A Peerless Aproach: Organophotoredox/Cu(I) Catalyzed, Regioselective, Visible Light Facilitated, Click Synthesis of 1,2,3-Triazoles via Azide–Alkyne [3 + 2] Cycloaddition

Article abstract of DOI:10.1007/s10562-017-2156-8

Abstract: A visible light initiated, mild, one pot, multicomponent copper catalyzed azide alkyne [3 + 2] cycloaddition in the presence of organo photoredox catalyst Eosin Y using EtOH:H₂O as reaction medium for the synthesis of substituted 1,2,3-triazoles is reported. A facile regioselective ring opening of epoxides followed by 1, 3 dipolar cycloaddition with alkynes under CFL (Compact fluorescent light) irradiation as a source of visible light resulting in the formation of C–N bonds, is the characteristic feature of the present strategy. Scope of the present protocol is further extended by using benzyl chloride in place of epoxide. Graphical Abstract: [Figure not available: see fulltext.].

Full text of DOI:10.1007/s10562-017-2156-8

Catal Lett
DOI 10.1007/s10562-017-2156-8
A Peerless Aproach: Organophotoredox/Cu(I) Catalyzed,
Regioselective, Visible Light Facilitated, Click Synthesis
of 1,2,3-Triazoles via Azide–Alkyne [3+2] Cycloaddition
Anu Mishra1 · Pratibha Rai1 · Madhulika Srivastava1 · Bhartendu Pati Tripathi1 ·
Snehlata Yadav1 · Jaya Singh2 · Jagdamba Singh1
Received: 17 May 2017 / Accepted: 30 July 2017
© Springer Science+Business Media, LLC 2017
Abstract A visible light initiated, mild, one pot, multicom-
ponent copper catalyzed azide alkyne [3+2] cycloaddition
in the presence of organo photoredox catalyst Eosin Y using
EtOH:H2O as reaction medium for the synthesis of substi-
tuted 1,2,3-triazoles is reported. A facile regioselective ring
opening of epoxides followed by 1, 3 dipolar cycloaddition
with alkynes under CFL (Compact fluorescent light) irradia-
tion as a source of visible light resulting in the formation
of C–N bonds, is the characteristic feature of the present
strategy. Scope of the present protocol is further extended
by using benzyl chloride in place of epoxide.
Graphical Abstract
Br
Br
O
HO
O
O
Cl
R3
R1
Br
Br
1
COOH
5
NaN3
2
R2
HO
R1
3
CuI
N
N
N
EtOH:Water/rt
N
N
N
N
HO
OR
N
N
R3
R1
When R1= Alkyl
R2
R2
R2
4
6
When R1= Aryl
Electronic supplementary material The online version of this
article (doi:10.1007/s10562-017-2156-8) contains supplementary
material, which is available to authorized users.
Keywords Visible light · [3+2] cycloaddition · Eosin Y ·
Regioselective · 1,2,3-Triazole
* Jagdamba Singh
dr.jdsau@gmail.com
1 Introduction
Jaya Singh
nimesh.singh@in.abb.com
Recently, the focus of the chemists is shifting towards syn-
thetic routes employing green aspects [1–5]. Taking into
consideration the increasing concern for the environment,
the chemists are making a constant effort to adopt syn-
thetic routes that discourage the involvement of hazardous
1
Environmentally Benign Synthesis Lab, Department
of Chemistry, University of Allahabad, Allahabad 211002,
India
2
Department of Chemistry, LRPG College, Sahibabad,
Uttar Pradesh, India
Vol.:(0123456789)
1 3

