Facile One-Pot Access to α-Diazo-β-ketosulfones from Sulfonyl Chlorides and α-Haloketones

Article abstract of DOI:10.1055/s-0040-1707525

A convenient one-pot approach to the preparation of α-diazo-β-ketosulfones from sulfonyl chlorides is described. It involves the conversion of the sulfonyl chloride to sodium sulfinate, alkylation of the latter with α-haloketones followed by diazo transfer using the 'sulfonyl-azide-free' ('SAFE') protocol in aqueous medium. The simple and expedient method relies on readily available starting materials and provides facile access to a wide variety of valuable diazo reagents for organic synthesis.

Full text of DOI:10.1055/s-0040-1707525

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2020, 52, A–H
paper
A
en
D. Dar’in et al.
Paper
Synthesis
Facile One-Pot Access to -Diazo--ketosulfones from Sulfonyl
Chlorides and -Haloketones
Dmitry Dar’ina
Grigory Kantina
Olga Bakulinaa
O
O
O
O
S
R2
SAFE
protocol
R1
Hal
Na2SO3
O
O
O
O
O
R2
R1SO2Na
N2
S
S
Mikhail Krasavin*a,b
0
0
0
0-0
0
0
2-
0
2
0
0-4
7
7
2
R1
R2
R1
Cl
NaHCO3
H2O/MeCN
r.t.
26 examples
39–84%
KI (5 mol%)
r.t.
a Saint Petersburg State University, Saint Petersburg 199034,
Russian Federation
b Laboratory of Chemical Pharmacology, Institute of Chemistry,
Saint Petersburg State University, 26 Universitetskyi prospekt,
Peterhof 198504, Russian Federation
one-pot
over 3 steps
m.krasavin@spbu.ru
Received: 01.03.2020
Accepted after revision: 01.04.2020
Published online: 28.04.2020
of diazo sulfones10 and their use in key steps of the synthe-
sis of complex molecules; total synthesis of exhibiting anti-
cancer activity (+)-digitoxigenin11 and synthetic approach
to daphniglaucin-type daphniphyllum alkaloids12 being no-
table examples. In connection with the high demand for
this class of diazo compounds, development of a simple and
convenient method for their preparation from available
starting materials would be highly desirable. The most
common method for producing diazo compounds contain-
ing electron-withdrawing groups is the diazo transfer reac-
tion. Recently, we reported a fundamentally new modifica-
tion of this general approach, which allows carrying out the
reaction in aqueous medium and avoiding preparation, iso-
lation, and handling of the sulfonyl azide diazo transfer re-
agent (an approach we dubbed the ‘Sulfonyl-Azide-Free’
protocol).13 The present work is devoted to the extension of
this method to the synthesis of diazo ketosulfones derived
from sulfonyl chlorides and -haloketones via a sequence of
one pot transformations (RSO2Cl → RSO2Na → RSO2CH2COR′
→ RSO2CN2COR′).
The conversion of a sulfonyl chloride to a sulfinic acid
salt followed by its in situ alkylation is often carried out in
water or in aqueous solvent mixtures.14 We reasoned that
this aspect would make this two-step sequence a conve-
nient preamble for the final synthetic step (diazo transfer).
Since the earlier described ‘SAFE’ diazo transfer is also car-
ried out in aqueous medium, the isolation of the final prod-
ucts (diazo ketosulfones) could, in principle, be reduced to
filtration or simple extraction with an organic solvent.
Table 1 presents the results of the preparation of diazo
ketosulfones by a three-step one-pot process. Commercially
available or synthetically accessible sulfonyl chlorides and
-haloketones, both aromatic and aliphatic, were used as
starting materials.
DOI: 10.1055/s-0040-1707525; Art ID: ss-2020-t0118-op
Abstract A convenient one-pot approach to the preparation of -di-
azo--ketosulfones from sulfonyl chlorides is described. It involves the
conversion of the sulfonyl chloride to sodium sulfinate, alkylation of the
latter with -haloketones followed by diazo transfer using the ‘sulfonyl-
azide-free’ (‘SAFE’) protocol in aqueous medium. The simple and expe-
dient method relies on readily available starting materials and provides
facile access to a wide variety of valuable diazo reagents for organic syn-
thesis.
Key words aliphatic diazo compounds, diazo ketosulfones, diazo
transfer, -haloketones, Rh(II)-catalyzed cyclization, pyrazole synthesis
To date, the chemistry of -diazocarbonyl compounds is
one of the most intensively developing and widely repre-
sented in the literature fields of chemical science. In recent
years, there has been an exponential increase in the num-
ber of scientific papers devoted to this topic. One of the as-
pects that determine the high interest in the chemistry of
diazo compounds is their unique and remarkably diverse
reactivity, including transformations both with the loss of a
nitrogen molecule (during their thermal, catalytic or photo-
lytic decomposition), and with the incorporation of nitro-
gen atoms into the molecule of the reaction product.1
-Diazo--ketosulfones (and diazo sulfones in general)
are a very promising class of aliphatic diazo compounds for
organic synthesis. Recently, reports on various transforma-
tions of these diazo substrates (cyclopropanation,2 inser-
tion into C–H3 and heteroatom–H4 bonds, Wolff rearrange-
ment,5 and others6) are increasingly appearing in the litera-
ture. Diazo sulfones manifested themselves as convenient
precursors for the construction of various heterocyclic
cores such as pyrazoles,7 azines,8 and other heterocycles.9
Of particular interest are enantioselective transformations
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–H
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
D. Dar’in et al.
Paper
Synthesis
Table 1 -Diazo--ketosulfones 1 Prepared
step, the sulfonyl chloride was introduced into the reaction
mixture as a solution in acetonitrile (which is rather critical
for highly hydrophobic sulfonyl chlorides). Generally, in or-
der to achieve maximum conversion, each step was carried
out over 14–18 hours. Upon addition of the aqueous solu-
tion we termed as the ‘SAFE’ cocktail13 (i.e., a solution of 3-
carboxybenzenesulfonyl chloride, sodium azide, and potas-
sium carbonate in water) to the reaction mixture, the diazo
transfer was complete within 6 hours. The solid reaction
products were isolated by filtration and, if necessary, crys-
tallized from an appropriate solvent. In some cases, the
product was extracted and purified by flash chromatogra-
phy on silica gel. The yields of the diazo ketosulfones thus
obtained (over three steps starting from the sulfonyl chlo-
ride) range from moderate to high. In one case (Table 1, en-
try 2), it was possible to compare the yield over three steps
(80%) with the yield of the final, SAFE diazotransfer step
(86%) previously reported for the same active-methylene
substrate (among several other sulfones that gave rise to -
sulfonyl diazocarbonyl compounds).13a In the case of steri-
cally hindered mesitylene sulfonyl chloride (entry 12), the
content of the desired diazo compound in the resulting re-
action mixture was rather low (according to 1H NMR analy-
sis), thus we failed to isolate the product in an appreciable
amount. Sterically hindered tert-butyl ketone (entry 19)
also gave a lower yield of the respective diazo compound 1s.
