Cu(OAc)2 promoted Chan-Evans-Lam C-N cross coupling reactions on the N- and N′-nitrogen atoms of sulfonimidamides with aryl boronic acids

Article abstract of DOI:10.1016/j.tet.2014.06.122

We report a highly efficient and mild protocol for Chan-Evans-Lam C-N cross coupling of sulfonimidamides and aryl boronic acids using Cu(OAc)₂ as mediator, triethylamine (TEA) as base and acetonitrile as solvent. The reaction proceeds at room temperature and provides high to excellent yields for a variety of boronic acids, allowing N-arylation of both N-protected (N-amine nitrogen) and N-deprotected (N'-imine nitrogen) sulfonimidamides.

Full text of DOI:10.1016/j.tet.2014.06.122

Tetrahedron xxx (2014) 1e6
Contents lists available at ScienceDirect
Tetrahedron
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Cu(OAc)2 promoted ChaneEvanseLam CeN cross coupling reactions
on the N- and N0-nitrogen atoms of sulfonimidamides with aryl
boronic acids
Ganesh C. Nandi a, Sudhakar R. Kota a, Thavendran Govender a, Hendrik G. Kruger a,
,b,
Per I. Arvidsson a
*
a Catalysis and Peptide Research Unit, University of KwaZulu-Natal, Durban, South Africa
b Science for Life Laboratory, Drug Discovery & Development Platform & Division of Translational Medicine and Chemical Biology, Department of
Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
a r t i c l e i n f o
a b s t r a c t
Article history:
We report a highly efficient and mild protocol for ChaneEvanseLam CeN cross coupling of sulfonimi-
damides and aryl boronic acids using Cu(OAc)2 as mediator, triethylamine (TEA) as base and acetonitrile
as solvent. The reaction proceeds at room temperature and provides high to excellent yields for a variety
of boronic acids, allowing N-arylation of both N-protected (N-amine nitrogen) and N-deprotected (N0-
imine nitrogen) sulfonimidamides.
Received 5 April 2014
Received in revised form 13 June 2014
Accepted 30 June 2014
Available online xxx
Ó 2014 Published by Elsevier Ltd.
Keywords:
Sulfonimidamides
Aryl boronic acid
CeN cross coupling reactions
Cu(OAc)2
Triethylamine
1. Introduction
has also been utilized as analogues of oncolytic sulfonylureas by
Lilly Research Laboratories7 and Schloss evaluated sulfonimida-
Although Levchenko et al.1 reported on the aza analogues of
sulfonamides, i.e., sulfonimidamides, already in 1962, this class of
compounds has received very little attention in the literature.2 This
is surprising given the interesting properties sulfonimidamides
might entail; replacement of one of the oxygen atoms in the sul-
fonamide functional group with a nitrogen atom generates a ster-
eogenic sulfur centre and brings about the possibility of
introducing additional structural diversity around the widely used
sulfonamide functional group.
Although sparse, some research during the past decades has
focused on the applications of sulfonimidamides in organic syn-
thesis, as well as their biological activity. The research groups of
Malacria and Dodd independently explored sulfonimidamides as
reagents in organic synthesis via iminations of sulfides, aziridina-
tion of olefins, and CeH aminations of hydro-carbons.3 Bolm et al.
used sulfonimidamides as organocatalysts,4 and as chiral ligands in
asymmetric reactions,5 most recently in the iridium-catalyzed
asymmetric hydrogenation of cyclic enamides.6 Sulfonimidamides
mides as transition state analogues for aspartic acid and metallo-
proteases.8 Our group recently reported the first in vivo application
of a sulfonimidamide as a potential bioisostere of the, in drug leads,
widespread sulfonamide.9
In view of their increasing medicinal and synthetic applicability,
it is important to develop more general, efficient, and mild routes to
synthesize N0- and N-functionalized sulfonimidamides. Previously,
the Bolm research group10 reported the stoichiometric copper
mediated arylation of N0-protected sulfonimidamides with aryl
halides. Independently, Malacriand co-workers11 described the
copper catalyzed arylation of N0-protected sulfonimidamides with
aryl iodides under microwave heating. Both of these reports are
restricted to functionalization of the primary amine functionality in
N0-protected sulfonimidamides and they required high tempera-
tures and provided moderate to good yields. Correspondingly, we
described the arylation of the imine nitrogen in N0-deprotected
sulfonimidamides using a Pd catalyst under high temperature mi-
crowave conditions.12 During the course of our study on
ChaneEvanseLam reaction, Battula et al.12b reported the copper
catalyzed N0-arylation of sulfonimidamides using aryl boronic acid
at room temperature; the reported method produces high yield of
product although with longer reaction times.
* Corresponding author. E-mail addresses: Per.Arvidsson@ki.se, Per.Arvidsson@
scilifelab.se (P.I. Arvidsson).
http://dx.doi.org/10.1016/j.tet.2014.06.122
0040-4020/Ó 2014 Published by Elsevier Ltd.
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G.C. Nandi et al. / Tetrahedron xxx (2014) 1e6
Table 1
As a part of our ongoing medicinal and synthetic research pro-
Optimization of ChaneEvanseLam N-arylation of the N0-imine nitrogen of sulfoni-
midamide 1b with 4-chlorophenyl boronic acid 3a
gram on sulfonimidamides,13 we were interested to find a general
route to sulfonimidamide derivatives that would hopefully work
under mild conditions and allow functionalization of both the
primary nitrogen (N-) in protected sulfonimidamides and the imine
nitrogen (N0-) of unprotected sulfonimidamides. Herein we report
the so-called ChaneEvanseLam cross coupling between sulfoni-
midamides and aryl boronic acids at room temperature using
Cu(OAc)2 as mediator, TEA as base, and acetonitrile as solvent.
2. Results and discussion
The original ChaneEvanseLam CeN/O cross coupling reaction,
described in 1998 in three consecutive publications by Chan,14
Lam15 and Evans,16 utilized boronic acids as electrophilic agents
and amines/alcohols as nucleophilic agents. Since then, several
applications have been developed, rendering this arylation protocol
as a useful tool for various C(sp2)-N bond formations in organic
synthesis.17
Entry
Catalyst (mol %)
Solvent
Base (equiv)
Yielda (%)
Time (h)
1.