A. Mishra et al.
chemicals. In this recent past, light has been utilized as one
of the most efficient and prominent resources to achieve
synthetically useful organic transformations [6–10]. A bulk
of chemists are experimenting with visible light (generally
CFLs and LEDs) because of its unique properties like easy
availability, easy handling and serving as an eco-efficient,
cost effective, environmentally benign and unending source
of energy for the construction of organic molecules [11, 12].
It is able to transfer the activation energy to the reactants
in chemical reactions. Thus visible light promoted cataly-
sis has originated as one of the most sustainable tools in
organic synthesis being accessible to a myriad of reactions
[13–17]. However, some organic molecules are unable to
absorb visible light [18]. To triumph over this barricade,
chemists use photo sensitizers. In literature various methods
have been revealed in which transition metals [19–22], nano-
particles [23–25] and certain organic dyes [26–29] are uti-
lized as photocatalysts. Howbeit trasition metals like Ru(II)
and Ir(II) complexes exhibit a number of impediments as
they proclaim adverse inherent malignancy, high toxicity,
low sustainability, short durability and expensiveness [30,
31]. Within this context, an organic dye, eosin Y (EY), is a
fascinating alternative to transition metal photocatalysts and
has lately been extensively used as a photoredox catalyst. It
undergoes redox quenching to generate radical anion or radi-
cal cation and this process has been done via photoexcitation
of eosin Y with simultaneous reductive or oxidative quench-
ing through acceptance or donation of an electron [30].
Over the past few years, nitrogen heterocycles have gained
substantial attention [32] (https://cen.acs.org/content/dam/
cen/supplements/CENsupplement092014.pdf, http://www.
fiercepharma.com/special-report/top-20-generic-molecules-
worldwide). In September 2014, C and EN Supplement pre-
sented top fifty drugs, most of them enclosed at least one
nitrogen-containing heterocycle (https://cen.acs.org/con-
tent/dam/cen/supplements/CENsupplement092014.pdf). It
is present in a range of natural products, biologically active
structures and medicinally important compounds. 1,2,3-tri-
azoles, five-membered nitrogen containing heterocycles,
reveal diverse biological activities such as being anti-allergic
[33], anti-HIV [34, 35], anti-microbial [36], anti-bacterial
[37], anticancerous [38], antifungal [39], antimalarial [40],
anti-inflammatory [41], antitubercular [42], β3-adrenergic
receptor agonist [43] and having antioxidant activity [44].
They also find industrial applications in optical brighteners,
corrosion decelerating agents, dyes, agrochemicals, fungi-
cides, herbicides and solar cells [45–48] (Fig. 1) [49–53].
Multicomponent reactions (MCRs) are highly cost-
effective, environmentally benign and absolutely appropri-
ate for combinatorial library synthesis and have thus gained
colossal advantages over conventional multi-step reaction
sequences managing to diminish waste, time and cost suc-
cessfully [54–58]. Huisgen 1,3-dipolar cycloaddition is one
of the prominent reaction for the synthesis of 1,2,3-triazoles
via copper-catalyzed azide–alkyne cycloaddition (CuAAC).
Various methods for the synthesis of 1,2,3-triazoles in dif-
ferent reaction conditions have been developed [59–74].
Although the reported methods have several merits, how-
ever they were associated with some drawbacks like use of
costly and bulky catalysts, non-reusability of catalyst, use
of base, difficulty in the recovery of high boiling solvent,
high temperature and use of excess amounts of reagents or
catalysts which entails to design a more facile and eco-effi-
cient protocol for the synthesis of 1,2,3-triazoles. In order to
extend our work on visible light induced synthesis [75–78],
here we have documented a visible light promoted Eosin Y
and copper (I) iodide catalyzed [3+2] cycloaddition for the
synthesis of 1,2,3-triazoles initiating from epoxides, sodium
azide and terminal alkynes. The scope of the present proto-
col has been further increased by using benzyl chloride in
place of epoxides (Scheme 1).
2 Results and Discussion
For the attainment of optimization, we took styrene oxide
(1a), sodium azide (2) and phenyl acetylene (3a) as model
substrates for the synthesis of 1,2,3-triazoles. During our ini-
tial attempts, we optimized the reaction conditions by using
varied catalysts, photosensitizers and different sources as
well as intensities of visible light (Table 1). Initially, we took
styrene oxide (1a, 1.0 mmol), sodium azide (2, 1.0 mmol)
and phenyl acetylene (3a, 1.0 mmol) under CFL (23 W) irra-
diation in the absence of catalyst at room temperature and
found that product did not form after 24 h of CFL irradia-
tion (Table 1, entry 1). After that, we performed our test
reaction in the presence of catalysts. In the first instance, we
used copper(II) chloride as a catalyst and afforded 41% yield
of product within 8 h (Table 1, entry 2). Similarly when
we used copper(I) oxide, it resulted in the product in 6 h
with 50% yield (Table 1, entry 3). However when we used
copper(I) iodide as a catalyst for the test reaction, surpris-
ingly an improved result was obtained with 60% yield of
the product in 5 h (Table 1, entry 4). On the basis of above
investigations, we concluded that catalyst is mandatory for
the reaction to proceed and copper(I) salts are suitable for
the present transformation as it forms copper(I) phenyla-
cetylide, which is the essential light absorbing species and
increases the efficiency of reaction in presence of visible
light [79–82]. Although the reactions proceeded well in the
presence of copper(I) iodide, the yield and reaction time
have not been much satisfactory. In order to further increase
the effectiveness of the model reaction, we decided to make
use of various types of photocatalysts. Within this context,
we used a range of photocatalysts (Table 1, entries 5–9) and
found that Eosin Y encouraged the reaction and furnished
1 3