A total of 26 diazo ketosulfones were synthesized, 15 of
which have not been previously described.
O
O
'SAFE
cocktail'
O
O
Hal
O
Na2SO3
R2
O
O
S
R1SO2Cl
R1SO2Na
R1
S
R2
R1
NaHCO3
H2O/MeCN
r.t., overnight
KI (5 mol%)
r.t., overnight
R2
6 h
N2
(10 mmol)
1
Entry R1
R2
Product
Yield (%)a
84b
1
2
Ph
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
1a
1b
1c
1d
1e
1f
4-MeC6H4
4-FC6H4
80c (63)d
73c (59)d
81c
3
4
4-ClC6H4
5
4-MeOC6H4
4-O2NC6H4
62d
6
39b
7
4-(AcNH)C6H4
2-FC6H4
1g
1h
1i
64c
8
65b
9
2,5-(MeO)2C6H3
3,4-(MeO)2C6H3
2-naphthyl
2,4,6-Me3C6H2
Me
68b
10
11
12
13
14
15
16
1j
67d
1k
1l
74c (60)d
0
1m
1n
1o
1p
72c (51)d
52b
i-Pr
c-hexyl
82b
2-thienyl
*
83b
17
18
Me
Me
1q
1r
48c
N
To illustrate the suitability of the diazo compounds ob-
tained in this work for further transformations, some
Rh(II)-catalyzed intramolecular cyclizations based on Csp3–
H carbenoid insertion were carried out using diazo com-
pounds 1i and 1z as starting materials (Scheme 1). As the
result, cyclic -acylsulfones were obtained under mild con-
ditions in moderate (2) and high (3) yield.
Ac
Me
71b
*
19
20
21
22
23
24
25
26
4-MeC6H4
Me
t-Bu
1s
47b,e,f
57b
Ph
1t
c-hexyl
4-MeOC6H4
4-ClC6H4
4-FC6H4
4-O2NC6H4
1u
1v
1w
1x
1y
1z
54b
3-Cl-4-MeOC6H3
4-MeC6H4
4-MeC6H4
4-MeC6H4
Ph(CH2)3
81c,f (62)d
61b
O
O
O
O
O
O
Rh2(esp)2
(1 mol%)
MeO
S
MeO
S
Me
Me
N2
O
DCM, r.t.
78c
O
Me
2, 41%
1i
3,4-(MeO)2C6H3
76d
O
O
O
4-O2NC6H4
59b
O
O
O
Rh2(esp)2
(1 mol%)
S
S
*
N2
NO2
DCM, r.t.
Ph
3,a 88%
27
Et
1aa
46d
Ph
Me
NO2
1z
N
H
Scheme 1 Rh(II)-catalyzed cyclization of diazo ketosulfones 1i,z via in-
tramolecular Csp3–H insertion. a trans-Configuration was assigned on the
basis 3JH,H value (10.2 Hz), which is in accordance with literature data.3c,10c
a Isolated yields.
b Purified by flash column chromatography.
c No additional purification was performed (purity >94%).
d Yield after crystallization (purity >97%).
e Double amount of K2CO3 was used in diazo transfer step.
f Diazo transfer step was run for 20 hours.
Also, a two-step pyrazole synthesis involving three
acetyldiazo sulfones 1b,j,q was performed (Scheme 2). In
the first step, the starting diazo sulfones were de-acylated
on treatment with alumina to give the terminal diazo sul-
fones which, without isolation, were introduced into a
[3+2] cycloaddition step with acetylenic esters.
Formation of the sulfinate salt from a sulfonyl chloride
and its subsequent alkylation with a chloromethyl ketone
occurred under mild conditions and proceeded in high
yields. To facilitate the initial sulfonyl chloride reduction
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–H

C
D. Dar’in et al.
Paper
Synthesis
R2
Oily precipitates were extracted with DCM (3 × 25 mL), the combined
organic phases were dried (CaCl2), and evaporated to dryness. Addi-
tional purification was used, if needed, by flash column chromatogra-
phy on silica gel or by recrystallization (as indicated).
O
O
O
O
O
O
O
Al2O3
R2
CO2Me
DCM, r.t.
S
R1
S
CO2Me
R1
Me
N2
S
R1
N
N
H
DCM, r.t.
N2
1b,j,q
R2 = H, CO2Me
4a–c
1-Diazo-1-(phenylsulfonyl)propan-2-one (1a)6a
O
O
O
O
S
S
The title compound was synthesized according to GP1 from commer-
cially available benzenesulfonyl chloride and chloroacetone and puri-
fied by flash column chromatography on silica gel (n-hexane/EtOAc
4:1); yield: 1.88 g (84%); yellow solid; mp 70.2–72.6 °C.
1Н NMR (400 MHz, СDCl3):  = 8.07–7.92 (m, 2 H), 7.77–7.67 (m, 1 H),
7.62 (t, J = 7.7 Hz, 1 H), 2.32 (s, 3 H).
CO2Me
CO2Me
N
N
H
N
N
H
N
CO2Me
Me
O
O
Ac
4a, 59%
MeO
MeO
S
4c, 61%
CO2Me
N
N
H
4b, 70%
13С NMR (101 MHz, СDCl3):  = 185.7 (C=O), 142.1, 134.2, 129.6,
Scheme 2 Synthesis of pyrazoles 4a–c from diazo ketosulfones 1b,j,q
127.2, 85.9 (C=N2), 27.0.
1-Diazo-1-tosylpropan-2-one (1b)13a
In conclusion, we have described a one-pot, facile, and
flexible approach to -diazo--ketosulfones from readily
available sulfonyl chlorides and -haloketones. The method
is convenient and practically simple while displaying a
wide scope with respect to various substituents and deliv-
ers the target diazo compounds in good to high yields. The
latter were shown to be directly employable in downstream
diazo group transformations en route to several important
heterocyclic systems.
