Switchable Synthesis of 3-Substituted 1H-Indazoles and 3,3-Disubstituted 3H-Indazole-3-phosphonates Tuned by Phosphoryl Groups

Article abstract of DOI:10.1021/acs.joc.7b02857

3-Alkyl/aryl-1H-indazoles and 3-alkyl/aryl-3H-indazole-3-phosphonates were synthesized efficiently through a 1,3-dipolar cycloaddition reaction between α-substituted α-diazomethylphosphonates and arynes under simple reaction conditions. The product distribution was controlled by the phosphoryl group, which acted both as a tuning group and a traceless group in the reaction.

Full text of DOI:10.1021/acs.joc.7b02857

Subscriber access provided by the University of Exeter
Note
Switchable Synthesis of 3-Substituted 1H-Indazoles and 3,3-
Disubstituted 3H-Indazole-3-phosphonates Tuned by Phosphoryl Groups
Guihua Chen, Minglin Hu, and Yungui Peng
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.7b02857 • Publication Date (Web): 28 Dec 2017
Downloaded from http://pubs.acs.org on December 28, 2017
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a free service to the research community to expedite the
dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts
appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been
fully peer reviewed, but should not be considered the official version of record. They are accessible to all
readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered
to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published
in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just
Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor
changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers
and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors
or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
The Journal of Organic Chemistry is published by the American Chemical Society.
1155 Sixteenth Street N.W., Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 8
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
Switchable Synthesis of 3-Substituted 1H-Indazoles and 3,3-
Disubstituted 3H-Indazole-3-phosphonates Tuned by Phosphoryl
Groups
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Guihua Chen, Minglin Hu, and Yungui Peng*
Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southꢀ
west University, Chongqing 400715, P. R. China
O
R2
R2
1
P(OR )2
O
R
R
R
R
TMS
OTf
R
R
R1 = iPr R2 P(OR )2
1
R1
CsF
=
Me
N
+
N
N
TBAF
N2
N
H
ABSTRACT: 3ꢀAlkyl/arylꢀ1Hꢀindazoles and 3ꢀalkyl/arylꢀ3Hꢀindazoleꢀ3ꢀphosphonates were synthesized efficiently through a 1,3ꢀ
dipolar cycloaddition reaction between αꢀsubstituted αꢀdiazomethylphosphonates and arynes under simple reaction conditions. The
product distribution was controlled by the phosphoryl group, which acted both as a tuning group and a traceless group in the reacꢀ
tion.
Indazole represents a common moiety shared by many
biologically interesting and pharmacologically important
compounds that exhibit potent antitumor, antiꢀHIV, antideꢀ
pressant, antiꢀinflammatory, and contraceptive activity, as well
and general synthetic approach for the preparation of 3Hꢀ
indazoles and 3ꢀalkylꢀ1Hꢀindazoles is highly desirable.
The tautomerism of indazoles involves a hydrogen or
functional group shift; for the tautomerization of 3Hꢀindazoles
to 1Hꢀindazoles, this mainly involves a 1,3ꢀmigration. In
Larock’s investigation of the 1,3ꢀcycloaddition between
arynes and dicarbonylꢀcontaining diazo compounds, the 3Hꢀ
indazoles were formed as intermediates; however, they
underwent acyl migration to give 1ꢀacylꢀ1Hꢀindazoles. In part,
this migration resulted from the higher stability of the 1Hꢀ
indazole compared with that of 3Hꢀindazole owing to its
higher aromaticity and much greater nucleophilicity of
nitrogen than that of carbon. We envisioned that the
introduction of a less migratable group would stabilize the 3Hꢀ
indazole. In the Ohira–Bestmann modification of the
Seyferth–Gilbert homologation, the Ohira–Bestmann reagent
is considered as a surrogate for the diazomethylphosphonate
anion by releasing the acetyl, which indicates that the acyl
as antagonistic activity towards the 5ꢀHT3 receptor (Figure
1
1
).
Figure 1. Selected marketed indazoleꢀcontaining drugs
Great efforts have been devoted to the development of
2
methods for the construction of indazole frameworks. Among
these protocols, the 1,3ꢀdipolar cycloaddition between arynes
and dipoles are the most efficient and have been developed
3
9
intensively. These studies mainly focused on the preparation
group is more prone to migration than the phosphoryl group.
4,5
6
of 1Hꢀindazole, which is the most stable isomer of indazole.
Moreover, Seyferth et al. reported the facile synthesis of
dimethylphosphonoꢀsubstituted diazoalkanes and their
reactions with olefins to give dimethylphosphonoꢀsubstituted
However, the developed methods mainly afforded 3ꢀarylꢀ1Hꢀ
indazoles; the synthesis of 3ꢀalkylꢀsubstituted indazoles have
been sporadically documented and all the existing methods
require the use of either harsh reaction conditions or special
2
ꢁ ꢀpyrazolin quantitatively with the retention of both the alkyl
10,11
and phosphoryl (Figure 2).
Seyferth’s work demonstrated
7
substrates, which severely limits their applications. In contrast,
the lower migration ability of the phosphoryl group and
provided a simple method for the preparation of various
substituted αꢀdiazophosphonates. On the other hand, dialkyl
the synthesis of 3Hꢀindazole has been less studied, in part
owing to its inclination to tautomerize to the most stable 1Hꢀ
isomer and undergo retroꢀcycloaddition to expel nitrogen.
There are limited reports of the synthesis of 3Hꢀindazoles and
8
the products were mainly spiro 3,3ꢀindazoles; the only one
4b
about nonspiro 3,3ꢀindazole was reported in 2008. Larock et
al. found that when disubstituted diazo compounds with at
least one alkyl or aryl group attached to the diazo carbon unꢀ
derwent 1,3ꢀdipolar cyclization with arynes, 3Hꢀindazoles
were obtained in moderate yields. However, the substrate
scope was limited. Therefore, the development of an efficient
Figure 2. Seyferth’s dimethyl αꢀdiazoalkylphosphonates
and the synthesis of ꢁ ꢀpyrazoline
2
acyl phosphonates are highly effective acylating agents and
1
2
have found wide applications in organic synthesis. Very
recently, Ramana et al. reported that either acyl or phosphoryl
1
3
can be released from the Ohira–Bestmann reagent. These
ACS Paragon Plus Environment

The Journal of Organic Chemistry
examples demonstrate that the phosphoryl group is a tuning
Page 2 of 8
reaction mixture was somewhat complex; therefore, CsF was
selected for further investigation (entries 5–8). The testing of
various solvents indicated that acetonitrile was the best choice
(entry 5). For reproducibility, the temperature was set at 40 °C.
We then examined the effect of phosphoryl groups. When
methyl was replaced with ethyl, the yield of 6b was reduced to
52%, and diethyl 3ꢀethylꢀ3Hꢀindazoleꢀ3ꢀphosphonate was
obtained in 41% yield (entry 9). This result was significant as
it indicated that the distribution of the products could be tuned
by changing the phosphoryl group. This was confirmed when
diisopropyl phosphonate 3b was used to obtain 5b in 95%
yield (entry 10). We then switched our focus to 3ꢀarylꢀ3Hꢀ
indazoles, which are suspected to be more prone to expelling
the phosphoryl group. The reaction with diisopropyl αꢀ
diazobenzylphosphonate 3e confirmed our concern; a complex
reaction mixture was obtained. Therefore, we reꢀscreened the
reaction conditions. Finally, the best condition, which
composed 1.25 equivalents of TBAF in acetone at 0 °C for 12
h, were obtained. Under this condition, 5e and 5b were
obtained in 92% and 98% yield, respectively (entries 11 and
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
group. Considering the limited methods for the synthesis of
3Hꢀindazoles and 3ꢀalkylꢀ1Hꢀindazoles as well as our ongoing
1
4,15,16
interest in the chemistry of αꢀdiazophosphonates,
herein,
we report our primary results on the synthesis of 1Hꢀ and 3Hꢀ
indazoles, in which both aryl and alkyl group can be
efficiently introduced onto the C3 of the indazoles. The
selectivity for the synthesis of 1Hꢀ and 3Hꢀindazoles can be
tuned by the phosphoryl group. Furthermore, a phosphoryl
group was introduced into the 3Hꢀindazoles, which could
potentially be bioactive concerning the diverse bioactivities of
17
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
phosphonates.
To develop a general method for the synthesis of 3,3ꢀ
disubstituted 3Hꢀindazoles and 3ꢀalkylꢀ1Hꢀindazoles, our
study commenced with a model reaction between dimethyl αꢀ
diazopropylphosphonate (1b) and oꢀ(trimethylsilyl)phenyl
triflate (4a) at room temperature (Table 1). Firstly, we
investigated the effect of various fluorides on the cyclization.
When potassium fluoride and one equivalent of 18ꢀcrownꢀ6
was used, 3ꢀethylꢀ1Hꢀindazole (6b) was obtained in 85% yield;
however, corresponding 3Hꢀindazole was not detected (entry
1
3).
