Zeo-click chemistry: Copper(I)-zeolite-catalyzed cascade reaction; One-pot epoxide ring-opening and cycloaddition

Article abstract of DOI:10.1002/ejoc.201000802

Copper(I)-modified zeolites, especially Cu^I-USY, proved to be very efficient catalysts in multi-component reactions of epoxides with sodium azide and terminal alkynes. Such catalysts allow highly regio- and stereoselective syntheses ofhydroxyme

Full text of DOI:10.1002/ejoc.201000802

FULL PAPER
DOI: 10.1002/ejoc.201000802
Zeo-Click Chemistry: Copper(I)–Zeolite-Catalyzed Cascade Reaction;
One-Pot Epoxide Ring-Opening and Cycloaddition
Thirupathi Boningari,[a,b,c] Andrea Olmos,[a] Benjaram M. Reddy,[c] Jean Sommer,[b] and
Patrick Pale*[a]
Dedicated to Professor Gregorio Asensio on his 60th birthday
Keywords: Alkynes / Copper / Click chemistry / Multicomponent reactions / Regioselectivity / Zeolites
Copper(I)-modified zeolites, especially CuI–USY, proved to
be very efficient catalysts in multi-component reactions of
cascade reaction was best performed in water at room tem-
perature, rendering all the processes truly green. Detailed
epoxides with sodium azide and terminal alkynes. Such cata- investigations revealed the role the CuI-modified zeolites
lysts allow highly regio- and stereoselective syntheses of
hydroxymethylated triazoles. These heterogeneous, modified
zeolites can easily be recovered and reused. Moreover, the
play both during the epoxide ring-opening and cycloaddition
steps.
could be catalyzed by CuI–zeolites in a very efficient way,
with the catalysts being recyclable several times (Figure 1a
and b).[3,4] We also demonstrated that CuI–zeolites can cat-
alyze a number of coupling reactions, such as the homocou-
pling of terminal alkynes (Figure 1c).[5] This set of reactions
led us to propose the new “zeo-click” concept (Figure 1),[6]
in analogy to the “click chemistry” principles developed by
Sharpless.[7]
We are now merging both domains, looking for the first
zeo-click MCR. Very recently, we showed that CuI–zeolites
are excellent catalysts for the three-component synthesis of
propargylamines (Figure 1d).[8] Now, we report that CuI–
zeolites catalyze another cascade reaction, starting from ep-
oxides. The latter react with terminal alkynes and sodium
azide in the presence of catalytic amounts of CuI–zeolites,
leading to hydroxymethylated 1,4-disubstituted 1,2,3-tri-
azoles in a one-pot, two-step, three-component process
(Figure 1e). The functionalized heterocycles thus produced
are useful compounds that can be used to selectively open
calcium channels in cells,[9] to inhibit enzymes,[10] and to
regulate plant growth.[11] They have also been used as pep-
tide mimics[12] and as key components in materials, such as
conducting or energetic polymers,[13,14] or spin-based mate-
rials.[15]
Introduction
The construction of complex architectures through an
intermolecular union of simple starting materials in a one-
pot operation still represents significant synthetic chal-
lenges. Such transformations, in which a product is as-
sembled through a cascade of elementary chemical reac-
tions, are called multi-component reactions (MCRs) and
have been the focus of many interesting achievements in
recent years.[1] MCRs are inherently “green” since they are
convergent, exhibit economy of steps and are usually atom-
economic, most of the incoming atoms being linked to-
gether in a single product. If such reactions could be run in
innocuous solvents and be promoted by catalysts that can
be recycled, such as heterogeneous catalysts, they would
thus comply with most of the Green Chemistry principles.[2]
Within this Green Chemistry context, we are currently
exploring the scope and limitations of metal-doped zeolites
as catalysts for organic synthesis. We recently demonstrated
that cycloadditions, such as the Huisgen and the Dorn reac-
tions leading to triazoles and pyrazolines, respectively,
[a] Laboratoire de Synthèse et Réactivité Organique, Institut de
Chimie, associé au CNRS (UMR 7177),
4 rue B. Pascal, Université L. Pasteur, 67000 Strasbourg, France
Fax: +33-3-90241517
Sodium azide ring-opening of epoxides is a well-known
reaction that usually leads to mixtures of β-hydroxy az-
ides,[16] which are usually further converted into 1,2-amino
alcohols or α-amino acids.[17] Various approaches have been
developed to achieve high regioselectivity under mild condi-
tions, especially through the use of Lewis acids
(Scheme 1),[18] although water alone also promotes this
ring-opening, depending on temperature and pH.[19]
E-mail: ppale@chimie.u-strasbg.fr
[b] Laboratoire de Physicochimie des Hydrocarbures, Institut de
Chimie, associé au CNRS (UMR 7177),
4 rue B. Pascal, Université L. Pasteur, 67000 Strasbourg, France
[c] Catalysis Laboratory, Indian Institute of Chemical Technology,
Habsiguda,
Tarnaka Road, Hyderabad 500-007, Andhra Pradesh, India
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201000802.