The title compound was synthesized according to GP1 from commer-
cially available p-TsCl and chloroacetone; yield: 1.91 g (80%). The
product was additionally purified by crystallization from MeOH;
yield: 1.50 g (63%); light yellow solid; mp 110.6–112.5 °C.
1Н NMR (400 MHz, СDCl3):  = 7.87 (d, J = 8.4 Hz, 2 H), 7.40 (d, J = 8.1
Hz, 2 H), 2.49 (s, 3 H), 2.31 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 185.9 (C=O), 145.5, 139.2, 130.1,
127.3, 86.1 (C=N2), 27.0, 21.7.
1-Diazo-1-[(4-fluorophenyl)sulfonyl]propan-2-one (1c)
The title compound was synthesized according to GP1 from commer-
cially available 4-fluorobenzenesulfonyl chloride and chloroacetone,
yield: 1.77 g (73%). The product was additionally purified by crystalli-
zation from MeOH; yield: 1.43 g (59%); light yellow solid; mp 110.3–
111.7 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 8.03 (dd, J = 8.9, 4.9 Hz, 2 H), 7.28 (t, J =
8.5 Hz, 2 H), 2.31 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 185.3 (C=O), 166.0 (d, J = 257.9 Hz),
138.0 (d, J = 3.1 Hz), 130.4 (d, J = 9.7 Hz), 116.8 (d, J = 22.8 Hz), 85.6
(C=N2), 27.0.
HRMS (ESI +ve): m/z calcd for C9H7FN2O3SNa [M + Na]+: 265.0054;
found: 265.0052.
All commercial reagents and solvents were used without further pu-
rification, unless otherwise noted. NMR spectroscopic data were re-
corded with a 400 MHz spectrometer (400.13 MHz for 1H and 100.61
MHz for 13C) in CDCl3 and in DMSO-d6 and were referenced to residual
solvent proton signals (H = 7.26 and H = 2.50, respectively) and sol-
vent carbon signals (C = 77.0 and C = 39.5, respectively). All chemical
shifts are reported in parts per million (ppm). Standard abbreviations
were used in the description of resonances. Coupling constants (J) are
quoted to the nearest 0.1 Hz. Mass spectra were recorded with a
HRMS-ESI-qTOF spectrometer (electrospray ionization mode). Melt-
ing points were determined with a melting point apparatus Stuart
SMP 50 in open capillary tubes. Analytical TLC was carried out on UV-
254 silica gel plates using appropriate eluents. Compounds were visu-
alized with short-wavelength UV light. Flash column chromatography
was performed using silica gel Merck grade 60 (0.040–0.063 mm)
230–400 mesh (isocratic or gradient elution as indicated).
1-Diazo-1-[(4-chlorophenyl)sulfonyl]propan-2-one (1d)16
The title compound was synthesized according to GP1 from commer-
cially available 4-chlorobenzenesulfonyl chloride and chloroacetone;
yield: 2.09 g (81%); light yellow solid; mp 113.2–115.0 °C.
1Н NMR (400 MHz, СDCl3):  = 7.95 (d, J = 8.8 Hz, 2 H), 7.58 (d, J = 8.8
CAUTION! The aqueous waste obtained in the SAFE diazotransfer reac-
tions should be disposed of according to the general guidelines for
aqueous solutions containing inorganic azides.15
Hz, 2 H), 2.31 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 185.2 (C=O), 141.0, 140.3, 129.8,
-Diazo--ketosulfones 1; General Procedure 1 (GP1)
128.9, 85.5 (C=N2), 27.0.
HRMS (ESI +ve): m/z calcd for C9H7ClN2O3SNa [M + Na]+: 280.9758;
found: 280.9772.
To a stirred solution of Na2SO3 (1.51 g, 12 mmol) and NaHCO3 (2.02 g,
2.4 mmol) in H2O (20 mL) was added a solution of the corresponding
sulfonyl chloride (10 mmol) in MeCN (5–10 mL) and the mixture was
stirred at r.t. for 12–16 h. To the resulting solution were added the
corresponding -haloketone (11 mmol) and KI (83 mg, 0.5 mmol) and
the mixture was stirred for 16–20 h. ‘SAFE’ cocktail [prepared by the
addition of 3-(chlorosulfonyl)benzoic acid (2.76 g, 12.5 mmol) to a
solution of NaN3 (1.0 g, 15 mmol) and K2CO3 (2.1 g, 15.0 mmol) in H2O
(20 mL) and stirring for 10 min] was added to the reaction mixture
and stirring was continued for 6 h. If a solid precipitate was formed,
the mixture was cooled to 5 °C, the product was filtered, washed with
H2O (30 mL) and cold H2O/EtOH mixture (1:1, 25 mL), and dried in air.
1-Diazo-1-[(4-methoxyphenyl)sulfonyl]propan-2-one (1e)
The title compound was synthesized according to GP1 from commer-
cially available 4-methoxybenzenesulfonyl chloride and chloroace-
tone and additionally purified by crystallization from MeOH; yield
1.57 g (62%); yellow solid; mp 78.8–80.5 °C.
1Н NMR (400 MHz, СDCl3):  = 7.92 (d, J = 9.0 Hz, 2 H), 7.04 (d, J = 9.0
Hz, 2 H), 3.91 (s, 3 H), 2.29 (s, 3 H).
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–H

D
D. Dar’in et al.
Paper
Synthesis
13С NMR (101 MHz, СDCl3):  = 185.9 (C=O), 164.1, 133.6, 129.7,
1-Diazo-1-[(3,4-dimethoxyphenyl)sulfonyl]propan-2-one (1j)
114.6, 86.1 (C=N2), 55.8, 27.0.
HRMS (ESI +ve): m/z calcd for C10H11N2O4S [M + H]+: 255.0434; found:
255.0434.
The title compound was synthesized according to GP1 from commer-
cially available 3,4-dimethoxybenzenesulfonyl chloride and chloroac-
etone and purified by crystallization from MeOH; yield: 1.90 g (67%);
yellow solid; mp 112.3–113.7 °C (dec.).
