Blue Light-Promoted N?H Insertion of Carbazoles, Pyrazoles and 1,2,3-Triazoles into Aryldiazoacetates

Article abstract of DOI:10.1002/adsc.201901343

Blue light irradiation of aryldiazoacetates leads to the formation of free carbenes, which can react with carbazoles, pyrazoles and 1,2,3-triazoles to afford the corresponding N?H inserted products. These reactions are performed under air and at room temperature, allowing the mild preparation of a variety of motifs found in biologically relevant targets. (Figure presented.).

Full text of DOI:10.1002/adsc.201901343

Title: Blue Light-Promoted N-H Insertion of Carbazoles, Pyrazoles and
1,2,3-Triazoles into Aryldiazoacetates
Authors: Mateus Stivanin, Alessandra Fernandes, Amanda Ferreira da
Silva, Celso Okada Jr, and Igor Jurberg
This manuscript has been accepted after peer review and appears as an
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of the final Version of Record (VoR). This work is currently citable by
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published online in Early View as soon as possible and may be different
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To be cited as: Adv. Synth. Catal. 10.1002/adsc.201901343
Link to VoR: http://dx.doi.org/10.1002/adsc.201901343

10.1002/adsc.201901343
Advanced Synthesis & Catalysis
FULL PAPER
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Blue Light-Promoted N-H Insertion of Carbazoles, Pyrazoles
and 1,2,3-Triazoles into Aryldiazoacetates
Mateus L. Stivanin, Alessandra A. G. Fernandes, Amanda F. da Silva, Celso Y. Okada
Jr, Igor D. Jurberga*
a
State University of Campinas, Institute of Chemistry. Rua Monteiro Lobato 270, 13083-862, Campinas, SP, Brazil
E-mail: ijurberg@unicamp.br
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######
Abstract. Blue light irradiation of aryldiazoacetates leads to
the formation of free carbenes, which can react with
carbazoles, pyrazoles and 1,2,3-triazoles to afford the
corresponding N-H inserted products. These reactions are
performed under air and at room temperature, allowing the
mild preparation of a variety of motifs found in biologically
relevant targets.
Keywords: Diazo Compounds; Photolysis; Heterocycles;
Visible Light; N-H Insertion
Previous metal catalyzed strategies have taken
Introduction
advantage
of
Cu(I)[12]
and
Pd(II)[13]-based
enantioselective protocols for the N-H insertion of
carbazoles (Scheme 1a), Au(I) catalysis for the
Visible light-promoted photochemistry has been
greatly advanced in recent years with the
development of several protocols mostly based in
photoredox catalysis[1] and to a lesser extent, electron
donor-acceptor (EDA) complex formation.[2]
simultaneous
cycloisomerization
of
vinyl
diazoacetates and formal N-H insertions of the
corresponding pyrazoles (Scheme 1b);[14] and Rh(II)
catalysis for the N-H insertion of benzotriazoles,
(Scheme 1c).[15]
In addition to these platforms, visible light-
promoted photolysis of organic substrates can be also
considered a synthetically useful strategy, but it is a
highly challenging reactivity to harvest,[3] as most
organic molecules do not absorb in the visible region.
A notable exception to this general trend has been
recently reported involving aryldiazoacetates. Upon
irradiation in the blue/ violet region of the visible
spectrum, the photoexcited diazo compound liberates
N2, thus generating a highly reactive carbene
intermediate, which can be trapped with several
reacting partners.[4] Examples of cyclopropanations
with styrene and arenes; and X-H insertions (X = C,
N, O) involving carboxylic acids, amines, alkanes
and arenes have been reported;[5,6] they have been
also reacted with ethyl diazoacetate to afford
trisubstituted olefins;[7] underwent cyclopropenation
reaction with alkynes;[8] sigmatropic shifts involving
sulfur ylides;[8,9] cyclopropenations with hindered
propargyl alcohols;[10] or cyclopropanations with
indoles.[11]
Scheme 1. Previous metal-catalyzed reports of N-H
insertion protocols of carbazoles, pyrazoles, and
benzotriazoles into aryldiazoacetates.
In this context, and as an alternative to metal
catalyzed processes, we became also interested in the
possibility of developing blue light-promoted N-H
insertion protocols of carbazoles, pyrazoles and 1,2,3-
triazoles into aryldiazoacetates.