A Peerless Aproach: Organophotoredox/Cu(I) Catalyzed, Regioselective, Visible Light…
OH
Cl
NH
O
O
N
N
N
NO2
N
N
OH
O
N
O
N
N
O
S
N
O
Anti-influenza A agent [49]
O
Anti-viral agent [50]
R1
O
N
N
R2
O
N
HO
N
N
N
H
N
O
O
N
N
O
O
HO
O
N
N
OCF3
N
N
O
O
OH
Hsp90 Inhibitor [52]
O
Anti-cancer agent [51]
DAGLβ Inhibitor [53]
Fig. 1 Some biologically important derivatives of 1,2,3-triazole
Previous works[59–74]
HO
R1
O
N
N
NaN3
High
N
N
N
N
HO
R1
Temprature
2
3
1
R1
4
Base
R2
R2
OR
R2
When R1= Aryl
When R1= Alkyl
Expensive
Catalysts
OR
Cl
N
N
R3
N
R3
5
6
R2
Present work
HO
R1
N
O
N
N
N
NaN3
HO
Eosin Y
CuI
N
N
R1
2
R1
1
R2
4
EtOH:H2O(1:1)
R2
R2
OR
When R1= Alkyl
When R1= Aryl
OR
CFL(23W)
rt
Cl
3
N
N
R3
N
R3
5
6
R2
Scheme 1 Synthesis of 1,2,3-triazole
1 3

A. Mishra et al.
Table 1 Optimization of reaction conditions
Entry
Catalyst
Time (h)
Yielda (%)
c
1
2
3
4
5
6
7
8
Noneb
CuCl2 (20 mol%)
Cu2O (20 mol%)
CuI (20 mol%)
24.0
8.0
6.0
5.0
4.5
4.5
4.0
3.5
3.5
3.5
3.5
3.5
3.5
3.5
12.0
3.5
3.5
3.5
3.5
12.0
–
41
50
60
71
72
78
76
82
72
75
82
78
82
25
75
77
82
82
Trace
CuI (20 mol%)+Iodine (0.1 mol%)
CuI (20 mol%)+CANd (0.1 mol%)
CuI (20 mol%)+RBe (0.1 mol%)
CuI (20 mol%)+EBf (0.1 mol%)
CuI (20 mol%)+Eosin Y (0.1 mol%)
CuI (10 mol%)+Eosin Y (0.1 mol%)
CuI (15 mol%)+Eosin Y (0.1 mol%)
CuI (30 mol%)+Eosin Y (0.1 mol%)
CuI (20 mol%)+Eosin Y (0.05 mol%)
CuI (20 mol%)+Eosin Y (0.2 mol%)
CuI+Eosin Yg
CuI+Eosin Y (18 W CFL)
CuI+Eosin Y (20 W CFL)
CuI+Eosin Y (23 W CFL)
CuI+Eosin Y (27 W CFL)
CuI+Eosin Y+TEMPOh
9
10
11
12
13
14
15
16
17
18
19
20
Reaction condition: 1a (1.0 mmol), 2 (1.0 mmol), 3a (1.0 mmol) in EtOH: H2O irradiated using CFL under open air at room temperature
aYield of the product (%)
bAbsence of catalysts
cNot detected
dCerric Ammonium Nitrate
eRose Bengal
fEosin Blue
gDark
h(2,2,6,6-Tetramethyl-piperidin-1-yl)oxyl
the products with 82% yields in 3.5 h (Table 1, entry 9). In
the next endeavour, we focused towards the optimization
of best catalyst loading for the present protocol (Table 1,
entries 9–14) which led us to infer that the reaction works
well with 20 mol% of Copper(I) iodide and 0.1 mol% of
Eosin Y (Table 1, entry 9).
After this we performed our model reaction with differ-
ent intensities of light source (Table 1, entries 16–19) and
observed that CFL (23W) is the ideal source of visible light
for the present protocol (Table 1, entry 18). Moreover, the
reaction was suppressed with TEMPO (2.0 mmol), clearly
indicating that the reaction proceeds through a free radical
pathway (Table 1, entry 20) [83–85].
1 3