1-Diazo-1-[(4-nitrophenyl)sulfonyl]propan-2-one (1f)17
1Н NMR (400 MHz, СDCl3):  = 7.61 (dd, J = 8.5, 2.3 Hz, 1 H), 7.42 (d, J =
2.2 Hz, 1 H), 7.00 (d, J = 8.6 Hz, 1 H), 3.98 (s, 3 H), 3.97 (s, 3 H), 2.30 (s,
3 H).
13С NMR (101 MHz, СDCl3):  = 185.8 (C=O), 153.9, 149.4, 133.6,
121.7, 110.7, 109.6, 86.0 (C=N2), 56.4 (2 C), 27.0.
The title compound was synthesized according to GP1 from commer-
cially available 4-nitrobenzenesulfonyl chloride and chloroacetone
and purified by flash column chromatography on silica gel (DCM);
yield: 1.05 g (39%); yellow solid; mp 144.7–145.9 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 8.44 (d, J = 8.9 Hz, 2 H), 8.23 (d, J = 8.9
HRMS (ESI +ve): m/z calcd for C11H12N2O5S [M + H]+: 285.0540; found:
Hz, 2 H), 2.33 (s, 3 H).
285.0538.
13С NMR (101 MHz, СDCl3):  = 184.6 (C=O), 150.9, 146.8, 129.0,
124.7, 84.9 (C=N2), 27.0.
1-Diazo-1-(naphthalen-2-ylsulfonyl)propan-2-one (1k)
HRMS (ESI +ve): m/z calcd for C9H7N3O5SNa [M + Na]+: 291.9999;
found: 292.0011.
The title compound was synthesized according to GP1 from commer-
cially available naphthalene-2-sulfonyl chloride and chloroacetone;
yield: 2.03 g (74%). The product was additionally purified by crystalli-
zation from MeOH; yield: 1.64 g (60%); yellow solid; mp 101.1–
102.3 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 8.58 (d, J = 1.4 Hz, 1 H), 8.04 (d, J = 8.5
Hz, 2 H), 7.96 (d, J = 8.0 Hz, 1 H), 7.92 (dd, J = 8.7, 1.8 Hz, 1 H), 7.74–
7.66 (m, 2 H), 2.33 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 185.7 (C=O), 138.8, 135.4, 132.0,
130.1, 129.8, 129.6, 129.2, 128.1, 128.0, 121.7, 85.9 (C=N2), 27.1.
HRMS (ESI +ve): m/z calcd for C13H10N2O3SNa [M + Na]+: 297.0304;
found: 297.0302.
N-{4-[(1-Diazo-2-oxopropyl)sulfonyl]phenyl}acetamide (1g)
The title compound was synthesized according to GP1 from commer-
cially available 4-acetamidobenzenesulfonyl chloride and chloroace-
tone, yield: 1.80 g (64%); light yellow solid; mp 134.8–136.4 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 7.91 (d, J = 8.9 Hz, 2 H), 7.86 (br s, 1 H),
7.74 (d, J = 8.9 Hz, 2 H), 2.30 (s, 3 H), 2.24 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 185.8 (C=O), 168.9 (CONH), 143.4,
136.3, 128.8, 119.5, 85.8 (C=N2), 27.0, 24.7.
HRMS (ESI +ve): m/z calcd for C11H11N3O4SNa [M + Na]+: 304.0362;
found: 304.0362.
1-(Methylsulfonyl)propan-2-one (1m)5c
The title compound was synthesized according to GP1 from commer-
cially available mesyl chloride and chloroacetone; yield: 1.17 g (72%).
The product was additionally purified by crystallization from MeOH;
yield: 0.83 g (51%); pale yellow solid; mp 43.2–44.8 °C.
1H NMR (400 MHz, CDCl3):  = 3.31 (s, 3 H), 2.41 (s, 3 H).
13C NMR (101 MHz, CDCl3):  = 185.8 (C=O), 84.1 (C=N2), 45.6, 26.9.
1-Diazo-1-[(2-fluorophenyl)sulfonyl]propan-2-one (1h)
The title compound was synthesized according to GP1 from commer-
cially available 2-fluorobenzenesulfonyl chloride and chloroacetone
and purified by flash column chromatography on silica gel (n-hexane/
EtOAc 4:1); yield: 1.57 g (65%); tan solid; mp 80.8–82.4 °C.
1Н NMR (400 MHz, СDCl3):  = 8.04 (ddd, J = 7.9, 7.2, 1.8 Hz, 1 H), 7.70
(dddd, J = 8.3, 7.5, 5.1, 1.8 Hz, 1 H), 7.39 (td, J = 7.7, 1.0 Hz, 1 H), 7.30
(ddd, J = 10.2, 8.3, 1.0 Hz, 1 H), 2.26 (s, 3 H).
1-Diazo-1-(isopropylsulfonyl)propan-2-one (1n)
13С NMR (101 MHz, СDCl3):  = 185.7 (C=O), 159.1 (d, J = 255.6 Hz),
136.5 (d, J = 8.8 Hz), 129.9 (s), 129.5 (d, J = 13.3 Hz), 124.9 (d, J = 3.5
Hz), 117.6 (d, J = 20.8 Hz), 86.6 (C=N2), 27.0.
HRMS (ESI +ve): m/z calcd for C9H7FN2O3SNa [M + Na]+: 265.0054;
found: 265.0057.
The title compound was synthesized according to GP1 from commer-
cially available propane-2-sulfonyl chloride and chloroacetone and
purified by flash column chromatography on silica gel (n-hexane/
EtOAc 6:1 to 3:1), yield: 0.99 g (52%); light yellow solid; mp 49.0–
52.2 °C.
1Н NMR (400 MHz, СDCl3):  = 3.51 (hept, J = 6.9 Hz, 1 H), 2.40 (s, 3 H),
1.45 (d, J = 6.9 Hz, 6 H).
13С NMR (101 MHz, СDCl3):  = 186.4 (C=O), 80.8 (C=N2), 58.4, 27.0,
15.6.
HRMS (ESI +ve): m/z calcd for C6H10N2O3SNa [M + Na]+: 213.0304;
found: 213.0295.
