1-Allyl- and 1-benzyl-3-methyl-1,2,3-triazolium salts via tandem click transformations

Article abstract of DOI:10.1055/s-0030-1257909

A series of 1-allylated and 1-benzylated 1,2,3-triazoles with varying substituents at the 4-position were prepared in yields ranging from 74-98% using a two-step one-pot click transformation. This tandem reaction involved the nucleophilic substitution of allyl chloride and benzyl bromide with sodium azide to form organic azide intermediates followed by Cu-catalyzed Huisgen 1,3-dipolar cycloaddition with alkyne reactants in a single reaction pot without the need for sequentially separating reaction steps. 1-Allyl- and 1-benzyl-4-alkyl-1,2,3-triazoles possessing linear alkyl chains underwent efficient N-alkylation at the 3-position with methyl iodide, while tert-butyl and phenyl derivatives did not. Each of the 1-allyl- and 1-benzyl-3-methyl-4- alkyl-1,2,3-triazolium iodide salts prepared was a viscous liquid at room temperature with a stable shelf life.

Full text of DOI:10.1055/s-0030-1257909

PAPER
3339
1-Allyl- and 1-Benzyl-3-methyl-1,2,3-triazolium Salts via Tandem Click
Transformations
1
-Allyl- an
a
d
1-Benzy
m
l-3-methyl-1,2,3-tria
e
zolium Sal
s
ts T. Fletcher,* Matthew E. Keeney, Sara E. Walz
Department of Chemistry, Creighton University, Omaha, NE 68178, USA
Fax +1(402)2805737; E-mail: jamesfletcher@creighton.edu
Received 9 March 2010; revised 18 May 2010
triazole derivatives as precursors to triazolium salts, an
approach that avoids the isolation of organic azides and
provides practical access to gram-scale quantities of tria-
zolium salts. We report herein the preparation of 1-allylat-
Abstract: A series of 1-allylated and 1-benzylated 1,2,3-triazoles
with varying substituents at the 4-position were prepared in yields
ranging from 74–98% using a two-step one-pot click transforma-
tion. This tandem reaction involved the nucleophilic substitution of
allyl chloride and benzyl bromide with sodium azide to form organ- ed and 1-benzylated 4-alkyl-1,2,3-triazoles and the
ic azide intermediates followed by Cu-catalyzed Huisgen 1,3-dipo-
formation of their analogous triazolium salts via alkyla-
lar cycloaddition with alkyne reactants in a single reaction pot
tion with methyl iodide. In addition to investigating how
without the need for sequentially separating reaction steps. 1-Allyl-
substituent identity impacts ease of preparation, the struc-
and 1-benzyl-4-alkyl-1,2,3-triazoles possessing linear alkyl chains
ture–property relationships resulting from alkyl group
variation at the 4-position of 1-allylated and 1-benzylated
1,2,3-triazole rings were examined.
underwent efficient N-alkylation at the 3-position with methyl io-
dide, while tert-butyl and phenyl derivatives did not. Each of the 1-
allyl- and 1-benzyl-3-methyl-4-alkyl-1,2,3-triazolium iodide salts
prepared was a viscous liquid at room temperature with a stable
shelf life.
Due to the orthogonal reactivity of the Cu-catalyzed
Huisgen 1,3-dipolar cycloaddition, this common click re-
action has proven amenable to incorporation within one-
pot multi-step transformations. Recent reports include
tandem click reactions coupled with azide formation from
halide,12–18 amine,19–21 boronic acid,22 epoxide23,24 and
alcohol25 precursors, as well as with trimethylsilylalkyne
deprotection.26–30
Key words: alkynes, azides, cycloaddition, ionic liquids, tandem
reaction
The 1,2,3-triazole heterocycle is an aromatic ring isoelec-
tronic with imidazole. Commonly synthesized via copper-
catalyzed Huisgen 1,3-dipolar cycloaddition reactions,
variation of substituent identity at the 1- and 4-positions
of the ring is trivial due to the high chemospecificity of
this transformation.1–4 While imidazole rings have found
widespread utility as components of ionic liquids, few ex-
amples of 1,2,3-triazole based ionic salts have been re-
ported.5–7
The general two-step one-pot procedure for preparing the
benzylated and allylated target compounds is summarized
in Scheme 1. The first reaction, a two-step one-pot tan-
dem process, involves the in situ formation of allyl and
benzyl azides followed by the Cu-catalyzed Huisgen 1,3-
dipolar cycloaddition with the terminal alkyne co-reac-
tant. Unlike previous reports describing the use of elevat-
ed temperatures12,13,17 or time-delayed introduction of
reagents promoting sequential steps,14,19–22 the tandem re-
actions involving allyl and benzyl halide reactants pro-
ceeded successfully at room temperature and permitted all
reagents to be introduced at the onset of the reaction.