2.
3.
4.
5.
6.
7.
8.
Cu(OAc)2 (10)
Cu(OAc)2 (10)
CuBr (10)
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
THF
DMF
DCM
Dioxane
EtOH
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
d
20b
28
24
5
d
d
16c
Trace
42b
70
24
24
24
24
24
24
12
24
24
48
14
24
24
14
24
10
5
CuI (10)
d
Cu(OAc)2 (100)
Cu(OAc)2 (200)
Cu(OAc)2 (150)
Cu(OAc)2 (150)
Cu(OAc)2 (150)
Cu(OAc)2 (150)
Cu(OAc)2 (150)
Cu(OAc)2 (150)
Cu(OAc)2 (150)
Cu(OAc)2 (50)
Cu(OAc)2 (100)
Cu(OAc)2 (200)
Cu(OTf)2 (100)
Cu(OAc)2 (50)
Cu(OAc)2 (100)
Cu(OAc)2 (150)
Cu(OAc)2 (100)
Cu(OAc)2 (100)
Cu(OAc)2 (100)
d
d
d
72
We synthesized tertiary N0-deprotected sulfonimidamides 1aec
and the protected primary sulfonimidamides 2a and 2b following
a similar approach as that described by Bolm’s group18 and outlined
in detail in our previous report (Scheme 1).12
d
78
9.
d
43c
81
10.
11.
12
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
d
d
84
d
62b
92
d
d
73b
81
d
d
91
d
13d
82
TEA (1)
TEA (1)
TEA (1)
TEA (1.5)
TEA (0.5)
Pyridine (1.0)
92e
90
5
5
8
7
91
88
86
a
Isolated yield.
Starting materials were still in the reaction.
Biaryls were formed through self-coupling of boronic acid.
A number of spots were generated.
The same results were obtained with 1.5 and 2.0 equiv of boronic acid.
b
c
d
e
Scheme 1. Synthetic routes to sulfonimidamides.
First, we attempted the synthesis of 4-(S-p-tolyl-N-(4-
chlorophenylsulfonimidoyl)morpholine) 4g. S-(p-Tolylsulfonimi-
doyl)morpholine 1b (1.0 equiv) was reacted with 4-chloro-phe-
nylboronic acid 3a (2.5 equiv) as a test substrate to optimize the
reaction conditions (Table 1). Initially, the model reaction was
carried out in MeOH with 10 mol % of Cu(OAc)2 catalyst at room
temperature. Only 20% product was formed after 24 h of stirring
with a lot of unreacted starting materials remaining (Table 1, entry
1). Attempt to heat the reaction mixture at 60 ꢀC gave the sulfi-
namide 5 as major product (Table 1, entry 2, Scheme 2)da side-
reaction previously reported by Malacria.11
Scheme 2. Reaction of N0-deprotected sulfonimidamide with 4-chlorophenyl boronic
acid at 60 ꢀC.
Other copper catalysts, such as CuBr and CuI were also evaluated
(Table 1, entries 3 & 4); CuBr provided 16% of the desired product
together with the diarylated product 6 (Scheme 3), which was
obtained by the homocoupling of the boronic acid; CuI yielded
trace amounts of the product in a complex reaction mixture.
Thereafter, we decided to increase the amount of Cu(OAc)2
until all of the starting materials was consumed. The reaction was
therefore performed with 100 mol % of Cu(OAc)2, but only 42% of
the product was obtained (Table 1, entry 5). Our efforts to com-
plete the sulfonimidamide during the reaction was successful
only when 150 mol % and 200 mol % of Cu(OAc)2 were used,
leading to 72% and 70% yield of product, respectively (Table 1,
entries 5 & 6). Employing 150 mol % of copper acetate as medi-
ator, we next screened various solvents, such as DCM, dioxane,
Scheme 3. Formation of diarylated product via homocoupling of 4-chlorophenyl bo-
ronic acid.
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G.C. Nandi et al. / Tetrahedron xxx (2014) 1e6
3
THF, EtOH and MeCN to identify the solvent of choice (Table 1,
entries 8e13). It was established that MeCN provides the best
result by yielding 92% of the expected product in 14 h (Table 1,
entry 13). In DMF, again the self condensed biarylated product 6
was obtained as a major product (Table 1, entry 9; Scheme 3). The
reaction was also conducted with 50 mol % and 100 mol % of
Cu(OAc)2 in MeCN but with lower yield (Table 1, entries 14 & 15).
In an attempt to decrease reaction times, we added triethylamine
(TEA) or pyridine as base to the reaction with MeCN as solvent.
After several attempts (Table 1, entries 18e23), the best yields
were obtained with 100 mol % of Cu(OAc)2 and 1.0 equiv of TEA in
MeCN; these conditions gave 92% of isolated product in 5 h re-
action time (Table 1, entry 19). To verify the optimum amount of
boronic acid needed, the reaction was investigated with 1.0, 1.5
and 2.0 equiv of boronic acid with 100 mol % of Cu(OAc)2 and
1.0 equiv of TEA. The use of 1.0 equiv of boronic acid provided
lesser yields and took longer reaction times than the use of 1.5
and 2.0 equiv of boronic acid. Overall, the best reaction condi-
tions were obtained when the sulfonimidamide (1.0 equiv) was
reacted with boronic acid (1.5 equiv) in the presence of Cu(OAc)2
(100 mol %), TEA (1.0 equiv) in MeCN at room temperature (Table
1, entry 19). The experiment to review the catalytic activity of
Cu(OTf)2 was unsuccessful for this transformation (Table 1,
entry 17).
It should be noted that, in our hands, the ChaneEvanseLam
coupling on the imine nitrogen of sulfonimidamides did not
work efficiently under catalytic conditions, as recently reported
by Battula et al. (10 mol % Cu(OAc)2, MeOH, 24 h, rt).12b The reason
for this discrepancy is unclear; we ran the reaction under atmo-
spheric conditions, but did not make any special arrangements for
copper re-oxidation that might have been beneficial for a catalytic
process.