View this journal online at
wileyonlinelibrary.com
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Zeo-Click Chemistry
of the zeolite frameworks would alter the regioselectivity
of the ring-opening step, either enhancing or reversing it,
depending on the zeolite used. It is worth noting that this
CuI–zeolite-catalyzed cascade reaction would be the first to
be promoted by a heterogeneous catalyst.[21]
Results and Discussion
Conditions
To explore the feasibility of this zeo-click MCR for epox-
ides, we first selected styrene oxide as the starting material,
because this reaction is the literature benchmark for epox-
ide ring-opening. Because most of the preceding reactions
with CuI–zeolites were best performed with CuI–USY, we
first used this modified zeolite to screen the reaction condi-
tions. The behavior of styrene oxide was thus examined in
the presence of phenylacetylene, sodium azide, and CuI–
USY in various polar solvents, which were selected to mini-
mize solubility problems and favor epoxide ring-opening
(Table 1).
Table 1. Establishing optimal conditions.[a]
Figure 1. The zeo-click concept, with CuI–zeolites as catalyst.
Entry Solvent Temp. [°C] Time [h] Ratio Yield [%][b,c]
1
2
3
4
5
6
7
8
THF
THF
DMF
DMF
MeOH
MeOH
H2O
20
66
20
100
20
78
20
90
20
20
20
20
20
20
20
2
–
–
–
–
–
0
traces
0
traces
traces
52
Scheme 1. Sodium azide mediated opening of epoxides and synthe-
sis of 1,2-amino alcohols or α-amino acids.
86:14
94:6
96:4
77
83
H2O
Although never previously explored, CuI–zeolites should
catalyze such ring-opening reactions, with the copper(I)
loaded into the zeolite acting as a Lewis acid. Because we
demonstrated that CuI–zeolites can catalyze the cycload-
dition of azides with terminal alkynes,[3] we reasoned that
[a] Reaction performed on 1 mmol of each component with a zeo-
lite loading of 20 mg.[22] [b] Yields of products purified by
chromatography. [c] The ring-opening product was also recovered.
In solvents of medium polarity, such as tetrahydrofuran
a one-pot cascade reaction should be accessible that would (THF), no transformation took place regardless of the tem-
convert epoxides into functionalized triazoles under the ac- perature (Table 1, Entries 1 and 2). Surprisingly, highly po-
tion of this type of heterogeneous catalyst (Scheme 2).[20] lar but aprotic solvents, such as N,N-dimethylformamide
Moreover, the discriminatory properties of zeolites would (DMF), led to the same lack of reaction. In sharp contrast,
be beneficial to this reaction. The different sizes and shapes protic solvents were able to promote the expected cascade
Scheme 2. One-pot CuI–zeolite-catalyzed ring-opening of epoxides and subsequent cycloaddition.
Eur. J. Org. Chem. 2010, 6338–6347
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P. Pale et al.
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reaction, leading to a mixture of regioisomeric hydroxy- the largest pore size, were better catalysts than the smaller
methylated 1,4-disubstituted triazoles in medium to high channel-type zeolites (Table 2, Entries 3 and 4 vs. 6 and 7).
yields (Table 1, Entries 5–8). Methanol required heating to
Size discrimination was nevertheless not the sole factor,
give a mixture of isomers in reasonable yield (Table 1, En- because CuI–mordenite, which exhibits small pores in one
try 6 vs. 5). Water proved to be the best choice; in this sol- of its channel systems, proved to be almost as effective as
vent, good yield and very high regioselectivity were CuI–USY in terms of both efficiency and regioselectivity
achieved even at room temperature (Table 1, Entry 7). Heat- (Table 2, Entry 5 vs. 3). However, the Si/Al ratio of the zeo-
ing improved both the regioselectivity and the yield, while lites also seems critical (Figure 2). A high ratio was clearly
dramatically accelerating the reaction (Table 1, Entry 8 vs. deleterious, whereas a very low ratio also diminished the
7).
catalyst efficiency; an optimum was found to exist for USY.
The major regioisomer resulted from epoxide ring-open-
ing at the benzylic position, as revealed by the NMR shifts
of the corresponding proton signal compared with that of
the alternative isomer (δ = 5.67 vs. 5.23 ppm). It is worth
noting that the regioselectivity achieved under such condi-
tions (95:5 on average; Table 1, Entries 7–8) is better than
the 85:15 regioselectivity observed for the ring-opening of
styrene oxide promoted by PEG,[20a] suggesting a role for
the CuI–zeolite in the ring-opening step of the present cas-
cade reaction.
Figure 2. Correlation between CuI–zeolite acidities and yields.
Catalysts
In terms of regioselectivity, it seems that the most active
zeolite catalysts were also the most selective ones (Table 2,
Entries 3 and 5 vs. 4 and 6–7). Again, the Si/Al ratio clearly
showed an optimum in the 3–10 range, corresponding to
the USY and MOR zeolites (Figure 3).
Water was thus selected as the reaction medium, and re-
actions were performed at room temperature to save energy
and to create the mild conditions required to better comply
with established “green principles”. Under these conditions,
the influence of the internal structure of the zeolite was
then investigated with a series of CuI–zeolites, which were
screened and compared as catalysts for the same reaction
(Table 2).