As ionic liquids have been suggested as new organic sol-
vents where the physical properties of the solvent can be
engineered via structural variation of its organic building
blocks,8–10 the use of click reaction approaches to prepare
new ionic liquid analogues appears attractive in pursuing
such investigations. But preparation of new 1,2,3-triazoli-
um salts using a click approach does have inherent con-
flicting demands. While smaller alkyl substituents on the
triazole ring may be desired to help maintain the room
temperature liquid properties of its triazolium salt, the ex-
plosive potential of such smaller organic azide precursors
increases as their size decreases.11 The common desire to
prepare ionic liquid salts in large-scale quantities also
adds to the potential danger of preparing 1,2,3-triazolium
derivatives directly from organic azide precursors.
NaN3
CuSO4
Na ascorbate
N
R1
N
N
R1 Br
R2
+
t-BuOH–H2O
r.t., 24 h
R2
R
R
1 = allyl (1)
1 = benzyl (2)
I–
R1
N
+
N
Me
MeI
MeCN, 40 °C, 48 h
N
To address such issues, the goal of this study was to utilize
a two-step one-pot click transformation to prepare 1,2,3-
R2
R1 = allyl (3)
1 = benzyl (4)
R
Scheme 1 Preparation of triazoles 1 and 2 from a two-step one-pot
reaction, and triazolium salts 3 and 4 from N-alkylation with methyl
iodide
SYNTHESIS 2010, No. 19, pp 3339–3345
Advanced online publication: 22.07.2010
DOI: 10.1055/s-0030-1257909; Art ID: M02010SS
x
x.
x
x
.
2
0
1
0
© Georg Thieme Verlag Stuttgart · New York

3340
J. T. Fletcher et al.
PAPER
Overall, product yields are appreciable to one-step meth- While a recent report has described the preparation of
ods utilizing organic azides directly.
1,2,3-triazolium salts with task-specific substituents,5 the
goal of this study was to examine how the systematic vari-
ation of simple alkyl substituent identity influenced the
room temperature physical state of this family of com-
pounds. It is noteworthy that the allyl group has been re-
ported to impart physical properties31–34 and reactivity35
unique to alkyl analogues in imidazolium ionic liquid sys-
tems, such as an improved ability to dissolve cellulose. So
although in our study the allyl group was utilized for syn-
thetic expediency, it has the potential to also impart novel
traits to this class of ionic liquids that warrants future
study.
The second step of the reaction sequence involving the N-
alkylation of the 1,2,3-triazole ring to form the desired
1,3,4-trialkyltriazolium salts occurs in analogous manner
to preparing 1,3-dialkylimidazolium salts;31 reacting with
excess methyl iodide in acetonitrile at 40 °C.5,6 In survey-
ing the ratio of reactants to products over time, it was ob-
served that the N-alkylation at the 3-position of the 1,2,3-
triazole ring was sensitive to steric bulk at the 4-position.
Linear alkyl groups ranging from C3 to C8 each reacted
successfully at similar rates, but the tert-butyl and phenyl
derivatives could not be fully converted to triazolium
products under the conditions surveyed, likely due to ster- As summarized in Table 1, the majority of the 1-allylated
ic bulk.
triazoles were room temperature liquids, while the major-
ity of the 1-benzylated derivatives were room temperature
solids. Each of the triazolium salts was a viscous liquid
and observed to have a stable shelf life. Within twelve
months of room temperature storage none of the reported
derivatives crystallized upon standing, nor did any deriv-
ative show signs of decomposition via NMR analysis.