With the optimized reaction conditions in hand, we investigated
the substrate scope of the reaction. Both electron withdrawing
and electron donating substituents on the aryl ring of the boronic
acid worked well in the reactions, offering products in good to
excellent yields (Chart 1). Also fused aryl boronic acids showed
good reactivity (Chart 1, 4d,j). In addition, modification of the sul-
fonimidamide partner was well tolerated as shown by replacing the
morpholine moiety with a pyrrolidine, to offer the products 4kem
(Chart 1) in similar yields and at comparable reaction rates. Het-
eroaromatic 2-thienylboronic acid yielded the corresponding
product 4n; in this case TEA was not tolerated as additive (led to
a complex reaction mixture) and thus the reaction was performed
with Cu(OAc)2 only that resulted lower yield and longer reaction
time 13 h.
Encouraged by the successful N0-arylation of the imine nitrogen
of N0-deprotected sulfonimidamides, we next attempted the re-
actions with the primary N-amino group of N0-protected sulfoni-
midamides (2a,b) with aryl boronic acids. We started our analysis
by reacting sulfonimidamide 2a (0.25 mmol) with 4-chlorophenyl
boronic acid 3a (2.5 equiv) in acetonitrile at room temperature by
using Cu(OAc)2 (100 mol %) as catalyst without any base; to our
surprise we got diarylated product 7 as the main product along
with the desired product 8a (Table 2, entry 1; Scheme 4). To over-
come this complexity, the reaction was performed with 1.0 equiv of
boronic acid using 100 mol % of catalyst. The reaction was then
completed within 7 h and gave 85% of isolated product (Table 2,
entry 2). Interestingly, the use of TEA as a basic additive was found
to lower the reaction times, enhance the yields, and helped to re-
duce the catalyst loading for the reaction (Table 2, entries 3e5).
Thus, the best yields, shortest reaction times, and overall best
condition for the arylation of the primary amine functionality of
protected sulfonimidamides was observed when 1.0 equiv of each
starting material was stirred with 50 mol % of Cu(OAc)2 and
1.0 equiv of TEA in MeCN at room temperature (Table 2, entry 4).
Table 2
Optimization of ChaneEvanseLam N-arylation of the N-amine functionality of sul-
fonimidamide 2aa
Entry
Catalyst (mol %)
Base (equiv)
Yieldb (%)
Time (h)
1.
2.
3.
4.
5.
Cu(OAc)2 (100)
Cu(OAc)2 (100)
Cu(OAc)2 (100)
Cu(OAc)2 (50)
Cu(OAc)2 (25)
d
20c
85d
91d
93d
73d
5
7
2
2
4
d
TEA (1.0)
TEA (1.0)
TEA (1.0)
a
All reactions were performed at room temperature.
Isolated yield.
Diarylated product 7 was formed as the major one (2.5 equiv of boronic acid was
b
c
used).
d
1.0 equiv of each substrate was used.
Scheme 4. Reaction of N0-protected sulfonimidamide 2a with excess 4-chlorophenyl
boronic acid 3a.
On the basis of the above optimized reaction conditions, the
scope and generality of this protocol was next examined by using
various sulfonimidamides 2 and substituted aryl boronic acids 3.
Chart 1. Substrate scope for the ChaneEvanseLam N0-functionalization of sulfonimi-
damides with aryl boronic acids.
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4
G.C. Nandi et al. / Tetrahedron xxx (2014) 1e6
Electron-rich, as well as electron-deficient, substituents on the
aryl boronic acids were well tolerated for this transformation
(Chart 2, 8aee). In addition, the benzofused boronic acid was also
nicely tolerated to yield the corresponding N-arylated sulfoni-
midamide (8f). Notably, the replacement of phenyl group with
tolyl group in the sulfonimidamide scaffold provides parallel
yields (8d,e).
4.2. General procedure for functionalization of the N0-imine
nitrogen of sulfonimidamides with aryl boronic acids for the
synthesis of N0-arylated sulfonimidamides (4aen)y
To a 0.5 ml acetonitrile solution of N-deprotected sulfonimida-
mide (imine nitrogen) (0.25 mmol) and aryl boronic acid
(1.5 equiv), Cu(OAc)2 (100 mol %) followed by TEA (1.0 equiv) were
added and the whole reaction mixture was stirred for the stipulated
period of time at room temperature. After completion of the re-
action (checked by TLC), sodium bicarbonate solution was added to
it and extracted with ethyl acetate (2ꢁ10 ml). The organic layer was
washed with water followed by brine solution. Then the ethyl ac-
etate layer was dried (Na2SO4), evaporated and purified by column
chromatography using 5e6% of ethyl acetate in hexane as eluent.
All the compounds were characterized by 1H NMR, 13C NMR and
mass spectrometry.
4.2.1. 4-(S-Phenyl-N0-(4-chlorophenylsulfonimidoyl)morpholine)
(4a). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 5% EtOAc in Hexane as eluent.
White solid; yield: 90%. Rf¼0.4 (1:10 EtOAc/Hexane); mp
109e111 ꢀC. IR (ATR):
n
¼2974, 2914, 2855, 1589, 1442, 1256, 790.
1H NMR (CDCl3, 400 MHz):
d
7.95e7.93 (m, 2H), 7.62e7.56 (m,
3H), 7.20 (d, J¼6.3 Hz, 2H), 7.16 (d, J¼6.3 Hz, 2H), 3.68e3.58
Chart 2. Substrate scope for the reactions of N-deprotected sulfonimidamides and aryl
boronic acids.
(m, 4H), 3.07e2.93 (m, 4H); 13C NMR (CDCl3, 100 MHz):
d
142.1, 134.9, 133.0, 129.2, 129.1, 128.1, 127.3, 124.9, 66.3, 46.7.
HRMS (ESI) calcd for C16H17ClN2O2S [MþH]þ 337.0772, found
We find that addition of TEA increase the reactivity of both the
N-amine and N0-imine sulfonimidamide nucleophiles in our stoi-
chiometric implementation of the ChaneEvanseLam coupling.
Although a more comprehensive study would be required to un-
derstand the full reaction mechanism, it is likely that the added
base facilitates NeH deprotonation and coordination to the copper
centre.17
337.0762.
4.2.2. 4-(S-Phenyl-N0-(4-fluorophenylsulfonimidoyl)morpholine)
(4b). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 6% EtOAc in Hexane as eluent.
White solid; yield: 84%. Rf¼0.4 (1:10 EtOAc/Hexane); mp
95e96 ꢀC. IR (ATR):
NMR (CDCl3, 400 MHz):
n
¼2975, 2889, 2854, 1726, 1493, 1284, 741. 1H
d 7.95e7.93 (m, 2H), 7.61e7.55 (m, 3H),
3. Conclusion
7.19e7.16 (m, 2H), 6.92 (t, J¼8.6 Hz, 2H), 3.64e3.59 (m, 4H),
3.06e2.95 (m, 4H); 13C NMR (CDCl3, 100 MHz):
d
158.6 (d,
In summary, we have developed a general, convenient, and mild
copper mediated approach for sulfonimidamide arylation based on
the ChaneEvanseLam protocol. The reported methodology can be
applied for N-arylation of both the primary N-amine of N0-pro-
tected sulfonimidamides, as well as on the N0-imine nitrogen of
tertiary sulfonimidamides. The reaction proceeds at room tem-
perature and provide high to excellent yields with short times using
a low cost catalyst and base. The methodology works well with
a variety of boronic acids. Considering an increased interest of the
sulfonimidamide moiety in the area of drug design, and the
structural diversity offered by this group as compared to the widely
used sulfonamide, we anticipate that this new protocol will find
broad application for the synthesis of various kinds of sulfonimi-
damide derivatives with so far unidentified properties and
opportunities.
J¼239 Hz), 139.3, 135.1, 132.9, 129.1, 128.1, 124.7 (d, J¼8.0 Hz), 115.7
(d, J¼22 Hz), 66.3, 46.7. HRMS (ESI) calcd for C16H17FN2O2S
[MþH]þ 321.1067, found 321.1068.
4.2.3. 4-(S-Phenyl-N0-(p-tolylsulfonimidoyl)morpholine) (4c). The
compound was purified via column chromatography (silica gel
100e200 mesh) using 5% EtOAc in Hexane as eluent. White solid;
yield: 82%. Rf¼0.4 (1:10 EtOAc/Hexane); mp 85e86 ꢀC. IR (ATR):
n
¼2981, 2909, 2861, 1606, 1501, 1258, 741. 1H NMR (CDCl3,
400 MHz):
d 7.97e7.95 (m, 2H), 7.60e7.53 (m, 3H), 7.13 (d,
J¼8.2 Hz, 2H), 7.04 (d, J¼8.2 Hz, 2H), 3.67e3.57 (m, 4H),
3.07e2.95 (m, 4H), 2.28 (s, 3H); 13C NMR (CDCl3, 100 MHz):
d
140.6, 135.4, 132.7, 131.5, 129.7, 129.0, 128.2, 123.6, 66.5, 46.9,
21.0. HRMS (ESI) calcd for C17H20N2O2S [MþH]þ 317.1318, found
317.1357.
4. Experimental section
4.1. General
4.2.4. 4-(S-Phenyl-N0-(benzo[d][1,3]dioxoylsulfonimidoyl)morpho-
line) (4d). The compound was purified via column chromatogra-
phy (silica gel 100e200 mesh) using 6% EtOAc in Hexane as eluent.
White solid; yield: 81%. Rf¼0.3 (1:10 EtOAc/Hexane); mp 91e92 ꢀC.
The starting material sulfonimidamides were synthesized fol-
lowing the reported method.12,18 The aryl boronic acids, Cu(OAc)2
and triethylamine were purchased from commercial suppliers and
used as received. 1H and 13C NMR spectra were recorded on Bruker
TOPSPIN 2.1 spectrometer operating at 400 and 100 MHz, re-
spectively. IR spectra of selected compounds (4e, 4i, 8b, 8c and 8d)
were recorded on BRUKER-ALPHA spectrophotometer. HRMS were
recorded on BRUKER micrOTOF-Q-II spectrometer. Melting points
were uncorrected.
IR (ATR):
n
¼2971, 2918, 2874, 1608, 1474, 1256, 743. 1H NMR (CDCl3,
400 MHz):
d
7.85e7.83 (m, 2H), 7.50e7.43 (m, 3H), 6.71 (s, 1H), 6.59
(d, J¼0.9 Hz, 2H), 5.81 (d, J¼1.3 Hz, 2H), 3.57e3.49 (m, 4H),
2.94e2.88 (m, 4H); 13C NMR (CDCl3, 100 MHz):
d
148.0, 143.0,
137.5, 135.1, 132.8, 129.1, 128.2, 116.0, 108.4, 105.6, 101.0, 66.3, 46.9.
y
For 4n, TEA was not added.
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G.C. Nandi et al. / Tetrahedron xxx (2014) 1e6
5
HRMS (ESI) calcd for C17H18N2O4S [MþH]þ 347.1060, found
124e125 ꢀC. IR (ATR):
n
¼2974, 2887, 2852, 1599, 1480, 1260, 933,
347.1054.
521. 1H NMR (CDCl3, 400 MHz):
d
7.80 (d, J¼8.2 Hz, 2H), 7.33 (d,
J¼8.1 Hz, 2H), 6.80 (s, 1H), 6.68 (s, 2H), 5.90 (d, J¼1.0 Hz, 2H),
4.2.5. 4-(S-Phenyl-N0-(4-cyanophenylsulfonimidoyl)morpholine)
(4e). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 6% EtOAc in Hexane as eluent.
White solid; yield: 85%. Rf¼0.4 (1:10 EtOAc/Hexane); mp 90e91 ꢀC.
3.65e3.61 (m, 4H), 3.04e2.94 (m, 4H), 2.43 (s, 3H); 13C NMR (CDCl3,
100 MHz):
d 147.9, 143.6, 142.8, 137.8, 132.2, 129.7, 128.3, 116.2,
108.4, 105.5, 101.0, 66.3, 46.8, 21.6. HRMS (ESI) calcd for
C
18H20N2O4S [MþH]þ 361.1216, found 361.1257.
IR (ATR):
(CDCl3, 400 MHz):
n
¼2956, 2899, 2851, 2222, 1598, 1497, 1232. 1H NMR
d
7.94 (d, J¼7.3 Hz, 2H), 7.65 (t, J¼7.3 Hz,1H), 7.59
4.2.11. 1-(S-p-Tolyl-N0-(4-methoxyphenylsulfonimidoyl)pyrrolidine)
(4k). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 6% EtOAc in Hexane as eluent.