Control experiments showed that no product was formed
without catalyst or with copper(I) chloride alone, even after
prolonged reaction times (Table 2, Entries 1 and 2). In con-
trast, every zeolite examined proved to be efficient as cata-
lyst, although variations in efficiency and selectivity were
Figure 3. Correlation between CuI–zeolite acidities and regioselec-
observed (Table 2, Entries 3–7). Cage-type zeolites, having tivities.
Table 2. Optimizing the zeolite catalysts.[a]
Entry
Catalyst
Topology
Pore size
Number of acidic sites
[mmol/g][b]
Time
Ratio
5a/6a
Yield[c]
[%]
[Å]
1
2
3
4
5
none
CuCl
–
–
–
–
–
–
4.39
6.67
1.48
3 d
3 d
22 h
22 h
22 h
–
–
0[d]
traces[d]
77
65
67
CuI–USY
CuI–Y
cage-type
cage-type
channel-type
7.4ϫ7.4
7.4ϫ7.4
7.6ϫ6.4
5.5ϫ5.5
5.1ϫ5.5
5.3ϫ5.6
6.5ϫ7.0
3.4ϫ3.8
94:6
84:16
94:6
CuI–MOR
6
7
CuI–ZSM5
CuI-β
channel-type
channel-type
1.04
22 h
22 h
86:14
88:12
63
0.90–1.23
45[d]
[a] Reaction was performed with styrene oxide (1 mmol), phenylacetylene (1 mmol), NaN3 (1.2 mmol), 20 h, with a zeolite loading[22] of
20 mg (ca. 0.08 mmol CuI). [b] For the corresponding acid zeolite. [c] Yields of products purified by chromatography. [d] The ring-opened
product was also recovered.
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Zeo-Click Chemistry
Figure 4. Role of CuI–zeolite in epoxide ring-opening: Yield and regioselectivity (select) in styrene oxide ring-opening by sodium azide
in the absence or presence of CuI–USY.
Further control experiments conducted without alkyne filtration and reused in the next run with or without regen-
revealed that the epoxide ring-opening reaction took several eration by heating before being reused. As shown in Fig-
hours and that CuI–zeolites clearly improved this reaction ure 5, the CuI–USY catalyst could be recycled five times
(Figure 4). Indeed, without catalyst, the ring-opening reac- without dramatic changes when the catalyst was regener-
tion of styrene oxide stopped at 60% conversion after 5 h, ated; a net decrease in efficiency was observed after three
whereas a classical evolution occurred in the presence of runs without regeneration. The regioselectivity was not af-
CuI–USY as catalyst, reaching complete conversion after fected in these successive reactions.
20 h. However, the regioselectivity did not dramatically
change with or without catalyst.
Scope and Limitations
These results confirmed that CuI–zeolites indeed play a
role in the epoxide ring-opening step of the cascade reaction
they catalyzed.
With the optimized conditions in hand, we examined the
scope and limitations of this zeo-click MCR starting from
epoxides. Various alkynes were allowed to react with styr-
ene oxide in the presence of CuI–USY as catalyst in water
at room temperature (Table 3). Under these conditions, tol-
ylacetylene gave the same regioselectivity as phenylacetyl-
ene but with higher yield (Table 3, Entry 2 vs. 1), suggesting
some electronic influence of the electron-donating methyl
group. However, the corresponding electron-deficient (tri-
fluorophenyl)acetylene gave an even better yield as well as
displaying a better regioselectivity (Table 3, Entry 3 vs. 1),
thus ruling out electronic effects in such a cascade reaction.
Indeed, aliphatic alkynes reacted in a manner similar to
phenylacetylene, giving the corresponding hydroxymethyl-
ated triazoles with mostly the same yields and selectivities
(Table 3, Entries 4 and 5 vs. 1). Interestingly, aliphatic di-
ynes could be fully converted into the corresponding bis-
(hydroxymethyl)triazole, with a high overall yield taking
into account the four steps involved in this cascade (Table 3,
Entry 6). No monotriazole intermediate could be detected
in this reaction.
Recycling
As expected, CuI–zeolites were easily separated by simple
filtration through a Nylon membrane. A simple wash al-
lowed the organic materials and the zeolite to be recovered.
The same reaction with styrene oxide was then per-
formed several times by using the same batch of CuI–USY
as catalyst. After each run, the catalyst was recovered by
As expected from our earlier zeo-click studies,[3] neither
alkynes carrying a free acid function nor disubstituted alk-
ynes reacted, and only the epoxide ring-opening products
were recovered (Table 3, Entries 7 and 8, respectively).
Although fully soluble in the aqueous reaction medium,
propargylated, unprotected carbohydrates did not react sig-
nificantly regardless of the temperature, which is again in
Figure 5. Recycling of CuI–USY with (front row) and without
(back row) heating before each run. The reactions were performed
with styrene oxide and phenylacetylene under the conditions de-
scribed above.