1
). Further analysis of the results revealed that neither 1ꢀ
With the best reaction conditions in hand, we
phenyl nor 1ꢀphosphoryl indazole were formed, which is
investigated the substrate scope of the 1,3ꢀdipolar cyclization
(Scheme 1). First, we investigated the reactions leading to
diisopropyl 3ꢀalkyl/arylꢀ3Hꢀindazoleꢀ3ꢀphosphonates (5). All
the diisopropyl αꢀdiazoalkylphosphonates (3) were cyclized
with benzyne generated in situ from 4a to give the products
in >90% yield. However, when diisopropyl αꢀ
diazoarylmethylphosphonates were used, the yields varied
depending on the substituents on the aryl. Electronꢀ
withdrawing groups such as F and Cl corroded the reactions;
the reaction time needed to be prolonged while the products
were obtained in moderate yields (5h, 5i). The steric effect
also had an impact on the yields, but was not obviously
compared with the electronic effect (5g vs 5j and 5f vs 5k).
The electronꢀrich aryne generated from 4b can cyclize with 3e
under the optimized reaction conditions to give the
corresponding 3Hꢀindazole 5l in 88% yield after 36 h. Fluoroꢀ
substiturted aryne generated from 4c can also participate in
this reaction to give the desired product 5m under slightly
modified conditions, albeit in decreased yield. Methyl
4b,4e
different from previous reports.
Our results indicated that
the phosphoryl group was a traceless group. Screening of other
a
Table 1. Optimization of Reaction Conditions
fluoride
time
(h)
yield (%)
entry 1/2/3
solvent
(equiv)
5
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
6
b
1
1b
1b
1b
1b
1b
1b
1b
1b
2
KF (1.5)
TBAF (1.5)
TBAF (2.0)
CsF (2.0)
THF
THF
THF
5
85
90
91
91
95
10
62
<5
2
5
3
4
3
4
b
CH CN
48
12
24
48
24
12
12
12
36
12
diazophenylacetate, previously used by Larock et al., was
reacted with 4a under our reaction conditions; the product,
methyl 3ꢀphenthylꢀ3Hꢀindazoleꢀ3ꢀcarboxylate 7, was obtained
in 85% yield after 90 h. These results were significant
concerning the difficulties in the preparation of 3,3ꢀ
disubstituted 3Hꢀindazoles. In fact, this is the first example of
the preparation of 3ꢀalkyl/arylꢀ3Hꢀindazoleꢀ3ꢀphosphonates,
which combine two biologically interesting scaffolds, indazole
and phosphoryl, in one molecule. These hybrid molecules are
promising for the development of novel drug leads in
medicinal chemistry.
3
c
5
CsF (4.0)
CH CN
3
6
7
8
9
CsF (4.0)
THF
CsF (4.0)
Acetone
Toluene
CsF (4.0)
CsF (4.0)
CH CN
41
95
92
85
98
52
ꢀ
3
1
0
3b
3e
3e
3b
CsF (4.0)
CH CN
3
d,e
1
1
TBAF (1.25)
TBAF (1.5)
Acetone
Acetone
<5
ꢀ
d,f
1
2
d,e
1
3
TBAF ((1.25) Acetone
ꢀ
Next, we evaluated the scope of the cyclization between
dimethyl αꢀdiazoalkylphosphonates (1) and arynes generated
in situ from 4. Different dimethyl αꢀdiazoalkylphosphonates
reacted smoothly, and 3ꢀalkylꢀ1Hꢀindazoles were obtained in
moderate to good yields (6aꢀ6d). It is worth to note that this
reaction has potential advantages over reported methods, in
which more steps (usually 2 additional steps from the parent
a
Unless otherwise noted, the reactions were carried out under the following
reaction conditions: 1 or 2 or 3 (0.24 mmol), 4a (0.20 mmol) in solvent (2.0 mL)
b
c
at rt. 1.5 Equiv 18ꢀcrownꢀ6 was added. The reaction was carried out at 40 °C.
d
e
f
3 (0.20 mmol), 4a (0.24 mmol). The reaction was carried out at 0 °C. The
reaction was carried out at −20 °C
common fluorides revealed that the use of both TBAF in THF
as well as CsF in acetonitrile provided 6b in >90% yield
1
Hꢀindazole) were needed or the products were concomitant
(entries 2–4). Although the reaction with TBAF was faster, the
with 1ꢀarylꢀ1Hꢀindazoles. αꢀDiazoarylmethylphosphonates
a
Scheme 1 Sustrate scope
ACS Paragon Plus Environment

Page 3 of 8
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
a
b
c
Unless otherwise noted, the reactions were performed in indicated conditions for 12 hs. 36 h. 0.1 mmol 3e, 0.3 mmol 4c
o
d
e
f
and 0.2 mmol TBAF was reacted in 2. 0 mL acetone at 0 C for 12 h. 90 h. 24 h. 48 h.
1
e–1n also reacted smoothly with 4 to give 3ꢀarylꢀ1Hꢀ
indazoles in moderate to excellent yields (6e–6p). All the reꢀ
actions between dimethyl αꢀdiazophosphonates 1 and arynes
furnished 3ꢀsubstituted 1Hꢀindazoles (6) as the sole products.
4
b,13,18
Based on the literature
and our results, the mechaꢀ
nism of above reaction was proposed (Figure 3). The alkyne I
undergoes 1, 3ꢀdipolar addition with αꢀdiazophosphonate II to
give the 3ꢀsubstitutedꢀ3Hꢀindazoleꢀ3ꢀphosphonate 5 which
undegoes two 1,5ꢀshifts to give 1Hꢀindazolꢀ1ꢀyl phosphonate
IV. Under the reaction condition, IV udergoes hydrolysis to
give 1Hꢀindazole 6. Alternatively, under the action of cesium
fluoride, αꢀdiazophosphonate II would undergo dephosphoꢀ
nylation to give αꢀdiazo intermediate V, which undergoes 1, 3ꢀ
dipolar addition with alkyne 1 to give 6. At this moment, we
can not exclude any of them. With diisopropyl αꢀ
diazoalkylphosphonate, the bulkier isopropyl make the
diisopropylphosphonyl group out of the plane so that the
otbital of it can not react effectively with that of N2’s, which
makes the 1,5ꢀshift unavalable.
Figure 3. Proposed mechanism
In summary, we have
diazoalkylphosphonates can undergo 1,3ꢀdipolar cycloaddition
with arynes to give 3ꢀalkyl/arylꢀ1Hꢀindazoles and 3ꢀalkyl/arylꢀ
Hꢀindazoleꢀ3ꢀphosphonates under simple reaction conditions.
The product distribution can be controlled by changing the
phosphoryl group. 1Hꢀindazoles were obtained in high yields
when dimethyl αꢀdiazoalkylphosphonates were used, whereas
shown
that
αꢀ
3
ACS Paragon Plus Environment

The Journal of Organic Chemistry
,3ꢀdisubstituted 3Hꢀindazoleꢀ3ꢀphosphonates were obtained
Page 4 of 8
3
Following general procedure A, the product was obtained in
1
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
efficiently using diisopropyl αꢀdiazoalkylphosphonates. The
phosphoryl group acted both as a tuning group and traceless
group. This is the first report of the synthesis of 3ꢀsubstituted
98% yield (60.8 mg) as colorless oil. H NMR (600 MHz,
CDCl ) δ 8.17ꢀ8.15 (m, 1H), 7.71ꢀ7.70 (m, 1H), 7.53ꢀ7.48 (m,
3
2H), 4.78ꢀ4.74 (m, 1H), 4.23ꢀ4.19 (m, 1H), 2.99ꢀ2.94 (m, 1H),
2.59ꢀ2.55 (m, 1H), 1.36ꢀ1.35 (m, 3H), 1.30ꢀ1.29 (m, 3H),
1.10ꢀ1.08 (m, 3H), 0.65ꢀ0.64 (m, 3H), 0.29ꢀ0.26 (m, 3H);
3Hꢀindoleꢀ3ꢀphosphonates.
Considering
the
diverse
bioactivities of indazoles and phosphonates, this method could
find further application in the pharmaceutical industry.
1
3
1
C{ H}NMR (151 MHz, CDCl
38.9, 129.6, 129.0, 123.5 (d, J = 1.8 Hz), 121.4, 98.8 (d, J =
142.5 Hz), 72.6 (d, J = 7.5 Hz), 72.4 (d, J = 7.5 Hz), 24.9 (d, J
6.0 Hz), 24.0, 23.9 (d, J = 3.0 Hz), 23.7 (d, J = 4.5 Hz), 22.7
) δ 159.3 (d, J = 4.0 Hz),
3
1
EXPERIMENT SECTION
=
(
31
All commercially available reagents were used as received
without further purification. Solvents used in the transforꢀ
mations were distilled from drying agents and stored. Flash
column chromatography was performed on silica gel; analytiꢀ
cal TLC was performed on glass plates precoated with silica
gel. NMR spectra were recorded on Bruker Avance 600 MHz
d, J = 6.0 Hz), 7.4 (d, J = 12.0 Hz); P NMR (243 MHz,
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
+
CDCl ) δ 15.11; HRMS: Calcd for C H N O P [M+H] :
3
15 24
2
3
3
11.1519; found: 311.1522.