Reaction completion was monitored via 1H NMR analysis
(Figures 1 and 2), where a singlet at ~4.3 ppm corre-
sponding to the new N-methyl group was clearly ob-
served. The N-alkylation at the 3-position of the triazole
ring5,6 also led to a pronounced downfield chemical shift
of the aromatic singlet (of approximately 2 ppm) corre-
sponding to the 1,2,3-triazole hydrogen at the 5-position. Circumventing the isolation of triazole reactants not only
Minor downfield shifts of hydrogen atoms located in close stands as a practical improvement in reaction efficiency,
proximity to the triazole ring were also observed.
but it is important from a safety standpoint as well, partic-
ularly in applications where the large-scale preparation of
target compounds is desired. This strategy was successful-
ly applied towards the multigram scale preparation of
1,2,3-triazolium-based ionic liquid derivatives by conve-
niently allowing multigram-scale batches of 1-allylated
and 1-benzylated 1,2,3-triazoles to be produced. The one
significant drawback initially observed for this approach
was that the use of typical 20% catalyst loadings compli-
cated product purification due to the formation of emul-
sions during standard extraction purifications and the
presence of solid residue contaminating the resulting tria-
zole products. To address such issues, as well as to mini-
mize the amount of catalyst reagent needed to
successfully prepare the desired products, the impact of
significantly decreased catalyst loading on gram-scale
product preparations was examined.
Figure 1 Comparison of 1H NMR spectra of 1b and 3b in CDCl3
Table 2 summarizes the results of decreasing the amount
of copper catalyst from the typical 20% to 5% or less in
the established tandem two-step one-pot reaction condi-
tions. In examining the observed ratio of alkyne reactant
to triazole product monitored by GC/MS analysis, 5% cat-
alyst loading led to product formation within 24 hours ap-
proaching the isolated yields observed for the milligram
scale preparations, while the use of 2% catalyst resulted in
essentially half-completed reactions in that timeframe. In-
terestingly, the use of only 1% catalyst loading resulted in
essentially no observed triazole product, even after ex-
tended reaction times. Hence, this study indicates that a
minimum of 5% catalyst loading is required to prepare 1-
allylated and 1-benzylated 1,2,3-triazoles in good yields
via tandem two-step one-pot reactions within 24–48 hours
reaction times under these conditions.
Figure 2 Comparison of 1H NMR spectra of 2a and 4a in CDCl3
Synthesis 2010, No. 19, 3339–3345 © Thieme Stuttgart · New York

PAPER
1-Allyl- and 1-Benzyl-3-methyl-1,2,3-triazolium Salts
3341
Table 1 Summary of Compounds Surveyeda
Compound
Yield (%)b Mp (°C)
Compound
Conversion (%)c,d
>98
I–
I–
I–
I–
I–
I–
N
N
N
N
N
N
N
+
N
Me
Me
Me
Me
Me
Me
N
N
N
N
N
N
N
N
N
N
N
N
N
1a
1b
1c
1d
1e
79
82
74
90
83
r.t. liq. 3a
N
N
N
N
N
+
N
N
N
N
N
N
r.t. liq. 3b
r.t. liq. 3c
r.t. liq. 3d
>98
>98
>98
>98
+
N
+
N
+
N
37–39
3e
+
N
1f
78
91
r.t. liq. 3f
33
21
I–
N
N
+
N
Me
N
N
N
1g
57–58
3g
I–
I–
I–
I–
I–
I–
N
N
N
N
N
N
N
N
N
N
N
Me
Me
Me
Me
Me
Me
+
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
2a
2b
2c
2d
2e
89
87
76
92
92
r.t. liq. 4a
>98
>98
>98
>98
>98
+
N
58–59
42–43
55–56
69–70
4b
4c
4d
4e
+
N
+
N
+
N
N
N
+
N
2f
89
98
82–83
4f
13
7
I–
N
Me
+
N
N
N
N
2g
128–129 4g
a See the experimental section for conditions.
b Isolated yield.
c Percent conversion as monitored by 1H NMR spectroscopy.
d Each product was a viscous liquid at r.t.
Synthesis 2010, No. 19, 3339–3345 © Thieme Stuttgart · New York

3342
J. T. Fletcher et al.
PAPER
Table 2 GC/MS Monitoring of Reaction Completion
CH2Cl2 (50 mL) and 5% aq NH4OH (50 mL), and the aqueous layer
was extracted with CH2Cl2 (50 mL). The combined organic layers
were dried (MgSO4) and the solution separated via gravity filtration
through fluted filter paper into a round-bottomed flask. Volatiles
were removed via rotary evaporation to give the final 1,2,3-triazole
product (Table 1).