A Peerless Aproach: Organophotoredox/Cu(I) Catalyzed, Regioselective, Visible Light…
Table 2 Optimization of solvents for the synthesis of compound 4a
Entry
Solvents
Time (h)
Yielda (%)
1
2
DMF
THF
24.0
6.0
Trace
45
3
4
5
6
DMSO
DCM
DCE
CH3CN
MeOH
10.0
10.0
24.0
10.0
7.0
21
26
Trace
49
70
7
8
9
H2O
EtOH
4.0
4.5
75
71
10
11
12
13
EtOH: H2O (1: 1)
EtOH: H2O (2: 1)
EtOH: H2O (3: 1)
Neat
3.5
3.5
3.5
24.0
82
78
78
b
–
Reaction condition: 1a (1.0 mmol), 2 (1.0 mmol), 3a (1.0 mmol) in solvent irradiated using CFL (23W) under open air at room temperature.
aYield of the product (%)
bNot detected.
After the finalization of the best catalytic system, we next
screened different solvents to further optimize the reaction
conditions (Table 2). Initially, we used DMF as a solvent
and found that after 24 h of CFL irradiation the product was
formed in traces (Table 2, entry 1). After that a batch of reac-
tions with polar aprotic solvents (Table 2, entries 2–6) were
performed but still neither yield nor time of reaction was
satisfactory for the desired transformation. Further we used
polar protic solvents (Table 2, entries 7–12) and discovered
that the present strategy is effective with them. Among them
EtOH:H2O (1:1) combination of solvent was observed as
most appropriate for the required transformation (Table 2,
entry 10). EtOH:H2O (1:1) solvent system might be effective
because of greater solubility of reactants in this medium or
due to an increase in the number of collisions between reac-
tants which resulted in enhancement of their ground state
energy and reaction rates [86–90]. A hypothesis is also asso-
ciated with it; the transition states of present reaction could
be stabilized by water as it has high static permittivity [91].
We also carried out the test reaction in neat condition but no
result was obtained even 24 h of CFL irradiation (Table 2,
entry 13). So the EtOH:H2O (1:1) mixed solvent system has
been found to be most effective, convenient and efficient for
the required transformation.
Once we had the optimal reaction conditions in hand,
we next sought to extend this methodology with scope
and limitations of the present synthetic strategy. In this
regard, we used different derivatives of epoxide (1) as
well as alkynes (3) (Table 3). It was observed that aryl
substituted epoxides afforded the reactions more effec-
tively in comparison to alkyl substituted epoxides. It was
interestingly observed that in the case of aryl substituted
epoxides a preferential attack on the more hindered car-
bon atom took place (Table 3, entries 1, 2, 3, 4 and 6) [59,
60, 63]. In contrast, alkyl substituted epoxides involved
attack at less hindered carbon atom (Table 3, entries 8,
10, 11 and 12). Similar less hindered attack was found
with glycidyl phenyl ether and isopropyl glycidyl ether
1 3

A. Mishra et al.
Table 3 Substrate scope for the synthesis of compound 4
Entry Epoxide (1)
1
Alkyne (3)
Product (4)
Yielda (%) Time (h) M. P. (℃)
82
3.5
126–127 °C [63]
2
72
5.0
62–63 °C [59]
3
4
74
82
5.0
3.5
65–67 °C [67]
123–125 °C [59]
5
6
73
75
4.5
4.0
126–128 °C [68]
– [60]
1 3

A Peerless Aproach: Organophotoredox/Cu(I) Catalyzed, Regioselective, Visible Light…
Table 3 (continued)
Entry Epoxide (1)
Alkyne (3)
Product (4)
Yielda (%) Time (h) M. P. (℃)
7
71
5.0
62–64 °C [59]
8
78
4.0
168–170 °C [63]
9
70
76
5.0
4.0
101–103 °C [67]
109–110 °C [59]
10
11
12
70
69
7.5
7.5
93–94 °C [67]
105–107 °C [63]
Reaction condition: 1 (1.0 mmol), 2 (1.0 mmol), 3 (1.0 mmol) in EtOH: H2O irradiated using CFL (23W) under open air at room temperature
aYield of the product (%)
(Table 3, entries 5 and 7) [60]. As in epoxides, alkynes
with aryl substitution react faster and more efficiently
than those with alkyl substitution. Adopting the same
experimental route, we further extended the scope of
this methodology for the synthesis of 1,2,3-triazole by
replacing epoxide by Benzyl chloride (5). It resulted in
1 3