1-Diazo-1-[(2,5-dimethoxyphenyl)sulfonyl]propan-2-one (1i)
The title compound was synthesized according to GP1 from commer-
cially available 2,5-dimethoxybenzenesulfonyl chloride and chloro-
acetone and purified by flash column chromatography on silica gel
(n-hexane/EtOAc 4:1 to 2:1); yield: 1.93 g (68%); yellow solid; mp
105.9–107.1 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 7.54 (d, J = 3.1 Hz, 1 H), 7.16 (dd, J = 9.1,
3.1 Hz, 1 H), 7.03 (d, J = 9.1 Hz, 1 H), 3.96 (s, 3 H), 3.85 (s, 3 H), 2.22 (s,
3 H).
13С NMR (101 MHz, СDCl3):  = 186.6 (C=O), 153.2, 150.9, 129.7,
121.8, 114.0, 113.9, 86.8 (C=N2), 56.8, 56.1, 27.0.
1-(Cyclohexylsulfonyl)-1-diazopropan-2-one (1o)
The title compound was synthesized according to GP1 from commer-
cially available cyclohexanesulfonyl chloride and chloroacetone and
purified by flash column chromatography on silica gel (n-hexane/
EtOAc 5:1); yield: 1.89 g (82%); yellow solid; mp 40.7–42.7 °C.
1Н NMR (400 MHz, СDCl3):  = 3.23 (tt, J = 12.1, 3.5 Hz, 1 H), 2.40 (s, 3
H), 2.24–2.16 (m, 2 H), 2.02–1.93 (m, 2 H), 1.80–1.73 (m, 1 H), 1.65–
1.52 (m, 2 H), 1.40–1.18 (m, 3 H).
HRMS (ESI +ve): m/z calcd for C12H12N2O5SNa [M + Na]+: 307.0359;
found: 307.0360.
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Synthesis
13С NMR (101 MHz, СDCl3):  = 186.6 (C=O), 80.9 (C=N2), 66.2, 27.1,
2-Diazo-2-(methylsulfonyl)-1-phenylethanone (1t)4a
25.5, 25.0, 24.9.
The title compound was synthesized according to GP1 from commer-
cially available mesyl chloride and -bromoacetophenone and puri-
fied by flash column chromatography on silica gel (n-hexane/EtOAc
8:1 to 4:1); yield: 1.28 g (57%); pale yellow solid; mp 121.1–121.9 °C
(dec.).
1Н NMR (400 MHz, СDCl3):  = 7.74–7.66 (m, 2 H), 7.66–7.60 (m, 1 H),
7.53 (t, J = 7.6 Hz, 2 H), 3.44 (s, 3 H).
HRMS (ESI +ve): m/z calcd for C9H15N2O3S [M + H]+: 231.0798; found:
231.0794.
1-Diazo-1-(thiophen-2-ylsulfonyl)propan-2-one (1p)
The title compound was synthesized according to GP1 from commer-
cially available thiophene-2-sulfonyl chloride and chloroacetone and
purified by flash column chromatography on silica gel (DCM); yield:
1.91 g (83%); yellow solid; mp 45.5–46.8 °C.
13С NMR (101 MHz, СDCl3):  = 183.3 (C=O), 135.6, 133.4, 129.1,
127.4, 82.0 (C=N2), 45.0.
1Н NMR (400 MHz, СDCl3):  = 7.81 (dd, J = 3.8, 1.3 Hz, 1 H), 7.76 (dd, J
= 5.0, 1.4 Hz, 1 H), 7.18 (dd, J = 5.0, 3.8 Hz, 1 H), 2.39 (s, 3 H).
HRMS (ESI +ve): m/z calcd for C9H9N2O3SNa [M + Na]+: 247.0148;
found: 247.0152.
13С NMR (101 MHz, СDCl3):  = 185.7 (C=O), 143.1, 134.3, 133.9,
127.9, 87.1 (C=N2), 27.1.
2-(Cyclohexylsulfonyl)-2-diazo-1-(4-methoxyphenyl)ethanone (1u)
HRMS (ESI +ve): m/z calcd for C7H6N2O3S2 [M + H]+: 230.9893; found:
230.9897.
The title compound was synthesized according to GP1 from commer-
cially available cyclohexanesulfonyl chloride and -chloro-p-meth-
oxyacetophenone. The isolated product was purified by flash column
chromatography on silica gel (n-hexane/EtOAc 8:1 to 3:1); yield: 1.74
g (54%); light yellow solid; mp 64.2–65.6 °C.
1Н NMR (400 MHz, СDCl3):  = 7.71 (d, J = 8.9 Hz, 1 H), 6.99 (d, J = 8.9
Hz, 1 H), 3.90 (s, 3 H), 3.68 (tt, J = 12.2, 3.5 Hz, 1 H), 2.22–2.15 (m, 2
H), 1.99–1.91 (m, 2 H), 1.79–1.72 (m, 1 H), 1.65 (qd, J = 12.4, 3.5 Hz, 2
H), 1.42–1.18 (m, 3 H).
13С NMR (101 MHz, СDCl3):  = 182.1 (C=O), 163.7, 129.9, 128.3,
114.3, 77.6 (C=N2), 64.7, 55.6, 25.13, 25.07, 25.02.
HRMS (ESI +ve): m/z calcd for C15H18N2O4SNa [M + Na]+: 345.0879;
found: 345.0881.
1-[(1-Acetylindolin-5-yl)sulfonyl]-1-diazopropan-2-one (1q)
The title compound was synthesized according to GP1 from commer-
cially available 1-acetylindoline-5-sulfonyl chloride and chloroace-
tone and purified by crystallization from MeOH; yield: 1.47 g (48%);
yellow solid; mp 152.6–153.2 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 8.18 (br d, J = 8.3 Hz, 1 H), 7.86–7.78
(m, 2 H), 4.18 (t, J = 8.6 Hz, 2 H), 3.22 (t, J = 8.6 Hz, 2 H), 2.23 (s, 3 H),
2.21 (br s, 3 H).
13С NMR (101 MHz, СDCl3):  = 186.0 (C=O), 170.3, 148.2, 135.3,
133.9, 128.6, 124.5, 115.6, 84.6 (C=N2), 49.3, 27.4, 24.6.
HRMS (ESI +ve): m/z calcd for C13H13N3O4SNa [M + Na]+: 330.0519;
found: 330.0527.