Time (h) Alkyne/triazole ratio observed
5% CuSO4
87:13
41:59
31:69
23:77
18:82
59:41
22:88
13:87
9:91
2% CuSO4
95:5
1% CuSO4
>99:1
>99:1
>99:1
>99:1
96:4
1a
1
2
91:9
1-Allyl-4-propyl-1,2,3-triazole (1a)
Yield: 476 mg (79%); colorless liquid.
1H NMR (300 MHz, CDCl3): d = 7.29 (s, 1 H), 6.02 (m, 1 H), 5.32
(m, 2 H), 4.95 (m, 2 H), 2.70 (t, J = 7.5 Hz, 2 H), 1.70 (m, 2 H), 0.98
(t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 148.68, 131.80, 120.61, 119.89,
52.71, 27.88, 22.88, 13.93.
4
72:28
67:33
57:43
86:14
69:31
58:42
56:44
51:49
24
72
1
2a
>99:1
>99:1
>99:1
>99:1
95:5
MS (EI, 70 eV): m/z = 151 (calcd for C8H13N3: 151).
2
1-Allyl-4-butyl-1,2,3-triazole (1b)
Yield: 542 mg (82%); colorless liquid.
1H NMR (300 MHz, CDCl3): d = 7.29 (s, 1 H), 6.02 (m, 1 H), 5.32
(m, 2 H), 4.95 (m, 2 H), 2.73 (t, J = 7.5 Hz, 2 H), 1.67 (m, 2 H), 1.40
(m, 2 H), 0.95 (t, J = 7.2 Hz, 3 H).
4
24
72
9:91
13C NMR (75 MHz, CDCl3): d = 148.96, 131.88, 120.58, 119.96,
In summary, a series of 1-allylated and 1-benzylated
1,2,3-triazoles have been prepared using a two-step one-
pot click transformation. This tandem reaction enabled
1,2,3-triazole analogues to be prepared in multigram
quantities while circumventing the need to isolate large
amounts of intermediate organic azide reactants or se-
quentially separate reaction steps. 1-Allyl- and 1-benzyl-
52.78, 31.82, 25.63, 22.54, 14.05.
MS (EI, 70 eV): m/z = 165 (calcd for C9H15N3: 165).
1-Allyl-4-pentyl-1,2,3-triazole (1c)
Yield: 533 mg (74%); colorless liquid.
1H NMR (300 MHz, CDCl3): d = 7.29 (s, 1 H), 6.02 (m, 1 H), 5.32
(m, 2 H), 4.95 (m, 2 H), 2.72 (t, J = 7.5 Hz, 2 H), 1.68 (m, 2 H), 1.35
4-alkyl-1,2,3-triazoles possessing linear alkyl chains un- (m, 4 H), 0.91 (t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 148.92, 131.80, 120.51, 119.88,
derwent efficient N-alkylation with methyl iodide, while
4-tert-butyl and phenyl derivatives did not readily form
their analogous triazolium salts. Surveying the structure-
property relationships between substituents at the 1- and
4-positions of the 1,2,3-triazole ring showed a rational
correlation between melting point and substituent identi-
ty, with each of the ionic salts prepared existing as liquids
at room temperature with stable shelf lives. Future work (m, 2 H), 4.95 (m, 2 H), 2.73 (t, J = 7.5 Hz, 2 H), 1.68 (m, 2 H), 1.33
will examine how additional variations of this class of
ionic liquids, including the identity of substituents at the
3-position, the counterion, and substituted benzyl units,
impact the physical properties of these compounds.
52.71, 31.60, 29.32, 25.84, 22.57, 14.15.
MS (EI, 70 eV): m/z = 179 (calcd for C10H17N3: 179).
1-Allyl-4-hexyl-1,2,3-triazole (1d)
Yield: 693 mg (90%); colorless liquid.
1H NMR (300 MHz, CDCl3): d = 7.29 (s, 1 H), 6.02 (m, 1 H), 5.32
(m, 6 H), 0.90 (t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 149.01, 131.88, 120.58, 119.95,
52.78, 31.82, 29.67, 29.16, 25.97, 22.79. 14.28.