A. Mishra et al.
Table 4 Substrate scope for the synthesis of compound 6
Entry Benzyl chloride (5)
1
Alkynes (3)
Product (6)
Time (h) Yielda (%) M.P. (℃)
1.5
85
127–129 °C [64]
2
3
3.0
2.5
75
87
– [70]
151–152 °C [64]
4
3.0
2.0
2.0
82
86
85
127–128 °C [71]
149–150 °C [64]
203–204 °C [64]
Cl
H3CO
5b
5
6
N
N
N
Br
6e
N
Cl
N
N
Br
Br
H3C
5c
3e
6f
CH3
7
2.0
87
141–142 °C [64]
N
Cl
N
N
O2N
O2N
5d
3a
6g
1 3

A Peerless Aproach: Organophotoredox/Cu(I) Catalyzed, Regioselective, Visible Light…
Table 4 (continued)
Entry Benzyl chloride (5)
Alkynes (3)
Product (6)
Time (h) Yielda (%) M.P. (℃)
8
2.5
86
244–245 °C [64]
N
Cl
N
N
O2N
O2N
H3C
5d
3e
6h
CH3
9
2.5
2.5
85
84
96–98 °C [70]
86–88 °C [64]
N
Cl
N
N
Cl
Cl
6i
5e
3a
10
N
Cl
N
N
Cl
Cl
5f
3a
6j
Reaction condition: 5 (1.0 mmol), 2 (1.0 mmol), 3 (1.0 mmol) in EtOH: H2O irradiated using CFL (23W) under open air at room temperature
aYield of the product (%)
the formation of a new series of derivatives of 1,2,3-tria-
consequently leads to the formation of the desired scaffold,
1,2,3-triazole.
zole (6) (Table 4, entries 1–10).
2.1 Mechanism
3 Conclusion
A proposed mechanistic route, the cornerstone of litera-
ture survey [21, 79–82, 84, 92–100], for 1,2,3-triazoles
has been postulated (Schemes 2, 3). On photo-absorption
Eosin Y, a photoredox catalyst gets excited to its singlet
state (1EY*) and is then converted to a more stable triplet
state (3EY*) via inter system crossing (ISC). After this it
undergoes a single electron transfer (SET) and converts
epoxide (1) into an arene radical cation (A) which fur-
ther gets converted into its stable benzyl cation (A’) form
[92]. Next azide attacks as a nucleophile, at the same time
Eosin Y undergoes a single electron transfer (SET) and
(B) results into (C). After that (C) takes a proton from the
solvent and converts into (D) which resulted in its active
1, 3 dipolar form (E). Simultaneously, phenyl acetylene
reacts with copper (I) iodide to form a light absorbing
species, copper (I) phenylacetylide (F). In last step (E) and
(F) undergo the well known [3 + 2] cycloaddition which
In conclusion, we have divulged the successful, visible-
light-promoted synthetic approach to accomplish a slick
synthesis of 1,2,3-triazole, a biologically and pharmaceu-
tically significant scaffold, via multicomponent [3 + 2]
CuAAC using epoxide (1), sodium azide (2) and terminal
alkyne (3) as reactants in presence of eosin Y, a photosensi-
tizer and copper iodide. The present synthetic strategy has
been pertained to the quick synthesis of 1,2,3-triazole using
commercially available substrates, without employing harsh
reaction conditions. The expansion of this methodology has
been achieved by the use of a range of epoxides as well as
phenylacetylene and benzyl chloride derivatives. The use
of ubiquitous visible light makes the adopted procedure
immensely green.
1 3

A. Mishra et al.
O
O
N N N
(2)
(A')
N N N
O
+
(B)
(A)
EY
Ref
[84, 92, 95–97]
O
N
N
N
O
(C)
(1a)
EtOH:H2O
OH
(3a)
N
N
N
Ref [79–82]
(D)
CuI
OH
Cu
Ref
[93, 98–100]
N
N
N
(E)
(F)
[3+2] Cycloaddition
HO
HO
N
N
N
N
N
N
Cu
4a
Scheme 2 Proposed mechanism for the synthesis of 1,2,3-triazole (4a)
1 3