Diisopropyl (3-propyl-3H-indazol-3-yl)phosphonate (5c)
Following general procedure A, the product was obtained in
1
spectrometer in CDCl or CD OD operating at 600 MHz for
3
3
99% yield (64.2 mg) as colorless oil. H NMR (600 MHz,
1
13
31
H NMR, 151 MHz for C NMR and 243 MHz for PNMR.
Chemical shifts were reported in ppm relative to TMS for H
NMR, for C NMR, CDCl (δ77.0) or CD OD (δ49.0) were
CDCl ) δ 8.14 (d, J = 6 Hz, 1H), 7.70 (d, J = 6 Hz, 1H), 7.53ꢀ
3
1
7.47 (m, 2H). 4.78ꢀ4.73 (m, 1H), 4.22ꢀ4.17 (m, 1H), 2.91ꢀ2.85
(m, 1H), 2.54ꢀ2.47 (m, 1H), 1.35 (d, J = 12 Hz, 3H), 1.29 (d, J
= 6 Hz, 3H), 1.08 (d, J = 6 Hz, 3H), 0.69 (t, J = 6 MHz, 3H),
0.63 (d, J = 6 Hz, 3H), 0.61ꢀ0.55 (m, 1H), 0.54ꢀ0.45 (m, 1H).
13
3
3
used as the internal standard. The coupling constants are in
Hertz (Hz). The following abbreviations are used for spin mulꢀ
tiplicity: s = singlet, brs = broad singlet, d = doublet, dd =
doublet of doublet, t = triplet, q = quartet, and m = multiplet.
ESI HRMS was recorded on Waters SYNAPT G2 (TOF MS
ES+). Melting points were determined on a digital meltingꢀ
point apparatus and uncorrected.
13
1
C{ H}NMR (151 MHz, CDCl ) δ 159.2 (d, J = 4.5 Hz),
3
1
1
7
3
1
39.2, 129.5 (d, J = 1.5 Hz), 128.9, 123.5 (d, J = 3.0 Hz),
21.4, 98.7 (d, J = 141.0 Hz), 72.6 (d, J = 7.5 Hz), 72.4 (d, J =
.5 Hz), 33.4 (d, J = 6.0 Hz), 24.0 (d, J = 3.0 Hz), 23.9 (d, J =
.0 Hz), 23.7 (d, J = 4.5 Hz), 22.7 (d, J = 6.0 Hz), 16.5 (d, J =
31
2.0 Hz), 13.7; P NMR (243 MHz, CDCl ) δ 14.99;
3
General procedure A: Synthesis of 3H-indazoles (5)
+
HRMS: Calcd for C H N O P [M+H] : 325.1676; found:
16
26
2
3
To the solution of TBAF (77 mg, 0.25 mmol, 85%) in acetone
3
25.1678.
o
(2.0 mL) at ꢀ20 C was added 3 (0.2 mmol), followed by the
addition of 4 (0.24 mmol) slowly, after the addition, the mixꢀ
ture was allowed to stir at 0 C for 12 hs. Then the mixture was
loaded to the silica gel column directly and eluated with ethyl
acetate –petroleum ether (1:5) to give 5.
Diisopropyl (3-benzyl-3H-indazol-3-yl)phosphonate (5d)
o
Following general procedure A, the product was obtained in
1
9
1% yield (67.7 mg) as colorless oil. H NMR (600 MHz,
CDCl ) δ 7.94 (d, J = 6.0 Hz, 1H), 7.82 (d, J = 6.0 Hz, 1H),
3
7.48 (t, J = 6.0 Hz, 1H), 7.42 (t, J = 6.0 Hz, 1H), 6.96ꢀ6.90 (m,
3H), 6.78ꢀ6.77 (m, 2H), 4.88ꢀ4.85 (m, 1H), 4.39ꢀ4.36 (m, 1H),
4.30ꢀ4.27 (m, 1H), 3.82ꢀ3.78 (m, 1H), 1.45 (d, J = 6.0 Hz, 3H),
General procedure B: Synthesis of 1H-indazoles (6)
To the mixture of CsF (122.0 mg, 0.8 mmol) in acetonitrile
(
2.0 mL) were added 1 (0.24 mmol), and 4 (0.2 mmol), then
1
6
4
1
.36 (d, J = 6.0 Hz, 3H), 1.15 (d, J = 6.0 Hz, 3H), 0.69 (d, J =
o
the mixture was allowed to stir at 40 C for 12 hs. After coolꢀ
ing to rt., brine (2.0 mL) was added and the mixture was exꢀ
tracted with ethyl acetate (2.0 mL x 4). The combined organic
solution was concentrated and purified via flash chromatogꢀ
raphy on silica gel using ethyl acetate –petroleum ether (1:8)
as eluate to give 6.
13
1
.0 Hz, 3H); C{ H}NMR (151 MHz, CDCl ) δ 159.4 (d, J =
3
.5 Hz), 138.3, 133.3 (d, J = 13.5 Hz), 129.5, 129.3, 128.9,
27.4, 126.6, 123.8 (d, J = 3.0 Hz), 121.2, 98.4 (d, J = 139.5
Hz), 72.9 (d, J = 7.5 Hz), 72.8 (d, J = 7.5 Hz), 37.6 (d, J = 6.0
Hz), 24.0, 23.9 (d, J = 4.5 Hz), 23.8 (d, J = 6.0 Hz), 22.7 (d, J
31
=
6.0 Hz); P NMR (243 MHz, CDCl ) δ 14.57; HRMS:
3
+
Calcd for C H N O PNa [M+Na] : 395.1495; found:
20
25
2
3
Diisopropyl (3-methyl-3H-indazol-3-yl)phosphonate (5a)
3
95.1505.
Following general procedure A, the product was obtained in
1
98% yield (58.0 mg) as colorless oil. H NMR (600 MHz,
Diisopropyl (3-phenyl-3H-indazol-3-yl)phosphonate (5e)
CDCl ) δ 8.20 (d, J = 12 Hz, 1H), 7.78 (d, J = 12 Hz, 2H),
3
Following general procedure A, the product was obtained in
7
.59ꢀ7.53 (m, 2H), 4.84ꢀ4.80 (m, 1H), 4.31ꢀ4.27 (m, 1H), 1.91
1
92% yield (65.9 mg) as white solid, mp 115ꢀ118 °C. H NMR
(d, J = 18 Hz, 3H), 1.41 (d, J = 6 Hz, 3H), 1.36 (d, J = 6 Hz,
(600 MHz, CDCl ) δ 8.23ꢀ8.21 (m, 1H), 8.06ꢀ8.05 (m, 1H),
3
3
H), 1.15 (d, J = 6 Hz, 3H), 0.73 (d, J = 6 Hz, 3H);
7.94 (d, J = 12 Hz, 2H), 7.59ꢀ7.58 (m, 2H), 7.38ꢀ7.36 (m, 2H),
7.32ꢀ7.30 (m, 1H), 4.66ꢀ4.61 (m, 1H), 4.28ꢀ4.23 (m, 1H), 1.25
1
3
1
C{ H}NMR (151 MHz, CDCl ) δ 158.3 (d, J = 4.5 Hz),
3
1
1
40.9, 129.8, 129.0, 123.1 (d, J = 3.0 Hz), 121.4, 94.1 (d, J =
43.5 HZ), 72.7 (d, J = 6.0 Hz), 72.5 (d, J = 7.5 Hz), 23.9 (d, J
(
d, J = 6.0 Hz, 3H), 1.11 (d, J = 6.0 Hz, 3H), 1.06 (d, J = 6.0
13 1
Hz, 3H), 0.66 (d, J = 6.0 Hz, 3H); C{ H}NMR (151 MHz,
=
=
3.0 Hz), 23.8 (d, J = 3.0 Hz), 23.7 (d, J = 4.5 Hz), 22.7 (d, J
CDCl ) δ 158.6 (d, J = 3.0 Hz), 139.0, 132.4 (d, J = 9.0 Hz),
31
3
6.0 Hz), 17.3 (d, J = 7.5 Hz); P NMR (243 MHz, CDCl ) δ
3
1
1
30.0, 129.3, 128.5 (d, J = 3.0 Hz), 128.2 (d, J = 3.0 Hz),
27.8 (d, J = 6.0 Hz), 124.8 (d, J = 3.0 Hz), 121.8, 100.2 (d, J
+
1
5.5; HRMS: Calcd for C H N O PNa [M+Na] : 319.1182;
1
4
21
2
3
found: 319.1183.