MS (EI, 70 eV): m/z = 193 (calcd for C11H19N3: 193).
1-Allyl-4-octyl-1,2,3-triazole (1e)
Yield: 740 mg (83%); white crystalline solid; mp 37–39 °C.
1H NMR (300 MHz, CDCl3): d = 7.29 (s, 1 H), 6.03 (m, 1 H), 5.34
(m, 2 H), 4.96 (m, 2 H), 2.73 (t, J = 7.5 Hz, 2 H), 1.69 (m, 2 H), 1.30
(m, 10 H), 0.90 (t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 149.04, 131.89, 120.56, 119.96,
52.79, 32.09, 29.73, 29.58, 29.51, 29.45, 25.98, 22.90. 14.33.
Reagent grade solvents (Pharmco), alkyne reagents (GFS), NMR
solvents (Cambridge Isotopes) and all other reagents (Aldrich) were
used as purchased. NMR analyses were obtained on a 300 MHz
Varian Inova system. GC/MS was acquired on a Agilent 6850
Series II GC with 5973 MS detector operating at 70 eV. Kinetic
GC/MS analysis surveyed a temperature range of 40 to 240 °C.
MALDI-TOF MS was acquired on an Applied Biosystems Voyager
DE Pro spectrometer using 2,5-dihydroxybenzoic acid as the ma-
trix.
MS (EI, 70 eV): m/z = 221 (calcd for C13H23N3: 221).
1-Allyl-4-tert-butyl-1,2,3-triazole (1f)
Yield: 516 mg (78%); colorless liquid.
1H NMR (300 MHz, CDCl3): d = 7.26 (s, 1 H), 6.03 (m, 1 H), 5.35
(m, 2 H), 4.95 (m, 2 H), 1.37 (s, 9 H).
13C NMR (75 MHz, CDCl3): d = 158.17, 131.90, 119.98, 118.45,
52.76, 30.97, 30.58.
Milligram Scale Tandem Click Preparation of 1,4-Disubstitut-
ed 1,2,3-Triazoles 1 and 2; General Procedure
To a 20 mL scintillation vial was added sequentially CuSO4 (64 mg,
0.4 mmol), sodium ascorbate (159 mg, 0.8 mmol), NaN3 (286 mg,
4.4 mmol), H2O (10 mL), t-BuOH (10 mL), alkyne reactant (4.0
mmol), and either allyl chloride (0.36 mL, 4.4 mmol) or benzyl bro-
mide (0.24 mL, 4.0 mmol). Following the addition of allyl chloride
or benzyl bromide reactant, the vial was sealed with a screw cap and
stirred rapidly at r.t. After 24 h, the mixture was partitioned between
MS (EI, 70 eV): m/z = 165 (calcd for C9H15N3: 165).
Synthesis 2010, No. 19, 3339–3345 © Thieme Stuttgart · New York

PAPER
1-Allyl- and 1-Benzyl-3-methyl-1,2,3-triazolium Salts
3343
1-Allyl-4-phenyl-1,2,3-triazole (1g)
MS (EI, 70 eV): m/z = 215 (calcd for C13H17N3: 215).
Yield: 671 mg (91%); white crystalline solid; mp 57–58 °C.
1-Benzyl-4-phenyl-1,2,3-triazole (2g)
Yield: 948 mg (98%); white crystalline solid; mp 128–129 °C.
1H NMR (300 MHz, CDCl3): d = 7.83 (m, 2 H), 7.70 (s, 1 H), 7.39
(m, 8 H), 5.60 (s, 2 H).
13C NMR (75 MHz, CDCl3): d = 148.50, 134.97, 130.82, 129.42,
129.07, 129.04, 128.42, 128.33, 125.97, 119.76, 54.49.
1H NMR (300 MHz, CDCl3): d = 7.87 (m, 2 H), 7.79 (s, 1 H), 7.45
(m, 2 H), 7.36 (m, 1 H), 6.09 (m, 1 H), 5.39 (m, 2 H), 5.04 (m, 2 H).
13C NMR (75 MHz, CDCl3): d = 148.30, 131.60, 130.90, 129.09,
128.41, 125.98, 120.43, 119.66, 53.02.
MS (EI, 70 eV): m/z = 185 (calcd for C11H11N3: 185).