A Peerless Aproach: Organophotoredox/Cu(I) Catalyzed, Regioselective, Visible Light…
Scheme 3 Proposed mecha-
nism for the synthesis of
1,2,3-triazole (6a)
16. Conner ES, Crocker KE, Fernando RG, Fronczek FR, Stanley
Acknowledgements We sincerely thank SAIF, Punjab University,
Chandigarh, for providing micro-analyses and spectra. The author A.
Mishra and P. Rai are thankful to UGC, New Delhi for the award of
Junior Research Fellowship (JRF) and Senior Research Fellowship
(SRF), respectively.
GG, Ragains JR (2013) Org Lett 15:5558
17. Hu F, Cao M, Ma X, Liu SH, Yin J (2015) J Org Chem 80:7830
18. Zeitler K (2009) Angew Chem Int Ed 48:9785
19. Konieczynska MD, Dai C, Stephenson CR (2012) Org Biomol
Chem 10:4509
20. Nicewicz DA, MacMillan DWC (2008) Science 322:77
21. Prier CK, Rankic DA, MacMillan DWC (2013) Chem Rev
113:5322
References
22. Han YY, Jiang H, Wang R, Yu S (2016) J Org Chem 81:7276
23. Saravanan R, Gupta VK, Narayanan V, Stephen A (2014) J Tai-
wan Inst Chem Eng 45:1910
1. Anastas PT, Warner JC (1998) Green chemistry: theory and prac-
tice. Oxford University Press, New York
24. Saravanan R, Khan MM, Gupta VK, Mosquera E, Gracia F,
Narayanan V, Stephen A (2015) RSC Adv 5:34645
25. Saravanan R, Gupta VK, Mosquera E, Gracia F (2014) J Mol Liq
198:409
2. Roopan SM, Khan FRN (2010) Chem Papers 64:812
3. Madhumitha G, Roopan SM (2013) J Nanomater 2013:1
4. Horvath IT (2002) Acc Chem Res 35:685
5. Song J, Han B (2015) Natl Sci Rev 2:255
26. Yang XJ, Chen B, Zheng LQ, Wu LZ, Tung CH (2014) Green
Chem 16:1082
6. Gualandi A, Marchini M, Mengozzi L, Natali M, Lucarini M,
Ceroni P, Cozzi PG (2015) ACS Catal 5:5927
27. Zou YQ, Chen JR, Liu XP, Lu LQ, Davis RL, Jørgensen KA,
Xiao WJ (2012) Angew Chem Int Ed 51:784
7. Xiea J, Jina H, Xua P, Zhu C (2014) Tetrahedron Lett 55:36
8. Noble A, MacMillan DWC (2014) J Am Chem Soc 136:11602
9. Xi Y, Yia H, Lei A (2013) Org Biomol Chem 11:2387
10. Maity S, Zheng N (2012) Synlett 23:1851
28. Rizzi V, Losito I, Ventrella A, Fini P, Fraix A, Sortino S, Agos-
tiano A, Longobardi F, Cosma P (2015) Phys Chem Chem Phys
17:26307
11. Cao MY, Ren X, Lu Z (2015) Tetrahedron Lett 56:3732
12. Narayanam JMR, Stephenson CRJ (2011) Chem Soc Rev 40:102
13. Zhang G, Kim G, Choi W (2014) Energy Environ Sci 7:954
14. Lang X, Chen X, Zhao J (2014) Chem Soc Rev 43:473
15. Sagadevan A, Lyu PC, Hwang KC (2016) Green Chem 18:4526
29. Hari DP, Hering T, Konig B (2012) Org Lett 14:5334
30. Keshari T, Yadav VK, Srivastava VP, Yadav LDS (2014) Green
Chem 16:3986
31. Yadav AK, Yadav LDS (2014) Tetrahedron Lett 55:2065
1 3