The resulting N-H-inserted compounds are
important, because they can be used as building
blocks or can be found as structural motifs in
numerous biologically active molecules. For instance,
carbazole 1 has been identified as a 5-HT serotonin
receptor modulator, which can be potentially targeted
1
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10.1002/adsc.201901343
Advanced Synthesis & Catalysis
for the treatment of depression, anxiety and other
mental disorders (CNS-related),[16] pyrazoles 2 and 3
have shown hypocholesterolemic activity[17] and
activity in the treatment of cardiac arrhythmias,[18]
respectively; 1,2,3-triazoles 4, 5 and 6 have shown
activity against CNS disorders associated to
phosphodiesterase 2 (PDE2), a potential target for
treating neurological and psychiatric disorders, such
as schizophrenia, psychosis and Parkinson´s
disease,[19] activity against CNS-related mental
disorders (e.g. depression and anxiety)[20] and activity
against V-containing integrins (potential targets in
the treatment of pathological fibrosis, transplant
rejection, cancer, osteoporosis and inflammatory
disorders),[21] respectively (Figure 1).
Table 1. Optimization studies using carbazole 8a.
entry
1
x
1
1
1
2
3
3
3
3
3
3
3
3
y
1
2
3
1
1
1
1
1
1
1
1
1
base (z)
yield (%)
60
-
2
-
61
65
82
90
43
67
67
66
3
-
4
-
5
-
6
7
8
9
10
11
12
DBU (20)
DIPEA (20)
DABCO (20)
K2HPO4 (20)
K2CO3 (20)
K3PO4 (20)
tBuOK (20)
58
64
66
aYields estimated by 1H NMR of the crude reaction mixture using
naphthalene as internal standard.
Figure 1. Examples of biologically relevant structures that
could be possibly derived from the N-H insertion of
carbazoles,
pyrazoles
or
1,2,3-triazoles
into
aryldiazoacetates.
Results and Discussion
Starting our optimization studies, the model
transformation was chosen to be the reaction between
aryldiazoacetate 7a and carbazole 8a, aiming at the
preparation of the corresponding N-H insertion
product 9a (Table 1).
Varying the relative amounts of 7a and 8a (Table 1,
Entries 1-5), reveals the optimal ratio of reagents as
3:1 of 7a:8a (Table 3, Entry 5).
Scheme 2. Scope of the N-H insertion of carbazoles 8 into
aryldiazoacetates 7. aIsolated yield. When performed in the
dark, it does not work in any extent (0% yield).
Considering the use of bases as additives, in 20
mol%, there was no positive impact observed in the
yield of 9a (Table 3, Entries 6-12).
Pd-catalyzed cross-coupling strategies employing
carbazole 9c have been also carried out as
representative transformations illustrating further
functionalization opportunities when employing such
aryl bromides. As a consequence of Sonogashira and
Suzuki reactions, carbazoles 10a and 10b could be
isolated in 91% and 77% yields, respectively.
(Scheme 3, see SI for full experimental details).
The evaluation of the reaction scope derived from
the N-H insertion of carbazoles
8
into
aryldiazoacetates 7, leading to the corresponding
products 9, shows good yields, 49-86%. This
demonstrates the reaction tolerance for different
substituents on the aromatic rings and ester moieties
of aryldiazoacetates 7 and the possibility of using
different bromination patterns on the carbazole ring
of 8 (Scheme 2).
Of note, during the preparation of our manuscript,
Empel, Patureau and Koenigs reported a similar N-H
insertion strategy employing carbazoles.[22]
Scheme 3. Examples of synthetic applications of carbazole
9c in Sonogashira and Suzuki cross-coupling reactions.
2
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10.1002/adsc.201901343
Advanced Synthesis & Catalysis
The optimization of the N-H insertion of pyrazoles
has been performed using aryldiazoacetate 7a and
pyrazole 11a, aiming at the preparation of the
corresponding insertion product 12a (Table 2).
Varying the stoichiometry of both reaction partners
in the absence of any base, during reaction times of
16h (Table 2, Entries 1-5), has shown a small
advantage of a 1:3 ratio of 7a:11a, which produced
the highest yield of this series, 72% (Table 2, entry 3).