1-Benzyl-4-propyl-1,2,3-triazole (2a)
MS (EI, 70 eV): m/z = 235 (calcd for C15H13N3: 235).
Yield: 718 mg (89%); colorless liquid.
Multigram Scale Tandem Click Preparation of 1,4-Disubstitut-
ed 1,2,3-Triazoles; General Procedure
1H NMR (300 MHz, CDCl3): d = 7.39 (m, 3 H), 7.29 (m, 2 H), 7.21
(s, 1 H), 5.52 (s, 2 H), 2.69 (t, J = 7.5 Hz, 2 H), 1.69 (m, 2 H), 0.97
(t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 148.95, 135.25, 129.24, 128.78,
128.14, 120.72, 54.16, 27.94, 22.86, 13.97.
To a 200 mL round-bottomed flask was added sequentially CuSO4
(399 mg, 2.5 mmol), sodium ascorbate (991 mg, 5.0 mmol), NaN3
(3.576 g, 55 mmol), H2O (50 mL), t-BuOH (50 mL), alkyne reactant
(50 mmol), and either allyl chloride (4.08 mL, 50 mmol) or benzyl
bromide (5.95 mL, 50 mmol). Following the addition of allyl chlo-
ride or benzyl bromide reactant, the flask was sealed with a rubber
septum and stirred rapidly at r.t. After 48 h, the mixture was parti-
tioned between CH2Cl2 (100 mL) and 5% aq NH4OH (100 mL), and
the aqueous layer was extracted with CH2Cl2 (100 mL). The com-
bined organic layers were dried (MgSO4) and the solution separated
via gravity filtration through fluted filter paper into a round-bot-
tomed flask. Volatiles were removed via rotary evaporation to give
the final 1,2,3-triazole product. Representative analogues prepared
in this manner: 1a (81%, 6.09 g); 2a (91%, 9.16 g).
MS (EI, 70 eV): m/z = 201 (calcd for C12H15N3: 201).
1-Benzyl-4-butyl-1,2,3-triazole (2b)
Yield: 746 mg (87%); white crystalline solid; mp 58–59 °C.
1H NMR (300 MHz, CDCl3): d = 7.38 (m, 3 H), 7.29 (m, 2 H), 7.21
(s, 1 H), 5.52 (s, 2 H), 2.72 (t, J = 7.5 Hz, 2 H), 1.62 (m, 2 H), 1.39
(m, 2 H), 0.94 (t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 149.20, 135.31, 129.28, 128.82,
128.20, 120.71, 54.20, 31.77, 25.67, 22.57, 14.06.
MS (EI, 70 eV): m/z = 215 (calcd for C13H17N3: 215).
Methyliodonium Salts 3 and 4; General Procedure
To a 20 mL scintillation vial was added sequentially 4-substituted
1-allyl- 1a–g or 1-benzyl-1,2,3-triazole 2a–g (1.0 mmol), MeCN (5
mL), and MeI (0.31 mL, 5.0 mmol). The vial was sealed with a
screw cap and stirred at 40 °C. After 48 h, the contents of the vial
were transferred to a round-bottomed flask and volatiles were re-
moved via rotary evaporation, resulting in isolated 1-allyl- and 1-
benzyl-3-methyl-4-alkyl-1,2,3-triazolium iodide salts as pale yel-
low to yellow viscous liquids. Isolated yields for those reactions
reaching completion as observed by 1H NMR (3a–e and 4a–e) was
>98% (Table 1).
1-Benzyl-4-pentyl-1,2,3-triazole (2c)
Yield: 692 mg (76%); white crystalline solid; mp 42–43 °C.
1H NMR (300 MHz, CDCl3): d = 7.39 (m, 3 H), 7.29 (m, 2 H), 7.21
(s, 1 H), 5.52 (s, 2 H), 2.71 (t, J = 7.5 Hz, 2 H), 1.62 (m, 2 H), 1.34
(m, 4 H), 0.91 (t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 149.22, 135.26, 129.25, 128.80,
128.16, 120.64, 54.18, 31.66, 29.31, 25.93, 22.60, 14.19.
MS (EI, 70 eV): m/z = 229 (calcd for C14H19N3: 229).
1-Benzyl-4-hexyl-1,2,3-triazole (2d)
Yield: 892 mg (92%); white crystalline solid; mp 55–56 °C.