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Table 3. Scope of the cascade reaction catalyzed by CuI–USY.[a]
[a] Reaction performed with styrene oxide (1 mmol), alkyne (1 mmol), and NaN3 (1.2 mmol), 20 h, with a zeolite loading[22] of 20 mg
(ca. 0.08 mmol CuI). [b] Only the major regioisomer is represented. [c] Yields of isolated products after chromatography; the intermediate
ring-opening product (2a) accounted for the mass balance. [d] Performed at 95 °C. [e] A co-solvent (toluene) was required.
agreement with our earlier studies (Table 3, Entries 9 and that no epimerization occurred at the anomeric center un-
10). The corresponding protected carbohydrates only re- der such conditions.
acted when a co-solvent was added to the reaction mixture
The reactivities of various epoxides were then examined
for solubility reasons, and high yield and regioselectivity by submitting them to the reaction with phenylacetylene
were thus achieved (Table 3, Entry 11). It is worth noting under the same conditions (Table 4). Vinylepoxides reacted
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Zeo-Click Chemistry
Table 4. Scope of the cascade reaction catalyzed by CuI–USY.[a]
[a] Reaction performed with epoxide (1 mmol), alkyne (1 mmol), and NaN3 (1.2 mmol), 20 h, with a zeolite loading[22] of 20 mg (ca.
0.08 mmol CuI). [b] Only the major isomer is represented. [c] Yields of isolated products after chromatography; the intermediate ring-
opening product accounted for the mass balance. [d] Prolonged reaction time (60 h) was required. [e] See text. [f] NaN3 (3 equiv.) and
alkyne (3 equiv.) were used. [g] Without or with various co-solvents (dichloromethane, toluene). [h] An unidentified oligomeric by-product
was also formed.
similarly to styrene oxide, except that the reaction was even more complex than anticipated, and control experiments
more regioselective. From (E)-4-phenyl-1,2-epoxybut-3-ene without alkyne were performed to gain a better understand-
(1b), a single regioisomer was produced. Comparison of the ing of this reaction.
NMR spectroscopic data with those of known com-
When styrene oxide and sodium azide (1:1.2 molar ratio)
pounds[23] revealed that the ring-opening step only occurred were mixed at room temperature in deuterated water in the
at the allylic position (Table 4, Entry 1). This result is in presence of CuI–USY, NMR spectroscopic analysis re-
sharp contrast with conventional aminolysis of vinyl epox- vealed that three new compounds were produced. However,
ides, which yield the other regioisomer, i.e., the amino al- solubility differences between these compounds did not al-
lylic alcohol.[24]
low accurate quantification. Thus, a series of experiments
Nonconjugated epoxides were also converted into the were performed under the same conditions and stopped by
corresponding hydroxymethylated triazoles, although in
variable yields, depending on the epoxide structures
(Table 4,
Entries 2–10).
1,2-Epoxycyclohexane
(1c)
smoothly gave the ring-opened and click-cyclized product
5i. The latter was obtained with high trans selectivity, sug-
gesting the occurrence of an SN2 pathway for the epoxide
ring-opening step, as expected (Table 4, Entry 2). Similarly,
3-phenyl-1,2-epoxypropane (1d) gave a single regioisomer
corresponding to opening at the terminal epoxide carbon
atom, in agreement with a pure SN2 pathway (Table 4, En-
try 3). Compared to conjugated epoxides, the regioselectiv-
ity was reversed in favor of the less hindered isomer, proba-
bly for electronic as well as steric reasons.
Epichlorohydrin (1e) also reacted well, both with aro-
matic and aliphatic alkynes, the latter being less reactive
Figure 6. Reaction of epichlorohydrin without alkyne in the pres-
ence of sodium azide and CuI–USY as catalyst; evolution of the
than the former. Surprisingly, the reaction proved to be mixture.
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Scheme 3. CuI–zeolite-catalyzed cascade reaction observed upon epichlorohydrin treatment with sodium azide, alkyne, and CuI–USY as
catalyst.
extraction at different times; the products were then quanti- pected product, again with very high regioselectivity, but
fied by NMR spectroscopic analysis of the crude material with modest yield due to the formation of oligomeric spe-
and of the pure material after purification (Figure 6). The cies (Table 4, Entry 10).
product 3e, resulting from the expected ring-opening at the
less substituted epoxide end, was initially formed but, soon
after, the formation of a new epoxide 7, corresponding to
ring-closing of the chlorohydrin 3e, was observed. After 2 h,
the ring-opening product of this new epoxide, the diazide
8, was also formed. Due to the ratio of styrene oxide and
sodium azide used, the reaction stopped at approximately
60% conversion.
Under the same conditions, but in the presence of aro-
matic or aliphatic alkyne, a mixture of compounds was pro-
duced, with the bis(triazoles) 9a and 9b formed as the major
products (Table 4, Entries 4 and 5). Nevertheless, the di-
azido alcohol 8 and the new epoxytriazole 10 could also be
isolated as minor products in approximately 15 and 7%
yield, respectively (Scheme 3). The bis(triazoles) 9a and 9b
clearly arose from reaction with the intermediate diazido
alcohol 8, whereas the epoxytriazole 10 came from the
azido epoxide 7, which is the precursor of 8. Such a com-
plex cascade seemed unprecedented, although epichlorohy-
drin ring-opening has been reported.[18,20] This behavior
further illustrates the role of CuI–zeolites in the cascade re-
action.
