Regio- and stereoselective syntheses of allylic thioethers under metal free conditions

Article abstract of DOI:10.1039/c7ra04817c

A metal free, regio and stereoselective syntheses of allylic thioethers using allyl iodides and aryl or alkyl disulfides as coupling partners is described. The densely functionalized allyl iodides having different stereochemistry (E & Z) reacted well with a variety of disulfides in a regio and stereoselective manner providing the resulting allyl aryl thioethers in 62-92% yields.

Full text of DOI:10.1039/c7ra04817c

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Regio- and stereoselective syntheses of allylic
thioethers under metal free conditions†
Cite this: RSC Adv., 2017, 7, 30594
Pratibha Singh,‡ Rekha Bai,‡ Rakhee Choudhary,‡ Mahesh C. Sharma
*
and Satpal Singh Badsara
Received 29th April 2017
Accepted 8th June 2017
A metal free, regio and stereoselective syntheses of allylic thioethers using allyl iodides and aryl or alkyl
disulfides as coupling partners is described. The densely functionalized allyl iodides having different
stereochemistry (E & Z) reacted well with a variety of disulfides in a regio and stereoselective manner
providing the resulting allyl aryl thioethers in 62–92% yields.
DOI: 10.1039/c7ra04817c
rsc.li/rsc-advances
via C–S bond formation between densely functionalized allyl
iodides and disuldes under metal free conditions (Scheme 2).
Introduction
Due to environmental concerns and cost issues, the metal-free
organic transformations are in great need. Enough progress
has been made in this direction by using various catalytic
systems in recent years;1 the peroxide alone or with additives
has emerged as the perfect substitute to the traditional transi-
tion metal catalysis for several organic transformations.2
Meanwhile, aryl thioethers have been found to play important
roles in organic synthesis, the pharmaceutical industry and
materials science.3,4 Various transition metals such as Pd,5a–d
Cu,5e–g Fe,5h,i Ni,5j,k In,5l Co,5m Au,5n Ag,5o Mg5p etc. have been used
so far for the syntheses of thioethers via C–S bond formation
between aryl halides or pseudo halides and thiols.6 Recently, the
syntheses of aryl thioethers and thioesters have been reported
under metal-free conditions via C–H functionalization using
a variety of sulphur surrogates.7,8 Various catalyst or catalytic
systems such as DTBP,7a,c,d,f,g TBHP,7h,i K2S2O8,7j–l AcOOH,8c etc.
have been used so far for the syntheses of thioethers via C–H
functionalization. In the case of syntheses of allyl aryl thio-
ethers, various metals such as Rh,9a In,9b Co,9c Ni,9d etc. were
used for the C–S coupling between allyl halides/acetates and
disuldes (Scheme 1). A palladium acetate catalyzed synthesis
of allyl aryl thioethers via cross-coupling reaction between
Baylis–Hillman acetates and diphenyl disuldes was reported
by Sreedhar and co-workers (Scheme 1).9e The syntheses of allyl
aryl thioethers via the C–S bond formation between allyl halides
and sulphur surrogate under metal free conditions is not well
studied. Therefore, we have decided to nd out suitable meth-
odology for the synthesis of allylic thioethers and herein report
the rst regio- and stereoselective syntheses of allylic thioethers
Results and discussion
Accordingly, we have selected the allyl iodide 1a (2.0 mmol) and
diphenyl disulde 2a (1.0 mmol) as model substrate and treated
them under the inuence of DCP (dicumyl peroxide, 10.0 mmol)
using CH3CN as solvent at 80 ꢀC for 48 h. The data collection of
isolated product revealed the formation of only allyl phenyl
thioether 4a in 42% yield (Table 1, entry 1). There was no
formation of the thioethers 3a and 3b which were conrmed by
GCMS of crude reaction mixture. It is to note here that complete
retention in stereochemistry across the double bond was ob-
tained in this reaction i.e. Z-selectivity.
Encouraged by these results, we decided to optimize the
reaction conditions for this fascinating C–S bond formation
strategy. Accordingly, a variety of oxidants were employed to
catalyze the reaction between 1a and 2a (Table 1). Oxidant such
as BPO (benzoyl peroxide), K2S2O8 could not provide the
encouraging results (entries 2 & 3). H2O2, TBHP (tert-butyl
MFOS Laboratory, Department of Chemistry (Centre of Advanced Study), University of
Rajasthan, JLN Marg, Jaipur, Rajasthan, India-302004. E-mail: badsarass4@uniraj.
ac.in; sattubhu2005@gmail.com
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c7ra04817c
‡ Authors contributed equally.
Scheme 1 Syntheses of allylic thioethers.
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possessing ester functionality provided the allyl iodides as Z-
isomer12 only whereas the alcohols possessing nitrile func-
tionality provided allyl iodides as E-isomer. Therefore, Z-isomer
of allyl iodides 1 and E-isomer of allyl iodide 5 was used as
coupling partner for C–S bond formation with disuldes.
Firstly, the various allyl iodides possessing ester function-
ality with Z stereochemistry were treated with different disul-
des 2 under the inuence of DTBP following the optimized
reaction conditions, provided the resulting allylic thioethers 4
in 62–85% isolated yields. The structures of these allylic thio-
ethers 4 were determined from their spectral (1H NMR, 13C
NMR and MS) data which suggested complete retention in
stereochemistry across the double bond in the products i.e. Z-
Scheme 2 Synthesis of allyl aryl thioethers 4a.
Table 1 Optimization of the reaction conditionsa
1
stereochemistry were observed (in H NMR the olenic proton
appeared at d 7.64–7.81 range conrm Z-stereochemistry).10a,b,11
Allyl iodides possessing substitutes at o/m/p-position under-
went regio- and stereo selective C–S coupling reaction with both
aryl and alkyl disuldes to provide the desired allyl aryl thio-
ethers (4a–d & 4f–r) and allyl alkyl thioethers (4e & 4s–v) in good
to excellent yields. We have also employed the allyl iodides 1 (E-
isomer) possessing alkyl group instead that of aryl group for the
C–S bond formation with disuldes under the optimized reac-
tion conditions, provided the desired allyl aryl thioethers 4w
and 4x in 72% and 70% yields respectively. In these case also
complete retention in stereochemistry across the double bond
in the products i.e. E-stereochemistry were observed.12
Entry
Oxidant (equiv.)
Time (h)
Yieldb (%)
1
2
3
DCP (5.0)
BPO (5.0)
12
12
12
12
12
12
12
48
48
48
48
48
42
36
30
51
58
55
60
68
88
82
76
48
K2S2O8 (5.0)
H2O2 (5.0)
TBHP (5.0)
TBPB (5.0)
DTBP (5.0)
DTBP (5.0)
DTBP (5.0)
DTBP (5.0)
DTBP (5.0)
DTBP (2.0)
4
5c
6
7
8
9d
10e
11f
12g
Subsequently, we have employed the densely functionalized
E-allyl iodides 5 possessing nitrile functionality for the C–S
coupling with variety of disuldes 2 under the inuence of DTBP
following the optimized reaction conditions. Both the aryl and
alkyl disulde coupled well with allyl iodides 5 to provide the
resulting allylic thioethers 6 in 72–92% yield. Substrates pos-
sessing substituent at o, m, p position of phenyl ring coupled well
under the reaction conditions employed. The structures of these
allylic thioethers 6 were determined from their spectral (1H NMR,
13C NMR and MS) data which suggest that a complete retention
in stereochemistry across the double bond in the products i.e. E-
a
Reaction conditions: allyl iodide 1a (2.0 mmol), diphenyl disulde 2a
(1.0 mmol) and oxidant (10.0 mmol) were reacted in CH3CN (2.0 mL) at
b
c
80 ꢀC for 12 h. Isolated yields are based on 1a. TBHP solution in
d
e
f
water. 2.0 mmol of 2a was used. 120 ꢀC. 1.0 mL CH3CN was used.
g
2.0 equivalent of DTBP was used.
hydroperoxide) and TBPB (tert-butyl peroxybenzoate) provided
slightly better results (entries 4–6). The DTBP (di-tert-butyl
peroxide) provided the desired product in 60% yield aer 12 h
(entry 7). When the same reaction was carried out for 48 h under
the inuence of DTBP, provided the thioether 4a in 68% yield
(entry 8). Interestingly, when the amount of disulde was
doubled, thioether 4a was obtained in 88% yield (entry 9).
Enhancement in the reaction temperature could not increase
the yield signicantly (entry 10). Diminishing the CH3CN and
DTBP amounts were not found favourable for this coupling
between 1a and 2a (entry 11 & 12).
1
stereochemistry were observed (in H NMR the olenic proton
appeared at d 6.47–6.76 range conrm E-stereochemistry).10a,b,11
To establish a possible reaction pathway for this method-
ology, we have performed few control experiments as shown in
Scheme 3. Initially, we have performed the C–S coupling reac-
tion between allyl iodide 1a and disulde 2a in absence of DTBP
Once we have optimized reaction conditions in hand (Table
1, entry 9), we then studied the substrate scope for this inter-
esting C–S bond formation. Accordingly, a variety of allyl
iodides 1 and 5 were synthesized from the Baylis–Hillman
alcohols following the literature procedures.10a,b It is worth
mentioning here that Baylis–Hillman adducts or their deriva-
tives possessing ester functionality (obtained from alkyl acry-
lates) and nitrile functionality (obtained from acrylonitrile) be
evidence for remarkable opposite stereochemical directions in
various organic transformations.10a,b,11 This effect of reversibility
might be attributed to the steric difference between the nitrile
(smaller) and ester (larger) functionalities. The alcohols
Scheme 3 Control experiments.
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disulde (2.0 mmol, 0.436 g) in CH3CN (2.0 mL) was added
oxidant (10.0 mmol) and then the reaction mixture was stirred
for 80 ꢀC under nitrogen atmosphere for 48 h. The solvent was
then removed under reduced pressure and the crude product
thus obtained was puried by column chromatography (silica
gel, 1% EtOAc in hexanes) to provide the allyl thioether 4a as
pale yellow colour liquid.
Scheme 4 Plausible mechanism for the synthesis of thioether 4a.
Representative example of Table 1: methyl-(Z)-3-phenyl-2-
((phenylthio)methyl)acrylate (entry 9, 4a)10c
The title compound was prepared following the general proce-
dure for Table 1, using allyl iodide 1a i.e. methyl-(Z)-2-
(iodomethyl)-3-phenylacrylate (2.0 mmol, 0.604 g), diphenyl
disulde (2.0 mmol, 0.436 g), DTBP (10 mmol, 1.46 g, 1.8 mL)
and CH3CN (2.0 mL), providing 4a as pale yellow liquid. Yield:
0.499 g, 88%; 1H NMR (400 MHz, CDCl3): d 3.77 (s, 3H), 4.05 (s,
2H), 7.20–7.32 (m, 3H), 7.38–7.42 (m, 7H), 7.79 (s, 1H); 13C NMR
(100 MHz, CDCl3): d 32.3, 52.3, 126.8, 128.2, 128.7, 129.0, 129.1,
129.6, 130.7, 134.8, 136.0, 141.6, 167.6.
under optimized reaction conditions and observed that no
reaction took place (Path A, Scheme 3). Next, the same reaction
was carried out in presence of TEMPO (2,2,6,6-tetramethylpi-
peridine-N-oxyl) using optimized reaction conditions which
provided the allylic thioether 4a in 76% isolated yield (Path B,
Scheme 3). It was found that the TEMPO coupled well with allyl
iodide 1a under same reaction conditions to provide coupled
product 7 in 82% isolated yield (Path C, Scheme 3). On the basis
of these control experiments we proposed plausible mechanism
which follows the radical pathway (Scheme 4).
A plausible mechanism for the syntheses of allylic thioethers
is presented in the Scheme 4 by taking 4a as model case. In the
presence of DTBP, the allyl iodide 1a generated allyl radical A. At
the same time disulde converted into phenyl sulphide radical.
The coupling of allyl radical A with phenyl sulphide radical
yielded into the resulting thioether 4a.
General procedure for Table 2
To a stirred solution of allyl iodide 1 (2.0 mmol) and disulde
(2.0 mmol) in CH3CN (2.0 mL) was added DTBP (10.0 mmol),
ꢀ
then the reaction mixture was stirred for 48 h at 80 C under
nitrogen atmosphere. The solvent was then removed under
reduced pressure and the crude product thus obtained was
puried by column chromatography (silica gel, 1% EtOAc in
hexanes) to provide the allyl thioether 4.
Conclusions
Methyl-(Z)-2-(((4-chlorophenyl)thio)methyl)-3-phenylacrylate
(4b). The title compound was prepared following the general
procedure for Table 2, using allyl iodide 1a i.e. methyl-(Z)-2-
(iodomethyl)-3-phenylacrylate (2.0 mmol, 0.604 g), bis(4-
chlorophenyl)disulde (2.0 mmol, 0.574 g), DTBP (10 mmol,
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4b as pale yellow
liquid. Yield: 0.522 g, 82%; 1H NMR (400 MHz, CDCl3): d 3.77 (s,
3H), 3.98 (s, 2H), 7.11 (d, J ¼ 8.8 Hz, 2H), 7.21 (d, J ¼ 8.8 Hz, 2H),
7.30–7.32 (m, 5H), 7.73 (s, 1H); 13C NMR (100 MHz, CDCl3):
d 32.5, 52.3, 128.0, 128.7, 129.0, 129.1, 129.4, 132.4, 132.9, 134.3,
134.7, 141.6, 167.4; HRMS (ESI) exact mass calcd for
In conclusions, we have developed a methodology for the
synthesis of allylic thioethers via C–S bond formation between
allyl iodides and disuldes under metal free conditions for the
rst time. A variety of densely functionalized allyl iodides and
disuldes coupled well under the inuence of DTBP provided
the thioethers in 62–92% yield. A complete stereo- and regio-
selectivity were observed in these transformations.
Experimental
C
17H15ClO2S + K (M + K), 357.0118; found: 357.0127.
General information
Methyl-(Z)-2-(((4-bromophenyl)thio)methyl)-3-phenylacrylate
All chemicals were purchased from commercial suppliers and
used without further purication. NMR spectra were recorded
on a Jeol resonance-400 instrument using CDCl3 as solvent.
Chemical shis are reported in parts per million (ppm) and
referenced to the residual solvent resonance. Coupling constant
(J) are reported in hertz (Hz). Standard abbreviations indicating
multiplicity were used as follows: s ¼ singlet, d ¼ doublet, t ¼
triplet, dd ¼ double doublet, q ¼ quartet, m ¼ multiplet. HRMS
data were collected on Waters – Xevo G2S QTof with UPLC H-
Class Ultra Performance Liquid chromatography-mass spec-
trometry (LC-MS) facility.
(4c). The title compound was prepared following the general
procedure for Table 2, using allyl iodide 1a i.e. methyl-(Z)-2-
(iodomethyl)-3-phenylacrylate (2.0 mmol, 0.604 g), bis(4-
bromophenyl)disulde (2.0 mmol, 0.752 g), DTBP (10 mmol,
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4c as pale yellow
liquid. Yield: 0.515 g, 71%; 1H NMR (400 MHz, CDCl3): d 3.80 (s,
3H), 4.00 (s, 2H), 7.16 (d, J ¼ 8.8 Hz, 2H), 7.29 (d, J ¼ 8.8 Hz, 2H),
7.31–7.33 (m, 5H), 7.75 (s, 1H); 13C NMR (100 MHz, CDCl3):
d 32.3, 52.4, 120.9, 127.9, 128.7, 129.1, 129.4, 131.9, 132.5, 141.7,
167.5; HRMS (ESI) exact mass calcd for C17H15BrO2S + Na (M +
Na), 384.9874; found: 384.9881.
Methyl-(Z)-2-(((3-chlorophenyl)thio)methyl)-3-phenylacrylate
(4d). The title compound was prepared following the general
General procedure for Table 1
To a stirred solution of allyl iodide 1a i.e. methyl-(Z)-2- procedure for Table 2, using allyl iodide 1a i.e. methyl-(Z)-2-
(iodomethyl)-3-phenylacrylate (2.0 mmol) and diphenyl (iodomethyl)-3-phenylacrylate (2.0 mmol, 0.604 g), bis(3-
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Table 2 DTBP-promoted C–S bond formation between allyl iodides 1
and disulfides 2a,b
2H), 3.79 (s, 3H), 7.25–7.40 (m, 3H), 7.41–7.52 (m, 2H), 7.68 (s,
1H); 13C NMR (100 MHz, CDCl3): d 25.9, 26.1, 26.9, 33.5, 44.5,
52.2, 128.6, 128.9, 129.5, 129.7, 135.1, 140.3, 167.9; HRMS (ESI)
exact mass calcd for C17H22O2S + Na (M + Na), 313.1238; found:
313.1059.
Methyl-(Z)-3-(4-chlorophenyl)-2-((phenylthio)methyl)acrylate
(4f).10c The title compound was prepared following the general
procedure for Table 2, using allyl iodide 1b i.e. methyl-(Z)-3-(4-
chlorophenyl)-2-(iodomethyl)acrylate (2.0 mmol, 0.673 g),
diphenyl disulde (2.0 mmol, 0.436 g), DTBP (10 mmol, 1.46 g,
1.8 mL) and CH3CN (2.0 mL), providing 4f as pale yellow liquid.
1
Yield: 0.484 g, 76%; H NMR (400 MHz, CDCl3): d 3.78 (s, 3H),
3.98 (s, 2H), 7.20–7.282 (m, 3H), 7.34 (s, 4H), 7.36 (d, J ¼ 8.4 Hz,
2H), 7.67 (s, 1H); 13C NMR (100 MHz, CDCl3): d 32.3, 52.4, 127.0,
128.8, 128.9, 129.0, 130.8, 131.1, 133.2, 135.0, 135.6, 140.1,
167.4.
Methyl-(Z)-3-(4-chlorophenyl)-2-(((4-chlorophenyl)thio)methyl)
acrylate (4g). The title compound was prepared following the
general procedure for Table 2, using allyl iodide 1b i.e. methyl-
(Z)-3-(4-chlorophenyl)-2-(iodomethyl)acrylate (2.0 mmol, 0.673
g), bis(4-chlorophenyl)disulde (2.0 mmol, 0.574 g), DTBP
(10 mmol, 1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4g as
pale yellow liquid. Yield: 0.600 g, 85%; 1H NMR (400 MHz,
CDCl3): d 3.77 (s, 3H), 3.93 (s, 2H), 7.14 (d, J ¼ 8.8 Hz, 2H), 7.222
(d, J ¼ 8.8 Hz, 2H), 7.228 (d, J ¼ 8.8 Hz, 2H), 7.28 (d, J ¼ 8.8 Hz,
2H), 7.64 (s, 1H); 13C NMR (100 MHz, CDCl3): d 32.5, 52.4, 128.5,
128.9, 129.0, 130.6, 132.6, 133.0, 133.2, 133.9, 135.1, 140.2,
167.2; HRMS (ESI) exact mass calcd for C17H14Cl2O2S + Na (M +
Na), 374.9989; found: 374.9922.
Methyl-(Z)-3-(4-chlorophenyl)-2-(((3-chlorophenyl)thio)methyl)
acrylate (4h). The title compound was prepared following the
general procedure for Table 2, using allyl iodide 1b i.e. methyl-
(Z)-3-(4-chlorophenyl)-2-(iodomethyl)acrylate (2.0 mmol, 0.673
g), bis(3-chlorophenyl)disulde (2.0 mmol, 0.574 g), DTBP
(10 mmol, 1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4h as
pale yellow liquid. Yield: 0.480 g, 68%; 1H NMR (400 MHz,
CDCl3): d 3.77 (s, 3H), 3.96 (s, 2H), 7.05–7.20 (m, 3H), 7.22–7.36
(m, 5H), 7.66 (s, 1H); 13C NMR (100 MHz, CDCl3): d 31.8, 52.5,
126.9, 128.2, 128.5, 129.0, 129.9, 130.0, 130.7, 133.0, 134.6,
135.2, 137.8, 140.5, 167.1; HRMS (ESI) exact mass calcd for
a
Reaction conditions: allyl iodide 1 (2.0 mmol), disulde 2 (2.0 mmol)
and DTBP (10.0 mmol) were reacted in CH3CN (2.0 mL) at 80 ꢀC for 48 h.
b
Isolated yields are based on allyl iodide 1.
C
17H14Cl2O2S + Na (M + Na), 374.9989; found: 374.9978.
Methyl-(Z)-2-(((4-bromophenyl)thio)methyl)-3-(4-
chlorophenyl)disulde (2.0 mmol, 0.574 g), DTBP (10 mmol,
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4d as pale yellow
liquid. Yield: 0.433 g, 68%; 1H NMR (400 MHz, CDCl3): d 3.82 (s,
3H), 4.05 (s, 2H), 7.08–7.24 (m, 3H), 7.26–7.42 (m, 6H), 7.79 (s,
1H); 13C NMR (100 MHz, CDCl3): d 31.9, 52.4, 126.7, 127.7,
128.3, 128.8, 129.2, 129.4, 129.8, 129.9, 134.61, 134.65, 138.2,
142.0, 167.5; HRMS (ESI) exact mass calcd for C17H15ClO2S + Na
(M + Na), 341.0379; found: 341.0367.
chlorophenyl) acrylate (4i). The title compound was prepared
following the general procedure for Table 2, using allyl iodide
1b i.e. methyl-(Z)-3-(4-chlorophenyl)-2-(iodomethyl)acrylate
(2.0 mmol, 0.673 g), bis(4-bromophenyl)disulde (2.0 mmol,
0.752 g), DTBP (10 mmol, 1.46 g, 1.8 mL) and CH3CN (2.0 mL),
providing 4i as yellow solid. Mp: 63 C; yield: 0.675 g, 85%; H
NMR (400 MHz, CDCl3): d 3.77 (s, 3H), 3.93 (s, 2H), 7.14 (d, J ¼
8.4 Hz, 2H), 7.22 (d, J ¼ 8.4 Hz, 2H), 7.27–7.29 (m, 4H), 7.64 (s,
1H); 13C NMR (100 MHz, CDCl3): d 32.3, 52.5, 121.2, 128.4,
128.9, 130.6, 131.9, 132.7, 133.0, 134.6, 135.1, 140.2, 167.2;
HRMS (ESI) exact mass calcd for C17H14BrClO2S + K (M + K),
434.9223; found: 434.9227.
1
ꢀ
Methyl-(Z)-2-((cyclohexylthio)methyl)-3-phenylacrylate (4e).
The title compound was prepared following the general proce-
dure for Table 2, using allyl iodide 1a i.e. methyl-(Z)-2-
(iodomethyl)-3-phenylacrylate (2.0 mmol, 0.604 g), dicyclohexyl
disulde (2.0 mmol, 0.44 mL), DTBP (10 mmol, 1.46 g, 1.8 mL)
and CH3CN (2.0 mL), providing 4e as pale yellow liquid. Yield:
Methyl-(Z)-2-((phenylthio)methyl)-3-(p-tolyl)acrylate (4j). The
title compound was prepared following the general procedure
for Table 2, using allyl iodide 1c i.e. methyl-(Z)-2-(iodomethyl)-3-
1
0.359 g, 62%; H NMR (400 MHz, CDCl3): d 1.06–1.38 (m, 6H),
1.62–1.75 (m, 2H), 1.78–1.93 (m, 2H), 2.61–2.66 (m, 1H), 3.61 (s,
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(p-tolyl)acrylate (2.0 mmol, 0.632 g), diphenyl disulde 134.6, 138.4, 142.0, 167.5; HRMS (ESI) exact mass calcd for
(2.0 mmol, 0.436 g), DTBP (10 mmol, 1.46 g, 1.8 mL) and CH3CN
C
17H15BrO2S + Na (M + Na), 384.9874; found: 384.9698.
(2.0 mL), providing 4j as pale yellow liquid. Yield: 0.447 g, 75%;
Methyl-(Z)-2-(((3-bromophenyl)thio)methyl)-3-(4-chlorophenyl)
1H NMR (400 MHz, CDCl3): d 2.37 (s, 3H), 3.81 (s, 3H), 4.09 (s, acrylate (4o). The title compound was prepared following the
2H), 7.18 (d, J ¼ 8.4 Hz, 2H), 7.21–7.29 (m, 3H), 7.38 (d, J ¼ general procedure for Table 2, using allyl iodide 1b i.e. methyl-
8.4 Hz, 2H), 7.40–7.42 (m, 2H), 7.80 (s, 1H); 13C NMR (100 MHz, (Z)-3-(4-chlorophenyl)-2-(iodomethyl)acrylate (2.0 mmol, 0.673
CDCl3): d 21.5, 32.3, 52.3, 126.7, 127.2, 129.0, 129.5, 129.8, g), bis(3-bromophenyl)disulde (2.0 mmol, 0.752 g), DTBP
130.6, 132.0, 136.3, 139.4, 141.9, 167.8; HRMS (ESI) exact mass (10 mmol, 1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4o as
calcd for C18H18O2S + K (M + K), 337.0665; found: 337.0652.
pale yellow liquid. Yield: 0.635 g, 80%; 1H NMR (400 MHz,
Methyl-(Z)-2-(((4-chlorophenyl)thio)methyl)-3-(p-tolyl)acrylate CDCl3): d 3.80 (s, 3H), 3.98 (s, 2H), 7.07 (t, J ¼ 8.0 Hz, 1H), 7.21–
(4k). The title compound was prepared following the general 7.23 (m, 1H), 7.26–7.32 (m, 5H), 7.43 (t, J ¼ 1.6 Hz, 1H), 7.69 (s,
procedure for Table 2, using allyl iodide 1c i.e. methyl-(Z)-2- 1H); 13C NMR (100 MHz, CDCl3): d 32.0, 52.5, 122.7, 128.3,
(iodomethyl)-3-(p-tolyl)acrylate (2.0 mmol, 0.632 g), bis(4- 129.0, 129.2, 129.9, 130.2, 130.7, 133.0, 135.2, 138.0, 140.5,
chlorophenyl)disulde (2.0 mmol, 0.574 g), DTBP (10 mmol, 167.2; HRMS (ESI) exact mass calcd for C17H14BrClO2S + K (M +
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4k as pale yellow K), 434.9223; found: 434.9226.
liquid. Yield: 0.551 g, 83%; 1H NMR (400 MHz, CDCl3): d 2.35 (s,
Methyl-(Z)-2-(((3-bromophenyl)thio)methyl)-3-(p-tolyl)acrylate
3H), 3.79 (s, 3H), 4.03 (s, 2H), 7.15 (d, J ¼ 8.4 Hz, 2H), 7.16 (d, J ¼ (4p). The title compound was prepared following the general
8.4 Hz, 2H), 7.26 (d, J ¼ 8.8 Hz, 2H), 7.29 (d, J ¼ 8.8 Hz, 2H), 7.75 procedure for Table 2, using allyl iodide 1c i.e. methyl-(Z)-2-
(s, 1H); 13C NMR (100 MHz, CDCl3): d 21.4, 32.5, 52.2, 127.0, (iodomethyl)-3-(p-tolyl)acrylate (2.0 mmol, 0.632 g), bis(3-
128.9, 129.4, 129.6, 131.8, 132.2, 132.9, 134.5, 139.4, 141.9, 167.5; bromophenyl)disulde (2.0 mmol, 0.752 g), DTBP (10 mmol,
HRMS (ESI) exact mass calcd for C18H17ClO2S + K (M + K), 1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4p as pale yellow
371.0275; found: 371.0271.
liquid. Yield: 0.467 g, 62%; 1H NMR (400 MHz, CDCl3): d 2.36 (s,
Methyl-(Z)-2-(((4-bromophenyl)thio)methyl)-3-(p-tolyl)acry- 3H), 3.81 (s, 3H), 4.06 (s, 2H), 7.08 (t, J ¼ 8.0 Hz, 1H), 7.17 (d, J ¼
late (4l). The title compound was prepared following the general 8.0 Hz, 2H), 7.24–7.32 (m, 4H), 7.46 (t, J ¼ 1.6 Hz, 1H), 7.77 (s,
procedure for Table 2, using allyl iodide 1c i.e. methyl-(Z)-2- 1H); 13C NMR (100 MHz, CDCl3): d 21.5, 32.0, 52.4, 122.7, 126.6,
(iodomethyl)-3-(p-tolyl)acrylate (2.0 mmol, 0.632 g), bis(4- 128.7, 129.5, 129.6, 130.1, 131.7, 132.5, 138.6, 139.6, 142.2,
bromophenyl)disulde (2.0 mmol, 0.752 g), DTBP (10 mmol, 167.6; HRMS (ESI) exact mass calcd for C18H17BrO2S + Na (M +
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4l as yellow solid. Na), 399.0030; found: 399.6734.
Mp: 61 ꢀC; yield: 0.505 g, 67%; 1H NMR (400 MHz, CDCl3): d 2.35
Methyl-(Z)-2-(((2-bromophenyl)thio)methyl)-3-phenylacrylate
(s, 3H), 3.79 (s, 3H), 4.02 (s, 2H), 7.14–7.19 (m, 4H), 7.27–7.31 (4q). The title compound was prepared following the general
(m, 4H), 7.74 (s, 1H); 13C NMR (100 MHz, CDCl3): d 21.5, 32.3, procedure for Table 2, using allyl iodide 1a i.e. methyl-(Z)-2-
52.3, 120.8, 126.9, 129.5, 129.6, 131.8, 131.9, 132.3, 135.2, 139.5, (iodomethyl)-3-phenylacrylate (2.0 mmol, 0.604 g), bis(2-
142.0, 167.7; HRMS (ESI) exact mass calcd for C18H17BrO2S + Na bromophenyl)disulde (2.0 mmol, 0.752 g), DTBP (10 mmol,
(M + Na), 399.0030; found: 398.9935.
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4q as pale yellow
Methyl-(Z)-2-(((3-chlorophenyl)thio)methyl)-3-(p-tolyl)acry- liquid. Yield: 0.537 g, 74%; 1H NMR (400 MHz, CDCl3): d 3.81 (s,
late (4m). The title compound was prepared following the 3H), 4.04 (s, 2H), 7.02 (td, J ¼ 8.0 Hz & 1.6 Hz, 1H), 7.19 (td, J ¼
general procedure for Table 2, using allyl iodide 1c i.e. methyl- 8.4 Hz & 1.2 Hz, 1H), 7.27 (dd, J ¼ 6.4 Hz & 1.6 Hz, 1H), 7.32–7.38
(Z)-2-(iodomethyl)-3-(p-tolyl)acrylate (2.0 mmol, 0.632 g), bis(3- (m, 3H), 7.41–7.45 (m, 2H), 7.50 (dd, J ¼ 6.4 Hz & 1.6 Hz, 1H),
chlorophenyl)disulde (2.0 mmol, 0.574 g), DTBP (10 mmol, 7.81 (s, 1H); 13C NMR (100 MHz, CDCl3): d 31.4, 52.4, 125.1,
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4m as pale 127.2, 127.6, 127.8, 128.8, 129.2, 129.5, 130.6, 133.0, 134.6,
1
yellow liquid. Yield: 0.438 g, 66%; H NMR (400 MHz, CDCl3): 137.3, 142.4, 167.5; HRMS (ESI) exact mass calcd for
d 2.35 (s, 3H), 3.81 (s, 3H), 4.07 (s, 2H), 7.05–7.24 (m, 5H), 7.25–
7.40 (m, 3H), 7.78 (s, 1H); 13C NMR (100 MHz, CDCl3): d 21.5,
C
17H15BrO2S + K (M + K), 400.9613; found: 400.9681.