1H NMR (300 MHz, CDCl3): d = 7.38 (m, 3 H), 7.29 (m, 2 H), 7.20
(s, 1 H), 5.52 (s, 2 H), 2.71 (t, J = 7.5 Hz, 2 H), 1.66 (m, 2 H), 1.32
(m, 6 H), 0.89 (t, J = 7.2 Hz, 3 H).
1-Allyl-3-methyl-4-propyl-1,2,3-triazolium Iodide (3a)
1H NMR (300 MHz, CDCl3): d = 8.93 (s, 1 H), 6.06 (m, 1 H), 5.58
(dd, J = 16.2, 0.6 Hz, 1 H), 5.44 (dd, J = 9.9, 0.6 Hz, 1 H), 5.29 (d,
J = 6.6 Hz, 2 H), 4.26 (s, 3H), 2.87 (t, J = 7.8 Hz, 2 H), 1.77 (m, 2
H), 1.00 (t, J = 7.5 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 149.19, 135.25, 129.22, 128.76,
128.13, 120.64, 54.15, 31.73, 29.56, 29.10, 25.94, 22.72, 14.22.
13C NMR (75 MHz, CDCl3): d = 144.55, 128.86, 128.10, 123.99,
55.97, 38.92, 25.66, 20.47, 13.60.
MS (MALDI): m/z [M – I]+ calcd for C9H16N3: 166; found: 166.
MS (EI, 70 eV): m/z = 243 (calcd for C15H21N3: 243).
1-Benzyl-4-octyl-1,2,3-triazole (2e)
Yield: 1.00 g (92%); white crystalline solid; mp 69–70 °C.
1-Allyl-4-butyl-3-methyl-1,2,3-triazolium Iodide (3b)
1H NMR (300 MHz, CDCl3): d = 8.95 (s, 1 H), 6.07 (m, 1 H), 5.62
(dd, J = 16.2, 0.6 Hz, 1 H), 5.48 (dd, J = 9.9, 0.6 Hz, 1 H), 5.32 (d,
J = 6.6 Hz, 2 H), 4.29 (s, 3 H), 2.92 (t, J = 7.8 Hz, 2 H), 1.72 (m, 2
H), 1.44 (m, 2 H), 0.92 (t, J = 7.5 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 144.83, 128.89, 128.16, 124.14,
56.09, 38.99, 28.93, 23.73, 22.14, 13.61.
1H NMR (300 MHz, CDCl3): d = 7.38 (m, 3 H), 7.29 (m, 2 H), 7.20
(s, 1 H), 5.52 (s, 2 H), 2.71 (t, J = 7.5 Hz, 2 H), 1.66 (m, 2 H), 1.28
(m, 10 H), 0.90 (t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 149.25, 135.32, 129.29, 128.82,
128.19, 120.71, 54.20, 32.08, 29.67, 29.56, 29.51, 29.44, 26.01,
22.90, 14.34.
MS (MALDI): m/z [M – I]+ calcd for C10H18N3: 180; found: 180.
MS (EI, 70 eV): m/z = 271 (calcd for C17H23N3: 271).
1-Allyl-3-methyl-4-pentyl-1,2,3-triazolium Iodide (3c)
1H NMR (300 MHz, CDCl3): d = 8.87 (s, 1 H), 6.02 (m, 1 H), 5.55
(dd, J = 16.2, 0.6 Hz, 1 H), 5.42 (dd, J = 9.9, 0.6 Hz, 1 H), 5.26 (d,
J = 6.6 Hz, 2 H), 4.23 (s, 3 H), 2.84 (t, J = 7.8 Hz, 2 H), 1.67 (m, 2
H), 1.28 (m, 4 H), 0.80 (t, J = 7.5 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 144.63, 128.62, 127.99, 123.87,
55.84, 38.87, 30.80, 26.47, 23.75, 21.89, 13.65.
1-Benzyl-4-tert-butyl-1,2,3-triazole (2f)
Yield: 762 mg (89%); white crystalline solid; mp 82–83 °C.
1H NMR (300 MHz, CDCl3): d = 7.38 (m, 3 H), 7.29 (m, 2 H), 7.18
(s, 1 H), 5.51 (s, 2 H), 1.35 (s, 9 H).
13C NMR (75 MHz, CDCl3): d = 158.43, 135.33, 129.28, 128.80,
128.27, 118.61, 54.17, 31.03, 31.61.