Conclusions
Cu-modified zeolites, especially CuI–USY, proved to be
very efficient catalysts for the one-pot synthesis of hydroxy-
methylated 1,4-substituted triazoles from epoxides, alkynes,
and sodium azide.
Such heterogeneous catalysts can easily be recovered and
reused up to five times without severe loss in efficiency, pro-
vided the catalyst is activated between each run. This CuI–
zeolite-catalyzed cascade reaction proved to be highly regio-
and stereoselective and tolerated a wide range of functional
groups.
Performed in water and at room temperature with CuI–
zeolites as heterogeneous catalysts, the present multi-com-
ponent reaction of epoxides with sodium azide and ter-
minal alkynes complies with most “Green Chemistry” prin-
ciples.
Detailed investigations revealed the role that CuI-modi-
fied zeolites played both during the epoxide ring-opening
and the cycloaddition steps.
With higher molar ratios of sodium azide, alkyne, and
epichlorhydrin, the formation of the double ring-opening
and double click product 9a was favored, and this signifi-
cantly improved the yield of isolated product (Table 4, En-
try 6).
The more water-soluble 2,3-epoxypropan-1-ol surpris-
ingly proved to be poorly reactive, giving only traces of ad-
ducts regardless of the nature of the alkyne, even in the
presence of co-solvents (Table 4, Entries 7 and 8). This is
reminiscent of the results observed with unprotected carbo-
hydrate (see Table 3, Entries 9 and 10). In contrast, the cor-
responding acetylated derivative reacted well and with a
very high regioselectivity (Table 4, Entry 9), revealing the
importance of electronic effects in this series. The corre-
Experimental Section
General: All starting materials were commercially available and
were used as received. The reactions were monitored by thin-layer
chromatography (TLC), carried out on silica plates (silica gel 60
F254, Merck) by using UV light and p-anisaldehyde for visualiza-
tion. Column chromatography was performed on silica gel 60
(0.040–0.063 mm, Merck) by using mixtures of ethyl acetate and
cyclohexane as eluents. Evaporation of solvents were conducted un-
der reduced pressure at temperatures below 30 °C unless otherwise
noted. Melting points were measured in open capillary tubes. 1H
and 13C NMR spectra were recorded with a Bruker Avance 300
spectrometer at 300 and 75 MHz, respectively. Chemical shifts (δ)
and coupling constants (J) are given in ppm and Hz, respectively.
sponding tetrahydropyranyl derivative also gave the ex- Chemical shifts are reported relative to residual solvent as an in-
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Zeo-Click Chemistry
1
ternal standard (CDCl3: δ = 7.24 ppm for H and δ = 77.23 ppm
for 13C). Carbon multiplicities were determined by DEPT 135 ex-
periments. Electron impact (EI) and electrospray (ESIMS) low/
high-resolution mass spectra were obtained from the Mass Spec-
trometry Department of the Institut de Chimie, Strasbourg.
25 °C): δ = 7.36–7.31 (m, 3 H), 7.21–7.16 (m, 3 H), 5.56 (dd, 3JH,H
3
2
3
= 8, JH,H = 4 Hz, 1 H), 4.54 (dd, JH,H = 12, JH,H = 8 Hz, 1 H),
2
3
4.14 (dd, JH,H = 12, JH,H = 4 Hz, 1 H), 2.79 (br. s, 1 H), 2.64 (t,
3JH,H = 7 Hz, 2 H), 1.64 (qt, JH,H = 8, JH,H = 7 Hz, 2 H), 0.92
3
3
(t, JH,H = 7 Hz, 3 H) ppm. 13C NMR (75 MHz, CDCl3, 25 °C): δ
3
= 148.5 (C), 136.5 (C), 129.3 (2 CH), 129.0 (CH), 127.2 (2 CH),
121.8 (CH), 67.2 (CH), 65.4 (CH2), 27.8 (CH2), 22.7 (CH2), 14.0
(CH3) ppm. HRMS: calcd. for C13H17N3ONa+ 254.127; found
254.147.
Preparation of CuI-USY:[25] Commercial NH4–USY was placed in
an oven and heated at 550 °C for 4 h to give H–USY. Subsequently,
H–USY (1 g) and CuCl (475 mg, 1.1 equiv.) were mixed by using
a mortar and charged in a closed reactor. The mixture of powders
was heated at 350 °C for 3 d under a nitrogen flow, quantitatively
yielding CuI–USY.
2-(4-Phenethyl-1H-1,2,3-triazol-1-yl)-2-phenylethanol (5e): Isolated
1
yield: 246 mg (84%); white solid; m.p. 64 °C. H NMR (300 MHz,
General Procedure for the CuI–Zeolite-Catalyzed, One-Pot Reaction
of Epoxides and Terminal Alkynes: To a suspension of CuI–USY
(20 mg, 0.07 equiv.) in H2O (3 mL) were successively added epoxide
1 (1.0 mmol, 1.0 equiv.), sodium azide (1.2 mmol, 1.2 equiv.), and
then alkyne 4 (1.2 mmol, 1.2 equiv.). After 20 h of stirring at 20 °C,
the mixture was diluted with ethyl acetate (5 mL), the catalyst was
removed by filtration, and the solvent was evaporated to provide
the crude product (usually ca. 95% purity as judged by NMR spec-
troscopic analysis). Column chromatography was then performed.
