Pd-catalyzed C-N coupling of vinylbromides and sulfonimidamides: A facile synthesis of N′-vinylsulfonimidamides

Article abstract of DOI:10.1039/c5ra10939f

N′-Vinyl sulfonimidamides have been synthesized through a Pd-catalyzed C-N cross coupling between the N′-(imine nitrogen) of N′-deprotected sulfonimidamides and vinyl bromides. The hitherto unreported products were obtained in moderate to excellent yield, and the C-C double bond geometry of the vinylic substrates were retained during the course of reaction. Single crystal X-ray crystallographic analysis confirmed the product structure. Furthermore, we demonstrate that the formed N′-vinyl sulfonimidamides could undergo hydrogenation with Pd-C/H₂ to provide N′-alkyl sulfonimidamides.

Full text of DOI:10.1039/c5ra10939f

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Pd-catalyzed C–N coupling of vinylbromides and
sulfonimidamides: a facile synthesis of
N0-vinylsulfonimidamides†
Cite this: RSC Adv., 2015, 5, 62084
Ganesh C. Nandi,ab Sudhakar R. Kota,a Prasad B. Wakchaure,c
Praveen K. Chinthakindi,a Thavendran Govender,a Hendrick G. Kruger,a
a
ad
*
*
Tricia Naicker and Per I. Arvidsson
N0-Vinyl sulfonimidamides have been synthesized through a Pd-catalyzed C–N cross coupling between the
N0-(imine nitrogen) of N0-deprotected sulfonimidamides and vinyl bromides. The hitherto unreported
products were obtained in moderate to excellent yield, and the C–C double bond geometry of the
vinylic substrates were retained during the course of reaction. Single crystal X-ray crystallographic
analysis confirmed the product structure. Furthermore, we demonstrate that the formed N0-vinyl
sulfonimidamides could undergo hydrogenation with Pd–C/H2 to provide N0-alkyl sulfonimidamides.
Received 9th June 2015
Accepted 13th July 2015
DOI: 10.1039/c5ra10939f
www.rsc.org/advances
methodology and for applications in medicinal chemistry and
agrochemistry. Some research groups applied sulfonimida-
Introduction
mides as a reagent in organic synthesis, mainly as a ‘N’-source
for metal-catalyzed nitrene transfer reactions, for imination of
suldes, aziridination of olens, and C–H aminations of
hydrocarbons.4 Additionally, sulfonimidamides have been used
as organocatalysts and as chiral ligands in asymmetric
synthesis; more recently they have been used in the iridium-
catalyzed asymmetric hydrogenation of cyclic enamides.5 Sul-
fonimidamide functional groups have also been used as
analogues of oncolytic sulfonylureas, sodium channel antago-
nists, pesticidal agents, and as transition state analogue
inhibitors of aspartic acid metalloproteases.6 Even more
recently, other groups, in addition to ours, have reported the
synthetic methodology for sulfonimidamide functionalization
and preparation.7 Given the growing bio- and synthetic impor-
tance of sulfonimidamides, we became interested in attempting
to prepare N-vinyl sulfonimidamides following the Pd-catalyzed
Buchwald–Hartwig8 C–N coupling procedure. To the best of our
knowledge, there is no report on the synthesis of N-vinyl sul-
fonimidamides through any methodology.
As part of our ongoing research project on sulfonimidamides
and acyl sulfonimidamides as bioisosteres in medicinal chem-
istry,1 we recently disclosed new synthetic protocols for prepa-
ration and modication of this functional group. In our rst
report,2a we used a Pd-catalyzed Buchwald-Hartwig2f,g C–N
coupling procedure for the arylation of the N0-(imine nitrogen)
of sulfonimidamides. Subsequently, we reported the synthesis
of N-acylated sulfonimidamides via Pd-catalyzed amidocarbo-
nylation of vinyl/aryl halides and triates.2b,c We have also
reported N0-arylation via Cu-mediated Chan–Lam–Evans cou-
pling,2d and N-alkynylation through a Cu-catalyzed dual N–H/C–H
activation protocol.2e Herein, we explore the Pd-catalyzed C–N
coupling of various vinyl bromides to the N0-(imine nitrogen) of
unprotected sulfonimidamides.