Synthesis 2010, No. 19, 3339–3345 © Thieme Stuttgart · New York

3344
J. T. Fletcher et al.
PAPER
MS (MALDI): m/z [M – I]+ calcd for C11H20N3: 194; found: 194.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synthesis. Included
are 1H NMR, 13C NMR and GC/MS characterization of each com-
pound described in this study.
1-Allyl-4-hexyl-3-methyl-1,2,3-triazolium Iodide (3d)
1H NMR (300 MHz, CDCl3): d = 8.74 (s, 1 H), 5.93 (m, 1 H), 5.46
(dd, J = 16.2, 0.6 Hz, 1 H), 5.24 (dd, J = 9.9, 0.6 Hz, 1 H), 5.17 (d,
J = 6.6 Hz, 2 H), 4.13 (s, 3 H), 2.75 (t, J = 7.8 Hz, 2 H), 1.57 (m, 2
H), 1.24 (m, 2 H), 1.11 (m, 4 H), 0.66 (t, J = 7.5 Hz, 3 H).
Acknowledgment
13C NMR (75 MHz, CDCl3): d = 144.31, 128.24, 127.77, 123.44,
55.52, 38.58, 30.62, 28.10, 26.43, 23.45, 21.83, 13.46.
This research was supported by an award from Research Corpora-
tion.
MS (MALDI): m/z [M – I]+ calcd for C12H22N3: 208; found: 208.
References
1-Allyl-3-methyl-4-octyl-1,2,3-triazolium Iodide (3e)
1H NMR (300 MHz, CDCl3): d = 8.75 (s, 1 H), 5.96 (m, 1 H), 5.49
(dd, J = 16.2, 0.6 Hz, 1 H), 5.34 (dd, J = 9.9, 0.6 Hz, 1 H), 5.20 (d,
J = 6.6 Hz, 2 H), 4.17 (s, 3 H), 2.78 (t, J = 7.8 Hz, 2 H), 1.61 (m, 2
H), 1.26 (m, 2 H), 1.08 (m, 8 H), 0.69 (t, J = 7.5 Hz, 3 H).
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MS (MALDI): m/z [M – I]+ calcd for C13H18N3: 216; found: 216.
1-benzyl-4-butyl-3-methyl-4-1,2,3-triazolium Iodide (4b)
1H NMR (300 MHz, CDCl3): d = 9.16 (s, 1 H), 7.63 (m, 2 H), 7.41
(m, 3 H), 5.96 (s, 2 H), 4.30 (s, 3 H), 2.91 (t, J = 7.9 Hz, 2 H), 1.74
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129.53, 129.07, 57.40, 38.99, 29.07, 23.87, 22.31, 13.71.
MS (MALDI): m/z [M – I]+ calcd for C14H20N3: 230; found: 230.
1-benzyl-3-methyl-4-pentyl-1,2,3-triazolium Iodide (4c)
1H NMR (300 MHz, CDCl3): d = 9.10 (s, 1 H), 7.59 (m, 2 H), 7.35
(m, 3 H), 5.92 (s, 2 H), 4.28 (s, 3 H), 2.87 (t, J = 7.9 Hz, 2 H), 1.72
(m, 2 H), 1.33 (m, 4 H), 0.84 (t, J = 7.4 Hz, 3 H).
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129.61, 129.11, 57.47, 39.28, 31.30, 26.93, 24.22, 22.33, 14.11.
MS (MALDI): m/z [M – I]+ calcd for C15H22N3: 244; found: 244.
1-Benzyl-4-hexyl-3-methyl-1,2,3-triazolium Iodide (4d)
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(m, 2 H), 1.39 (m, 6 H), 0.83 (t, J = 7.4 Hz, 3 H).
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129.40, 128.89, 57.26, 38.98, 31.14, 28.70, 27.01, 24.03, 22.39,
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MS (MALDI): m/z [M – I]+ calcd for C18H28N3: 286; found: 286.
Synthesis 2010, No. 19, 3339–3345 © Thieme Stuttgart · New York

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1-Allyl- and 1-Benzyl-3-methyl-1,2,3-triazolium Salts
3345
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Synthesis 2010, No. 19, 3339–3345 © Thieme Stuttgart · New York