=
138.0 Hz), 73.5 (d, J = 9.0 Hz), 73.1 (d, J = 7.5 Hz), 24.0 (d,
J = 3.0 Hz), 23.9 (d, J = 3.0 Hz), 23.2 (d, J = 6.0 Hz), 22.7 (d,
Diisopropyl (3-ethyl-3H-indazol-3-yl)phosphonate (5b)
4
ACS Paragon Plus Environment

Page 5 of 8
The Journal of Organic Chemistry
3
1
J = 6.0 Hz); P NMR (243 MHz, CDCl ) δ 12.01; HRMS:
158.6 (d, J = 4.5 Hz), 138.9, 130.1, 129.6 (dd, J = 6.0, 7.5 Hz),
129.5, 128.1 (d, J = 9.0 Hz), 124.7 (d, J = 1.5 Hz), 121.9,
115.5 (d, J = 1.5 Hz), 115.3 (d, J = 1.5 Hz), 99.6 (d, J = 139.5
Hz), 73.5 (d, J = 7.5 Hz), 73.2 (d, J = 7.5 Hz), 24.0 (d, J = 6.0
Hz), 23.9 (d, J = 6.0 Hz), 23.3 (d, J = 6.0 Hz), 22.7 (d, J = 6.0
3
+
1
2
3
4
5
6
7
8
9
Calcd for C H N O P [M+H] : 359.1519; found: 359.1518.
19
24
2
3
Diisopropyl
yl)phosphonate (5f)
Following general procedure A, the product was obtained in
(3-(4-methoxyphenyl)-3H-indazol-3-
31
Hz); P NMR (243 MHz, CDCl ) δ 11.87; HRMS: Calcd for
3
1
+
9
6% yield (74.5 mg) as colorless oil. H NMR (600 MHz,
C H FN O P [M+H] : 377.1425; found: 377.1427.
19 23
2
3
CDCl ) δ 8.22ꢀ8.21 (m, 1H), 8.03ꢀ8.02 (m, 1H), 7.85ꢀ7.84 (m,
3
2
(
3
H), 7.59ꢀ7.57 (m, 2H), 6.90 (d, J = 12.0 Hz, 2H), 4.66ꢀ4.61
m, 1H), 4.29ꢀ4.24 (m, 1H), 3.78 (s, 3H), 1.25 (d, J = 6.0 Hz,
H), 1.12 (d, J = 6.0 Hz, 3H), 1.09 (d, J = 6.0 Hz, 3H), 0.67 (d,
Diisopropyl (3-(m-tolyl)-3H-indazol-3-yl)phosphonate (5j)
Following general procedure A, the product was obtained in
1
84% yield (62.6 mg) as colorless oil. H NMR (600 MHz,
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
13
1
J = 6.0 Hz, 3H); C{ H}NMR (151 MHz, CDCl ) δ 159.5,
CDCl ) δ 8.22 (s, 1H), 8.03 (s, 1H), 7.75ꢀ7.72 (m, 2H), 7.59ꢀ
3
3
1
58.5 (d, J = 3.0 Hz), 139.3, 129.9, 129.2, 129.0 (d, J = 6.0
Hz), 124.7 (d, J = 3.0 Hz), 124.1 (d, J = 7.5 Hz), 121.7, 113.9
d, J = 3.0 Hz), 99.8 (d, J = 139.5 Hz), 73.4 (d, J = 7.5 Hz),
2.9 (d, J = 7.5 Hz), 55.2, 24.0 (d, J = 3.0 Hz), 23.9 (d, J = 3.0
7.58 (m, 2H), 7.27ꢀ7.24 (m, 1H), 7.13ꢀ7.12 (m, 1H), 4.66ꢀ4.63
(m, 1H), 4.26ꢀ4.23 (m, 1H), 2.35 (s, 3H), 1.26 (d, J = 6.0 Hz,
3H), 1.11 (d, J = 6.0 Hz, 3H), 1.08 (d, J = 6.0 Hz, 3H), 0.66 (d,
(
13
1
7
J = 6.0 Hz, 3H); C{ H}NMR (151 MHz, CDCl ) δ 158.6 (d,
3
3
1
Hz), 23.2 (d, J = 4.5 Hz), 22.7 (d, J = 6.0 Hz); P NMR (243
MHz, CDCl ) δ 12.28; HRMS: Calcd for C H N O P
[M+H] : 389.1625; found: 389.1628.
J = 4.5 Hz), 139.1, 138.1, 132.2 (d, J = 7.5 Hz), 130.0, 129.25,
129.0 (d, J = 1.5 Hz), 128.5 (d, J = 6.0 Hz), 128.3 (d, J = 3.0
Hz), 124.8 (d, J = 4.5 Hz), 124.8 (d, J = 7.5 Hz), 121.8, 100.2
(d, J = 139.5 Hz), 73.5 (d, J = 7.5 Hz), 73.0 (d, J = 7.5 Hz),
24.0 (d, J = 3.0 Hz), 23.9 (d, J = 3.0 Hz), 23.2 (d, J = 6.0 Hz),
3
20 26
2
4
+
Diisopropyl (3-(p-tolyl)-3H-indazol-3-yl)phosphonate(5g)
Following general procedure A, the product was obtained in
3
1
22.7 (d, J = 6.0 Hz), 21.5; P NMR (243 MHz, CDCl ) δ
3
1
+
8
7% yield (64.8 mg) as colorless oil. H NMR (600 MHz,
12.08; HRMS: C H N O PNa [M+Na] : 395.1495; found:
20 25
2
3
CDCl ) δ 8.20ꢀ8.19 (m, 1H), 8.03ꢀ8.02 (m, 1H), 7.80ꢀ7.78 (m,
395.1494.
3
2
(
3
H), 7.57ꢀ7.56 (m, 2H), 7.16 (d, J = 12.0 Hz, 2H), 4.65ꢀ4.61
m, 1H), 4.26ꢀ4.23 (m, 1H), 2.31 (s, 3H), 1.24 (d, J = 6.0 Hz,
H), 1.10 (d, J = 6.0 Hz, 3H), 1.07 (d, J = 6.0 Hz, 3H), 0.65 (d,
Diisopropyl
(3-(2-methoxyphenyl)-3H-indazol-3-
yl)phosphonate (5k)
13
1
J = 6.0 Hz, 3H); C{ H}NMR (151 MHz, CDCl ) δ 158.5 (d,
Following general procedure A, the product was obtained in
3
1
J = 4.5 Hz), 139.2, 138.0, 129.9, 129.2, 129.13, 129.12, 127.6
95% yield (73.8 mg) as colorless oil. H NMR (600 MHz,
(
1
=
=
d, J = 4.5 Hz), 124.7 (d, J = 3.0 Hz), 121.7, 100.1 (d, J =
38.0 Hz), 73.4 (d, J = 7.5 Hz), 72.9 (d, J = 7.5 Hz), 24.0 (d, J
3.0 Hz), 23.9 (d, J = 3.0 Hz), 23.2 (d, J = 6.0 Hz), 22.7 (d, J
CDCl ) δ 8.45 (d, J = 6.0 Hz, 1H), 8.20 (d, J = 12.0 Hz, 1H),
3
7.69 (d, J = 12.0 Hz, 1H), 7.53 (t, J = 6.0 Hz, 1H), 7.44 (t, J =
6.0 Hz, 1H), 7.29 (t, J = 6.0 Hz, 1H), 7.07 (t, J = 6.0 Hz, 1H),
6.69 (d, J = 6.0 Hz, 1H), 4.89ꢀ4.83 (m, 1H), 4.14ꢀ409 (m, 1H),
3.25 (s, 3H), 1.30 (d, J = 6.0 Hz, 3H), 1.26 (d, J = 6.0 Hz, 3H),
1.11 (d, J = 6.0 Hz, 3H), 0.58 (d, J = 6.0 Hz, 3H);
31
6.0 Hz), 21.0; P NMR (243 MHz, CDCl ) δ 12.16; HRMS:
3
+
Calcd for C H N O PNa [M+Na] : 395.1495; found:
20
25
2
3
395.1501.
