.01 (s, 9H, SiMe3), 0.20 (s, 9H, SiMe3), 1.4
(s, 9H, C(CH3) ), 4.94 (d, 1H, NH), 5.57 (s, 1H, CH), 6.57 (d,
J= 8.4 Hz, 2H, Ar), 6.64 (d, J= 8.4 Hz, 2H, Ar), 7.68 (s, 1H,
HC═), 7.97 (d, J= 8.6 Hz, 2H, Ar), 8.18 (d, J= 8.6 Hz, 2H, Ar);
13CNMR (100 MHz, CDCl3): d À0.550, 1.07 (SiMe3), 27.21 (C
(CH3)), 50.83 (CH), 58.2 (C(CH3)), 111.4, 120.9, 123.8, 126.14,
127.9, 135.03, 139.2, 143.7, 147.4, 152.05 (Ar, vinyl), 155.8
(tetrazole-C-5) ppm; GC–MS, (EI), m/z: 522 (10%, [M]+), 446
(30%), 207 (100%, [C15H13N]+).
N-{[(4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-
1H-tetrazol-5-yl)methyl}pentan-1-amine (6l). mp 131–134ꢀC;
FTIR (potassium bromide); 838, 1248 (Si–CH3), 1498, 1615
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
(C6H4), 3339 (N–H) cmÀ1 1H NMR (400 MHz, CDCl3): d
;
tetrazol-5-yl)methyl}2-chloroaniline (6h).
164–166ꢀC; FTIR (potassium bromide): 1248, 839 (Si–CH3),
1597, 1506 (C6H4), 3425 (NH) cmÀ1 1H NMR (400 MHz,
White solid, mp
À0.11 (s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 0.85–1.51 (m, 11H,
CH3), 1.61 (s, 9H, C(CH3)), 2.46–2.52 (m, 2H, CH2), 5.2
(s, 1H, (CH)), 7.13 (d, J = 8.0 Hz, 2H, Ar), 7.19 (d, J = 8.0 Hz,
2H, Ar), 7.67 (s, 1H, HC═); 13C NMR (100 MHz, CDCl3): ): d
À0.54, 0.94 (SiMe3), 12.9(CH3),21.49(CH2), 28.37, 28.62,
28.69(CH2) 28.98 (C(CH3)3), 30.42–30.49 (CH2), 47.04
(CH), 57.89 (C(CH3)–), 126.4, 127.4, 136.5, 141.9, 152.8 (Ar,
vinyl), 154.6 (tetrazole-C-5) ppm; GC–MS, (EI): m/z, 471
(25%, [M]+), 444 (20%), 405 (37%), 386 (20%), 207 (100%,
[C15H13N]+), 73 (70%, [SiMe3]+).
;
CDCl3): d À0.18 (s, 9H, SiMe3), 0.10 (s, 9H, SiMe3), 1.62
(s, 9H, C(CH3) ), 5.32 (d, J = 8 Hz, 1H, NH), 6.09 (d, J = 8 Hz,
1H,CH ), 6.51 (dd, J = 7.3, 0.8 Hz, 1H, Ar), 6.57–6.63
(m, 1H, Ar), 6.95–6.99 (m, 1H, Ar), 7.10 (d, J = 8.0 Hz, 2H,
Ar), 7.18–7.22 (m, 3H, Ar), 7.6 (s, 1H, HC═); 13C NMR
(100 MHz, CDCl3): d À0.50, 0.9, (SiMe3), 29.0 (C(CH3)), 53.0
(CH), 60.8 (C(CH3)3), 111.8, 118.2, 119.7, 126.15, 126.5, 127.6,
128.6, 135.11, 140.6, 142.4, 146.8, 152.5 (Ar, vinyl), 153.6
(tetrazole-C-5) ppm; GC–MS (EI): m/z, 511 ( 14%, [M]+), 386
(25%, [M À C5H9N4]+), 207 (100%, [C15H13N]+), 73 (67%,
[SiMe3]+).
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-cyclohexyl-1H-
tetrazol-5-yl)methyl}-4-fluoroaniline (6m).
FTIR (potassium bromide); 838, 1248 (Si–CH3), 1498, 1615
(C6H4), 3339 (N–H) cmÀ1 1H NMR (400MHz, CDCl3):
mp 155–157ꢀC;
;
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-tert-butyl-1H-
dÀ0.01 (s, 9H, SiMe3), 0.197 (s, 9H, SiMe3), 1.28–1.33(m, CH2
of c-hex), 1.35–1.45 (m, CH2 of c-hex), 1.61(m, CH2 of c-hex),
1.71–1.74 (m, CH2 of c-hex), 2.025 (d. J = 12.0 Hz, 2H, CH2 of
c-hex), 2.13 (d, J = 12.0 Hz, 2H, CH2 of c-hex), 3.94 (m, 1H, CH
of c-hex), 4.85 (s, 1H, NH), 5.97 (d, J = 8.0 Hz, 1H, CH),6.74
(t, J = 8.0 Hz, 2H, Ar), 6.94 (t, J = 8.0 Hz, Ar), 7.04–7.11 (dd,
tetrazol-5-yl)methyl}2-boromoaniline (6i).