2-[(3-Chloro-4-methoxyphenyl)sulfonyl]-1-(4-chlorophenyl)-2-
diazoethanone (1v)
The title compound was synthesized according to GP1 from commer-
cially available 3-chloro-4-methoxybenzenesulfonyl chloride and
-bromo-p-chloroacetophenone. In diazo transfer step, the mixture
was stirred for 15 h; yield: 3.12 g (81%). The product was additionally
purified by crystallization from MeOH; yield: 2.39 (62%); yellow
solid; mp 117.3–118.2 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 8.03–7.93 (m, 2 H), 7.54 (d, J = 8.6 Hz, 2
H), 7.45 (d, J = 8.6 Hz, 2 H), 7.06 (d, J = 9.4 Hz, 1 H), 4.01 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 181.5 (C=O), 159.7, 139.6, 134.0,
1-Diazo-1-[(4-methylbenzyl)sulfonyl]propan-2-one (1r)
The title compound was synthesized according to GP1 from commer-
cially available p-TsCl and chloroacetone and purified by flash column
chromatography on silica gel (n-hexane/EtOAc 8:1 to 4:1); yield: 1.79
g (71%); white solid; mp 92.8–94.0 °C.
1Н NMR (400 MHz, СDCl3):  = 7.27–7.18 (m, 4 H), 4.49 (s, 2 H), 2.39
(s, 3 H), 2.13 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 186.4 (C=O), 139.9, 130.7, 130.9,
124.3, 81.8 (C=N2), 63.3, 26.5, 21.2.
HRMS (ESI +ve): m/z calcd for C11H12N2O3SNa [M + Na]+: 275.0461;
found: 275.0455.
133.4, 130.0, 129.3, 129.2, 128.9, 123.4, 111.5, 83.8 (C=N2), 56.7.
HRMS (ESI +ve): m/z calcd for C15H10Cl2N2O4SNa [M + Na]+: 406.9631;
found: 406.9631.
1-Diazo-3,3-dimethyl-1-tosylbutan-2-one (1s)
2-Diazo-1-(4-fluorophenyl)-2-tosylethanone (1w)4a
The title compound was synthesized according to GP1 from commer-
cially available p-TsCl and -bromopinacolone. In diazo transfer step,
double amount of K2CO3 was used and the mixture was stirred for 15
h. The isolated product was purified by flash column chromatography
on silica gel (n-hexane/EtOAc 9:1 to 5:1); yield: 1.32 g (47%); yellow
solid; mp 118.2–119.2 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 7.94 (d, J = 8.4 Hz, 2 H), 7.35 (d, J = 8.3
Hz, 2 H), 2.46 (s, 3 H), 1.19 (s, 9 H).
13С NMR (101 MHz, СDCl3):  = 192.9 (C=O), 145.1, 138.7, 129.6,
128.3, 79.9 (C=N2), 45.1, 26.1, 21.7.
The title compound was synthesized according to GP1 from commer-
cially available p-TsCl and -chloro-p-fluoroacetophenone and puri-
fied by flash column chromatography on silica gel (n-hexane/EtOAc
8:1 to 4:1); yield: 1.94 g (61%); pale yellow solid; mp 94.7–96.2 °C.
1Н NMR (400 MHz, СDCl3):  = 7.92 (d, J = 8.4 Hz, 2 H), 7.62 (dd, J = 8.9,
5.2 Hz, 2 H), 7.36 (d, J = 8.0 Hz, 2 H), 7.14 (t, J = 8.6 Hz, 2 H), 2.47 (s, 3
H).
13С NMR (101 MHz, СDCl3):  = 181.4 (C=O), 165.4 (d, J = 255.3 Hz),
164.1, 145.5, 138.6, 132.1 (d, J = 3.2 Hz), 130.2 (d, J = 9.3 Hz), 129.8,
128.1, 116.1 (d, J = 22.2 Hz), 83.7 (C=N2), 21.7.
HRMS (ESI +ve): m/z calcd for C15H12FN2O3S [M + H]+: 319.0547;
found: 319.0548.
HRMS (ESI +ve): m/z calcd for C12H17N2O3S [M + H]+: 281.0954; found:
281.0963.
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–H

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D. Dar’in et al.
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Synthesis
2-Diazo-1-(4-nitrophenyl)-2-tosylethan-1-one (1x)4b
Compounds 2 and 3; General Procedure 2 (GP2)
The title compound was synthesized according to GP1 from commer-
cially available p-TsCl and -bromo-p-nitroacetophenone; yield:
2.69 g (78%); pale yellow solid; mp 147.1–147.9 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 8.30 (d, J = 8.8 Hz, 2 H), 7.85 (d, J = 8.4
Hz, 2 H), 7.72 (d, J = 8.8 Hz, 2 H), 7.37 (d, J = 8.1 Hz, 2 H), 2.48 (s, 3 H).
To a solution of diazo ketosulfone 1i or 1z (0.5 mmol) in anhyd DCM
(3 mL) was added a solution of Rh2(esp)2 (3.8 mg, 0.005 mmol, 1
mol%) in DCM (1 mL) under stirring at r.t. Gas evolution was observed.
The mixture was stirred for 1.5 h, the solvent was removed in vacuo
and the residue was subjected to flash column chromatography on
silica gel, eluting with n-hexane/EtOAc (from 9:1 to 1:1).
13С NMR (101 MHz, СDCl3):  = 181.5 (C=O), 150.0, 145.9, 140.9,
138.4, 130.0, 128.7, 128.0, 124.0, 85.3 (C=N2), 21.7.
HRMS (ESI +ve): m/z calcd for C15H11N3O5SNa [M + Na]+: 368.0312;
found: 368.0321.
1-(6-Methoxy-4,4-dioxido-2,3-dihydrobenzo[b][1,4]oxathiin-3-
yl)ethanone (2)
The title compound was synthesized according to GP2 from diazo
ketosulfone 1i; yield: 52 mg (41%); tan solid; mp 111.3–111.9 °C.
2-Diazo-1-(3,4-dimethoxyphenyl)-2-tosylethan-1-one (1y)
1Н NMR (400 MHz, СDCl3):  = 7.23 (d, J = 3.0 Hz, 1 H), 7.08 (dd, J = 9.2,
3.0 Hz, 1 H), 6.95 (d, J = 9.2 Hz, 1 H), 4.86 (dd, J = 13.3, 3.2 Hz, 1 H),
4.77 (dd, J = 13.3, 10.3 Hz, 1 H), 4.49 (dd, J = 10.3, 3.2 Hz, 1 H), 3.84 (s,
3 H), 2.60 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 194.7, 154.5, 147.9, 125.7, 123.4,
120.1, 105.4, 68.2, 66.3, 56.0, 32.0.