Considering different bases, used in a catalytic
amount of 20 mol % (Table 2, Entries 6-13), has
revealed a positive impact of the use of K3PO4, this
time producing a 90% yield for 12a (Table 2, Entry
13). Further investigation on different catalytic
amounts of K3PO4 (Table 2, Entries 14-18)
demonstrated the use of 10 mol% as optimal,
exhibiting an estimated 95% yield (Table 2, Entry 16).
Finally, shorter reaction times of 1h and 8h produce
40% and 90%, respectively (Table 2, Entries 17 and
18), thus showcasing the advantage of longer reaction
times (Table 2, Entry 16).
Table 2. Optimization studies using pyrazole 11a.
entry
x
y
base (z)
time
(h)
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
1
yield
(%)
50
68
72
64
56
27
87
89
77
79
85
89
90
78
92
95
78
80
40
90
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1
1
1
2
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
3
1
1
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
-
-
-
-
-
DBU (20)
DIPEA (20)
2,6-lutidine (20)
NEt3 (20)
DABCO (20)
K2HPO4 (20)
K2CO3 (20)
K3PO4 (20)
K3PO4 (2)
K3PO4 (5)
K3PO4 (10)
K3PO4 (50)
K3PO4 (100)
K3PO4 (10)
K3PO4 (10)
Scheme 4. Scope of N-H insertion of pyrazoles 11 into
aryldiazoacetates 7. aIsolated yield. When performed in the
dark, it does not work in any extent (0% yield).
the lower extreme of this range, 46%, being derived
from the use of pyrazole 11g. In addition,
asymmetrically substituted pyrazoles 11g and 11h,
both lead to mixtures of regioisomers, 12g + 12g´ and
12h + 12h´, respectively, but each product can be
readily separated by flash column chromatography
(Scheme 4, molecules 12g and 12g´; and 12h and
12h´). When pyrazole 11a is kept fixed and the
aryldiazoacetate component is varied, again good
yields are obtained for the corresponding insertion
products 12j-12s, which are produced in a range of
47-79% (Scheme 4, molecules 12j-12s). In addition,
aryldiazoketones, such as 2-diazo-1,2-diphenylethan-
1-one 7p or 1-diazo-1-phenylpropan-2-one 7q, can
8
aYields estimated by 1H NMR of the crude reaction using naphthalene as
internal standard.
With the optimal reaction conditions in hand, we
moved on to investigate the scope of the N-H
insertion of pyrazoles 11 into aryldiazoacetates 7 to
afford the corresponding coupled products 12. In this
regard, the evaluation of different pyrazoles 11a-11h,
while keeping aryldiazoacetate 7a fixed, leads to the
corresponding inserted products 12a-12h[23] in
general good yields, 46-98% (Scheme 4, molecules
12a-12h), with the higher limit of this yield range,
98%, being derived from the use of pyrazole 11c and
undergo
a
blue
light-promoted
Wolff
rearrangement[24] (see the SI for their UV-Vis
absorption spectra), leading to the formation of
ketene intermediates, which can be trapped by
pyrazole to afford amides 12t and 12u, in 88% and
61% yields, respectively (Scheme 4, molecules 12t
and 12u).
The optimization of the N-H insertion protocol
involving 1,2,3- triazoles was performed by reacting
aryldiazoacetate 7a with 1,2,3-triazole 13a, aiming at
3
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10.1002/adsc.201901343
Advanced Synthesis & Catalysis
the preparation of the corresponding N2-insertion
product 14a´. Varying the relative amounts of 7a and
13a (Table 3, Entries 1-5) shows that the 1:2 ratio for
7a:13a is optimal, producing the highest yield of the
series, 64% (Table 3, Entry 2). When considering the
eventual addition of bases, in 20 mol%, no
improvement in the yield of 14a´ is remarked (Table
3, Entries 6-10). As a consequence, the optimal
reaction conditions are established this time in the
absence of any base (Table 3, Entry 2). At this point,
the scope of the N-H insertion of 1,2,3-triazoles 13
into aryldiazoacetates 7, leading to the corresponding
insertion products 14´ was evaluated (Scheme 5).