13
1
C{ H}NMR (151 MHz, CDCl ) δ 160.0, 157.8, 157.7, 141.1,
3
Diisopropyl
(3-(4-chlorophenyl)-3H-indazol-3-
131.6 (d, J = 6.0 Hz), 129.8, 129.5, 128.6, 124.1, 121.0, 120.8,
112.1, 100.7 (d, J = 136.5 Hz), 73.1 (d, J = 9.0 Hz), 73.0 (d, J
= 7.5 Hz), 55.2, 24.1 (d, J = 3.0 Hz), 23.9 (d, J = 4.5 Hz), 23.6
yl)phosphonate (5h)
Following general procedure A, the product was obtained in
1
31
8
7% yield (68.3 mg) as colorless oil. H NMR (600 MHz,
(d, J = 6.0 Hz), 22.5 (d, J = 6.0 Hz); P NMR (243 MHz,
+
CDCl ) δ 8.24ꢀ8.23 (m, 1H), 8.02ꢀ8.01 (m, 1H), 7.89ꢀ7.87 (m,
CDCl ) δ 12.03; HRMS: Calcd for C H N O P [M+H] :
3
3
20 26
2
4
2
(
H), 7.63ꢀ7.60 (m, 2H), 7.35 (d, J = 12.0 Hz, 2H), 4.66ꢀ4.63
m, 1H), 4.27ꢀ4.24 (m, 1H), 1.26 (d, J = 6.0 Hz, 3H), 1.12 (d,
J = 6.0 Hz, 3H), 1.10 (d, J = 6.0 Hz, 3H), 0.66 (d, J = 6.0 Hz,
389.1625; found: 389.1627
Diisopropyl
(3-phenyl-3H-[1,3]dioxolo[4,5-f]indazol-3-
13
1
3
1
1
H); C{ H}NMR (151 MHz, CDCl ) δ 158.6 (d, J = 4.5 Hz),
yl)phosphonate (5l)
3
38.6, 134.4 (d, J = 3.0 Hz), 130.8 (d, J = 9.0 Hz), 130.2,
29.5, 129.2 (d, J = 6.0 Hz), 128.6 (d, J = 1.5 Hz), 124.7 (d, J
Following general procedure A, the product was obtained in
1
88% yield (70.8 mg) as colorless solid, mp 90ꢀ93 °C. H
=
3.0 Hz), 122.0, 99.6 (d, J = 138.0 Hz), 73.6 (d, J = 7.5 Hz),
NMR (600 MHz, CDCl ) δ 7.88 (d, J = 6.0 Hz, 2H), 7.67 (s,
3
7
2
3.3 (d, J = 7.5 Hz), 24.0 (d, J = 6.0 Hz), 23.9 (d, J = 6.0 Hz),
1H), 7.50 (t, J = 6.0 Hz, 2H), 7.44 (t, J = 6.0 Hz, 1H), 7.25 (s,
1H), 6.06 (s, 2H), 4.81ꢀ4.74 (m, 2H), 1.39 (d, J = 6.0 Hz, 6H),
3
1
3.3 (d, J = 6.0 Hz), 22.7 (d, J = 6.0 Hz); P NMR (243 MHz,
+
13
1
CDCl ) δ 11.60; HRMS: Calcd for C H ClN O P [M+H] :
1.25 (d, J = 12.0 Hz, 6H); C{ H}NMR (151 MHz, CDCl ) δ
3
19 23
2
3
3
393.1129; found: 393.1131.
150.4, 150.3, 149.7, 145.9, 142.0, 141.9, 132.7, 128.8, 127.8,
117.8 (d, J = 7.5 Hz), 101.9, 98.05, 94.09, 74.1 (d, J = 6.0 Hz),
31
Diisopropyl
(3-(4-fluorophenyl)-3H-indazol-3-
23.8 (d, J = 4.5 Hz), 23.3 (d, J = 6.0 Hz); P NMR (243 MHz,
+
yl)phosphonate (5i)
CDCl ) δ 7.92; HRMS: Calcd for C H N O P [M+H] :
3
20 24
2
5
Following general procedure A, the product was obtained in
403.1417; found: 403.1418.
1
7
5% yield (56.4 mg) as colorless oil. H NMR (600 MHz,
CDCl ) δ 8.24ꢀ8.23 (m, 1H), 8.03ꢀ8.02 (m, 1H), 7.92ꢀ7.91 (m,
Diisopropyl
(5,6-difluoro-3-phenyl-3H-indazol-3-
3
2
1
6
H), 7.61ꢀ7.60 (m, 2H), 7.07 (t, J = 6.0 Hz, 2H), 4.65ꢀ4.62 (m,
H), 4.27ꢀ4.24 (m, 1H), 1.25 (d, J = 6.0 Hz, 3H), 1.12 (d, J =
.0 Hz, 3H), 1.08 (d, J = 6.0 Hz, 3H), 0.66 (d, J = 6.0 Hz, 3H);
yl)phosphonate (5m)
Following general procedure A except that 3e（28.2 mg， 0.1
mmol）and 4c (100.3 mg, 0.3 mmol) were used, the product
was obtained in 47% yield (18.0 mg) as colorless solid, mp
13
1
C{ H}NMR (151 MHz, CDCl ) δ 162.7 (d, J = 249.0 Hz),
3
5
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 6 of 8
1
7
4.0ꢀ74.4 °C. H NMR (600 MHz, CD OD) δ 8.27 (t, J = 6.0
7.52 (t, J = 6.0 Hz, 2H), 7.44 (t, J = 6.0 Hz, 1H), 7.30 (t, J =
6.0 Hz, 1H), 7.18 (t, J = 6.0 Hz, 1H), 7.13 (d J = 12.0 Hz, 1H);
3
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
Hz, 1H), 7.99 (t, J = 6.0 Hz, 1H), 7.86 (t, J = 6.0 Hz, 2H),
7.43 (t, J = 6.0 Hz, 2H), 7.39ꢀ7.38 (m, 1H), 4.61ꢀ4.53 (m, 1H),
4.46ꢀ4.38 (m, 1H), 1.21 (d, J = 6.0 Hz, 3H), 1.20 (d, J = 6.0
Hz, 3H), 1.07 (d, J = 6.0 Hz, 3H), 0.93 (d, J = 6.0 Hz, 3H);
C{ H}NMR (151 MHz, CD OD) δ 155.5, 154.5 (dd, J = 3.0,
5.1 Hz), 153.7 (d, J = 15.1 Hz), 152.8 (dd, J = 3.0, 15.1 Hz),
52.1 (dd, J = 3.0, 15.1 Hz) 136.9 (d, J = 7.6 Hz), 132.4 (d,
13
1
C{ H}NMR (151 MHz, CDCl ) δ 145.6, 141.7, 133.5, 129.0,
3
128.2, 127.8, 126.8, 121.3, 121.0, 120.9, 110.4; HRMS: Calcd
+
for C H N [M+H] : 195.0917; found: 195.0924.
13
11
2
1
3
1
3
5h
1
1
3-(4-Methoxyphenyl)-1H-indazole (6f)
Following general procedure B, the product was obtained in
1
J = 7.6 Hz), 131.4, 130.7, 130.3, 130.0 (d, J = 3.0 Hz), 129.8
d, J = 3.0 Hz), 129.6, 128.9 (d, J = 4.5 Hz), 114.8 (dd, J =
96% yield (43.0 mg) as colorless solid, mp 95ꢀ97 °C. H
(
NMR (600 MHz, CDCl ) δ 11.33 (brs, 1H), 7.98ꢀ7.93 (m, 3H),
3
1
1
7
2
.5, 22.7 Hz), 106.5 (d, J = 21.1 Hz), 104.2 (d, J = 19.6 Hz),
02.3 (d, J = 141.9 Hz), 77.6 (d, J = 7.6 Hz), 75.6 (dd, J =
7.30 (t, J = 6.0 Hz, 1H), 7.18 (t, J = 6.0 Hz, 2H), 7.05, (d, J =
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
6.0 Hz, 2H), 3.86 (s, 3H);
13
1
.6, 25.7 Hz), 24.1 (dd, J = 3.0, 6.0 Hz), 23.8 (d, J = 4.5 Hz),
C{ H}NMR (151 MHz, CDCl ) δ 159.7, 145.5, 141.8, 128.9,
3
31
3.4 (dt, J = 6.0, 12.1 Hz); P NMR (243 MHz, CD OD) δ
126.6, 126.3, 121.1, 120.9, 114.4, 110.3, 55.4; HRMS: Calcd
3
+
+
1
1.01; HRMS: Calcd for C H F N O P [M+H] : 395.1331;
for C H N O [M+H] : 225.1022; found: 225.1028.
1
9
22
2
2
3
14 13
2
found: 395.1329.
3
-(p-tolyl)-1H-indazole (6g)
5
d
3
-Methyl-1H-indazole (6a)
Following general procedure B, the product was obtained in
1
Following general procedure B, the product was obtained in
92% yield (24.3 mg) as colorless solid, mp 120ꢀ122 °C. H
NMR (600 MHz, CDCl ) δ 9.18 (brs, 1H), 7.68 (d, J = 12.0
Hz, 1H), 7.43 (d, J = 12.0 Hz, 1H), 7.36 (t, J = 6.0 Hz, 1H),
83% yield (34.6 mg) as colorless solid, mp 126ꢀ129 °C. H
1
NMR (600 MHz, CDCl ) δ 10.97 (brs, 1H), 7.99 (d, J = 6.0
3
Hz, 1H), 7.90 (d, J = 6.0 Hz, 2H), 7.34ꢀ7.30 (m, 3H), 7.22ꢀ
3
13
1
7.16 (m, 2H), 2.43 (s, 3H); C{ H}NMR (151 MHz, CDCl ) δ
3
1
3
1
7
.14 (t, J = 6.0 Hz, 1H), 2.63 (s, 3H); C{ H}NMR (151 MHz,
145.7, 141.8, 138.0, 130.7, 129.6, 127.6, 126.7, 121.2, 121.1,
+
CDCl ) δ 143.3, 141.2, 126.7, 122.8, 120.18, 120.15, 109.7,
1
1
121.0, 110.3, 21.3; HRMS: Calcd for C H N [M+H] :
3
14 13
2
+
1.9; HRMS: Calcd for C H N [M+H] : 133.0760; found:
209.1073; found: 209.1081.