A. Mishra et al.
62. Shao C, Wang X, Xu J, Zhao J, Zhang Q, Hu Y (2010) J Org
Chem 75:7002
32. Lindsley CW, (2013) ACS Chem Neurosci 4:905
33. Buckle DR, Outred DJ, Rockell CJM, Smith H, Spicer BA (1986)
J Med Chem 29:2267
63. Alonso F, Moglie Y, Radivoy G, Yus M (2011) J Org Chem
76:8394
34. Alvarez R, Velazquez S, San-Felix A, Aquaro S, Clercq ED,
Perno CF, Karlsson A, Balzarini J, Camarasa MJ (1994) J Med
Chem 37:4185
64. Naeimi H, Dadashzadeh S, Moradian M, (2015) Res Chem
Intermed 41:2687
65. Alonso F, Moglie Y, Radivoy G, Yusa M (2010) Adv Synth Catal
352:3208
35. Wang Z, Wu B, Kuhen KL, Bursulaya B, Nguyen TN, Nguyen
DG, He Y (2006) Bioorg Med Chem Lett 16:4174
36. Boechat N, Ferreira VF, Ferreira SB, Lourdes Md, Ferreira G,
Silva FdeCda, Bastos MM, Costa MdS, Lourenco MCS, Pinto
AC, Krettli AU, Aguiar AC, Teixeira BM, Silva NVda, Mar-
tins PRC, Bezerra FAFM, Camilo ALS, Silva GPda, Costa CCP
(2011) J Med Chem 54:5988
66. Kumar P, Joshi C, Srivastava AK, Gupta P, Boukherroub R, Jain
SL (2016) ACS Sustain Chem Eng 4:69
67. Yadav JS, Reddy BVS, Reddy GM, Chary DN (2007) Tetrahe-
dron Lett 48:8773
68. Sharghi H, Beyzavi MH, Safavi A, Doroodmand MM, Khalifeh
R (2009) Adv Synth Catal 351:2391
37. Genin MJ, Allwine DA, Anderson DJ, Barbachyn MR, Emmert
DE, Garmon SA, Graber DR, Grega KC, Hester JB, Hutchin-
son DK, Morris J, Reischer RJ, Ford CW, Zurenko GE, Hamel
JC, Schaadt RD, Stapert D, Yagi BH (2000) J Med Chem
43:953
69. Chassaing S, Sido ASS, Alix A, Kumarraja M, Pale P, Sommer
J, (2008) Chem Eur J 14:6713
70. Otvos SB, Mandity IM, Kiss L, Fulop F, (2013) Chem Asian J
8:800
71. Ozcubukcu S, Ozkal E, Jimeno C, Pericas MA (2009) Org Lett
11:4680
38. Chen Y, Lopez-Sanchez M, Savoy DN, Billadeau DD, Dow GS,
Kozikowski AP (2008) J Med Chem 51:3437
72. Bai SQ, Jiang L, Zuo JL, Hor TSA (2013) Dalton Trans 42:11319
73. Jiang L, Wang Z, Bai SQ, Hor TSA (2013) Dalton Trans 42:9437
74. Bai SQ, Jiang L, Tan AL, Yeo SC, Younga DJ, Hor TSA, (2015)
Inorg Chem Front 2:1011
39. Aher NG, Pore VS, Mishra NN, Kumar A, Shukla PK, Sharma
A, Bhat MK, (2009) Bioorg Med Chem Lett 19:759
40. Asif M (2014) Int J Adv Res Chem Sci 1:22
41. Kim TW, Yong Y, Shin SY, Jung H, Park KH, Lee YH, Lim Y,
Jung KY (2015) Bioorg Chem 59:1
75. Mishra A, Srivastava M, Rai P, Yadav S, Tripathi BP, Singh J,
Singh J (2016) RSC Adv 6:49164
42. Kumar K, Carrère-Kremer S, Kremer L, Guérardel Y, Biot C,
Kumar V (2013) Organometallics 32:5713
76. Yadav S, Srivastava M, Rai P, Singh J, Singh J (2015) New J
Chem 39:4556
43. Brockunier LL, Parmee ER, Ok HO, Candelore MR, Cascieri
MA, Colwell LF, Deng L, Feeney WP, Forrest MJ, Hom GJ,
MacIntyre DE, Tota L, Wyvratt MJ, Fisher MH, Weber AE
(2000) Bioorg Med Chem Lett 10:2111
77. Yadav S, Srivastava M, Rai P, Singh J, Singh J (2015) Tetrahe-
dron Lett 56:5831
78. Yadav S, Srivastava M, Rai P, Tripathi BP, Mishra A, Singh J,
Singh J (2016) New J Chem 40:9694
44. Mady MF, Awad GEA, Jørgensen KB (2014) Eur J Med Chem
84:433
79. Buckley BR, Dann SE, Harris DP, Heaney H, Stubbs EC (2010)