The title compound was synthesized according to GP1 from commer-
cially available p-TsCl and 2-bromo-3′,4′-(dimethoxy)acetophenone
and purified by crystallization from MeOH/MeCN (2:1); yield: 2.74 g
(76%), yellow solid; mp 133.0–133.9 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 7.96 (d, J = 8.4 Hz, 2 H), 7.36 (d, J = 8.0
Hz, 2 H), 7.26 (dd, J = 8.4, 2.1 Hz, 1 H), 7.15 (d, J = 2.1 Hz, 1 H), 6.87 (d,
J = 8.4 Hz, 1 H), 3.94 (s, 3 H), 3.88 (s, 3 H), 2.46 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 181.3 (C=O), 153.3, 149.3, 145.3,
138.8, 129.7, 128.5, 128.2, 121.5, 110.6, 110.2, 82.7 (C=N2), 56.1, 56.0,
21.7.
HRMS (ESI +ve): m/z calcd for C11H13O5S [M + H]+: 257.0478; found:
257.0481.
[(2R/S,3S/R)-1,1-Dioxido-3-phenyltetrahydrothiophen-2-yl](4-
nitrophenyl)methanone (3)
HRMS (ESI +ve): m/z calcd for C17H15N2O5SNa [M + Na]+: 383.0672;
found: 383.0682.
The title compound was synthesized according to GP2 from diazo
ketosulfone 1z; yield: 152 mg (88%); pale yellow solid; mp 149.4–
151.1 °C.
1Н NMR (400 MHz, СDCl3):  = 8.35 (d, J = 9.0 Hz, 2 H), 8.22 (d, J = 9.0
Hz, 2 H), 7.41–7.28 (m, 5 H), 4.97 (d, J = 10.2 Hz, 1 H), 4.37 (ddd, J =
12.4, 10.2, 5.9 Hz, 1 H), 3.59 (ddd, J = 12.9, 6.7, 1.5 Hz, 1 H), 3.33 (td, J =
13.0, 6.9 Hz, 1 H), 2.70–2.62 (m, 1 H), 2.60–2.49 (m, 1 H).
13С NMR (101 MHz, СDCl3):  = 188.1, 150.9, 140.5, 138.8, 130.1,
129.3, 128.2, 127.2, 124.1, 73.2, 54.0, 44.5, 28.3.
HRMS (ESI +ve): m/z calcd for C17H16NO5S [M + H]+: 346.0744; found:
346.0748.
2-Diazo-1-(4-nitrophenyl)-2-[(3-phenylpropyl)sulfonyl]ethanone
(1z)
The title compound was synthesized according to GP1 from commer-
cially available 3-phenylpropane-1-sulfonyl chloride and -bromo-p-
nitroacetophenone. The isolated product was purified by flash col-
umn chromatography on silica gel (n-hexane/EtOAc 8:1 to 3:1); yield:
2.20 g (59%); tan solid; mp 116.3–117.5 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 8.35 (d, J = 8.9 Hz, 2 H), 7.81 (d, J = 8.9
Hz, 2 H), 7.39–7.30 (m, 2 H), 7.28–7.23 (m, 1 H), 7.21–7.18 (m, 2 H),
3.51–3.45 (m, 2 H), 2.82 (t, J = 7.4 Hz, 2 H), 2.27–2.16 (m, 2 H).
Pyrazoles 4; General Procedure 3 (GP3)
13С NMR (101 MHz, СDCl3):  = 181.7 (C=O), 150.2, 140.5, 139.7,
To a solution of diazo ketosulfone 1b, 1j, or 1q (1.0 mmol) in anhyd
DCM (15 mL) was added Al2O3 (10 g) and the suspension was stirred
at r.t. in the dark for 12–15 h (controlled by TLC). Al2O3 was filtered off
and washed with DCM (2 × 8 mL). The filtrate was evaporated in vac-
uo at 30 °С to reduce the volume by three quarters. To the resulting
yellow solution was added methyl propiolate (267 L, 3.0 mmol) or
dimethyl acetylenedicarboxylate (245 L, 2.0 mmol) and the mixture
was kept in the dark at r.t. for 18–20 h. The discolored reaction mix-
ture was concentrated under reduced pressure, the residual solid was
washed with hexane, and dried in vacuo to afford the desired pyra-
zole.
128.8, 128.6, 128.4, 126.7, 124.3, 81.9 (C=N2), 56.4, 33.8, 24.3.
HRMS (ESI +ve): m/z calcd for C17H15N3O5SNa [M + Na]+: 396.0625;
found: 396.0637.
2-Diazo-2-(ethylsulfonyl)-1-(2-methyl-1H-indol-3-yl)ethanone
(1aa)
The title compound was synthesized according to GP1 from commer-
cially available ethanesulfonyl chloride and 2-chloro-1-(2-methyl-
1H-indol-3-yl)ethanone. The stirring in alkylation step was continued
for 3 days. The isolated product was additionally purified by crystalli-
zation from MeCN; yield: 1.34 g (46%); light yellow solid; mp 145.0–
147.2 °C (dec.).
1Н NMR (400 MHz, СDCl3):  = 12.14 (s, 1 H), 7.54 (d, J = 7.2 Hz, 1 H),
7.44 (dd, J = 6.8, 1.7 Hz, 1 H), 7.24–7.18 (m, 2 H), 3.69 (q, J = 7.4 Hz, 2
H), 2.59 (s, 3 H), 1.34 (t, J = 7.4 Hz, 3 H).
Methyl 3(5)-Tosyl-1H-pyrazole-5(3)-carboxylate (4a)
The title compound was synthesized according to GP3 from diazo
ketosulfone 1b and methyl propiolate. The product was additionally
purified by flash column chromatography (DCM/acetone 95:5 to
85:15); yield: 165 mg (59%); white solid; mp 167.7–169.8 °C.
13С NMR (101 MHz, СDCl3):  = 177.3 (C=O), 144.2, 135.1, 125.1,
1Н NMR (400 MHz, СDCl3):  = 11.64 (br s, 1 H), 7.95 (d, J = 8.3 Hz, 2
H), 7.35 (d, J = 8.4 Hz, 2 H), 7.32 (s, 1 H), 3.96 (s, 3 H), 2.44 (s, 3 H).
122.7, 122.1, 119.1, 112.3, 111.5, 79.5 (C=N2), 51.4, 13.6, 7.4.