In a first moment, aryldiazoacetate 7a is kept fixed,
while we investigated the 1,2,3-triazole components
11a-11i. For these cases, the corresponding N-H
insertion products 14a´-14i´[25] could be produced in
good yields, 50-64%, as the major regioisomers (N2)
out of three possible N-H insertions, occurring either
at N1, N2 or N3, (Scheme 5, molecules 14a´-14i´).
This reasonably small window in yield range allows
us to infer that the electronic influence of the
substituents has little impact on the reactivity of the
triazole rings. When 1,2,4-triazole 13j is employed,
the corresponding N-H insertion product 14j´ is
produced as the sole regioisomer and can be isolated
in 85% yield. This result suggests that other triazoles
might be also competent substrates.
Then, evaluating different aryldiazoacetates 7 in
the presence of 1,2,3-triazole 13a allows the
preparation of the corresponding N-H inserted
compounds 14k´-14q´, again in a narrow range of
similar yields, 43-60% (Scheme 5, molecules 14k´-
14q´).
Table 3. Optimization studies using 1,2,3-triazole 13a.
Scheme 5. Scope of N-H insertion of 1,2,3-triazoles 10
into aryldiazoacetates 7. Isolated yield. When performed
a
in the dark, it does not work in any extent (0% yield).
1
bEstimated yield based on H NMR of the crude reaction
mixture, using 1,3,5-trimethoxybenzene as internal
reference. nd: not detected.
entry
1
2
3
4
5
6
7
8
x
1
1
1
2
3
1
1
1
1
1
y
1
2
3
1
1
2
2
2
2
2
base (z)
yield (%)
-
-
-
-
52
64
58
54
46
56
57
56
55
56
unlikely that K3PO4 can directly deprotonate
pyrazoles 11 (or any of the other aza-arenes, 8 or 13).
Our current mechanistic hypothesis is that the
reaction starts with the photochemical generation of a
free carbene intermediate, derived from the
-
DIPEA (20)
2,6-lutine (20)
NEt3 (20)
K2CO3 (20)
K3PO4 (20)
corresponding aryldiazoacetate 7.[5] Then,
a
nucleophilic attack promoted by the aza-arene 8, 11
or 13 takes place, being followed by a proton transfer
event to afford the corresponding N-H inserted
compounds 9, 12 or 14´, respectively. In the protocol
employing pyrazoles 11, the presence of K3PO4 might
be possibly improving the efficiency of this last
elementary step[27,28] (Scheme 6b), therefore
increasing the overall yield of the transformation.
9
10
aYields estimated by 1H NMR of the crude reaction using 1,3,5-
trimethoxybenzene as internal standard.
The acidity of these three aza-arenes (carbazoles 8,
pyrazoles 11 and 1,2,3-triazoles 13) are well known
in DMSO: pKacarbazoles ≈ 19.9, pKapyrazoles ≈ 19.8 and
pKa1,2,3-triazoles ≈ 13.9 (Scheme 6a).[26] Even if the
reaction takes place in a diferent solvent (DCM), it is
4
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10.1002/adsc.201901343
Advanced Synthesis & Catalysis
General Procedure for the blue light-promoted N-H
insertion of 1,2,3-triazoles 13 into aryldiazoacetates 7.
Under air, at room temperature, a 4-mL vial is
charged with aryldiazoacetate 7 (1 equiv.), 1,2,3-triazole
13 (2 equiv.) and DCM (0.1
M in respect to
aryldiazoacetate). The reaction mixture is stirred at room
temperature under blue light irradiation for 16 h (using two
LED lamps, 15 W each, displaced at approximate distances
of 5 cm each from the reaction vessel). Then, the reaction
mixture is concentrated under reduced pressure and
purified by flash column chromatography to afford the title
compounds in the stated yields.
Scheme 6. a) pKa scale of aza-arenes in DMSO. b)
Current mechanistic hypothesis explaining the role of the
base in the protocol employing pyrazoles 11.
Conclusions
In summary, we have demonstrated that the blue
light-promoted photolysis of aryldiazoacetates 7 can
be used to trap carbazoles 8, pyrazoles 11 and 1,2,3-
triazoles 13, in order to afford the corresponding N-
H-insertion compounds 9, 12 and 14´, respectively.