CDCl3, 25 °C): δ = 7.33–7.31 (m, 3 H), 7.26–7.10 (m, 8 H), 5.66
3
3
2
3
(dd, JH,H = 8, JH,H = 4 Hz, 1 H), 4.48 (dd, JH,H = 12, JH,H
=
8 Hz, 1 H), 4.17 (dd, 2JH,H = 12, 3JH,H = 4 Hz, 1 H), 2.92–2.89 (m,
4 H) ppm. 13C NMR (75 MHz, CDCl3, 25 °C): δ = 147.7 (C), 141.2
(C), 136.4 (C), 129.2 (2 CH), 129.0 (CH), 128.6 (2 CH), 128.5 (2
CH), 127.2 (2 CH), 126.3 (CH), 121.1 (CH), 67.1 (CH), 65.2 (CH2),
35.6 (CH2), 27.7 (CH2) ppm. HRMS: calcd. for C18H20N3O+
294.160; found 294.158.
1,4-Bis[1-(2-hydroxy-1-phenylethyl)-1H-1,2,3-triazol-4-yl]butane (5f):
Isolated yield: 246 mg (57%); white solid; m.p. 182 °C. 1H NMR
(300 MHz, CDCl3, 25 °C): δ = 7.32–7.26 (m, 8 H), 7.22–7.18 (m, 4
Some of the adducts are known compounds, and triazoles 5a,[20]
6a,[21] 5b,[20,21] 5i,[3b] 9a,b,[26] and 10[27] have been reported, as have
intermediates 7[28] and 8.[29]
3
3
2
H), 5.60 (dd, JH,H = 8, JH,H = 4 Hz, 2 H), 4.49 (dd, JH,H = 12,
3JH,H = 8 Hz, 2 H), 4.12 (dd, JH,H = 12, JH,H = 4 Hz, 2 H), 2.59
2
3
Preparation of 2-(Oxiran-2-ylmethoxy)tetrahydro-2H-pyran (1i): In
a 50 mL round-bottom flask were dissolved m-chloroperbenzoic
acid (1.45 g, 8.45 mmol, 1.2 equiv.) and sodium hydrogen carbon-
ate (0.72 g, 8.5 mmol, 1.21 equiv.) in CHCl3 (20 mL), and the re-
sulting solution was cooled to 0 °C in an ice bath. To this cold
solution was added 2-(allyloxy)tetrahydro-2H-pyran (1 g,
7.04 mmol), and the reaction mixture was stirred at 0 °C for 16 h.
The reaction mixture was then transferred to a separatory funnel
and washed with aqueous NaOH (10%, 2ϫ20 mL) and with dis-
tilled water. The organic phase was dried with anhydrous Na2SO4
and concentrated under vacuum. The product was purified by col-
umn chromatography (cHex/Et2O, 80:20 with 1% of Et3N) to give
pure 1i as a colorless liquid. Yield: 403 mg (36%). NMR spectro-
scopic analysis of the product showed the presence of two dia-
stereoisomers in a 1:1 ratio. 1H NMR (300 MHz, CDCl3, 25 °C): δ
(t, JH,H = 6 Hz, 4 H), 1.63–1.58 (m, 4 H) ppm. 13C NMR
3
(75 MHz, CDCl3, 25 °C): δ = 147.7 (2 C), 136.5 (2 C), 129.1 (4CH),
128.9 (2 CH), 127.3 (4CH), 122.0 (2 CH), 67.2 (2 CH), 65.0 (2
CH2), 28.4 (2 CH2), 25.2 (2 CH2) ppm. HRMS: calcd. for
+
C24H29N6O2 433.235; found 433.229.
[1-(2-Hydroxy-1-phenylethyl)-1H-1,2,3-triazol-4-yl]methyl β-D-2,3,4,6-
O-Tetracetylglucoside (5g): Isolated yield: 689 mg (94%); white so-
1
lid; m.p. 46 °C. H NMR (300 MHz, CDCl3, 25 °C): δ = 7.47 (d,
3
3JH,H = 7 Hz, 1 H), 7.26–7.11 (m, 5 H), 5.58 (ddd, JH,H = 11,
3JH,H = 8, 4JH,H = 3 Hz), 5.34 (t, 3JH,H = 9 Hz, 1 H), 5.08 (t, 3JH,H
= 4 Hz, 1 H), 4.94 (t, 3JH,H = 10 Hz, 1 H), 4.71–4.65 (m, 2 H), 4.56
3
(d, JH,H = 12 Hz, 1 H), 4.50–4.41 (m, 1 H), 4.13–4.03 (m, 2 H),
4.01–3.92 (m, 2 H), 3.10 (br. s, 1 H), 1.97–1.82 (m, 12 H) ppm. 13
C
NMR (75 MHz, CDCl3, 25 °C): δ = 170.8 (C), 170.5 (C), 170.2
(C), 169.7 (C), 143.5 (C), 136.0 (C), 129.3 (2 CH), 127.4 (CH),
124.1 (2 CH), 123.8 (CH), 94.9 (CH), 71.0 (CH), 70.1 (CH), 68.5
(CH), 67.6 (CH), 67.2 (CH), 64.9 (CH2), 61.8 (CH2), 61.3 (CH2),
20.9 (CH3), 20.8 (CH3), 20.7 (CH3) ppm. HRMS: calcd. for
C25H31N3O11Na+ 572.186; found 572.180.