-(4-Chlorophenyl)-1H-indazole (6h)
8
9
2
33.0768.
5e
3
5c
3
-Ethyl-1H-indazole (6b)
Following general procedure B, the product was obtained in
1
Following general procedure B, the product was obtained in
9
NMR (600 MHz, CDCl ) δ 8.82 (brs, 1H), 7.64 (d, J = 12.0
Hz, 1H), 7.35 (d, J = 12.0 Hz, 1H), 7.28 (t, J = 6.0 Hz, 1H),
7
6
81% yield (37.0 mg) as colorless solid, mp 146ꢀ149 °C. H
1
5% yield (27.7 mg) as colorless solid, mp 70ꢀ73 °C. H
NMR (600 MHz, CDCl ) δ 10.01 (brs, 1H), 7.95 (d, J = 6.0
3
Hz, 1H), 7.92 (d, J = 12.0 Hz, 2H), 7.47 (d, J = 6.0 Hz, 2H),
7.37 (t, J = 6.0 Hz, 1H), 7.28 (d, J = 6.0 Hz, 1H), 7.23ꢀ7.20 (m,
3
13
1
.05 (t, J = 6.0 Hz, 1H), 2.975 (q, J = 6.0 Hz, 2H), 1.36 (t, J =
1H); C{ H}NMR (151 MHz, CDCl ) δ 144.6, 141.7, 134.1,
3
13
1
.0 Hz, 3H); C{ H}NMR (151 MHz, CDCl ) δ 148.5, 141.3,
132.0, 129.1, 128.8, 127.0, 121.7, 120.8, 110.2; HRMS: Calcd
3
+
126.7, 121.9, 120.3, 120.1, 109.9, 20.4, 13.3; HRMS: Calcd
for C H N [M+H] : 147.0917; found: 147.0924.
for C H ClN [M+H] : 229.0527; found: 229.0529.
13
10
2
+
9
11
2
5c
3-(4-Fluorophenyl)-1H-indazole (6i)
7
c
3-Propyl-1H-indazole (6c)
Following general procedure B, the product was obtained in
9
Following general procedure B, the product was obtained in
1
64% yield (27.2 mg) as colorless solid, mp 134ꢀ136 °C. H
1
1% yield (29.2 mg) as colorless oil. H NMR (600 MHz,
NMR (600 MHz, CDCl ) δ 10.70 (brs, 1H), 7.97ꢀ7.94 (m, 3H),
3
CDCl ) δ 8.87 (brs, 1H), 7.63 (d, J = 6.0 Hz, 1H), 7.35 (d, J =
7.35 (t, J = 6.0 Hz, 1H), 7.26ꢀ7.23 (m, 1H), 7.21 (t, J = 6.0 Hz,
3
13
1
1
1
6
1
2.0 Hz, 1H), 7.28 (t, J = 12.0 Hz, 1H), 7.05 (t, J = 6.0 Hz,
H), 2.92 (t, J = 6.0 Hz, 2H), 1.83ꢀ1.77 (m, 2H), 0.94 (t, J =
3H); C{ H}NMR (151 MHz, CDCl ) δ 163.7, 162.0, 144.8,
3
141.7, 129.7 (d, J = 4.5 Hz), 129.4 (d, J = 7.5 Hz), 126.9,
121.5, 120.8, 115.9 (d, J = 21.0 Hz), 110.2; HRMS: Calcd for
13
1
.0 Hz, 3H); C{ H}NMR (151 MHz, CDCl ) δ 147.3, 141.2,
3
+
26.7, 122.3, 120.3, 120.1, 109.8, 29.1, 22.4, 14.1; HRMS:
C H FN [M+H] : 213.0823; found: 213.0831.
13
10
2
+
Calcd for C H N [M+H] : 161.1073; found: 161.1076.
10
13
2
3
-(m-Tolyl)-1H-indazole (6j)
5
c
3
-Benzyl-1H-indazole (6d)
Following general procedure B, the product was obtained in
1
Following general procedure B, the product was obtained in
8
NMR (600 MHz, CDCl ) δ 9.44 (brs, 1H), 7.43 (d, J = 6.0 Hz,
1H), 7.27 (d, J = 12.0 Hz, 1H), 7.22 (t, J = 6.0 Hz, 3H), 7.17 (t,
J = 6.0 Hz, 2H), 7.10 (t, J = 6.0 Hz, 1H), 6.96 (t, J = 6.0 Hz,
1H), 4.30 (s, 2H); C{ H}NMR (151 MHz, CDCl ) δ 145.8,
1
1
67% yield (27.9 mg) as colorless oil. H NMR (600 MHz,
1
2% yield (34.1 mg) as colorless solid, mp 127ꢀ130 °C. H
CDCl ) δ 11.44 (brs, 1H), 7.99 (d, J = 12.0 Hz, 1H), 7.84ꢀ7.81
3
(m, 2H), 7.41 (t, J = 6.0 Hz, 1H), 7.28ꢀ7.25 (m, 2H), 7.18ꢀ7.15
3
13
1
(m, 1H), 7.07 (d, J = 6.0 Hz, 1H), 2.40 (s, 3H); C{ H}NMR
(151 MHz, CDCl ) δ 145.7, 141.7, 138.6, 133.4, 129.0, 128.9,
3
1
3
1
128.5, 126.7, 125.0, 121.2, 121.03, 120.95, 110.4, 21.5;
3
+
41.4, 138.9, 128.8, 128.5, 126.8, 126.3, 122.1, 120.5, 120.4,
HRMS: Calcd for C H N [M+H] : 209.1073; found:
14 13
2
+
09.9, 33.6; HRMS: Calcd for C H N [M+H] : 209.1073;
209.1079.
14 13
2
found: 209.1078.
5k
3
-(2-Methoxyphenyl)-1H-indazole (6k)
4
e
3
-Phenyl-1H-indazole (6e)
Following general procedure B, the product was obtained in
1
Following general procedure B, the product was obtained in
9
NMR (600 MHz, CDCl ) δ 11.15 (brs, 1H), 8.02ꢀ7.99 (m, 3H),
89% yield (39.9 mg) as colorless oil. H NMR (600 MHz,
1
3% yield (36.1 mg) as colorless solid, mp 108ꢀ111 °C. H
CDCl ) δ 11.05 (brs, 1H), 7.75ꢀ7.72 (m, 2H), 7.44 (t, J = 6.0
3
Hz, 1H), 7.25 (t, J = 6.0 Hz, 1H), 7.12ꢀ7.07 (m, 4H), 3.79 (s,
3
6
ACS Paragon Plus Environment

Page 7 of 8
The Journal of Organic Chemistry
1
3
1
3
1
H); C{ H}NMR (151 MHz, CDCl ) δ 157.4, 143.1, 141.5,
Following general procedure A, the product was obtained in
85% yield (42.8 mg) as colorless oil. H NMR (600 MHz,
3
1
1
2
3
4
5
6
7
8
9
31.5, 129.7, 126.3, 122.4, 122.2, 122.0, 121.0, 120.5, 111.5,
110.4, 55.5. HRMS: Calcd for C H N O [M+H] : 225.1022;
+
CDCl ) δ 8.15 (d, J = 6.0 Hz, 1H), 7.87 (d, J = 12.0 Hz, 1H),
1
4
13
2
3
found: 225.1026.
7.62ꢀ7.57 (m, 2H), 7.50ꢀ7.49 (m, 2H), 7.36ꢀ7.35 (m, 3H), 3.76
13
1
(s, 3H); C{ H}NMR (151 MHz, CDCl ) δ 167.3, 157.5,
3
3-(o-Tolyl)-1H-indazole (6l)
Following general procedure B, the product was obtained in
137.7, 132.8, 130.4, 130.0, 129.0, 128.8, 127.3, 124.8, 122.1,
+
101.1, 53.4; HRMS: Calcd for C H N O [M+H] : 253.0972;
15 13
2
2
1
7
2% yield (30.0 mg) as colorless solid, mp 121ꢀ123 °C. H
found: 253.0970.
NMR (600 MHz, CDCl ) δ 11.21 (brs, 1H), 7.54ꢀ7.50 (m, 2H),
3
7
7
.34ꢀ7.33 (m, 2H), 7.28ꢀ7.27 (m, 1H), 7.17 (t, J = 6.0 Hz, 1H),
.03 (t, J = 6.0 Hz, 1H), 6.78 (d, J = 12.0 Hz, 1H), 2.31 (s, 3H);
C{ H}NMR (151 MHz, CDCl ) δ 145.9, 141.0, 137.6, 132.4,
ASSOCIATED CONTENT
Supporting Information
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
13
1
3
1
2
2
30.8, 130.8, 128.5, 126.7, 125.9, 122.2, 121.0, 120.9, 110.2,
0.4; HRMS: Calcd for C H N [M+H] : 209.1073; found:
09.1080.