White solid; yield: 87%. Rf¼0.3 (1:10 EtOAc/Hexane); mp
(t, J¼7.8 Hz, 2H), 7.51 (d, J¼8.5 Hz, 2H), 7.28 (d, J¼8.5 Hz, 2H),
3.69e3.60 (m, 4H), 3.09e2.93 (m, 4H); 13C NMR (CDCl3, 100 MHz):
d
148.7, 134.4, 133.3, 133.2,129.3,128.1, 123.9,119.7, 104.8, 66.2, 46.7.
HRMS (ESI) calcd for
328.1164.
C
17H17N2O3S [MþH]þ 328.1114, found
108e110 ꢀC. IR (ATR):
(CDCl3, 400 MHz):
n
¼3034, 2955, 2880, 1501, 980, 744. 1H NMR
d
7.91 (d, J¼8.2 Hz, 2H), 7.31 (d, J¼8.0 Hz, 2H),
7.16 (d, J¼8.8 Hz, 2H), 6.79 (d, J¼8.9 Hz, 2H), 3.76 (s, 3H), 3.26e3.20
4.2.6. 4-(S-Phenyl-N0-(4-methoxyphenylsulfonimidoyl)morpholine)
(4f). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 6% EtOAc in Hexane as eluent.
White solid; yield: 71%. Rf¼0.4 (1:10 EtOAc/Hexane); mp 98e99 ꢀC.
(m, 2H), 3.18e3.12 (m, 2H), 2.42 (m, 3H), 1.67e1.64 (m, 4H); 13C
NMR (CDCl3, 100 MHz):
d 154.9, 143.0, 137.5, 134.1, 129.6, 128.1,
124.6, 114.4, 55.6, 48.4, 25.4, 21.6. HRMS (ESI) calcd for C18H22N2O2S
[MþH]þ 331.1474, found 331.1490.
IR (ATR):
400 MHz):
n
¼2953, 2864, 2835, 1528, 1218, 916. 1H NMR (CDCl3,
d
7.96e7.94 (m, 2H), 7.59e7.54 (m, 3H), 7.16 (d, J¼8.8 Hz,
4.2.12. 1-(S-p-Tolyl-N0-(4-fluorophenylsulfonimidoyl)pyrrolidine)
(4l). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 5% EtOAc in Hexane as eluent.
White solid; yield: 93%; Rf¼0.4 (1:10 EtOAc/Hexane); mp 96e97 ꢀC.
2H), 6.80 (d, J¼8.9 Hz, 2H), 3.77 (s, 3H), 3.63e3.59 (m, 4H),
3.03e2.98 (m, 4H); 13C NMR (CDCl3, 100 MHz):
d
155.4, 136.3, 135.3,
132.7, 129.0, 128.1, 124.6, 114.4, 66.7, 55.6, 46.9. HRMS (ESI) calcd for
C
17H20N2O3S [MþH]þ 333.1267, found 333.1209.
IR (ATR):
(CDCl3, 400 MHz):
n
¼2972, 2949, 2874, 1594, 1492, 1209, 750. 1H NMR
d
7.90 (d, J¼8.3 Hz, 2H), 7.32 (d, J¼7.7 Hz, 2H),
4.2.7. 4-(S-p-Tolyl-N0-(4-chlorophenylsulfonimidoyl)morpholine)
(4g). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 5% EtOAc in Hexane as eluent.
White solid; yield: 82%. Rf¼0.4 (1:10 EtOAc/Hexane); mp
7.18e7.15 (m, 2H), 6.91 (t, J¼8.7 Hz, 2H), 3.26e3.20 (m, 2H),
3.16e3.11 (m, 2H), 2.43 (s, 3H), 1.69e1.65 (m, 4H); 13C NMR (CDCl3,
100 MHz):
d
158.5 (d, J¼238 Hz), 143.2, 140.3, 133.8, 129.6, 128.1,
124.6 (d, J¼8.0 Hz), 115.5 (d, J¼21.9 Hz), 48.4, 25.3, 21.6. HRMS (ESI)
103e104 ꢀC. IR (ATR):
n
¼2961, 2922, 2824, 1722, 1591, 1484, 1228,
calcd for C17H19FN2OS [MþH]þ 319.1274, found 319.1269.
925, 714. 1H NMR (CDCl3, 400 MHz):
d
7.81 (d, J¼8.1 Hz, 2H), 7.34 (d,
J¼8.0 Hz, 2H), 7.18 (d, J¼8.9 Hz, 2H), 7.15 (d, J¼9.0 Hz, 2H),
4.2.13. 1-(S-p-Tolyl-N0-(p-tolylsulfonimidoyl)pyrrolidine) (4m). The
compound was purified via column chromatography (silica gel
100e200 mesh) using 5% EtOAc in Hexane as eluent. White solid;
yield: 94%; Rf¼0.4 (1:10 EtOAc/Hexane); mp 105e106 ꢀC. IR (ATR):
3.64e3.60 (m, 4H), 3.02e2.95 (m, 4H), 2.44 (s, 3H); 13C NMR (CDCl3,
100 MHz): d 143.8, 142.3, 131.9, 129.8, 129.1, 128.2, 127.1, 124.9, 66.3,
46.7, 21.6. HRMS (ESI) calcd for C17H19ClN2O2S [MþH]þ 351.0928,
found 351.0917.
n
¼3020, 2947, 2914, 1609, 1505, 1450, 812. 1H NMR (CDCl3,
400 MHz):
d
7.92 (d, J¼8.2 Hz, 2H), 7.31 (d, J¼8.0 Hz, 2H), 7.12 (d,
4.2.8. 4-(S-p-Tolyl-N0-(4-fluorophenylsulfonimidoyl)morpholine)
(4h). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 5% EtOAc in Hexane as eluent.
White solid; yield: 86%. Rf¼0.4 (1:10 EtOAc/Hexane); mp
J¼8.2 Hz, 2H), 7.02 (d, J¼8.1 Hz, 2H), 3.25e3.21 (m, 2H), 3.18e3.13
(m, 2H), 2.42 (s, 3H), 2.27 (s, 3H), 1.67e1.64 (m, 4H); 13C NMR
(CDCl3, 100 MHz):
d 143.0, 141.6, 134.2, 131.1, 129.7, 129.6, 128.1,
123.5, 48.4, 25.4, 21.6, 20.9. HRMS (ESI) calcd for C18H22N2OS
113e114 ꢀC. IR (ATR):
(CDCl3, 400 MHz):
n
¼2922, 2848, 1494, 1257, 740. 1H NMR
[MþH]þ 315.1525, found 315.1570.
d
7.82 (d, J¼8.2 Hz, 2H), 7.34 (d, J¼8.1 Hz, 2H),
7.18e7.15 (m, 2H), 6.92 (t, J¼8.6 Hz, 2H), 3.64e3.57 (m, 4H),
4.2.14. 1-(S-Phenyl-N0-(2-thienylsulfonimidoyl)morpholine)
(4n). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 6% EtOAc in Hexane as eluent.
White solid; yield: 38%. Rf¼0.3 (1:10 EtOAc/Hexane); Pale yellow
3.04e2.94 (m, 4H), 2.44 (s, 3H); 13C NMR (CDCl3, 100 MHz):
d
158.5
(d, J¼248 Hz), 143.8, 139.6, 132.1, 129.7, 128.2, 124.7 (d, J¼8.6 Hz),
115.6 (d, J¼22 Hz), 66.3, 46.8, 21.6. HRMS (ESI) calcd for
C
17H19FN2O2S [MþH]þ 335.1224, found 335.1225.
solid; mp 82e84 ꢀC. IR (ATR):
n
¼3020, 2913, 2842, 1608, 1504, 295.
1H NMR (CDCl3, 400 MHz):
d
7.93 (d, J¼7.2 Hz, 2H), 7.61 (t, J¼7.4 Hz,
4.2.9. 4-(S-p-Tolyl-N0-(p-tolylsulfonimidoyl)morpholine)
(4i). The
1H), 7.58 (t, J¼7.8 Hz, 2H), 6.81e6.79 (m, 1H), 6.75e6.73 (m, 1H),
compound was purified via column chromatography (silica gel
100e200 mesh) using 5% EtOAc in Hexane as eluent. White
solid; yield: 80%. Rf¼0.4 (1:10 EtOAc/Hexane); mp 98e100 ꢀC. IR
6.60e6.58 (m, 1H), 3.70 (t, J¼4.7 Hz, 4H), 3.07e3.04 (m, 4H); 13C
NMR (CDCl3, 100 MHz):
d 145.9, 134.6, 133.1, 129.2, 128.1, 125.8,
116.8, 116.2, 66.3, 46.8. HRMS (ESI) calcd for C14H16N2O2S2 [MþH]þ
(ATR):
400 MHz):
n
¼2953, 2924, 2854, 1507, 1107. 1H NMR (CDCl3,
309.0725, found 309.0723.
d
7.83 (d, J¼8.2 Hz, 2H), 7.33 (d, J¼8.1 Hz, 2H), 7.12 (d,
J¼8.2 Hz, 2H), 7.03 (d, J¼8.2 Hz, 2H), 3.67e3.57 (m, 4H),
4.3. General procedure for functionalization of the N-amine
functionality of N0-protected sulfonimidamides with aryl bo-
ronic acids for the synthesis of N-arylated sulfonimidamides
(8aef)
3.05e2.94 (m, 4H), 2.43 (s, 3H), 2.28 (s, 3H); 13C NMR (CDCl3,
100 MHz):
d 143.6, 140.9, 132.5, 131.5, 129.7, 129.6, 128.3, 123.6,
66.4, 46.8, 21.6, 20.9. HRMS (ESI) calcd for C18H22N2O2S [MþH]þ
331.1474, found 331.1466.
To a 0.5 ml acetonitrile solution of N0-protected sulfonimida-
mide (0.25 mmol) and aryl boronic acid (1.0 equiv), Cu(OAc)2
(50 mol %) followed by TEA (1.0 equiv) were added and the whole
reaction mixture was stirred for the stipulated period of time at
room temperature. After completion of reaction (checked by TLC),
4.2.10. 4-(S-p-Tolyl-N0-(benzo[d][1,3]dioxoylsulfonimidoyl)morpho-
line) (4j). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 5% EtOAc in Hexane as eluent.
White solid; yield: 84%. Rf¼0.4 (1:10 EtOAc/Hexane); mp
Please cite this article in press as: Nandi, G. C.; et al., Tetrahedron (2014), http://dx.doi.org/10.1016/j.tet.2014.06.122

6
G.C. Nandi et al. / Tetrahedron xxx (2014) 1e6
sodium bicarbonate solution was added to it and extracted with
ethyl acetate (2ꢁ10 ml). The organic layer was washed with water
followed by brine solution. Then the ethyl acetate layer was dried
(Na2SO4), evaporated and purified by column chromatography
using 12e15% of ethyl acetate in hexane as eluent. All the com-
pounds were characterized by 1H NMR, 13C NMR and mass
spectrometry.
21.7, 20.9,14.4. HRMS (ESI) calcd for C17H20N2O3S [MþH]þ 333.1267,
found 333.1251.
4.3.6. N0-Carbethoxy-4-phenylsulfonimid-N-(benzo[d][1,3]dioxoyl)
amide (8f). The compound was purified via column chromatogra-
phy (silica gel 100e200 mesh) using 15% EtOAc in Hexane as eluent.
White solid; yield: 82%. Rf¼0.3 (1:5 EtOAc/Hexane); mp 97e98 ꢀC.
IR (ATR):
400 MHz):
n
¼2983, 2920, 2851, 1685, 1481, 1240. 1H NMR (CDCl3,
4.3.1. N0-Carbethoxyphenylsulfonimid-N-(4-chlorophenyl)amide
(8a). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 12% EtOAc in Hexane as eluent.
White solid; yield: 93%. Rf¼0.5 (1:5 EtOAc/Hexane); mp 94e95 ꢀC.
d
8.77 (br, 1H), 7.91 (d, J¼7.4 Hz, 2H), 7.58 (t, J¼7.4 Hz,
1H), 7.49 (t, J¼8.0 Hz, 2H), 6.65e6.62 (m, 3H), 5.92 (s, 2H), 4.14 (q,
J¼7.0 Hz, 2H), 1.25 (t, J¼7.0 Hz, 3H); 13C NMR (CDCl3, 100 MHz):
d
158.3, 148.2, 146.5, 138.4, 133.5, 129.2, 128.6, 128.0, 118.3, 108.4,
IR (ATR):
400 MHz):
n
¼3094, 2929, 2855, 1656, 1491, 1211. 1H NMR (CDCl3,
106.5, 101.7, 62.5, 14.4. HRMS (ESI) calcd for C16H16N2O5S [MþH]þ
d
9.19 (br, 1H), 7.92 (d, J¼7.6 Hz, 2H), 7.58 (t, J¼7.4 Hz,
349.0852, found 349.0850.
2H), 7.49 (t, J¼7.7 Hz, 1H), 7.18 (d, J¼8.6 Hz, 2H), 7.02 (d, J¼8.6 Hz,
2H), 4.14 (q, J¼7.1 Hz, 2H), 1.23 (t, J¼7.1 Hz, 3H); 13C NMR (CDCl3,
4.3.7. N0-Carbethoxyphenylsulfonimid-N,N-di(4-chlorophenyl) amide
(7). The compound was purified via column chromatography (silica
gel 100e200 mesh) using 12% EtOAc in Hexane as eluent. White solid;
yield: 63%. Rf¼0.7 (1:5 EtOAc/Hexane); mp 97e98 ꢀC.1H NMR (CDCl3,
100 MHz):
d 157.9, 138.4, 134.3, 133.8, 131.5, 129.6, 129.4, 127.9,
124.0, 62.7, 14.5. HRMS (ESI) calcd for C15H15ClN2O3S [MþH]þ
339.0564, found 339.0562.
400 MHz):
d
7.92e7.90 (m, 2H), 7.66 (t, J¼7.3 Hz,1H), 7.53 (t, J¼8.0 Hz,
4.3.2. N0-Carbethoxyphenylsulfonimid-N-(p-tolyl)amide (8b). The
compound was purified via column chromatography (silica gel
100e200 mesh) using 13% EtOAc in Hexane as eluent. White solid;
yield: 84%. Rf¼0.5 (1:5 EtOAc/Hexane); mp 116e118 ꢀC. IR (ATR):
2H), 7.27 (d, J¼8.8 Hz, 4H), 7.22 (d, J¼8.8 Hz, 4H), 4.13 (q, J¼7.0 Hz, 2H),
1.25 (t, J¼7.0 Hz, 3H); 13C NMR (CDCl3,100 MHz):
d 157.0, 139.8, 139.5,
134.2, 133.7, 130.2, 129.7, 129.4, 127.8, 62.3, 14.5. HRMS (ESI) calcd for
C
21H18Cl2N2O3S [MþH]þ 449.0487, found 449.0481.
n
¼3243, 2955, 2922, 2853, 1725, 1613, 1363, 1266. 1H NMR (CDCl3,
400 MHz):
d
8.73 (br, 1H), 7.91e7.89 (m, 2H), 7.59 (t, J¼7.5 Hz, 1H),
Acknowledgements
7.48 (t, J¼7.6 Hz, 2H), 7.03 (d, J¼8.2 Hz, 2H), 6.94 (d, J¼8.3 Hz, 2H),
4.17 (q, J¼7.1 Hz, 2H), 2.26 (s, 3H), 1.28 (t, J¼7.0 Hz, 3H); 13C NMR
This work is based on the research supported in part by the
National Research Foundation of South Africa for the Grant 87706.
We are also grateful to UKZN for postdoctoral fellowships to G.C.N.
and S.R.K. and for additional financial support.
(CDCl3, 100 MHz):
d 158.3, 138.7, 136.1, 133.5, 132.5, 130.1, 129.2,
127.9, 123.3, 62.5, 20.9, 14.4. HRMS (ESI) calcd for C16H18N2O3S
[MþH]þ 319.1110, found 319.1133.
4.3.3. N0-Carbethoxyphenylsulfonimid-N-(4-fluorophenyl)amide
(8c). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 14% EtOAc in Hexane as eluent.
White solid; yield: 88%. Rf¼0.4 (1:5 EtOAc/Hexane); mp 86e87 ꢀC.
References and notes
1. (a) Levchenko, E. S.; Sheinkman, I. E.; Kirsanov, A. V. Zh. Obshch. Khim. 1960, 30,
1941; (b) Levchenko, E. S.; Derkach, N. Y.; Kirsanov, A. V. Zh. Obshch. Khim. 1962,
32, 1208.
2. (a) Robak, M. T.; Herbage, M. A.; Ellman, J. A. Chem. Rev. 2010, 110, 3600; (b)
Zhou, P.; Chen, B. C.; Davis, F. A. Tetrahedron 2004, 60, 8003; (c) Paitoon, R.;
Harmata, M. Chemtracts 2006, 19, 143; (d) Collet, F.; Dodd, R. H.; Dauban, P.
Chem. Commun. 2009, 5061; (e) Carreno, M. C.; Hernandez-Torres, G.; Rib-
agorda, M.; Urbano, A. Chem. Commun. 2009, 6129.
3. (a) Leca, D.; Toussaint, A.; Mareau, C.; Fensterbank, L.; Lacote, E.; Malacria, M.
Org. Lett. 2004, 6, 3573; (b) Di Chenna, P. H.; Robert-Peillard, F.; Dauban, P.;
Dodd, R. H. Org. Lett. 2004, 6, 4503; (c) Liang, C.; Robert-Peillard, F.; Fruit, C.;
Muller, P.; Dodd, R. H.; Dauban, P. Angew. Chem., Int. Ed. 2006, 45, 4641.