These mild and efficient photochemical N-
alkylation strategies have proved to be quite general
for the preparation of motifs potentially useful in a
number of biological applications. From
mechanistic perspective, the observation of different
regioisomers in N-H insertions involving
asymmetrically substituted pyrazoles 11 and 1,2,3-
triazoles 13, suggests that these are not concerted
processes. In this context, proton exchanges might
play an important role and the catalytic addition of a
base may improve yields in some cases, as it has been
remarked here for the protocol involving pyrazoles 11.
Acknowledgements
Fapesp (2017/24017-0) and CNPq (INCT Catálise) are greatly
acknowledged for financial support. The authors are grateful to
Dr. Deborah Simoni for X-ray crystal structures of 12g and 14e´.
The authors also thank CNPq for PhD fellowships to M. L. S. and
C. Y. O. Jr., Fapesp for a PhD Fellowship to A. A. G. F
(2017/22164-6) and CAPES for a PhD fellowship to A. F. S.
a
References
[1] For a representative review, see: C. K. Prier, D. A.
Rankic, D. W. C. MacMillan, Chem. Rev. 2013, 113,
5322-5363.
[2] For a representative review, see: C. G. S. Lima, T. M.
Lima, M. Duarte, I. D. Jurberg, M. W. Paixão, ACS.
Catal. 2016, 6, 1389-1407.
[3] See for instance: H. Yu, J. Li, D. Wu, Z. Qiu, Y. Zhang,
Chem. Soc. Rev. 2010, 39, 464-473.
Experimental Section
[4] For reviews on photochemical reactions involving
diazo compounds, see: a) Ł. W. Ciszewski, K.
Rybicka-Jasińska, D. Gryko, Org. Biomol Chem. 2019,
17, 432-448. b) N. R. Candeias, C. A. M. Afonso, Curr.
Org. Chem. 2009, 13, 763-787. c) O. S. Galkina, L. L.
Rodina, Russ. Chem. Rev. 2016, 85, 537-555.
[5] I. D. Jurberg, H. M. L. Davies, Chem. Sci. 2018, 5112-
5118.
[6] For other previous contributions of our group to the
chemistry of aryldiazoacetates, see also: a) I. D.
Jurberg, H. M. L. Davies, Org. Lett. 2017, 19, 5158-
5161. b) S. Thurow, A. A. G. Fernandes, Y. Quevedo-
Acosta, M. F. de Oliveira, M. G. de Oliveira, I. D.
Jurberg, Org. Lett. 2019, 21, 6909-6913.
See the SI for full experimental data.
General Procedure for the blue light-promoted N-H
insertion of carbazoles 8 into aryldiazoacetates 7.
Under air, at room temperature, a 4-mL vial is
charged with aryldiazoacetate 7 (3 equiv.), carbazole 8 (1
equiv.) and DCM (0.1 M in respect to carbazole). The
reaction mixture is stirred at room temperature under blue
light irradiation for 16 h (using two LED lamps, 15 W each,
displaced at approximate distances of 5 cm each from the
reaction vessel). Then, the reaction mixture is concentrated
under reduced pressure and purified by flash column
chromatography or preparative thin-layer chromatography
to afford the title compounds in the stated yields.
[7] T. Xiao, M. Mei, Y. He, L. Zhou, Chem. Commun.
2018, 54, 8865-8868.
General procedure for the blue light-promoted N-H
insertion of pyrazoles 11 into aryldiazoacetates 7.
Under air, at room temperature, a 4-mL vial is
charged with aryldiazoacetate 7 (1 equiv.), pyrazole 11 (3
equiv.), K3PO4 (10 mol%) and DCM (0.1 M in respect to
aryldiazoacetate). The reaction mixture is stirred at room
temperature under blue light irradiation for 16 h (using two
LED lamps, 15 W each, displaced at approximate distances
of 5 cm each from the reaction vessel). Then, the reaction
mixture is concentrated under reduced pressure and
purified by flash column chromatography to afford the title
compounds in the stated yields.
[8] R. Hommelsheim, Y. Guo, Z. Yang, C. Empel, R. M.
Koenigs, Angew. Chem. Int. Ed. 2019, 58, 1203-1207.
[9] a) Z. Yang, Y. Guo, R. M. Koenigs, Chem. Eur. J.
2019, 25, 6703-6706. b) J. Yang, J. Wang, H. Huang, G.
Qin, Y. Jiang, T. Xiao, Org. Lett. 2019, 21, 2654-2657.