Although Levchenko et al.,3 reported the synthesis of sulfo-
nimidamides already in 1960, the interest in this functional
group has remained low until quite recently. However, during
the last decade, attention on this functional group has
increased tremendously, both in the area of synthetic
The N-alkenyl functional group represent a very versatile
class of olenic compounds as the electron releasing ability of
the nitrogen lone pair strongly polarizes the double bond;
thereby offering high levels of reactivity in combination with
strong differentiation of the two sp2 carbon atoms. In fact, this
reactivity of N-alkenyls is the basis for enamine activation in the
very fruitful research area of organocatalysis9–11 – another area
of interest in our research group. Consequently, N-alkenyl
functional groups are widely used as synthetic intermediates in
the preparation of heterocycles12 and in asymmetric synthesis of
amides and amino acids.13 In addition, N-alkenyl functional
groups can be found in many natural products, that include
aCatalysis and Peptide Research Unit, University of KwaZulu-Natal, Durban, South
Africa. E-mail: Per.Arvidsson@scilifelab.se
bOrganic Chemistry Section, National Institute for Interdisciplinary Science and
Technology (CSIR), Trivandrum 695019, India
cOrganic Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala
Biomedical Center, Uppsala University, P.O. Box 574, 751 23 Uppsala, Sweden
dScience for Life Laboratory, Drug Discovery & Development Platform & Division of
Translational Medicine and Chemical Biology, Department of Medical Biochemistry
and Biophysics, Karolinska Institutet, Stockholm, Sweden
† Electronic supplementary information (ESI) available. CCDC 1049804. For ESI
and crystallographic data in CIF or other electronic format see DOI:
10.1039/c5ra10939f
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anti-anthelmintic chondriamides,14 cytotoxic tripeptide cas- improve the yield of the reaction, but performing the reaction at
pergillamides,15 protease inhibitors TMC-95-A-D,16 antibiotic 110 C, provided 92% of isolated product within 4 h (Table 1,
ꢀ
CJ-15801,17 anti-inammatory frangufoline,18 as well as anti- entry 3). Pd(OAc)2 was found to be similarly effective as
tumor lobatomide A–F,19 salicylihalamide
A
and related Pd2(dba)3 and afforded 89% of the product (Table 1, entry 4).
Interestingly, under MW irradiation the reaction completed
within 1.5 h but provided only 82% of product (Table 1, entry 5).
We were also able to demonstrate that the reaction could be
performed under another Buchwald's procedure22 for N-vinyl-
ation, i.e., stoichiometric CuI/N,N0-dimethylethylenediamine
compounds.20
Results and discussion
The starting sulfonimidamides were not commercially acces-
sible, and hence prepared according to literature procedures
(Scheme 1).2a,21
(DMEDA) mediation, rather than catalytic Pd-/BINAP condi-
tions, albeit with longer reactions times and lower yield (79%)
of product (Table 1, entry 6).
We commenced our studies with the reaction of sulfonimi-
damide 1a and 1-(1-bromovinyl)-4-chlorobenzene as model
substrates for optimization and the results have been depicted
in Table 1. First, we attempted our previously reported reaction
condition2a (Table 1, entry 1) for N-arylation of sulfonimidamide
[i.e. catalyst Pd(PhCH2CH2NH2)(Cl) (RuPhos) and NaOtBu base
With the optimized reaction conditions (Table 1, entry 3) at
hand; we next investigated the substrate scope of this N0-vinyl-
ation reaction by varying vinyl halides and sulfonimidamides.
Representative results are shown in Chart 1. Various aryl
vinylbromides were successfully employed for this trans-
formation. Both unsubstituted- and –Cl/–OMe substituted aryl
(trans-) vinyl bromides provided the corresponding N0-vinyl
sulfonimidamides (3a–c, 3h–j, 3o, p) in good to excellent yields.
The phenylvinyl bromide with cis-orientation also gave satis-
factory results whilst retaining the double-bond geometry (3e,
3l, 3n). Vinylbromides with heteroaryl groups were equally
effective for this transformation (3d, 3k).
ꢀ
in THF under MW irradiation at 100 C]; surprisingly, this did
not lead to any detectable N0-vinylated product. Next, we
attempted the model reaction with the catalyst Pd2(dba)3 (1
mol%), ligand BINAP (1.5 mol%), base NaOtBu (1.5 equiv.) in
toluene at 100 ꢀC for 12 h; gratifyingly, these reaction conditions
gave 78% of the expected product with some unreacted starting
materials (Table 1, entry 2). A longer reaction time did not
Although the cyclic aliphatic vinyl bromide afforded the
corresponding product (3g) in moderate yield, both acyclic
aliphatic vinyl bromides 2-bromo-1-propene and 1-bromo-1-
propene resulted a complex reaction mixture. Even a-bromo
styrene worked well for this transformation and provided very
good yields of terminal alkenes (3f, 3m). Modication of the
sulfonimidamide moiety was tolerated satisfactorily as shown
by replacing the morpholine functionality with piperidine/
pyrrolidine to offer the products (3n, 3o) in very good yields.
The structures of all the newly synthesized compounds were
deduced from full spectroscopic characterization and
unequivocally established by X-ray single crystal diffraction
analysis of one representative compound (3c, Fig. 1).23
Scheme 1 Synthesis of sulfonimidamides.
Table 1 Optimization of reaction conditions for the N0-vinylation of sulfonimidamidesa
Entry
Condition
Yieldb (%)
1
2
3
4
5
6
Pd(PhCH2CH2NH2)(Cl)(RuPhos) (3.0 mol%), NaOtBu (1.2 equiv.), THF, 100 ꢀC, MW, 2.5 h
Pd2(dba)3 (1 mol%), BINAP (1.5 mol%), NaOtBu (1.5 equiv.), toluene, 100 ꢀC, 12 h
Pd2(dba)3 (1 mol%), BINAP (1.5 mol%), NaOtBu (1.5 equiv.), toluene, 110 ꢀC, 4 h
Pd(OAc)2 (1 mol%), BINAP (1.5 mol%), NaOtBu (1.5 equiv.), toluene, 110 ꢀC, 5 h
Pd2(dba)3 (1 mol%), BINAP (1.5 mol%), NaOtBu (1.5 equiv.), toluene, 150 ꢀC, MW, 1.5 h
CuI (1.0 equiv.), DMEDA (2.0 equiv.), K2CO3(2.0 equiv.), toluene, 110 ꢀC, 7 h
—
78c
92
89
82
79
a
Sulfonimidamide and vinyl bromide were used 1.0 equiv. each. b Isolated yield. c Some starting materials were unreacted.
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Scheme 2 Decomposition of N0-vinyl sulfonimidamides in CDCl3.
Scheme
3
Pd–C
catalyzed
hydrogenation
of
N0-vinyl
sulfonimidamides.
sulfonimidamides 3 decomposed to starting sulfonimidamide 4
and aryl acetaldehyde 5 (Scheme 2) when CDCl3 was used as
solvent for recording the NMR spectra. Hence, we replaced
CDCl3 by CD3CN as solvent for NMR spectroscopic character-
ization of the products. For authentication, in a separate
experiment, sulfonimidamide 4 and phenyl acetaldehyde (1 : 1)
were mixed in CDCl3 in an NMR tube; the resulting NMR
spectra matched that obtained from the reaction product 3a in
CDCl3, thus independently verifying the decomposition of 3 to 4
and 5 under slightly acidic conditions. To verify the reversibility
of the process, sulfonimidamide 4 and phenyl acetaldehyde 5
(1 : 1) were reuxed in toluene in the presence of catalytic p-
toluenesulfonic acid (PTSA); LCMS analysis of the reaction
mixture conrmed the formation of 3 albeit in trace amount.
In order to demonstrate the reactivity and utility of the newly
prepared N-vinyl sulfonimidamides, we decided to reduce the
N-alkenyl group to the corresponding N-alkane derivative. An
attempt to reduce the double bond following our previously
reported BH3$DMS mediated reduction2e proved unsuccessful.
However, for these substrates Pd–C catalyzed hydrogenation
provided the expected N0-alkyl sulfonimidamides 6 in good yield
(Scheme 3). Under the same conditions, compound 3p gave the
corresponding amine 6b through a one-pot reduction of both
the olen and the nitro functionality, thus making an inter-
esting building block for further transformations.
Chart 1 Substrate scope for the N0-vinylation of the sulfonimidamides
under optimized reaction conditions.
According to a search performed using the Cambridge Struc-
tural Database, this structure is the rst of its kind to be
reported. Comparable sulfonimidamide and sulfonimidate
structures displayed a fairly trigonal pyramidal shape with
respect to the groups bonded to sulphur atom; bond angles S1–
O3–C13 109ꢀ, S1–O3–N1 104ꢀ, while S1–O3–N2 122ꢀ (deviation).
In addition, the X-ray structure of 3c displayed a slightly longer
˚
S1–N1 bond length of 1.6 A as compared to analogous struc-
˚
tures that displayed approximately 1.5 A. The S1]N2 double
˚
bond length in the structure of 3c is 1.51 A, which is also slightly
˚
longer than other reported structures (1.4–1.52 A). Similar to
other enamine systems, the C]C bond displays (E)-congura-
tion, and the conformation of the bond between the N0-atom
and the C3 is trans-, so that the styryl group points away from
the bulky substituents of the sulfone group and the conjugated
p-system that includes the N0-atom, the C]C bond, and the
phenyl ring, is perfectly planar.
The N0-alkenyl compounds reported here are expected to be
very sensitive towards acid. Not too surprising, the N-vinyl
Conclusions
In summary, we have described a Pd-catalyzed C–N coupling
reaction of N0-deprotected sulfonimidamides and vinyl bromides
for the synthesis of N0-vinyl sulfonimidamides. A variety of a/b-
vinyl bromides and cyclic vinyl bromides were successfully
coupled to different N0-deprotected sulfonimidamides. The
coupling took place with retained stereochemistry around the
vinylic double bond. The structure of the N0-vinyl
Fig. 1 ORTEP diagram of 3c.
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sulfonimidamide product was indisputably proven by single 120–122 ꢀC. IR (ATR): n ¼ 2901, 2856, 2843, 1625, 1445, 1297, 916
crystal X-ray diffraction. In addition, we demonstrated the reac- cmꢃ1. 1H NMR (400 MHz, CD3CN): d ¼ 7.90 (d, J ¼ 7.3 Hz, 2H),
tivity of the newly formed N0-alkenyl group through hydrogena- 7.71 (t, J ¼ 7.3 Hz, 1H), 7.63 (t, J ¼ 7.7 Hz, 2H), 7.32–7.24 (m, 5H),
tion of N0-vinyl sulfonimidamides to N0-alkyl sulfonimidamides. 6.19 (d, J ¼ 13.6 Hz, 1H), 3.65 (t, J ¼ 4.6 Hz, 4H), 2.97–2.89 (m, 4H).
The preliminary observation of the dynamic nature of these N- 13C NMR (100 MHz, CD3CN): d ¼ 137.9, 135.0, 134.2, 131.3, 130.3,
vinyl sulfonimidamides suggest that they can be used as precur- 130.2, 129.4, 128.9, 127.3, 118.0, 66.8, 47.7. HRMS (ESI) calcd for
sors for many other synthetic transformations and further studies C18H19ClN2O2S [M + H]+ 363.0928, found 363.0918.
along these lines are currently underway in our laboratory.
4-[S-Phenyl-N0-(4-methoxyphenylvinyl)sulfonimidoyl]morpho-
line (3c). White solid, Rf ¼ 0.25 (20% ethyl acetate/hexane) mp
110–111 ꢀC. IR (ATR): n ¼ 2966, 2916, 2855, 1511, 1599, 1252,
1110 cmꢃ1. 1H NMR (400 MHz, CD3CN): d ¼ 7.90 (d, J ¼ 7.4 Hz,
2H), 7.70 (t, J ¼ 7.4 Hz, 1H), 7.63 (t, J ¼ 7.4 Hz, 2H), 7.26 (d, J ¼ 8.6
Experimental
General
The starting material sulfonimidamides were synthesized in the Hz, 2H), 7.10 (d, J ¼ 13.6 Hz, 1H), 6.83 (d, J ¼ 8.7 Hz, 2H), 6.18 (d, J
laboratory following the reported method.2a,21 Vinyl bromide [(E)- ¼ 13.7 Hz, 1H), 3.76 (s, 3H), 3.64 (t, J ¼ 4.7 Hz, 4H), 2.94–2.90 (m,
2-bromoethenyl]benzene and 1-[(E)-2-bromoethenyl]-4-methoxy- 4H). 13C NMR (100 MHz, CD3CN): d ¼ 159.0, 135.2, 134.0, 131.5,
benzene,24 1-[(E)-2-bromoethenyl]-4-chlorobenzene,25 2-[(E)-2-bro- 130.1, 128.9, 127.2, 127.0, 119.2, 114.9, 66.8, 55.8, 47.7. HRMS
moethenyl]thiophene,26
[(Z)-2-bromoethenyl]benzene,27
1- (ESI) calcd for C19H22N2O3S [M + H]+ 359.1423, found 359.1428.
bromocyclohex-1-ene28 were synthesized using reported proce-
4-[S-Phenyl-N0-(2-thienylvinyl)sulfonimidoyl]morpholine (3d).
dures. (1-Bromoethenyl)benzene and Pd-catalysts, ligands were White solid, Rf ¼ 0.30 (20% ethyl acetate/hexane), mp 134–135 ꢀC.
1
purchased from various suppliers and used as received. H and IR (ATR): n ¼ 2961, 2862, 2840, 1631, 1457, 1275, 1103, 924 cmꢃ1
.
13C NMR spectra were recorded on Bruker Avance III spectrometer 1H NMR (400 MHz, CD3CN): d ¼ 7.92 (d, J ¼ 7.4 Hz, 2H), 7.73 (t, J
operating at 400 and 100 MHz, respectively. CD3CN and CDCl3 ¼ 7.4 Hz, 1H), 7.65 (t, J ¼ 7.8 Hz, 2H), 7.35–7.33 (m, 1H), 7.24 (d, J
were purchased from Merck and used as received. IR spectra were ¼ 4.9 Hz, 1H), 7.16 (d, J ¼ 13.6 Hz, 1H), 7.07 (m, 1H), 6.29 (d, J ¼
recorded on BRUKER-ALPHA spectrophotometer. HRMS were 17.1 Hz, 1H) 3.67 (t, J ¼ 4.7 Hz, 4H), 3.00–2.90 (m, 4H). 13C NMR
recorded on BRUKER micrOTOF-Q-II spectrometer. Melting (100 MHz, CD3CN): d ¼ 140.7, 135.1, 134.0, 130.1, 129.2, 128.9,
points were uncorrected.
General procedure for the reaction of sulfonimidamides and C16H18N2O2S2 [M + H]+ 335.0882, found 335.0882.
vinyl halides for the synthesis of N0-vinyl sulfonimidamides (3a–
4-[S-Phenyl-N0-(phenylvinyl)sulfonimidoyl]morpholine (3e).
126.9, 125.6, 119.1, 114.4, 66.8, 47.7. HRMS (ESI) calcd for
p). A Schlenk tube under nitrogen atmosphere was charged with White solid, Rf ¼ 0.30 (15% ethyl acetate/hexane) mp 115–
ꢀ
sulfonimidamide (1.0 equiv.), vinyl bromide (1.0 equiv.), 116 C. IR (ATR): n ¼ 2966, 2915, 2854, 1621, 1445, 1254, 923
Pd2(dba)3 (1 mol%), (ꢁ)-BINAP (1.5 mol%), NaOt-Bu (1.5 equiv.), cmꢃ1. 1H NMR (400 MHz, CD3CN): d ¼ 7.96 (d, J ¼ 7.1 Hz, 2H),
and 2 mL of dry toluene. The reaction was stirred at 110 ꢀC for 4–6 7.84 (d, J ¼ 7.3 Hz, 2H), 7.72 (t, J ¼ 7.4 Hz, 1H), 7.66 (t, J ¼ 7.3 Hz,
h and then allowed to cool to room temperature. The reaction 2H), 7.31 (t, J ¼ 7.6 Hz, 2H), 7.14 (t, J ¼ 7.3 Hz, 1H), 6.68 (d, J ¼
mixture was ltered through Celite and the ltrate was puried 8.6 Hz, 1H), 5.65 (d, J ¼ 8.5 Hz, 1H), 3.64–3.62 (m, 4H), 2.97–2.85
through neutral alumina column chromatography using 5–10% (m, 4H). 13C NMR (100 MHz, CD3CN): d ¼ 138.7, 135.0, 134.2,
ethyl acetate in hexane as eluent to obtain the pure N0-vinyl 130.3, 129.3, 129.0, 128.9, 127.7, 126.4, 115.3, 66.7, 47.6. HRMS
sulfonimidamides.
(ESI) calcd for C18H20N2O2S [M + H]+ 329.1318, found 329.1319.
General procedure for the Pd–C catalyzed hydrogenation of
4-[S-Phenyl-N0-(1-phenylvinyl)sulfonimidoyl]morpholine (3f).
N0-vinyl sulfonimidamides (6a, b). To a N2 ushed round bottom White solid, Rf ¼ 0.30 (20% ethyl acetate/hexane) mp 98–99 ꢀC. IR
ask, vinyl sulfonimidamides (0.3 mmol, 1.0 equiv.) in EtOAc (2 (ATR): n ¼ 3061, 2966, 2915, 2855, 1681, 1596, 1445, 1254, 1111,
1
mL) and Pd/C 10% wt (0.5 equiv.) were taken and stirred under H2 927 cmꢃ1. H NMR (400 MHz, CD3CN): d ¼ 7.91 (d, J ¼ 7.4 Hz,
atmosphere for 4–6 h. The reaction mixture was ltered through 2H), 7.78 (d, J ¼ 8.4 Hz, 2H), 7.68 (t, J ¼ 7.4 Hz, 1H), 7.61 (t, J ¼ 7.8
Celite, washed with EtOAc (2 ꢂ 5 mL) and puried by column Hz, 2H), 7.37–7.30 (m, 3H), 5.12 (s, 1H), 4.93 (s, 1H), 3.61 (t, J ¼
chromatography using 25–50% ethyl acetate in hexane as eluent 4.7 Hz, 4H), 2.99–2.92 (m, 4H). 13C NMR (100 MHz, CD3CN): d ¼
to obtain the pure N0-alkyl sulfonimidamides.
147.0, 141.6, 137.1, 134.4, 130.7, 129.7, 129.5, 129.4, 127.2, 98.6,
4-[S-Phenyl-N0-(phenylvinyl)sulfonimidoyl]morpholine (3a). 67.4, 48.0. HRMS (ESI) calcd for C18H20N2O2S [M + H]+ 329.1318,
White solid, Rf ¼ 0.30 (15% ethyl acetate/hexane), mp 126–127 ꢀC. found 329.1309.
IR (ATR): n ¼ 3061, 2870, 2850, 1630, 1446, 1446, 1257, 1171,
4-[S-Phenyl-N0-(1-cyclohexenyl)sulfonimidoyl]morpholine (3g).
1108, 921 cmꢃ1. 1H NMR (400 MHz, CD3CN): d ¼ 7.91 (d, J ¼ 7.4 White solid, Rf ¼ 0.25 (20% ethyl acetate/hexane), mp 84–85 ꢀC. IR
Hz, 2H), 7.71 (t, J ¼ 7.2 Hz, 1H), 7.6 (t, J ¼ 7.8 Hz, 2H), 7.33 (d, J (ATR): n ¼ 2918, 2852, 1619, 1443, 1253, 1109 cmꢃ1. 1H NMR (400
¼ 7.5 Hz, 2H), 7.27–7.24 (m, 3H), 7.12 (t, J ¼ 7.2 Hz, 1H), 6.23 (d, MHz, CD3CN): d ¼ 7.83 (d, J ¼ 7.2 Hz, 2H), 7.63 (t, J ¼ 7.2 Hz, 1H),
J ¼ 13.6 Hz, 1H), 3.65 (t, J ¼ 4.7 Hz, 4H), 2.95–2.91 (m, 4H). 13
C
7.57 (t, J ¼ 7.5 Hz, 2H), 5.27 (t, J ¼ 3.8 Hz, 1H), 3.61 (t, J ¼ 4.6 Hz,
NMR (100 MHz, CD3CN): d ¼ 139.0, 135.1, 134.1, 130.2, 129.5, 4H), 2.89 (t, J ¼ 4.6 Hz, 4H), 2.21–2.19 (m, 2H), 2.05–2.02 (m, 2H),
129.3, 128.9, 126.6, 125.9, 119.4, 66.8, 47.7. HRMS (ESI) calcd for 1.69–1.63 (m, 2H), 1.56–1.50 (m, 2H). 13C NMR (100 MHz,
C
18H20N2O2S [M + H]+ 329.1318, found 329.1324.
CD3CN): d ¼ 139.3, 136.9, 133.4, 129.9, 128.8, 112.6, 67.0, 47.9,
4-[S-Phenyl-N0-(4-chlorophenylvinyl)sulfonimidoyl]morpho- 31.8, 25.6, 24.2, 23.2. HRMS (ESI) calcd for C16H22N2O2S [M + H]+
line (3b). White solid, Rf ¼ 0.35 (15% ethyl acetate/hexane), mp 307.1474. Found 307.1460.
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4-[S-p-Tolyl-N0-(phenylvinyl)sulfonimidoyl]morpholine (3h).
White solid, Rf ¼ 0.30 (15% ethyl acetate/hexane), mp 98–99 ꢀC.
IR (ATR): n ¼ 2963, 2854, 1624, 1441, 1259, 1105, 920 cmꢃ1. 1H
NMR (400 MHz, CD3CN): d ¼ 7.78 (d, J ¼ 8.2 Hz, 2H), 7.43 (d, J ¼
8.0 Hz, 2H), 7.32 (d, J ¼ 7.5 Hz, 2H), 7.27–7.23 (m, 3H), 7.11 (t, J
¼ 7.3 Hz, 1H), 6.21 (d, J ¼ 13.6 Hz, 1H), 3.64 (t, J ¼ 4.6 Hz, 4H),
2.93–2.89 (m, 4H), 2.44 (s, 3H). 13C NMR (100 MHz, CD3CN): d ¼
145.2, 139.1, 132.0, 130.7, 129.5, 129.4, 129.0, 126.5, 125.8,
119.1, 66.8, 47.7, 21.5. HRMS (ESI) calcd for C19H22N2O2S [M +
H]+ 343.1474, found 343.1468.
4-[S-p-Tolyl-N0-(4-chlorophenylvinyl)sulfonimidoyl]morpholine
(3i). White solid, Rf ¼ 0.35 (15% ethyl acetate/hexane), mp 82–84
ꢀC. IR (ATR): n ¼ 2962, 2917, 2850, 1624, 1255, 916 cmꢃ1. 1H NMR
(400 MHz, CD3CN): d ¼ 7.77 (d, J ¼ 8.3 Hz, 2H), 7.43 (d, J ¼ 8.3 Hz,
2H), 7.30–7.23 (m, 5H), 6.17 (d, J ¼ 13.6 Hz, 1H), 3.64 (t, J ¼ 4.7 Hz,
4H), 2.94–2.88 (m, 4H), 2.43 (s, 3H). 13C NMR (100 MHz, CD3CN):
d ¼ 145.1, 137.9, 131.8, 131.0, 130.6, 130.3, 129.2, 128.9, 127.1,
117.6, 66.6, 47.5, 21.4. HRMS (ESI) calcd for C19H21ClN2O2S [M +
H]+ 377.1085, found 377.1089.
128.7, 126.4, 97.6, 66.7, 47.3, 21.3. HRMS (ESI) calcd for
C19H22N2O2S [M + H]+ 343.1474, found 343.1480.
1-[S-p-Tolyl-N0-(phenylvinyl)sulfonimidoyl]piperidine (3n).
White solid, Rf ¼ 0.40 (15% ethyl acetate/hexane), mp 85–86 ꢀC.
IR (ATR): n ¼ 3061, 3026, 2936, 2850, 1625, 1596, 1446, 1248, 914
cmꢃ1. 1H NMR (400 MHz, CD3CN): d ¼ 7.83–7.81 (m, 4H), 7.45
(d, J ¼ 8.0 Hz, 2H), 7.29 (t, J ¼ 7.6 Hz, 2H), 7.12 (t, J ¼ 7.4 Hz,
1H), 6.64 (d, J ¼ 8.6 Hz, 1H), 5.58 (d, J ¼ 8.5 Hz, 1H), 2.99–2.88
(m, 4H), 2.44 (s, 3H), 1.59–1.54 (m, 4H), 1.42–1.37 (m, 2H). 13
C
NMR (100 MHz, CD3CN): d ¼ 144.8, 138.8, 133.1, 130.6, 129.1,
128.9, 128.7, 128.4, 126.1, 114.3, 48.2, 26.0, 24.1, 21.4. HRMS
(ESI) calcd for C20H24N2OS [M + H]+ 341.1682, found 341.1696.
4-[S-Phenyl)-N0-(4-chlorophenylvinyl)sulfonimidoyl]pyrrolidine
(3o). White solid, Rf ¼ 0.30 (15% ethyl acetate/hexane), mp 78–
1
80 C. IR (ATR): n ¼ 2905, 2849, 1621, 1447, 1291, 918 cmꢃ1. H
ꢀ
NMR (400 MHz, CD3CN): d ¼ 7.96 (d, J ¼ 7.3 Hz, 2H), 7.68 (t, J ¼ 7.4
Hz, 1H), 7.61 (t, J ¼ 7.4 Hz, 2H), 7.31–7.27 (m, 3H), 7.23 (d, J ¼ 8.5
Hz, 2H), 6.13 (d, J ¼ 13.6 Hz, 1H), 3.18 (t, J ¼ 6.6 Hz, 4H), 1.71–1.67
(m, 4H). 13C NMR (100 MHz, CD3CN): d ¼ 138.3, 136.7, 133.8,
131.4, 131.0, 130.1, 129.4, 128.8, 127.1, 117.0, 49.3, 25.9. HRMS
(ESI) calcd for C18H19ClN2OS [M + H]+ 347.0979, found 347.0985.
4-[S-4-Nitrophenyl-N0-(phenylvinyl)sulfonimidoyl]morpholine
(3p). Yellow oil, Rf ¼ 0.30 (20% ethyl acetate/hexane), IR (ATR):
n ¼ 3100, 2919, 2857, 1573, 1349, 970, cmꢃ1. 1H NMR (400 MHz,
CD3CN): d ¼ 8.40 (dt, J ¼ 8.8, 1.8 Hz, 2H), 8.11 (dt, J ¼ 8.8, 1.8 Hz,
2H), 7.35 (d, J ¼ 7.7 Hz, 2H), 7.27 (t, J ¼ 7.5 Hz, 2H), 7.22 (d, J ¼
13.6 Hz, 1H), 7.14 (t, J ¼ 7.2 Hz, 1H), 6.28 (d, J ¼ 13.6 Hz, 1H),
3.66 (t, J ¼ 4.2 Hz, 4H), 3.06–2.96 (m, 4H). 13C NMR (100 MHz,
CD3CN): d ¼ 151.4, 141.2, 138.6, 130.2, 129.4, 128.2, 126.8, 126.0,
125.3, 120.5, 66.7, 47.6. HRMS (ESI) calcd for C18H19N3O4S [M +
H]+ 374.1172, found 374.1169.
4-[S-p-Tolyl-N0-(4-methoxyphenylvinyl)sulfonimidoyl]morpho-
line (3j). White solid, Rf ¼ 0.25 (20% ethyl acetate/hexane) mp
101–103 ꢀC. IR (ATR): n ¼ 2964, 2913, 2856, 1515, 1601, 1250, 1108
cmꢃ1. 1H NMR (400 MHz, CD3CN): d ¼ 7.77 (d, J ¼ 8.2 Hz, 2H),
7.43 (d, J ¼ 8.1 Hz, 2H), 7.25 (d, J ¼ 8.6 Hz, 2H), 7.09 (d, J ¼ 13.7
Hz, 1H), 6.83 (d, J ¼ 8.6 Hz, 2H), 6.16 (d, J ¼ 13.6 Hz, 1H), 3.76 (s,
3H), 3.63 (t, J ¼ 4.6 Hz, 4H), 2.92–2.87 (m, 4H), 2.44 (s, 3H). 13
C
NMR (100 MHz, CD3CN): d ¼ 159.0, 145.1, 132.1, 131.6, 130.6,
129.0, 127.4, 127.0, 118.9, 114.9, 66.8, 55.8, 47.7, 21.5. HRMS (ESI)
calcd for C20H24N2O3S [M + H]+ 373.1580, found 373.1564.
4-[S-p-Tolyl-N0-(2-thienylvinyl)sulfonimidoyl]morpholine (3k).
White solid, Rf ¼ 0.35 (25% ethyl acetate/hexane), mp 126–128 ꢀC.
IR (ATR): n ¼ 2957, 2917, 2864, 2845, 1629, 1592, 1453, 1279,
1108, 921 cmꢃ1. 1H NMR (400 MHz, CD3CN): d ¼ 7.77 (d, J ¼ 8.2
Hz, 2H), 7.43 (d, J ¼ 8.0 Hz, 2H), 7.32–7.30 (m, 1H), 7.20 (d, J ¼ 5.0
Hz, 1H), 7.12 (d, J ¼ 13.6 Hz, 1H), 7.03 (m, 1H), 6.24 (d, J ¼ 13.6
Hz, 1H), 3.64 (t, J ¼ 4.7 Hz, 4H), 2.92–2.88 (m, 4H), 2.44 (s, 3H).
13C NMR (100 MHz, CD3CN): d ¼ 145.2, 140.8, 132.1, 130.7, 129.4,
129.0, 126.9, 125.6, 119.0, 114.2, 66.8, 47.7, 21.5. HRMS (ESI)
calcd for C17H20N2O2S2 [M + H]+ 349.1038, found 349.1044.
4-[S-p-Tolyl-N0-(phenylvinyl)sulfonimidoyl]morpholine (3l).
White solid, Rf ¼ 0.25 (15% ethyl acetate/hexane), mp 109–110 ꢀC.
IR (ATR): n ¼ 3061, 3019, 2902, 2861, 2844, 1620, 1445, 1417,
4-[S-p-Tolyl-N0-(phenylethyl)sulfonimidoyl]morpholine (6a).
Pale yellow oil, Rf ¼ 0.30 (20% ethyl acetate/hexane), IR (ATR): n
1
¼ 2954, 2924, 2852, 1459, 1281, 1256, 930 cmꢃ1. H NMR (400
MHz, CDCl3): d ¼ 7.66 (d, J ¼ 8.3 Hz, 2H), 7.30–7.27 (m, 6H),
7.22–7.17 (m, 1H), 3.58–3.56 (m, 4H), 3.55–3.50 (m, 1H), 3.33–
3.26 (m, 1H), 2.99–2.87 (m, 2H), 2.81–2.76 (m, 2H), 2.60–2.55
(m, 2H), 2.41 (s, 3H); 13C NMR (100 MHz, CDCl3): d ¼ 143.0,
141.0, 132.0, 129.4, 129.2, 128.3, 128.1, 126.1, 66.4, 46.8, 44.1,
39.2, 21.5. HRMS (ESI) calcd for C19H24N2O2S [M + H]+ 345.1637,
found 345.1619.
4-[S-4-Aminophenyl-N0-(phenylethyl)sulfonimidoyl]morpho-
line (6b). Yellow oil, Rf ¼ 0.20 (50% ethyl acetate/hexane) IR
(ATR): n ¼ 3439, 3164, 2944, 1631, 1375, 918, 749; 1H NMR (400
MHz, CDCl3): d ¼ 7.56 (dt, J ¼ 8.7, 1.8 Hz, 2H), 7.28 (d, J ¼ 4.3
Hz, 4H), 7.21–7.17 (m, 1H), 6.66 (dt, J ¼ 8.7, 1.7 Hz, 2H), 4.05 (br,
2H), 3.59–3.57 (m, 4H), 3.55–3.49 (m, 1H), 3.31–3.24 (m, 1H),
2.98–2.88 (m, 2H), 2.81–2.76 (m, 2H), 2.60–2.55 (m, 2H). 13C
NMR (100 MHz): d ¼ 150.5, 140.9, 130.3, 129.2, 128.3, 126.1,
114.1, 66.4, 46.8, 44.2, 39.1. HRMS (ESI) calcd for C18H23N3O2S
[M + H]+ 346.1568, found 346.1584.
1
1273, 1149, 1109, 922 cmꢃ1. H NMR (400 MHz, CD3CN): d ¼
7.84–7.82 (m, 4H), 7.47 (d, J ¼ 8.1 Hz, 2H), 7.30 (t, J ¼ 7.6 Hz,
2H), 7.13 (t, J ¼ 7.3 Hz, 1H), 6.66 (d, J ¼ 8.56 Hz, 1H), 5.63 (d, J ¼
8.6 Hz, 1H), 3.65–3.62 (m, 4H), 2.93–2.87 (m, 4H), 2.46 (s, 3H).
13C NMR (100 MHz, CD3CN): d ¼ 145.3, 138.6, 131.9, 130.7,
129.1, 128.9, 128.9, 127.8, 126.3, 115.0, 66.6, 47.5, 21.4. HRMS
(ESI) calcd for C19H22N2O2S [M + H]+ 343.1474, found 343.1476.
4-[S-p-Tolyl-N0-(1-phenylvinyl)sulfonimidoyl]morpholine (3m).
White solid, Rf ¼ 0.30 (20% ethyl acetate/hexane), mp 89–91 ꢀC.
IR (ATR): n ¼ 3059, 2915, 2853, 1681, 1596, 1441, 1259, 1107, 921
cmꢃ1. 1H NMR (400 MHz, CD3CN): d ¼ 7.80–7.76 (m, 4H), 7.42 (d,
J ¼ 8.1 Hz, 2H), 7.37–7.30 (m, 3H), 5.09 (s, 1H), 4.91 (s, 1H), 3.61 (t,
J ¼ 4.6 Hz, 4H), 2.97–2.93 (m, 4H), 2.43 (s, 3H). 13C NMR (100
MHz, CD3CN): d ¼ 146.4, 144.7, 140.5, 133.3, 130.5, 128.9, 128.8,
Acknowledgements
This work is based on research supported in part by the
National Research Foundation of South Africa (grant number
87706).
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