+
The Supporting Information is available free of charge on the
ACS Publications website at DOI:
1
4
13
2
1
13
Copies of H and C NMR spectra (PDF)
5
k
3
-(Naphthalen-1-yl)-1H-indazole(6m)
AUTHOR INFORMATION
Corresponding Author
Following general procedure B, the product was obtained in
68% yield (33.2 mg) as white solid, mp 164ꢀ168 °C. H NMR
(600 MHz, CDCl ) δ 12.15 (brs, 1H), 8.23 (d, J = 12.0 Hz,
1H), 8.00 (d, J = 12.0 Hz, 1H), 7.96 (d, J = 6.0 Hz, 1H), 7.83ꢀ
7.81 (m, 1H), 7.63ꢀ7.59 (m, 2H), 7.51 (t, J = 6.0 Hz, 1H), 7.43
1
3
*Eꢀmail: pengyungui@hotmail.com or pyg@swu.edu.cn
ORCID
(t, J = 6.0 Hz, 1H), 7.21ꢀ7.18 (m, 1H), 7.07 (t, J = 6.0 Hz, 1H),
Yungui Peng: 0000ꢀ0002ꢀ5815ꢀ1261
Notes
1
3
1
6
1
1
.77ꢀ6.72 (m, 1H); C{ H}NMR (151 MHz, CDCl ) δ 145.0,
41.0, 134.1, 132.2, 130.5, 128.9, 128.3, 126.8, 126.5, 126.2,
3
26.1, 125.5, 122.7, 121.1, 121.0, 110.2; HRMS: Calcd for
The authors declare no competing financial interest.
+
C H N [M+H] : 245.1073; found: 245.1075.
1
7
13
2
ACKNOWLEDGMENT
This research was supported by grants from National Science
Foundation of China (21472151), Fundamental Research Funds
for the Central Universities (XDJK2015C102 and SWU114078)
and China Postdoctoral Science Foundation (2015M582494).
3
-(Naphthalen-2-yl)-1H-indazole(6n)
Following general procedure B, the product was obtained in
1
8
9% yield (43.5 mg) as white solid, mp 128ꢀ131 °C. H NMR
(600 MHz, CDCl ) δ 12.18 (brs, 1H), 8.46 (s, 1H), 8.17 (d, J =
3
6
.0 Hz, 1H), 8.08 (d, J = 6.0 Hz, 1H), 7.95 (d, J = 12.0 Hz,
REFERENCES
1H), 7.89ꢀ7.86 (m, 2H), 7.49ꢀ7.48 (m, 2H), 7.20ꢀ7.11 (m, 3H);
1
3
1
C{ H}NMR (151 MHz, CDCl ) δ 145.5, 141.8, 133.7, 133.2,
(1) For selected general reviews about indazole, see: (a) Stadlbauer,
W. Science of Synthesis 2002, 12, 227. (b) Hugo, C.; Alejandra, G.;
Mercedes, G.; Vicente, J. A.; Carmen, O. d. O. Mini Rev. Med. Chem.
2005, 5, 869. (c) Yet, L. Comprehensive Heterocyclic Chemistry III;
Ramsden, C. A.; Scriven, E. F. V.; Taylor, R. J. K. Elsevier: Oxford,
2008, pp. 1ꢀ141. (d) Schmidt, A.; Beutler, A.; Snovydovych, B. Eur. J.
Org. Chem. 2008, 4073. (e) Makhluf, J. H.; Wayne, E. C.; Mark, J. K.
Mini Rev. Med. Chem. 2012, 12, 1293; (f) Shafakat Ali, N. A.; Ahꢀ
mad Dar, B.; Pradhan, V.; Farooqui, M. Mini Rev. Med. Chem. 2013,
13, 1792. (g) Gaikwad, D. D.; Chapolikar, A. D.; Devkate, C. G.;
Warad, K. D.; Tayade, A. P.; Pawar, R. P.; Domb, A. J. Eur. J. Med.
Chem. 2015, 90, 707.
3
131.1, 128.6, 128.3, 127.8, 126.8, 126.6, 126.4, 126.2, 125.7,
121.4, 121.10, 121.07, 110.4; HRMS: Calcd for C H N
2
1
7
13
+
[
M+H] : 245.1073; found: 245.1075.
5
d
3
-Phenyl-1H-[1,3]dioxolo[4,5-f]indazole (6o)
Following general procedure B, the product was obtained in
1
8
3% yield (39.5 mg) as colorless solid, mp 221ꢀ224 °C. H
NMR (600 MHz, CDCl ) δ 7.88 (d, J = 6.0 Hz, 2H), 7.50 (t, J
3
=
6.0 Hz, 2H), 7.42 (t, J = 6.0 Hz, 1H), 7.26 (s, 1H), 6.67 (s,
13 1
1
H), 6.01 (s, 2H). 4.87 (brs, 1H); C{ H}NMR (151 MHz,
CDCl ) δ 149.2, 145.2, 145.1, 138.5, 133.4, 128.9, 128.1,
3
1
27.4, 115.4, 101.6, 97.8, 89.6; HRMS: Calcd for C H N O
14 11 2 2
+
[
M+H] : 239.0815; found: 239.0820.
(2) For selected general reviews about synthesis of indazole, see: 1a,
1d.
5,6-difluoro-3-phenyl-1H-indazole (6p)
Following general procedure B, the product was obtained in
35% yield (16.0 mg) as colorless solid, mp 148.4ꢀ148.8 °C. H
NMR (600 MHz, CD OD) δ 7.85 (d, J = 6.0 Hz, 2H), 7.80 (t,
(3) For selected recent general reviews about 1,3ꢀdipolar cycloaddiꢀ
tion, see: (a) Hashimoto, T.; Maruoka, K. Chem. Rev. 2015, 115, 5366.
1
(
b) Singh, M. S.; Chowdhury, S.; Koley, S. Tetrahedron 2016, 72,
3
1603. For selected recent review about aryne, see: (c) Bhunia, A.;
Yetra, S. R.; Biju, A. T. Chem. Soc. Rev. 2012, 41, 3140. (d) Gampe,
C. M.; Carreira, E. M. Angew. Chem. Int. Ed. 2012, 51, 3766. (e)
Tadross, P. M.; Stoltz, B. M. Chem. Rev. 2012, 112, 3550. (f) Duꢀ
brovskiy, A. V.; Markina, N. A.; Larock, R. C. Org. Biomol. Chem.
2013, 11, 191. (g) Yoshida, S.; Hosoya, T. Chem. Lett. 2015, 44, 1450.
(h) Bhojgude, S. S.; Bhunia, A.; Biju, A. T. Acc. Chem. Res. 2016, 49,
1658. (i) GarciaꢀLopez, J.ꢀA.; Greaney, M. F. Chem. Soc. Rev. 2016,
45, 6766. (j) Shi, J.; Li, Y.; Li, Y. Chem. Soc. Rev. 2017, 46, 1707.
J = 6.0 Hz, 1H), 7.50 (t, J = 6.0 Hz, 2H), 7.41 (s, 2H);
1
3
1
C{ H}NMR (151 MHz, CD OD) δ 153.3 (d, J = 16.6 HZ),
3
1
1
51.6 (d, J = 16.6 HZ), 149.5 (d, J = 16.6 HZ), 147.9 (d, J =
6.6 HZ), 134.1, 130.0, 129.4, 128.3, 116.9, 108.0 (d, J = 19.6
HZ), 98.7 (d, J = 21.1 HZ); HRMS: Calcd for C H F N
1
3
9
2
2
+
[
M+H] : 231.0728; found: 231.0729.
Methyl 3-phenyl-3H-indazole-3-carboxylate (7)
7
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 8 of 8
(
4) For selected examples for the synthesis of 1Hꢀindazole via dipoꢀ
Chem. 2016, 36, 976. (c) Yashin, N. V.; Averina, E. B.; Kuznetsova,
T. S.; Zefirov, N. S. Russ. Chem. Bull. 2016, 65, 877.
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
lar 1, 3ꢀcycloaddition, see: (a) Inamoto, K.; Katsuno, M.; Yoshino, T.;
Arai, Y.; Hiroya, K.; Sakamoto, T. Tetrahedron 2007, 63, 2695. (b)
Liu, Z.; Shi, F.; Martinez, P. D. G.; Raminelli, C.; Larock, R. C. J.
Org. Chem. 2008, 73, 219. (c) Hari, Y.; Sone, R.; Aoyama, T. Org.
Biomol. Chem. 2009, 7, 2804. (d) Spiteri, C.; Keeling, S.; Moses, J. E.