3
3
4
= 4.63 (ddd, JH,H = 7, JH,H = 4, JH,H = 3 Hz, 1 H), 3.92 (dd,
3JH,H = 12, JH,H = 3 Hz, 0.5 H), 3.88–3.79 (m, 1 H), 3.74–3.63
(m, 1 H), 3.52–3.45 (m, 1 H), 3.37 (dd, JH,H = 12, JH,H = 6 Hz,
0.5 H), 3.19–3.13 (m, 1 H), 2.78 (ddd, JH,H = 5, JH,H = 4, JH,H
3
2
3
2
3
4
2
3
= 2 Hz, 1 H), 2.66 (dd, JH,H = 5, JH,H = 3 Hz, 0.5 H), 2.57 (dd,
2JH,H = 5, 3JH,H = 3 Hz, 0.5 H), 1.84–1.47 (m, 6 H) ppm. 13C NMR
(75 MHz, CDCl3, 25 °C): δ = 99.1 (CH), 98.9 (CH), 68.7 (CH2),
67.5 (CH2), 62.4 (CH2), 62.2 (CH2), 51.1 (CH), 50.8 (CH), 44.8
(CH2), 44.7 (CH2), 30.7 (CH2), 30.6 (CH2), 25.6 (CH2), 19.5 (CH2),
19.4 (CH2) ppm. HRMS: calcd. for C8H14O2Na+ 165.089; found
165.086.
(E)-4-Phenyl-2-(4-phenyl-1H-1,2,3-triazol-1-yl)but-3-en-1-ol (5h):
Isolated yield: 172 mg (59%); white solid; m.p. 85 °C. 1H NMR
(300 MHz, CDCl3, 25 °C): δ = 7.81 (s, 1 H), 7.66–7.62 (m, 2 H),
3
3
7.37–7.22 (m, 8 H), 6.62 (d, JH,H = 16 Hz, 1 H), 6.45 (dd, JH,H
3
3
3
3
= 16, JH,H = 8 Hz, 1 H), 5.25 (ddd, JH,H = 8, JH,H = 7, JH,H
4 Hz, 1 H), 4.59 (br. s, 1 H), 4.29 (dd, JH,H = 12, JH,H = 7 Hz, 1
=
2
3
H), 4.19 (dd, JH,H = 12, JH,H = 4 Hz, 1 H) ppm. 13C NMR
(75 MHz, CDCl3, 25 °C): δ = 147.2 (C), 135.6 (C), 135.3 (2 CH),
130.2 (C), 128.9 (2 CH), 128.8 (2 CH), 128.7 (CH), 128.3 (CH),
126.9 (2 CH), 125.7 (2 CH), 123.1 (CH), 120.2 (CH), 65.8 (CH2),
64.7 (CH) ppm. HRMS: calcd. for C18H18N3O+ 292.145; found
292.142.
2
3
2-Phenyl-2-{4-[4-(trifluoromethyl)phenyl]-1H-1,2,3-triazol-1-yl}eth-
anol (5c): Isolated yield: 302 mg (92%); white solid; m.p. 108 °C.
1H NMR (300 MHz, CDCl3, 25 °C): δ = 7.87 (s, 1 H), 7.72 (d,
3
3JH,H = 8 Hz, 1 H), 7.52 (d, JH,H = 8 Hz, 2 H), 7.35–7.26 (m, 5
3
3
2
H), 5.73 (dd, JH,H = 8, JH,H = 4 Hz, 1 H), 4.61 (dd, JH,H = 12,
3JH,H = 8 Hz, 1 H), 4.36 (br. s, 1 H), 4.23 (dd, JH,H = 12, JH,H
=
2
3
4 Hz, 1 H) ppm. 13C NMR (75 MHz, CDCl3, 25 °C): δ = 146.0
1-Phenyl-3-(4-phenyl-1H-1,2,3-triazol-1-yl)propan-2-ol (5j): Isolated
yield: 162 mg (58%); white solid; m.p. 140 °C. 1H NMR (300 MHz,
CDCl3, 25 °C): δ = 7.80 (s, 1 H), 7.70–7.67 (m, 2 H), 7.38–7.21 (m,
1
(C), 135.9 (C), 133.6 (C), 130.2 (q, JC,F = 33 Hz, 1 C), 129.2 (2
CH), 129.1 (2 CH), 127.3 (2 CH), 125.8 (CH), 125.7 (2 CH), 122.4
(C), 121.6 (CH), 67.7 (CH2), 64.8 (CH) ppm. HRMS: calcd. for
C17H14F3N3ONa+ 356.099; found 356.093.