Chem Commun 46:2274
45. Fan WQ, Katritzky AR (1996) In: Katritzky AR, Rees CW,
Scriven EFV (eds) Comprehensive heterocyclic chemistry II,
vol 4. Elsevier Science, Oxford, p 1
80. Buschbeck R, Low PJ, Lang H (2011) Coord Chem Rev 255:241
81. Sagadevan A, Ragupathi A, Lin CC, Hwu JR, Hwang KC (2015)
Green Chem 17:1113
46. Gouault N, Cupif JF, Sauleau A, David M (2000) Tetrahedron
Lett 41:7293
82. Sagadevan A, Ragupathi A, Hwang KC (2013) Photochem Pho-
tobiol Sci 12:2110
47. Loi CH, Busetti F, Linge KL, Joll CA (2013) J Chromatogr A
1299:48
83. Yadav AK, Yadav LDS (2015) Tetrahedron Lett 56:686
84. Yadav AK, Yadav LDS (2015) Green Chem 17:3515
85. Yadav AK, Yadav LDS (2015) Org Biomol Chem 13:2606
86. Prasad AN, Thirupathi B, Raju G, Srinivas R, Reddy BM (2012)
Catal Sci Technol 2:1264
48. Liu YS, Ying GG, Shareef A, Kookana RS (2013) J Contam
Hydrol 151:131
49. Cheng H, Wan J, Lin MI, Liu Y, Lu X, Liu J, Xu Y, Chen J, Tu
Z, Cheng YSE, Ding K (2012) J Med Chem 55:2144
50. Giffin MJ, Heaslet H, Brik A, Lin YC, Cauvi G, Wong CH,
McRee DE, Elder JH, Stout CD, Torbett BE (2008) J Med Chem
51:6263
87. Li XT, Liu YH, Liua X, Zhang ZH (2015) RSC Adv 5:25625
88. Byrne FP, Jin S, Paggiola G, Petchey THM, Clark JH, Farmer
TJ, Hunt AJ, McElroy CR, Sherwood J, (2016) Sustain Chem
Process 4:7
51. Lauria A, Delisi R, Mingoia F, Terenzi A, Martorana A, Barone
G, Almerico AM (2014) Eur J Org Chem 2014:3289
52. Taddei M, Ferrini S, Giannotti L, Corsi M, Manetti F, Giannini
G, Vesci L, Milazzo FM, Alloatti D, Guglielmi MB, Castorina
M, Cervoni ML, Barbarino M, Foderà R, Carollo V, Pisano C,
Armaroli S, Cabri W (2014) J Med Chem 57:2258
53. Hsu KL, Tsuboi K, Whitby LR, Speers AE, Pugh H, Inloes J,
Cravatt BF (2013) J Med Chem 56:8257
89. Prat D, Hayler J, Wells A (2014) Green Chem 16:4546
90. Jiang X, Wang Y, Li M, Sci Rep 4:6070 (doi:10.1038/srep06070
91. Pirrung MC (2006) Chem Eur J 12:1312
92. Guo L, Yang C, Zheng L, Xia W (2013) Org Biomol Chem
11:5787
93. Nguyen TH, Maity S, Zheng N (2014) Beilstein J Org Chem
10:975
94. Teply F (2011) Collect Czech Chem Commun 76:859
95. Mitra S, Ghosh M, Mishra S, Hajra A (2015) J Org Chem
80:8275
54. Toure BB, Hall DG (2009) Chem Rev 109:4439
55. Ramón DJ, Yus M (2005) Angew Chem Int Ed 44:1602
56. Voigt B, Linke M, Mahrwald R (2015) Org Lett 17:2606
57. Cioc RC, Ruijter E, Orru RVA (2014) Green Chem 16:2958
58. Alvim HGO, Silva Júnior ENda, Neto BAD (2014) RSC Adv
4:54282
96. Fidaly K, Ceballos C, Falguières A, Veitia MSI, Guy A, Ferroud
C (2012) Green Chem 14:1293
97. Hari DP, König B (2011) Org Lett 13:3852
98. Xuan J, Xia XD, Zeng TT, Feng ZJ, Chen JR, Lu LQ, Xiao WJ
(2014) Angew Chem Int Ed 53:5653
59. Naeimi H, Nejadshafiee V (2014) New J Chem 38:5429
60. Murty MSR, Katiki MR, Kommula D, (2016) Can Chem Trans
4:47
99. Lu Z, Shen M, Yoon TP (2011) J Am Chem Soc 133:1162
100. Rueping M, Leonori D, Poisson T (2011) Chem Commun
47:9615
61. Zhang L, Chen X, Xue P, Sun HHY, Williams ID, Sharpless KB,
Fokin VV, Jia G (2005) J Am Chem Soc 127:15998
1 3