Org. Lett. 2010, 12, 3368. (e) Li, P.; Zhao, J.; Wu, C.; Larock, R. C.;
Shi, F. Org. Lett. 2011, 13, 3340. (f) Kovács, S.; Csincsi, Á. I.; Nagy,
T. Z.; Boros, S.; Timári, G.; Novák, Z. Org. Lett. 2012, 14, 2022. (g)
Li, P.; Wu, C.; Zhao, J.; Rogness, D. C.; Shi, F. J. Org. Chem. 2012,
(15) (a) Zhang, H.; Wen, X.; Gan, L.; Peng, Y. Org. Lett. 2012, 14,
2126. (b) Wen, X.; Chen, J.; Peng, Y. Adv. Synth. Catal. 2014, 356,
3794. (c) Du, T.; Du, F.; Ning, Y.; Peng, Y. Org. Lett. 2015, 17, 1308.
(d) Chen, J.; Wen, X.; Wang, Y.; Du, F.; Cai, L.; Peng, Y. Org. Lett.
2016, 18, 4336. (e) Du, F.; Yin, L.; Ning, Y.; Peng, Y. Adv. Synth.
Catal. 2016, 358, 2280.
(16) For selected recent examples about the application of αꢀ
diazophosphonate in other groups, see: (a) Hashimoto, T.; Kimura, H.;
Kawamata, Y.; Maruoka, K. Nat. Chem. 2011, 3, 642. (b) Wang, J.;
Boyarskikh, V.; Rainier, J. D. Org. Lett. 2011, 13, 700. (c) Verma, D.;
Mobin, S.; Namboothiri, I. N. N. J. Org. Chem. 2011, 76, 4764. (d)
Zhou, C.ꢀY.; Wang, J.ꢀC.; Wei, J.; Xu, Z.ꢀJ.; Guo, Z.; Low, K.ꢀH.;
Che, C.ꢀM. Angew. Chem. Int. Ed. 2012, 51, 11376. (e) Schnaars, C.;
Hansen, T. Org. Lett. 2012, 14, 2794. (f) Lindsay, V. N. G.; Fiset, D.;
Gritsch, P. J.; Azzi, S.; Charette, A. B. J. Am. Chem. Soc. 2013, 135,
1463. (g) Cai, Y.; Lyu, H.; Yu, C.; Miao, Z. Adv. Synth. Catal. 2014,
356, 596. (h) Ye, F.; Wang, C.; Zhang, Y.; Wang, J. Angew. Chem.
Int. Ed. 2014, 53, 11625. (i) Zhou, Y.; Ye, F.; Wang, X.; Xu, S.;
Zhang, Y.; Wang, J. J. Org. Chem. 2015, 80, 6109. (j) Ahamad, S.;
Kant, R.; Mohanan, K. Org. Lett. 2016, 18, 280. (k) Chen, D.; Zhu,
D.ꢀX.; Xu, M.ꢀH. J. Am. Chem. Soc. 2016, 138, 1498. (l) Chaturvedi,
A. K.; Kant, R.; Rastogi, N. J. Org. Chem. 2016, 81, 11291. (m) Raꢀ
makrishna, K.; Thomas, J. M.; Sivasankar, C. J. Org. Chem. 2016, 81,
9826. (n) Zhou, Y.; Ye, F.; Zhou, Q.; Zhang, Y.; Wang, J. Org. Lett.
2016, 18, 2024 and references cited in 14a.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
7
7, 3149.
(
5) For selected examples for the synthesis of 1Hꢀindazole via methꢀ
ods other than dipolar cycloaddition, see: (a) Inamoto, K.; Katsuno,
M.; Yoshino, T.; Suzuki, I.; Hiroya, K.; Sakamoto, T. Chem. Lett.
2
004, 33, 1026. (b) Viña, D.; del Olmo, E.; LópezꢀPérez, J. L.; San
Feliciano, A. Org. Lett. 2007, 9, 525. (c) Counceller, C. M.; Eichman,
C. C.; Wray, B. C.; Stambuli, J. P. Org. Lett. 2008, 10, 1021. (d)
Thomé, I.; Besson, C.; Kleine, T.; Bolm, C. Angew. Chem. Int. Ed.
2
2
013, 52, 7509. (e) Yu, D.ꢀG.; Suri, M.; Glorius, F. J. Am. Chem. Soc.
013, 135, 8802. (f) Zhang, T.; Bao, W. J. Org. Chem. 2013, 78, 1317.
(
g) Hu, J.; Xu, H.; Nie, P.; Xie, X.; Nie, Z.; Rao, Y. Chem. Eur. J.
014, 20, 3932. (h) Chen, C.ꢀy.; Tang, G.; He, F.; Wang, Z.; Jing, H.;
Faessler, R. Org. Lett. 2016, 18, 1690. (i) Wang, Q.; Li, X. Org. Lett.
016, 18, 2102. (j) Xu, P.; Wang, G.; Wu, Z.; li, S.; Zhu, C. Chem.
2
2
Sci. 2017, 8, 1303. (k) C. Wiethan, C. M. Lavoie, A. Borzenko, J. S.
K. Clark, H. G. Bonacorso, M. Stradiotto, Org. Biomol. Chem. 2017,
1
5, 5062.
6) Minkin, V. I.; Garnovskii, A. D.; Elguero, J.; Katritzky, A. R.;
Denisko, O. V. Adv. Heterocycl. Chem. 2000, 76, 157. See also 1d.
7) (a) Collot, V.; Varlet, D.; Rault, S. Tetrahedron Lett. 2000, 41,
363. (b) Hari, Y.; Shoji, Y.; Aoyama, T. Synthesis 2004, 2004, 1183.
c) Campetella, S.; Palmieri, A.; Petrini, M. Eur. J. Org. Chem. 2009,
184. See also 4c, 5a, 5b, 5c, 5d, 5g, 5h.
8) For review, see: (a) Billups, W. E. Acc. Chem. Res. 1978, 11, 245.
For primary work, see: (b) Anet, R.; Anet, F. A. L. J. Am. Chem. Soc.
964, 86, 525. During our preparation of this manuscript, a new reꢀ
(
(17) For selected recent reviews, see: (a) Pradere, U.; Garnierꢀ
Amblard, E. C.; Coats, S. J.; Amblard, F.; Schinazi, R. F. Chem. Rev.
2014, 114, 9154. (b) Horsman, G. P.; Zechel, D. L. Chem. Rev. 2017,
117, 5704.
(
4
(
(18) (a) Kirby, A. J. Stereoelectronic Effects; Oxford University
PresS, 1996. (b) Yamazaki, T.; Baum, G.; Shechter, H. Tetrahedron
Lett. 1974, 15, 4421 and references cited therein.
3
(
1
port has appeared: Cheng, B.; Zu, B.; Bao, B.; Li, Y.; Wang, R.; Zhai,
H. J. Org. Chem. 2017, 82, 8228.
(
(
9) (a) Gilbert, J. C.; Weerasooriya, U. J. Org. Chem. 1982, 47, 1837.
b) Ohira, S. Synth. Commun. 1989, 19, 561. (c) Mueller, S.; Liepold,
B.; Roth, G. J.; Bestmann, H. J. Synlett 1996, 521.
10) (a) Seyferth, D. Chem. Rev. 1955, 55, 1155. (b) Seyferth, D.;
(
Hilbert, P.; Marmor, R. S. J. Am. Chem. Soc. 1967, 89, 4811. (c)
Seyferth, D.; Marmor, R. S. J. Org. Chem. 1971, 36, 128. (d) Seyferth,
D.; Marmor, R. S.; Hilbert, P. J. Org. Chem. 1971, 36, 1379.
(
11) For selected reviews about the construction of heterocycles using
OhiraꢀBestmann reagent, see: (a) Mohapatra, S.; Bhanja, C.; Jena, S.;
Chakroborty, S.; Nayak, S. Synth. Commun. 2013, 43, 1993. (b) Baiju,
T. V.; Namboothiri, I. N. N. Chem. Rec. 2017, 17, 939.
(
12) For selected recent examples, see: (a) Evans, D. A.; Johnson, J.
S.; Olhava, E. J. J. Am. Chem. Soc. 2000, 122, 1635. (b) Evans, D. A.;
Scheidt, K. A.; Fandrick, K. R.; Lam, H. W.; Wu, J. J. Am. Chem. Soc.
2
003, 125, 10780. (c) Jiang, H.; Paixão, M. W.; Monge, D.; Jørgensen,
K. A. J. Am. Chem. Soc. 2010, 132, 2775.
13) Phatake, R. S.; Mullapudi, V.; Wakchaure, V. C.; Ramana, C. V.
Org. Lett. 2017, 19, 372.
14) For selected reviews about αꢀdiazophosphonate, see: (a) Mariꢀ
(
(
nozzi, M.; Pertusati, F.; Serpi, M. Chem. Rev. 2016, 116, 13991. (b)
Miao, Z.; Cai, Y.; Ge, H.; Fu, J.; Abudukeremu, M. Chin. J. Org.
8
ACS Paragon Plus Environment