2
3
3
8 H), 4.48 (dd, JH,H = 13, JH,H = 3 Hz, 1 H), 4.34 (tdd, JH,H
=
=
3
3
2
3
8, JH,H = 6, JH,H = 3 Hz, 1 H), 4.24 (dd, JH,H = 13, JH,H
2
3
2-Phenyl-2-(4-propyl-1H-1,2,3-triazol-1-yl)ethanol (5d): Isolated
8 Hz, 1 H), 3.24 (br. s, 1 H), 2.88 (dd, JH,H = 14, JH,H = 6 Hz, 1
2
3
yield: 183 mg (79%); colorless oil. 1H NMR (300 MHz, CDCl3,
H), 2.81 (dd, JH,H = 13, JH,H = 7 Hz, 1 H) ppm. 13C NMR
Eur. J. Org. Chem. 2010, 6338–6347
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
6345

P. Pale et al.
FULL PAPER
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[5]
M. Keller, A. Sani Souna Sido, P. Pale, J. Sommer, Chem. Eur.
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(75 MHz, CDCl3, 25 °C): δ = 147.5 (C), 136.8 (C), 130.7 (C), 129.6
(2 CH), 129.1 (2 CH), 129.1 (2 CH), 128.4 (CH), 127.3 (CH), 125.9
(2 CH), 121.4 (CH), 71.6 (CH), 53.4 (CH2), 41.2 (CH2) ppm.
HRMS: calcd. for C17H18N3O+ 280.145; found 280.145.
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2-Hydroxy-3-(4-phenyl-1H-1,2,3-triazol-1-yl)propyl Acetate (5k):
Isolated yield: 183 mg (70%); white solid; m.p. 90 °C. 1H NMR
[6]
[7]
[8]
[9]
[10]
3
(600 MHz, CDCl3, 25 °C): δ = 7.86 (s, 1 H), 7.77 (d, JH,H = 8 Hz,
2 H), 7.39 (dd, 3JH,H = 8, 3JH,H = 7 Hz, 2 H), 7.32 (t, 3JH,H = 7 Hz,
2
3
2
1 H), 4.58 (dd, JH,H = 14, JH,H = 3 Hz, 1 H), 4.41 (dd, JH,H
=
=
3
3
3
3
14, JH,H = 7 Hz, 1 H), 4.37 (dtd, JH,H = 7, JH,H = 6, JH,H
2
3
3 Hz, 1 H), 4.23 (dd, JH,H = 12, JH,H = 4 Hz, 1 H), 4.14 (dd,
2JH,H = 12, JH,H = 6 Hz, 1 H), 2.10 (s, 3 H) ppm. 13C NMR
3
(75 MHz, CDCl3, 25 °C): δ = 171.2 (C), 147.7 (C), 130.2 (C), 129.0
(2 CH), 128.5 (CH, 1 C), 125.7 (2 CH), 121.5 (CH), 68.7 (CH2),
65.8 (CH), 53.4 (CH2), 21.0 (CH3) ppm. HRMS: calcd. for
C13H16N3O3H+ 262.119; found 262.121.
[11]
[12]
1-(4-Phenyl-1H-1,2,3-triazol-1-yl)-3-(tetrahydro-2H-pyran-2-yloxy)-
propan-2-ol (5l): Isolated yield: 103 mg (34%) as a 1:1 mixture of
1
[13]
diastereoisomers. White waxy solid. H NMR (300 MHz, CDCl3,
25 °C): δ = 7.84 (s, 1 H), 7.68–7.64 (m, 2 H), 7.31–7.18 (m, 3 H),
2
3
4.54–4.11 (m, 5 H), 3.85–3.75 (m, 1 H), 3.7 (dd, JH,H = 11, JH,H
[14]
[15]
R. Reed Jr., US Pat. 6103029, June 1997.
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3
2
= 4, 0.5 Hz), 3.58 (d, JH,H = 5 Hz, 1 H), 3.53 (dd, JH,H = 11,
3JH,H = 5, 0.5 Hz), 3.46–3.38 (m, 1 H), 1.76–1.62 (m, 2 H), 1.39–
1.51 (m, 4 H) ppm. 13C NMR (75 MHz, CDCl3, 25 °C): δ = 147.6
(C), 130.7 (C), 128.9 (2 CH), 128.2 (CH), 125.8 (2 CH), 121.5 (CH),
121.4 (CH), 101.0 (CH), 100.6 (CH), 70.7 (CH), 70.5 (CH), 69.6
(CH2), 69.5 (CH2), 64.1 (CH2), 63.6 (CH2), 53.5 (CH2), 53.2 (CH2),
30.9 (CH2), 30.8 (CH2), 25.3 (CH2), 25.2 (CH2), 20.5 (CH2), 20.1
(CH2) ppm. HRMS: calcd. for C16H21N3O3Na+ 326.148; found
326.147.
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Supporting Information (see footnote on the first page of this arti-
cle): Copies of 1H and 13C NMR spectra of the new compounds
described in the Experimental Section.
Acknowledgments
The authors thank the Centre National de la Recherche Sci-
entifique (CNRS) and the French Ministry of Research as well as
the Loker Institute, Los Angeles, for financial support. T. B. thanks
the French Embassy in New Delhi, India for support of his stay in
France under the “Sandwich PhD” Program.
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Eur. J. Org. Chem. 2010, 6338–6347
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
6347