4. Worch, C.; Bolm, C. Synlett 2009, 2425.
IR (ATR):
n
¼3107, 2953, 2922, 2850, 1671, 1507, 1258, 1203. 1H NMR
(CDCl3, 400 MHz):
d
9.16 (br, 1H), 7.92 (d, J¼7.7 Hz, 2H), 7.57 (t,
J¼7.4 Hz, 1H), 7.48 (t, J¼7.9 Hz, 2H), 7.10e7.07 (m, 2H), 6.92e6.88
(m, 2H), 4.15e4.09 (m, 2H), 1.20 (dt, J1¼2.0 Hz, J2¼7.0 Hz, 3H); 13
C
NMR (CDCl3, 100 MHz):
d
160.9 (d, J¼244 Hz), 157.9, 138.2, 133.5,
131.0 (d, J¼2.8 Hz), 129.2, 127.9, 125.7 (d, J¼8.2 Hz), 116.2 (d,
J¼22 Hz), 62.4, 14.2. HRMS (ESI) calcd for C15H15FN2O3S [MþH]þ
323.0860, found 323.0865.
5. Steurer, M.; Bolm, C. J. Org. Chem. 2010, 75, 3301.
6. Patureau, F. W.; Worch, C.; Siegler, M. A.; Spek, A. L.; Bolm, C.; Reek, J. N. H. Adv.
Synth. Catal. 2012, 354, 59.
4.3.4. N0-Carbethoxy-p-tolylsulfonimid-N-(4-chlorophenyl)amide
(8d). The compound was purified via column chromatography
(silica gel 100e200 mesh) using 12% EtOAc in Hexane as eluent.
White solid; yield: 87%. Rf¼0.5 (1:5 EtOAc/Hexane); mp
7. Toth, J. E.; Grindey, G. B.; Ehlhardt, W.; Ray, J.; Boder, G. B.; Bewley, J. R.; Klin-
german, K.; Gates, S.; Rinzel, S.; Schultz, R.; Weir, L.; Worzalla, J. J. Med. Chem.
1997, 40, 1018.
8. Cathers, B.; Schloss, J. V. Bioorg. Med. Chem. Lett. 1999, 9, 1527.
9. Sehgelmeble, F.; Janson, J.; Ray, C.; Rosqvist, S.; Gustavsson, S.; Nilsson, L. I.;
Minidis, A.; Holenz, J.; Rotticci, D.; Lundkvist, J.; Arvidsson, P. I. ChemMedChem
2012, 7, 396.
103e104 ꢀC. IR (ATR):
(CDCl3, 400 MHz):
n
¼3100, 2980, 1668, 1490, 1211. 1H NMR
d
7.79 (d, J¼8.4 Hz, 2H), 7.27 (d, J¼9.4 Hz, 2H),
7.17 (d, J¼8.7 Hz, 2H), 7.02 (d, J¼8.7 Hz, 2H), 4.13 (q, J¼7.1 Hz, 2H),
10. Worch, C.; Bolm, C. Synthesis 2008, 739.
2.39 (s, 3H), 1.23 (t, J¼7.0 Hz, 3H); 13C NMR (CDCl3, 100 MHz):
^
11. Azzaro, S.; Fensterbank, L.; Lacote, E.; Malacria, M. Synlett 2011, 849.
12. (a) Maldonado, M. F.; Sehgelmeble, F.; Bjarnemark, F.; Svensson, M.; Ahman, J.;
Arvidsson, P. I. Tetrahedron 2012, 68, 7456; (b) Battula, S. R. K.; Subbareddy, G.
V.; Chakravarthy, I. E. Tetrahedron Lett. 2014, 55, 517.
13. Borhade, S. R.; Sandstrom, A.; Arvidsson, P. I. Org. Lett. 2013, 15, 1056.
14. Chan, D. M. T.; Monaco, K. L.; Wang, R.-P.; Winters, M. P. Tetrahedron Lett. 1998,
39, 2933.
d
158.0,144.9,135.2,134.4,131.3,130.0,129.6,127.9,123.9, 62.6, 21.7,
14.4. HRMS (ESI) calcd for C16H17ClN2O3S [MþH]þ 353.0721, found
353.0722.
4.3.5. N0-Carbethoxy-4-tolylsulfonimid-N-4-tolylamide
(8e). The
15. Lam, P. Y. S.; Clark, C. G.; Saubern, S.; Adams, J.; Winters, M. P.; Chan, D. M. T.;
compound was purified via column chromatography (silica gel
100e200 mesh) using 12% EtOAc in Hexane as eluent. White solid;
yield: 85%. Rf¼0.5 (1:5 EtOAc/Hexane); mp 95e97 ꢀC. IR (ATR):
Combs, A. Tetrahedron Lett. 1998, 39, 2941.
16. Evans, D. A.; Katz, J. L.; West, T. R. Tetrahedron Lett. 1998, 39, 2937.
17. For review see (a) Qiao, J. X.; Lam, P. Y. S. Synthesis 2011, 829; (b) Rao, K. S.; Wu,
T.-S. Tetrahedron 2012, 68, 7735; (c) Ley, S. V.; Thomas, A. W. Angew. Chem., Int.
Ed. 2003, 42, 5400 For book; (d) Qiao, J. X.; Lam, P. Y. S. In Boronic Acids:
Preparation and Applications in Organic Synthesis, Medicine and Materials,
2nd ed.; Hall, D. G., Ed.; Wiley-VCH GmbH & KGaA: Weinheim, Germany, 2011;
Vols. 1 and 2, http://dx.doi.org/10.1002/9783527639328; (e) King, A E.; Brunold,
T. C.; Stahl, S. S. J. Am. Chem. Soc. 2009, 131, 5044.
n
¼3035, 2919, 2779, 1654, 1498, 1210. 1H NMR (CDCl3, 400 MHz):
d
8.85 (br, 1H), 7.79 (d, J¼8.4 Hz, 2H), 7.24 (d, J¼8.5 Hz, 2H), 7.00 (d,
J¼8.3 Hz, 2H), 6.95 (d, J¼8.4 Hz, 2H), 4.12 (q, J¼7.1 Hz, 2H), 2.38 (s,
3H), 2.24 (s, 3H), 1.23 (t, J¼7.0 Hz, 3H); 13C NMR (CDCl3, 100 MHz):
d
158.3, 144.4, 135.8, 135.5, 132.7, 130.0, 129.8, 128.0, 123.2, 62.3,
18. Bolm, C.; Garcia Machenco, O. Beilstein J. Org. Chem. 2007, 3.
Please cite this article in press as: Nandi, G. C.; et al., Tetrahedron (2014), http://dx.doi.org/10.1016/j.tet.2014.06.122