[10] F. He, R. M. Koenigs, Chem. Commun. 2019, 55,
4881-4884.
[11] X. Zhang, C. Du, H. Zhang, X.-C. Li, Y.-L. Wang, J.-
L. Niu, M.-P. Song, Synthesis 2019, 51, 889-898.
[12] H.-Q. Shen, B. Wu, H.-P. Xie, Y.-G. Zhou, Org. Lett.
2019, 21, 2712-2717.
[13] V. Arredondo, S. C. Hiew, E. S. Gutman, I. D. U. A.
Premachandra, D. L. Van Vraken, Angew. Chem. Int.
Ed. 2017, 56, 4156-4159.
5
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10.1002/adsc.201901343
Advanced Synthesis & Catalysis
[14] G. Xu, C. Zhu, W. Gu, J. Li, J. Sun, Angew. Chem. Int.
Ed. 2015, 54, 883-887.
can be obtained free of charge from The Cambridge
Crystallographic
Data
Centre
via
[15] K. Wang, P. Chen, D. Ji, X. Zhang, G. Xu, J. Sun,
Angew. Chem. Int. Ed. 2018, 57, 12489-12493.
[16] "Oxazinocarbazoles for the Treatment of CNS
Diseases" R. E. Tenbrink et al. WO2001/09142 (A1)
2001.
[17] A. D. White, C. F. Purchase II, J. A. Picard, M. K.
Anderson, S. B. Mueller, T. M. A. Bocan, R. F.
Bousley, K. L. Mahelehle, B. R. Krause, P. Lee, R. L.
Stanfield, J. F. Reindel, J. Med. Chem. 1996, 39, 3908-
3919.
[18] "Potassium Channel Inhibitors" C. J. Dinsmore et al.
WO2006/015159 (A2) 2006.
[19] "Triazolyl Pyrimidinone Compounds as PDE2
Inhibitors". D.-M. Shen et al. WO2016/145614 (A1),
2016.
www.ccdc.cam.ac.uk/data_request/cif.
[24] B. Bernardim, A. M. Hardman-Baldwin, A. C. B.
Burtoloso, RSC Adv. 2015, 5, 13311-13314.
[25] CCDC-1958171 contains the supplementary
crystallographic data of 14e' for this paper. These data
can be obtained free of charge from The Cambridge
Crystallographic
Data
Centre
via
www.ccdc.cam.ac.uk/data_request/cif.
[26] F. G. Bordwell, Acc. Chem. Res. 1988, 21, 456-463.
[27] The proposed mechanistic pathway proceeding via a
nucleophilic addition of the aza-arene onto the carbene,
followed by protonation of the resulting ylide/enolate)
is supported by previous observations. See: a) H. Saito,
D. Morita, T. Uchiyama, M. Miyake, S. Miyairi,
Tetrahedron Lett. 2012, 53, 6662-6664. b) B. Xu; S.-F.
Zhu; X.-L. Xie; J.-J. Shen; Q.-L. Zhou; Angew. Chem.
Int. Ed. 2011, 50, 11483-11486.
[20] "3-Substituted Propanamine Compounds" C.-E. Park
et al. WO2009/148290 (A2) 2009.
[21] "3-Substituted Propionic Acids as Alpha V Integrin
Inhibitors" G. Zhao et al. WO2018/089353 (A1) 2018.
[22] C. Empel, F. W. Patureau, R. M. Koenigs J. Org.
Chem. 2019, 84, 11316-11322.
[28] For other examples of meaningful proton transfer
events in reactions involving diazo compounds, see:
y.-Y, Ren, S.-F. Zhu, Q.-L. Zhou, Org. Biomol. Chem.
2018, 16, 3087-3094.
[23] CCDC-1958170 contains the supplementary
crystallographic data of 12g for this paper. These data
6
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Advanced Synthesis & Catalysis
FULL PAPER
Blue Light-Promoted N-H Insertion of Carbazoles,
Pyrazoles
and
1,2,3-Triazoles
into
Aryldiazoacetates
Adv. Synth. Catal. Year, Volume, Page – Page
Mateus L. Stivanin, Alessandra A. G. Fernandes,
Amanda F. da Silva, Celso Y. Okada Jr, Igor D.
Jurberg*
7
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