HRMS (ESI +ve): m/z calcd for C13H13N3O3SNa [M + Na]+: 314.0570;
13С NMR (101 MHz, СDCl3):  = 158.9, 145.0, 137.2, 130.0, 128.2,
found: 314.0571.
109.7, 52.9, 21.6.*
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–H

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D. Dar’in et al.
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Synthesis
HRMS (ESI +ve): m/z calcd for C12H12N2O4SNa [M + Na]+: 303.0410;
found: 303.0412.
Breinbauer, R. Tetrahedron 2017, 73, 6815. (g) Zhao, X.; Zhang,
Y.; Wang, J. Chem. Commun. 2012, 48, 10162. (h) Davies, H. M.
L.; Morton, D. Chem. Soc. Rev. 2011, 40, 1857.
(2) Liu, W.; Fang, L.; Wan, Y.; Zhang, J.; Deng, G.; Wang, J. Tetrahe-
dron 2019, 75, 855.
Dimethyl 3(5)-[(3,4-Dimethoxyphenyl)sulfonyl]-1H-pyrazole-4,5-
dicarboxylate (4b)
(3) (a) Chen, X.; Hu, X.; Bai, S.; Deng, Y.; Jiang, H.; Zeng, W. Org. Lett.
2016, 18, 192. (b) Brouder, T. A.; Slattery, C. N.; Ford, A.; Rao
Khandavilli, U. B.; Skořepova, E.; Eccles, K. S.; Lusi, M.;
Lawrence, C. E.; Maguire, A. R. J. Org. Chem. 2019, 84, 7543.
(c) Cui, X.; Xu, X.; Jin, L.-M.; Wojtasa, L.; Zhang, X. P. Chem. Sci.
2015, 6, 1219.
(4) (a) Chan, C.-K.; Wang, H.-S.; Hsu, R.-T.; Chang, M.-Y. Synthesis
2017, 49, 2045. (b) Chan, C.-K.; Wang, H.-S.; Hsu, R.-T.; Chang,
M.-Y. Synthesis 2017, 49, 2423.
(5) (a) Huang, Z.; Wang, C.; Tokunaga, E.; Sumii, Y.; Shibata, N. Org.
Lett. 2015, 17, 5610. (b) Huang, Z.; Jia, S.; Wang, C.; Tokunaga, E.;
Sumii, Y.; Shibata, N. J. Fluorine Chem. 2017, 198, 61.
(c) Safrygin, A.; Dar’in, D.; Kantin, G.; Krasavin, M. Eur. J. Org.
Chem. 2019, 4721.
The title compound was synthesized according to GP3 from diazo
ketosulfone 1j and dimethyl acetylenedicarboxylate; yield: 269 mg
(70%); white solid; mp 183.7–186.1 °C (CHCl3).
1Н NMR (400 MHz, DMSO-d6):  = 15.11 (br s, 1 H), 7.57 (dd, J = 8.5,
2.2 Hz, 1 H), 7.45 (d, J = 2.1 Hz, 1 H), 7.21 (d, J = 8.6 Hz, 1 H), 3.89 (s, 3
H), 3.88 (s, 3 H), 3.88 (s, 3 H), 3.86 (s, 3 H). 13С NMR (101 MHz, СDCl3):
 = 162.4, 154.4, 149.7, 131.8, 122.6, 117.4, 112.6, 111.3, 56.7, 56.6,
53.19, 53.18.*
HRMS (ESI +ve): m/z calcd for C15H16N2O8SNa [M + Na]+: 407.0520;
found: 407.0523.
Methyl 3(5)-[(1-Acetylindolin-5-yl)sulfonyl]-1H-pyrazole-5(3)-
carboxylate (4c)
(6) (a) Pal, A.; Koduri, N. D.; Wang, Z.; Lopez Quiroz, E.; Chong, A.;
Vuong, M.; Rajagopal, N.; Nguyen, M.; Roberts, K. P.; Hussaini, S.
R. Tetrahedron Lett. 2017, 58, 586. (b) Kong, L.; Han, X.; Li, X.
Chem. Commun. 2019, 55, 7339. (c) Nagode, S. B.; Kant, R.;
Rastogi, N. Org. Lett. 2019, 21, 6249. (d) Pang, W.; Zhu, S.; Xing,
C.; Luo, N.; Jianga, H.; Zhu, S. J. Fluorine Chem. 2008, 129, 343.
(e) Huang, J.; Hu, X.; Chen, F.; Gui, J.; Zeng, W. Org. Biomol.
Chem. 2019, 17, 7042. (f) Adly, F. G.; Marichev, K. O.; Jensen, J.
A.; Arman, H.; Doyle, M. P. Org. Lett. 2019, 21, 40.
The title compound was synthesized according to GP3 from diazo
ketosulfone 1q and dimethyl acetylenedicarboxylate; yield: 213 mg
(61%); white solid; mp 246.5–247.3 °C (MeOH).
1Н NMR (400 MHz, DMSO-d6):  = 14.78 (br s, 1 H), 8.14 (d, J = 7.8 Hz,
1 H), 7.81–7.75 (m, 2 H), 7.22 (s, 1 H), 4.16 (t, J = 8.6 Hz, 2 H), 3.88 (s, 3
H), 3.21 (t, J = 8.5 Hz, 2 H), 2.21 (s, 3 H).
13С NMR (101 MHz, СDCl3):  = 169.9, 148.0, 134.2, 128.4, 124.5,
115.9, 109.5, 52.7, 49.3, 27.4, 24.3.*
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HRMS (ESI +ve): m/z calcd for C15H15N3O5SNa [M + Na]+: 372.0625;
found: 372.0626.
* Signals of 3-C and 5-C carbon atoms of pyrazole ring (and carbonyl
atom of 5-CO2Me for 4a and 4c) do not appear in 13C NMR spectra,
due to low intensity because of NH-tautomerism.
Funding Information
This work was supported by the Russian Foundation for Basic Re-
search (project grant 19-03-00775).
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Acknowledgment
Research Centre for Magnetic Resonance and the Center for Chemical
Analysis and Materials Research of Saint Petersburg State University
Research Park are thanked for obtaining the analytical data.
Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/s-0040-1707525.
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Chem. Soc. 2008, 130, 5042. (b) Hodgson, D. M.; Glen, R.;
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C. J.; Elcoate, C. J.; Lawrence, C. E.; Maguire, A. R. J. Am. Chem.
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