153–155ꢀC; FTIR (potassium bromide): 1247, 841 (Si–CH3),
1593, 1503 (C6H4), 3411 (NH) cmÀ1 1H NMR (400 MHz,
White solid, mp
;
CDCl3): d À0.12 (s, 9H, SiMe3), 0.16 (s, 9H, SiMe3), 1.70
(s, 9H, C(CH3)), 5.4 (d, J = 8 Hz, 1H, NH), 6.15 (d, J = 8 Hz,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2013
One-Pot Synthesis of New 1,5-Disubstituted Tetrazoles Bearing 2,2-Bis(trimethylsilyl)
Ethenyl Groups via the Ugi Four-Component Condensation Reaction
J = 12, 8.0Hz, 4H, Ar), 7.68 (s, 1H, HC═); 13C NMR (100 MHz,
CDCl3): d À0.52, 1.08 (SiMe3), 23.7, 24.7, 28.6, 31.5 32.07
(CH2 of C-hex), 47.5 (CH of C-hex), 58.8 (CH), 113.9, 114.9,
122.6, 126.3, 127.4, 136.9, 145.99, 146.5, 152.7, (Ar, vinyl),
154.6 (tetrazole-C-5) ppm; 521 (25%, [M]+), 412 (45%), 207
(90%, [C15H13N]+), 73 (100%, [SiMe3]+).
[7] Ugi, I. Angew Chem Int Ed Engl 1962, 1, 8.
[8] Ugi, I.; Steinbruckner, C. Chem Ber 1961, 94, 734.
[9] Mayer, J.; Umkehrer, M.; Kalinski, C.; Ross, G.; Kolb, J.;
Burdacka, C.; Hiller, W. Tetrahedron Lett 2005, 46, 7393.
[10] (a) Butler, R. N.; Comprehensive Heterocyclic Chemistry;
Katritzky, A. R.; Rees, C. W.; Scriven, E. F. V., Eds; Permagon: Oxford,
UK, 1996, Vol. 4; (b) Demko, Z. P.; Sharpless, K. B. Org Lett 2002, 4,
2525.
[11] (a) Rendler, S.; Oestreich, M. Synthesis 2005, 11, 1727–1747;
(b) Wan, J. P.; Liu, Y. Curr Org Chem 2011, 15, 2758; (c) Dilman, A. D.;
Ioffe, S. L. Chem Rev 2003, 103, 733.
[12] (a) Pawluc, P.; Hreczycho, G.; Marciniec, B. J Org Chem 2006,
71, 8676–8679; (b) Mise, T.; Takaguchi, Y.; Wakatsuki, Y.; Takaguchi, Y.;
Umemiya, T.; Shimizu, S., Y. Chem Commun 1998, 6, 699.
[13] (a) Pawluc, P.; Hreczycho, G.; Walkowia, J.; Marciniec, B.
Synlett 2007, 2061; (b) Hreczycho, G.; Pawluc, P.; Marciniec, B.; Synthe-
sis 2006, 1370
[14] (a) Safa, K. D.; Ghorbanpour, K.; Hassanpour, A.; Tofangdar-
zadeh, S. J Organomet Chem 2009, 694, 1907; (b) Safa, K. D.;
Behmagham, F.; Ghorbanpour, K. J Organomet Chem 2011, 696, 1840.
[15] Safa, K. D., Vahid Mardipour, J.; Mosaei Oskoei, Y. J Organomet
Chem 2011, 696, 802.
N-{[4-(2,2-Bis(trimethylsilyl)ethenyl)phenyl](1-cyclohexyl-1H-
tetrazol-5-yl)methyl}aniline (6n).
mp 131–134ꢀC; FTIR
(potassium bromide); 840, 1248 (Si–CH3), 1560, 1604 (Ph),
3374 (N–H) cmÀ1
;
1H NMR (400 MHz, CDCl3): dÀ0.004
(s, 9H, SiMe3), 0.197 (s, 9H, SiMe3), 1.25–1.41 (CH2 of C-hex),
3.68 (s, 1H, NH), 5.94 (d, J = 8.0 Hz, 1H, CH),6.69
(d, J = 8.0 Hz, 2H, Ar), 6.85 (t, J = 8.0 Hz, Ar), 7.05–7.10
(m, 4H, Ar), 7.24(d, J = 8.0 Hz, 2H, Ar) 7.67 (s, 1H, HC═); 13C
NMR (100MHz, CDCl3): d À0.52, 1.06 (SiMe3), 23.7–32.07
(C-hex), 47.4 (CH of C-hex), 58.4 (CH), 113.5, 118.34, 120.52,
121.77, 126.37, 127.26, 127.46, 128.26, 145.99, 152.92,
(Ar, vinyl), 154.05 (tetrazole-C-5) ppm; GC–MS, (EI): m/z, 503
(30%, [M]+), 429 (45%), 207 (90%, [C15H13N]+), 73 (100%,
[SiMe3]+).
[16] Mojtahedi, M. M.; Abaee, M. S., Abbasi, H. Can J Chem
2006, 84, 429.
[17] Thorman, M.; Almstetter, M.; Tremi, A.; Heiser, U.;
Buchholz, M. WO patent. 2008, 55950. Chem Abstr 2008, 148, P55950.
[18] Kalinski, C.; Umkehrer, M.; Gonnard, S.; Jager, N.; Ross, G.;
Hiller, W. Tetrahedron Lett 2006, 47, 2041.
[19] (a) Short, K. M.; Ching, B. W.; Mjalli, A. M. M. Tetrahedron
1997, 53, 6653; (b) Hanusch-Kompa, C.; Ugi, I. Tetrahedron Lett 1998,
39, 2725; (c) Zhang, J.; Jacobson, A.; Rusche, J. R.; Herlihy, W. J Org
Chem 1999, 64, 1074; (d) Marcaccini, S.; Miguel, D.; Torroba, T.;
Garcia-Valverde, M. J Org Chem 2003, 68, 3315.
Acknowledgment. Financial support of this work by the
Tabriz University is gratefully appreciated, and also we
thank Dr. J. D. Smith for his helpful comments.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet