Sulfated tungstate/dioxygen: A new catalytic system for oxysulfonylation of styrenes to form β-keto sulfones

Article abstract of DOI:10.1039/d0nj01763a

A new system for synthesis of a wide range of β-keto sulfones using sulfated tungstate as a heterogeneous catalyst and oxygen as an environmentally benign oxidant with aryl hydrazides and styrenes as reacting counterparts has been developed. The preliminary experimental results support the involvement of free radical species. Thus, aryl sulfonyl free radicals, generated by oxidation of aryl sulfonyl hydrazides, subsequently undergo a tandem addition to styrenes to form intermediate benzyl free radicals, and oxygen capture and oxidation to furnish β-keto sulfones. The method is mild and efficient with easy workup procedures. The catalyst is recyclable. This journal is

Full text of DOI:10.1039/d0nj01763a

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Sulfated tungstate/dioxygen: A new catalytic system for
oxysulfonylation of styrenes to form β-keto sulfones
Received 00th January 20xx,
Accepted 00th January 20xx
Ganesh Wagha, Snehalata Autadea Raghavendra V. Kulkarni,b Krishnacharya G. Akamanchi*c
DOI: 10.1039/x0xx00000x
www.rsc.org/
Abstract: A new system for synthesis of a wide range of β-keto sulfones using sulfated tungstate as heterogeneous catalyst
and oxygen as an environmentally benign oxidant with reacting counterparts aryl hydrazides and styrenes has been
developed. The preliminary experimental results support the involvement of free radical species. Thus, aryl sulfonyl free
radicals, generated by oxidation of aryl sulfonyl hydrazides, subsequently undergo in tandem addition to styrenes to form
intermediate benzyl free radicals, oxygen capture and oxidation to furnish β-keto sulfones. The method is mild, efficient
with easy workup procedures. The catalyst is recyclable.
keto sulfones. β-Keto sulfides or β-hydroxy sulfones, have been
oxidized directly to give β-keto sulfones,26, 27 however, draw back of
Introduction
Sulfones are an important class of organic compounds useful as
intermediates in organic synthesis1-6 and in medicinal chemistry
displaying diverse biological activities.7-10 Sulfones as intermediates
these methods are need of stoichiometric amounts of high
molecular weight oxidizing agents such as IBX, potassium hydrogen
persulfate resulting in large out put of effluents. Oxidative coupling
of ketones and sulfinates in presence of different oxidizing agents are
also known for synthesis of β-keto sulfones. For example, synthesis
of β-keto sulfones via in situ generated α-tosyloxy ketones by the
reaction between ketone and sodium sulfinates employing
hypervalent iodine compound [hydroxy(tosyloxy)iodo]benzene
(HTIB) as oxidant.28 Drawbacks of this method is use of expensive and
high molecular weight oxidizing agent in stoichiometric amounts,
with moderate yields.
can be converted into
alkenes, alkynes, chalcones, 2,3-
dihydrofurans, 1,2,3-triazoles, pyrroles, and 4H-pyrans.11-20 Among
sulfones β-keto sulfones, with active methylene groups, are versatile
intermediates and amenable for transformations such as alkylations,
acylations, conjugate additions, and condensations. Additionally, β-
keto sulfones are precursors for optically active β-hydroxy sulfones
which serve as chiral synthons.21 Therefore expectedly, β-keto
sulfones have received much attention towards development of new
synthetic methods to access them. There are several methods for
synthesis of β-keto sulfones. Generally considered methods for
synthesis include alkylation of sodium sulfinate salts with α-halo
ketones,22 and acylation of alkyl sulfones with carboxylic acid
derivatives such as acid chlorides, esters or N-acyl benzotriazoles.23-
Recently sulfonyl free radical mediated reactions with alkenes,29-36
activated alkene37-41 and alkynes42-45 to form β-keto sulfones have
generated considerable interest. Oxysulfonylation of alkenes has
been developed as a valuable strategy for the synthesis of β-keto
sulfones. For example, copper-catalyzed air oxidation of alkenes with
sulfonylhydrazides by Wei and Wang,31 and potassium persulfate
(K2S2O8)-mediated oxysulfonylations of simple alkenes in aqueous
sodium arenesulfinates in the presence of O2 by Yadav and
coworkers.32 Yadav and coworkers subsequently, reported two more
systems for oxysulfonations employing AgNO3 as catalyst; the first
25
Many oxidative methodologies are reported for synthesis of β-
A Department of Pharmaceutical Sciences and Technology, Institute of Chemical
Technology, Matunga, Mumbai 400019, India. B BLDEA’s SSM College of Pharmacy &
Research Centre, Vijayapur, India 586 103. c Department of Allied Health Sciences, Shri
B.M. Patil Medical College,Hospital and Research Centre, BLDE Deemed to be
University, Vijayapur, India 586 103
†. Electronic Supplementary Information (ESI) available: [The copies of 1H and 13C
NMR spectra for compounds 3a-3n, 5a-5k, 6 and 7]. See DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
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with thiophenols as the sulphur source in the presence of a reactions, N-formylation, transamidation, N-monoalkylation
View Article Onlionef
combination of air/ K2S2O8 as oxidants33 and the second with sodium primary amines, etherification, synthesisDOoI:f10a.1m03id9/inDe0sN,J0117,36,35A-
arenesulfinates using K2S2O8 as oxidant.34 Liu and co-workers triarylbenzenes,64 and formation of triazoles.65 It is pertinent to
disclosed CF3COOH-promoted oxysulfonylation of alkenes with mention here that is the success of sulfated tungstate as catalyst in
sulfonyl hydrazides in the presence of O2 under elevated amidation,66 trans-amidation67 trans-uridation68
temperature.35 Use of nonrecyclable and
environtmetally transformations involving amines as nucleophiles is attributed to its
problamatic heavy metal catalysts is the major draw back of these mild acidity. Due to mild acidity the amine substrates were spared
methods. from strongly binding with the catalyst. In continuation of our
and other
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Suitability of HBr/DMSO as oxidation system for the synthesis of β- explorations and expand utility of sulfated tungstate, as catalyst
keto sulfones from ketones and sodium sulfinates has been particularly in oxidative transformations, herein we disclose a new
explored46. However, shortcomings of this method are use of highly application for oxysulfonation of styrenes towards synthesis of β-
corrosive HBr as activator and formation toxic dimethyl sulfide as by keto sulfones.
product.
Results and discussion
Dioxygen is an environmentally benign and cost-effective oxidant.
From a green and sustainable chemistry point of view, direct
oxidative functionalizations of organic molecules utilizing dioxygen is
For preliminary investigations styrene 1a and tosyl hydrazide 2a were
chosen as model substrates. The investigations included screening
of sulfated tungstate and related substances for catalysis, study of
reaction parameters such as solvent, catalyst loading, reaction
temperature, time and few control experiments. and . The study
results are presented in Table 1.
an attractive option in organic synthesis especially for oxygen-
48
containing molecules.47,
Strategies utilizing metal-catalyzed
50
oxidative difunctionlizations such as dioxygenation49,
amino
oxygenation,51 oxyalkylation,52 oxyphosphorylation,53-55 and
57
oxysulfonylation56,
of alkenes or alkynes to form oxygenated
compounds have emerged as very useful alternative. However all
these metal-catalyzed reactions are conducted under homogeneous
conditions presenting issue of catalyst recoveries and recycle. There
are significant advancements in heterogeneous metal catalyzed
transformations for synthesis of fine chemicals and functional
materials owing to their advantages such as high efficiency,
robustness, easy recovery and high potential for recycle.
Experiments were conducted employing sulfated tungstate and
related substances such as sodium tungstate, tungsten trioxide, as
catalysts and oxygen as oxidant. All the three substances were found
to be viable as catalysts (Table 1, entries 1-3). and sulfated tungstate
emerged as superior catalyst furnishing 3a in the highest yield of 88
% in 16 h (Table 1, entry 1). Whereas, sodium tungstate and tungsten
trioxide were noticeably inferior giving 3a in low yields of 60 % and
32 % respectively even with extended reaction time of 24 h (Table 1,
entries 2 and 3). Hydrogen peroxide was explored as alternative
oxidant with the superior catalyst sulfated tungstste. However
hydrogen peroxide was found to be less efficient giving lower yield
of 72 % yield of 3a (Table 1, entry 4). Noticeable observation was
sulfated tungstate got completely dissolved in the reaction medium
as the reaction progressed the forming a homogeneous solution and
could not be recovered by precipitation during the workup either
indicating decompostion of the catalyst. An experiment, performed
by substituting dioxygen by air, furnished 3a in low yield of 54 %
(Table 1, entry 5). To evaluate impact of solvent polarity, reactions
were carried out at 100 °C and for 24 h in both nonpolar and polar
Tungstates have high affinity for oxygen and show high efficacy in
utilisation of peroxides in variety of oxidative transformations
including oxidations of alcohols,58, 59 sulfides60 cyclohexene to adipic
63
acid,61 and amines to nitrones.62, In all these transformations
tungstate-peroxide complex is an active species and the reactions are
performed using aqueous hydrogen peroxide under phase transfer
catalysis conditions. Major challenge here in these reactions is
prevention of the active tungsten species from leaching out.
Recently our group has introduced sulfated tungstate as
heterogeneous mild solid acid catalyst. Its attractive features such as
mildness, high efficiency, and robustness motivated us to explore its
applications resulting in achievement of variety of transformations
including Ritter, Biginelli, Kindler, Strecker, Willgerodt–Kindler
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solvents respectively. Yields were low in all cases, however, an An experiment was performed in the absence of the catalyst. The
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DOI: 10.1039/D0NJ01763A
interesting trend of increase followed by decrease in yields from 28 reaction was extremely slow giving just 10 % yield even after reflux
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8
% to 64% to 55 % was observed in going from toluene to dioxane to for 24 h. (Table 1, entry 13). This conclusively proved that sulfated
DMSO respectively (Table 1, entries 6-8). The high yield of 88 % of 3a tungstate acts as catalyst. A control experiment conducted under
in the reaction performed in MeCN as solvent conforms to this trend nitrogen atmosphere and in absence of dioxygen failed to yield 3a
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(Table 1, entry 1).
(Table 1, entry 14). This outcome indicated the necessity of dioxygen
to effect the transformation. Based on all these preceding
investigations, the reaction conditions: 10 wt % catalyst loading,
MeCN as a solvent, reflux temperature, oxygen atmosphere and
reaction time of 14 h were considered as optimum and adopted for
further studies.
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Table 1: Optimization of reaction conditions.a
Entry
Catalyst (wt. %)
Oxidant
Solvent
Temp.
(oC)b
Time
(h)
Yield
(%)c
The substrate scope was studied with series of substituted styrenes
as well as sulfonyl hydrazides. First, oxysulfonylation of differently
substituted styrenes was investigated with tosyl hydrazine 2a. As
mentioned in Table 2, a range of styrenes with electron rich
substituents at different positions such as p-methyl, o-methyl, m-
methyl, p-tert-butyl, and p-methoxy were studied and in all cases
reactions occurred smoothly giving good yields of β-keto sulfones
3b-3f respectively. Halogen substituted styrenes also performed
well under the standard reaction conditions furnishing
corresponding halo-substituted β-keto sulfones 3g-3i in moderate to
good yields. The electron withdrawing group in 4-cyanostyrene did
not show any impact. The reaction was smooth with yield of β-keto
sulfones 3j falling in the same range. Both polycyclic and internal
alkenes 2-vinylnaphthalene and 2’-methylstyrene reacted with ease
yielding corresponding products 3k and 3l in 67 % and 73 %
respectively. To assess the scope of the methodology with the
sulfonylhydrazide counterpart phenyl, and differently substituted
phenyl, and 2-thenyl sulfonylhydrazides were investigated. Among
the substrates reaction between phenylsulfonyl hydrazide and
styrene 1a gave product 3m in 86 % whereas in all other cases the
substitution had marginal impact and yields of β-keto sulfones 3n-3t
were within 70±5 %. The reaction also works well with heterocyclic
sulfonyl hydrazide such as 2-thienylsulfonyl hydrazide giving
moderate yield of 68 %. In conclusion, the investigations with variety
of substrates established general applicability of the developed
methodology.
1
2
Sulfated tungstate (10 %)
Sodium tungstate (10 %)
Tungstan trioxide (10 %)
Sulfated tungstate (10 %)
Sulfated tungstate (10 %)
Sulfated tungstate (10 %)
Sulfated tungstate (10 %)
Sulfated tungstate (10 %)
Sulfated tungstate (5 %)
Sulfated tungstate (25 %)
Sulfated tungstate (10 %)
Sulfated tungstate (10 %)
--
O2
O2
MeCN
MeCN
MeCN
MeCN
MeCN
toluene
dioxane
DMSO
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
reflux
reflux
reflux
reflux
reflux
100
16
24
24
24
24
24
24
24
16
16
24
14
16
24
88
60
3
O2
32
4
H2O2
air
72d
54
5
6
O2
28
7
O2
100
64
8
O2
100
55
9
O2
reflux
reflux
r.t
62
10
11
12
13
14
O2
89e
20
O2
O2
reflux
reflux
reflux
88
O2
10
Sulfated tungstate (10 %)
N2
N.Df
a
Reaction conditions: 1a (1 mmol) , 2a (1.2 mmol), solvent (7 mL). b heating in waterbath.
C isolated yield. d 3 equivalent of 30% H2O2. e Solvent (15 mL). f N.D = Not detected.
The catalyst loading was optimized by carrying out reactions by both
decreasing and increasing the catalyst loading. Reactions with
catalyst loading decreased to 5 % and increased to 25 % gave 3a in
62% (Table 1, entry 9) and 89 % (Table 1, entry 10) yields respectively;
a significantly lower and no significant improvement over standard
yield of 88 % with 10 % loading.
experiments were performed. To collect information on effect of
temperature an experiment was conducted at reaction
Few general and control
temperature. The reaction rate was very slow and furnished 3a in just
20 % yield in 24 h (Table 1, entry 11). Similarly a reaction was
performed for a shorter reaction time of 14 h and the yield remained
same at 88 % (Table 1, entry 12).
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Table 2: Synthesis of β-keto sulfones using differently substituted
styenes and arylsulfonyl hydrazide 2a.a
Recyclability of the catalyst was tested on the modeVl ireewaAcrttiicolenO.nFlioner
DOI: 10.1039/D0NJ01763A
recycle the catalyst was recovered by diluting the reaction mass by
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O
O
O
O
adding ethyl acetate followed by filtration, washing and heating in
an oven at 120 °C for 1 h to remove solvent and moisture.
S
S
O
O
3a (88%) 14h
8
3b (85%) 14h
9
O
O
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S
O
3c (81%) 15h
Figure 1: Recyclability study of the catalyst.
88
88
86
86
84
83
100
50
0
O
O
O
O
S
S
O
O
3d (72%) 18h
3e (76%) 14h
O
O
O
O
S
S
O
O
fresh cycle 1 cycle 2 cycle 3 cycle 4 cycle 5
catalyst cycle
O
Cl
3f (82%) 16h
3g (68%) 16h
O
O
O
O
S
S
The recovered catalyst was reused several times and the results are
given in Figure 1. It can be seen that the catalyst was reusable at
least five times without any significant loss in activity as judged by
recovery of the product with marginal drop in yield from 88 % to 83
% with fresh and the fifth recycle, respectively.
O
O
F
Br
3h (77%) 16h
3i (75%) 16h
O
O
O
O
S
S
O
O
NC
3j (71%) 18h
3k (67%) 16h
There are similar reaction systems in literature for oxysulfonation of
styrenes using combination of sulfonyl hydrazides and dioxygen in
presence of a catalyst. Those systems are compiled in Table 3.
Comparing the systems on different matrices such as recovery, and
re-usability, environmental benign nature, mildness, and non-
corrosive nature of the catalyst, the present system shows distinct
advantages.
O
O
O
O
O
O
S
S
S
O
O
O
3l (73%) 17h
3n (68%) 18h
3m (86%) 14h
O
O
O
O
S
S
O
O
3p (65%) 16h
3o (70%) 15h
F
O
O
O
Table 3. Oxysulfonation of styrenes using of aryl sulfonyl hydrazide
as aryl sulfonyl free radical precursor and dioxygen as oxidant.
O
O
S
S
O
O
Entry
Reaction
Yield
(%)
Reference
Environmental consideration/
drawbacks
3r (71%) 16h
3q (68%) 15h
Br
conditions
Cl
O
O
O
O
S
S
1
50-72
31
Cu(OAc)2,
Homogeneous, nonrcoverable,
O
O
70 °C
nonrecyclable, transition metal catalyst
3t (75%) 16h
3s (73%) 16h
2
67-85
51-90
35
69
CF3COOH,
Homogeneous catalysis, with corrosive
nonrecyclable acid,
O
O
70 °C
S
S
O
3a
TBAB,
TBHP,
60 °C
Nonrecoverable, Nonrecyclable.
difficult to separate catalyst, hazardous
reagent
3u (68%) 18h
Reagent and conditions: styrenes (1 equiv.), arylsulfonyl hydrazide (1.2 equiv.), sulfated tungstate (15
wt.%), Acetonitrile as solvent. a Isolated yield after column chromatography.
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4
65-88
This work
Sulfated
tungstate,
MeCN,
reflux
Heterogeneous easily recoverable,
recyclable, environmentally
benign catalyst
aTBAB - tetrabutyl ammonium bromide, TBHP - t-butylhydroperoxide.
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Towards getting mechanistic insight some control experiments were
performed. An experiment, carried out in presence of radical
scavenger such as 2, 2, 6, 6-tetramethylpiperidine 1-oxyl (TEMPO)
yield the desired product suggesting involvement of free radical
intermediate.
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Scheme 1: Reaction in presence of TEMPO.
A tentative mechanism is presented in Figure 2. This mechanism is
consistent with literature precedence on catalytic activity of sodium
tungstate in oxidation reactions using hydrogen peroxide, many
reports on 18O2 studies establishing, in oxysulfonylation reactions
using sulfonylhydrazide/ dioxygen systems, dioxygen as the source
of oxygen in the product,29,31,33,34 and the result of the control
experiments. In presence of oxygen, tungstate forms
bisperoxytungstate A a fairly active species towards nucleophiles.60
Conclusion:
In summary, a new free radical mediated oxidation system consisting
of sulfated tungstate as heterogeneous catalyst and environmentally
benign oxygen as oxidant has been successfully introduced for
synthesis of β -keto sulfones. The new catalytic oxidation system
shows wide substrate scope under mild conditions. The work up
procedure is simple, the catalyst can be easily recovered and
recycled. This disclosure may trigger development of many
innovative methodologies based on free radical mediated
environmentally friendly, safe, oxidative transformations.
The nucleophile, arylsulfonyl hydrazide attacks onto
A and
undergoes oxidation to form the aryl sulfonyldiazine I. The
sulfonyldiazine I on further oxidation in presence dioxygen produces
arylsulfonyl radical II by loss of nitrogen and hydroperoxide radical.
Arylsulfonyl radical II in tandem adds on to styrene to form
resonance stabilised benzyl radical III, reacts with dioxygen to form
benzylperoxy radical IV, couples with the hydroperoxide radical
(HOO·) to form a monoalkyl tetroxide V, and finally Russell
fragmentation to afford β-keto sulfones with formation of molecular
oxygen and water.29, 70, 71
General methods
All chemicals were of reagent grade, procured from M/s. S. D. Fine
Chemicals, M/s. Loba Chemie, India, M/s. Avra Synthesis Pvt Ltd, India,
Sigma-Aldrich Chemicals Pvt Ltd., India and used as received without further
purification. All 1H NMR and 13C NMR spectra were recorded on Agilent
FTNMR 400 or 500 MHz and 101 or 126 MHz spectrophotometers
respectively. Chemical shift values are expressed in δ units relative to
tetramethylsilane (TMS) signal as an internal reference standard in CDCl3. The
following abbreviations are used for the multiplicities: s, singlet; d, doublet;
dd, doublet of doublet; ddd, doublet of doublet of doublet; t, triplet; q,
Figure 2: Postulated reaction mechanism.
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quadruplet; m, multiplet; dt, doublet of triplet; br, broad; for proton spectra, δ 7.73 (dd, J = 15.7, 6.9 Hz, 4H), 7.44 – 7.30 (m, 4H), 4.68 (s, 2H), 2.40 (d, J
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DOI: 10.1039/D0NJ01763A
coupling constants (J) are reported in hertz (Hz). Melting points were recorded = 17.5 Hz, 6H).
on THERMONIK-Campbell Melting Point apparatus-Instrument having an oil 13C NMR (101 MHz, CDCl3) δ 188.26, 145.30, 138.70, 135.71, 135.13,
heating system with stirring and are uncorrected. Purification of compounds 129.78, 129.67, 128.69, 128.60, 126.62, 63.53, 21.69, 21.29.
was carried out by column chromatography using Silica gel #100-200 as
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stationary phase. Aryl sulfonyl hydrazides were procured from local suppliers, 1-(2-tolyl)-2-(4-tosyl)ethan-1-one (3d)
White solid, mp 103-105 °C (Lit46 104-106 °C), 1H NMR (400 MHz,
CDCl3) δ 7.77 (m, J = 15.0, 7.5 Hz, 4H), 7.48 – 7.24 (m, 4H), 4.67 (s, 2H),
2.47 – 2.38 (m, 6H).
M/s. Loba Chemie, India, M/s. Avra Synthesis Pvt Ltd, India, Sigma-Aldrich
Chemicals Pvt Ltd., India.
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13C NMR (101 MHz, CDCl3) δ 188.26, 145.30, 138.70, 135.71, 135.13,
129.78, 129.67, 128.69, 128.60, 126.62, 63.53, 21.69, 21.29.
Typical Procedure for synthesis of ß-keto sulfones using sulfated tungstate/ O2
system
1-(4-(tert-butyl)phenyl)-2-(4-tosyl)ethan-1-one (3e)
White solid, mp 94-96 °C (Lit46 95-97 °C), 1H NMR (400 MHz, CDCl3) δ
7.86 (d, J = 8.4 Hz, 2H), 7.74 (d, J = 8.2 Hz, 2H), 7.74 (d, J = 8.2 Hz, 2H),
7.47 (d, J = 8.3 Hz, 2H), 7.31 (d, J = 7.9 Hz, 2H), 4.67 (s, 2H), 2.42 (s, 3H),
1.32 (s, 9H).
A stirred mixture of styrene (0.5 mmol), aryl sulfonyl hydrazide (0.6 mmol)
and 10 wt % of sulfated tungstate in 7 mL of acetonitrile under oxygen
atmosphere was refluxed for the specified time. Progress of the reaction was
monitored by TLC using hexane/EtOAc as a mobile phase. After completion
of the reaction the, reaction mass was diluted with 10 mL of ethyl acetate and
the catalyst was filtered, washed with ethyl acetate (2 x 10 mL) (catalyst was
dried in an oven at 120 °C for 1 h for recycle study). The filtrate was
concentrated under reduced pressure to obtained a residue. To this residue were
added water (15 mL) and ethyl acetate (15 mL) and stirred. Organic phase was
separated, dried over anhydrous sodium sulfate and concentrated under
reduced pressure. The resulting crude product was purified by column
chromatography [silica gel (#100-200); hexane/EtOAc (4:1)] to afford an
analytically pure β-keto sulfones.
13C NMR (101 MHz, CDCl3) δ 187.59, 158.34, 145.24, 133.20, 129.76,
129.33, 128.58, 125.81, 63.51, 35.26, 30.96, 21.69.
1-(4-methoxyphenyl)-2-(4-tosyl)ethan-1-one (3f)
White solid, mp 123-124 °C (Lit28 124-124.8 °C), 1H NMR (400 MHz,
CDCl3) δ 7.92 (d, J = 8.8 Hz, 2H), 7.73 (d, J = 8.0 Hz, 2H), 7.31 (d, J = 7.9
Hz, 2H), 6.92 (d, J = 8.8 Hz, 2H), 4.64 (s, 2H), 3.86 (s, 2H), 2.42 (s, 3H).
13C NMR (101 MHz, CDCl3) δ 186.30, 164.51, 145.23, 135.76, 131.90,
129.76, 128.92, 128.54, 114.03, 63.55, 55.59, 21.69.
Typical procedure for radical trapping experiment:
1-(4-chlorophenyl)-2-(4-tosyl)ethan-1-one (3g)
To a stirred mixture of styrene (0.5 mmol), tosylsulfonyl hydrazide (0.6 mmol),
sulfated tungstate (10 wt %) in 10 mL of acetonitrile under oxygen atmosphere
was added TEMPO (2 mmol) and refluxed for 24 h. Even after 24 h, formation
of desired product 3a was not observed.
White solid, mp 133-134 °C (Lit28 135.7-136.5 °C), 1H NMR (400 MHz,
CDCl3) δ 7.89 (d, J = 7.8 Hz, 2H), 7.73 (d, J = 7.6 Hz, 2H), 7.44 (d, J = 7.9
Hz, 2H), 7.33 (d, J = 7.5 Hz, 2H), 4.69 (s, 2H), 2.44 (s, 3H).
13C NMR (101 MHz, CDCl3) δ 187.03, 145.56, 141.07, 135.49, 134.03,
30.77, 129.89, 129.18, 128.53, 63.69, 21.72.
Spectral data
1-phenyl-2-(4-tosyl)ethan-1-one (3a)
1-(4-bromophenyl)-2-(4-tosyl)ethan-1-one (3h):-
White solid, mp 103-104 °C (Lit72 105-107 °C), 1H NMR (400 MHz, CDCl3)
δ 7.91 (d, J = 7.5 Hz, 2H), 7.74 (d, J = 8.0 Hz, 2H), 7.59 (t, J = 7.2 Hz, 1H),
7.45 (t, J = 7.6 Hz, 2H), 7.33 – 7.28 (m, 2H), 4.70 (s, 2H), 2.41 (s, 3H).
13C NMR (101 MHz, CDCl3) δ 188.11, 145.32, 135.74, 134.26, 130.06,
129.79, 129.28, 128.79, 128.56, 63.55, 21.66.
White solid, mp 143-145 °C (Lit75 145-147 °C), 1H NMR (400 MHz, CDCl3)
δ 7.79 (d, J = 8.2 Hz, 2H), 7.72 (d, J = 7.9 Hz, 2H), 7.60 (d, J = 8.1 Hz, 2H),
7.32 (d, J = 7.8 Hz, 2H), 4.65 (s, 2H), 2.43 (s, 3H).
13C NMR (101 MHz, cdcl3) δ 187.23, 145.54, 135.48, 134.43, 132.17, 130.79,
129.92, 129.88, 128.52, 63.67, 21.71.
1-(4-fluorophenyl)-2-(4-tosyl)ethan-1-one (3i)
1-(4-tolyl)-2-(4-tosyl)ethan-1-one (3b)
White solid, mp 133-134 °C (Lit28 133.9-135 °C),1H NMR (400 MHz, CDCl3)
δ 7.98 (dd, J = 8.6, 5.3 Hz, 1H), 7.84 – 7.57 (m, 3H), 7.32 (d, J = 8.0 Hz, 2H),
7.14 (t, J = 8.5 Hz, 2H), 4.66 (s, 2H), 2.43 (s, 3H).
White solid, mp 114-117 °C (Lit73 114-116 °C), 1H NMR (400 MHz, CDCl3)
δ 7.83 (d, J = 8.2 Hz, 2H), 7.73 (d, J = 8.2 Hz, 2H), 7.31 (d, J = 7.9 Hz, 2H),
7.26 (d, J = 8.3 Hz, 2H), 4.67 (s, 2H), 2.41 (d, J = 7.0 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 187.62, 145.54, 145.27, 135.71, 133.31,
129.77, 129.51, 129.48, 128.56, 63.53, 21.76, 21.69.
13C NMR (101 MHz, CDCl3) δ 186.53, 167.72, 166.66, 145.50, 135.53,
132.29, 132.19, 130.79, 129.86, 128.52, 116.18, 115.96, 63.71, 21.70.
4-(2-(4-tosyl)acetyl)benzonitrile (3j)
1-(3-tolyl)-2-(4-tosyl)ethan-1-one (3c)
White solid, mp 114-117 °C (Lit46 115-116 °C), 1H NMR (400 MHz, CDCl3)
White solid, mp 82-84 °C (Lit73 82-84 °C) 1H NMR: (400 MHz, CDCl3)
6 | J. Name., 2012, 00, 1-3
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δ 8.05 (d, J = 8.2 Hz, 2H), 7.77 (d, J = 8.2 Hz, 2H), 7.71 (d, J = 8.1 Hz, 2H),
7.34 (d, J = 7.9 Hz, 2H), 4.70 (s, 2H), 2.44 (s, 3H).
View Article Online
DOI: 10.1039/D0NJ01763A
2-((4-methoxyphenyl)sulfonyl)-1-phenylethan-1-one (3q)
13C NMR (101 MHz, CDCl3) δ 187.14, 145.81, 138.49, 135.31, 132.58,
129.99, 129.75, 128.48, 117.56, 117.42, 63.85, 21.73.
White solid, mp 102-104 °C (Lit79 105-106 °C), 1H NMR (400 MHz, CDCl3)
δ 7.92 (d, J = 7.3 Hz, 2H), 7.78 (d, J = 8.2 Hz, 2H), 7.58 (d, J = 6.8 Hz, 1H),
7.46 (d, J = 7.1 Hz, 2H), 6.96 (d, J = 8.1 Hz, 2H), 4.70 (s, 2H), 3.85 (s, 3H).
13C NMR (101 MHz, CDCl3) δ 188.31, 164.10, 134.28, 131.80, 130.83,
129.28, 128.81, 125.65, 114.34, 63.68, 55.69.
1-(naphthalen-2-yl)-2-(4-tosyl)ethan-1-one (3k)
White solid, mp 143-145 °C (Lit73 140-143 °C), 1H NMR (400 MHz, CDCl3)
δ 8.43 (s, 1H), 7.95 (d, J = 8.5 Hz, 2H), 7.90 – 7.83 (m, 2H), 7.75 (d, J = 8.1
Hz, 2H), 7.59 (dt, J = 25.2, 7.3 Hz, 2H), 7.30 (d, J = 7.9 Hz, 2H), 4.82 (s,
2H), 2.39 (s, 3H).
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2-((4-fluorophenyl)sulfonyl)-1-phenylethan-1-one (3r)
White solid, mp 148-150 °C (Lit78 148-150 °C),1H NMR (400 MHz, CDCl3)
δ 7.90 (ddd, J = 7.0, 6.1, 3.3 Hz, 1H), 7.61 (t, J = 7.4 Hz, 1H), 7.47 (t, J = 7.7
Hz, 1H), 7.23 (d, J = 9.3 Hz, 1H), 7.18 (d, J = 8.6 Hz, 1H), 4.72 (s, 1H).
13C NMR (101 MHz, CDCl3) δ 187.94, 167.37, 164.81, 135.58, 134.47,
131.67, 131.57, 129.20, 128.89, 116.61, 116.38, 63.41.
13C NMR (101 MHz, CDCl3) δ 187.97, 145.37, 135.97, 133.07, 132.24,
132.16, 129.93, 129.81, 129.32, 128.78, 128.62, 127.76, 127.08, 123.92,
63.77, 21.66.
1-phenyl-2-(4-tosyl)propan-1-one (3l)
2-((4-chlorophenyl)sulfonyl)-1-phenylethan-1-one (3s)
White solid, mp 130-132 °C (Lit78 131.5-132.5 °C),1H NMR (400 MHz,
CDCl3) δ 7.91 (dd, J = 8.4, 1.1 Hz, 2H), 7.81 (d, J = 8.7 Hz, 2H), 7.61 (d, J =
7.4 Hz, 1H), 7.54 – 7.44 (m, 4H), 4.72 (s, 2H).
White solid, mp 101-102 °C (Lit76 97-100 °C), 1H NMR (400 MHz, CDCl3)
δ 8.12 – 7.79 (m, 2H), 7.66 (s, 2H), 7.62 – 7.57 (m, 1H), 7.47 (t, J = 7.8 Hz,
2H), 7.30 (d, J = 8.1 Hz, 2H), 5.16 (q, J = 6.9 Hz, 1H), 2.43 (s, 3H), 1.55 (d,
J = 6.9 Hz, 3H).
13C NMR (101 MHz, CDCl3) δ 187.84, 141.09, 137.04, 135.55, 134.50,
130.14, 129.49, 129.21, 128.91, 63.32.
13C NMR (126 MHz, CDCl3) δ 192.65, 145.38, 136.27, 134.04, 132.92,
129.85, 129.55, 129.21, 128.75, 64.98, 21.71, 13.24.
2-((4-bromophenyl)sulfonyl)-1-phenylethan-1-one (3t)
1-phenyl-2-(phenylsulfonyl)ethan-1-one (3m)
White solid, mp 122-124 °C (Lit79 122-123 °C), 1H NMR (400 MHz, CDCl3)
δ 7.91 (dd, J = 8.4, 1.1 Hz, 2H), 7.74 (d, J = 8.7 Hz, 2H), 7.67 (d, J = 8.7 Hz,
2H), 7.62 (t, J = 7.4 Hz, 1H), 7.47 (t, J = 7.8 Hz, 2H), 4.71 (s, 2H).
13C NMR (101 MHz, CDCl3) δ 187.82, 137.59, 135.54, 134.51, 132.48,
130.17, 129.74, 129.20, 128.91, 63.28.
White solid, mp 92-93 °C (Lit77 92-93 °C), 1H NMR (400 MHz, CDCl3) δ
7.89 (dd, J = 13.5, 7.3 Hz, 4H), 7.73 – 7.43 (m, 6H), 4.71 (s, 2H).
13C NMR (101 MHz, CDCl3) δ 187.92, 134.36, 134.22, 129.46, 129.26,
129.18, 128.84, 128.76, 128.56, 63.42.
2-(phenylsulfonyl)-1-(2-tolyl)ethan-1-one (3n)
1-phenyl-2-((thiophen-2-yl)sulfonyl)ethan-1-one (3u)
Yellow solid80, mp 102-104 °C, 1H NMR (400 MHz, CDCl3) δ 7.93 (d, J =
7.5 Hz, 2H), 7.72 (d, J = 4.1 Hz, 1H), 7.69 (m, 1H), 7.60 (d, J = 7.0 Hz, 1H),
7.47 (t, J = 7.4 Hz, 2H), 7.15 – 7.06 (m, 1H), 4.83 (s, 2H).
13C NMR (101 MHz, CDCl3) δ 187.87, 135.51, 135.05 , 134.48, 129.21,
128.91, 127.96, 64.28.
White solid, mp 69-71 °C (Lit46 68-69 °C), 1H NMR: (400 MHz, CDCl3)
δ 7.85 (d, J = 7.4 Hz, 2H), 7.74 – 7.59 (m, 4H), 7.52 (t, J = 7.7 Hz, 2H), 7.39
(d, J = 7.4 Hz, 1H), 4.73 (s, 2H), 2.38 (s, 3H).
13C NMR: (101 MHz, CDCl3) δ 190.31, 140.05, 138.87, 135.57, 134.14,
132.83, 132.30, 130.33, 129.18, 128.44, 125.91, 65.43, 21.54.
2-(phenylsulfonyl)-1-(3-tolyl)ethan-1-one (3o)
White solid78, mp 110-112 °C, 1H NMR: (400 MHz, CDCl3) δ 7.88 (d, J = 7.5
Hz, 2H), 7.71 (d, J = 8.9 Hz, 2H), 7.65 (t, J = 7.4 Hz, 1H), 7.53 (t, J = 7.8 Hz,
2H), 7.41 (d, J = 7.6 Hz, 1H), 7.34 (t, J = 7.5 Hz, 1H), 4.71 (s, 2H), 2.38 (s,
3H).
Acknowledgement:
The authors Ganesh Wagh and Snehalata Autade are thankful to
UGC-CSIR and UGC-SAP respectively for financial support.
13C NMR: (101 MHz, CDCl3) δ 188.09, 138.75, 138.68, 135.69, 135.20,
134.19, 129.63, 129.15, 128.72, 128.58, 126.57, 63.38, 21.30.
Conflict of Interest: The authors declare no financial conflict of
1-(naphthalen-2-yl)-2-(phenylsulfonyl)ethan-1-one (3p)
White solid, mp 152-154 °C (Lit78 151-154 °C), 1H NMR (400 MHz, CDCl3)
δ 8.45 (s, 1H), 8.00 – 7.84 (m, 6H), 7.58 (ddd, J = 23.4, 15.3, 7.3 Hz, 5H),
4.85 (s, 2H).
interest.
References and Notes:
13C NMR (101 MHz, CDCl3) δ 187.80, 136.01, 134.23, 132.25, 132.14,
129.94, 129.48, 129.37, 129.19, 128.82, 128.60, 128.29, 127.77, 127.12,
126.74, 125.38, 123.87, 63.61.
1.
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163x47mm (300 x 300 DPI)