Methyl-(Z)-2-(((2-bromophenyl)thio)methyl)-3-(4-chlorophenyl)
31.9, 52.3, 126.6, 128.1, 129.60, 129.65, 129.67, 129.9, 131.8, acrylate (4r). The title compound was prepared following the
134.6, 138.4, 139.6, 142.2, 167.5; HRMS (ESI) exact mass calcd general procedure for Table 2, using allyl iodide 1b i.e. methyl-
for C18H17ClO2S + Na (M + Na), 355.0535; found: 355.0531.
(Z)-3-(4-chlorophenyl)-2-(iodomethyl)acrylate (2.0 mmol, 0.673
g), bis(2-bromophenyl)disulde (2.0 mmol, 0.752 g), DTBP
Methyl-(Z)-2-(((3-bromophenyl)thio)methyl)-3-
phenylacrylate (4n). The title compound was prepared following (10 mmol, 1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4p as
the general procedure for Table 2, using allyl iodide 1a i.e. yellow solid. Mp: 74 ꢀC; yield: 0.595 g, 75%; 1H NMR (400 MHz,
methyl-(Z)-2-(iodomethyl)-3-phenylacrylate (2.0 mmol, 0.604 g), CDCl3): d 3.80 (s, 3H), 3.99 (s, 2H), 7.03 (t, J ¼ 7.2 Hz, 1H), 7.19 (t,
bis(3-bromophenyl)disulde (2.0 mmol, 0.752 g), DTBP J ¼ 7.6 Hz, 1H), 7.26–7.38 (m, 5H), 7.50 (d, J ¼ 8.0 Hz, 1H), 7.72
(10 mmol, 1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4n as (s, 1H); 13C NMR (100 MHz, CDCl3): d 31.4, 52.5, 125.4, 127.7,
pale yellow liquid. Yield: 0.566, 78%; 1H NMR (400 MHz, 127.922, 127.928, 129.03, 130.9, 131.0, 133.0, 133.1, 135.2,
CDCl3): d 3.81 (s, 3H), 4.04 (s, 2H), 7.07 (t, J ¼ 8.0 Hz, 1H), 7.23 136.9, 141.0, 167.2; HRMS (ESI) exact mass calcd for C17H14
-
(d, J ¼ 8.0 Hz, 1H), 7.29 (d, J ¼ 8.0 Hz, 1H), 7.33–7.44 (m, 5H), BrClO2S + K (M + K), 434.9223; found: 434.9214.
7.46 (s, 1H), 7.79 (s, 1H); 13C NMR (100 MHz, CDCl3): d 32.0,
Methyl-(Z)-2-((benzylthio)methyl)-3-phenylacrylate (4s). The
52.4, 122.7, 127.7, 128.8, 128.9, 129.2, 129.4, 129.7, 130.2, 132.7, title compound was prepared following the general procedure
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for Table 2, using allyl iodide 1a i.e. methyl-(Z)-2-(iodomethyl)-3-
phenylacrylate (2.0 mmol, 0.604 g), dibenzyl disulde
(2.0 mmol, 0.492 g), DTBP (10 mmol, 1.46 g, 1.8 mL) and CH3CN
(2.0 mL), providing 4s as pale yellow liquid. Yield: 0.417 g, 70%;
1H NMR (400 MHz, CDCl3): d 3.46 (s, 2H), 3.64 (s, 2H), 3.72 (s,
3H), 7.10–7.16 (m, 5H), 7.21–7.22 (m, 3H), 7.28–7.30 (m, 2H),
7.63 (s, 1H); 13C NMR (100 MHz, CDCl3): d 28.5, 37.4, 52.3, 127.0,
128.5, 128.7, 129.0, 129.1, 129.8, 134.9, 138.3, 140.8, 168.0;
HRMS (ESI) exact mass calcd for C18H18O2S + Na (M + Na),
321.0925; found: 321.0920.
Methyl-(E)-2-(((4-chlorophenyl)thio)methyl)-4-methylpent-2-
enoate (4x). The title compound was prepared following the
general procedure for Table 2, using allyl iodide 1d i.e. methyl-
(E)-2-(iodomethyl)-4-methylpent-2-enoate (2.0 mmol, 0.536 g),
bis(3-chlorophenyl)disulde (2.0 mmol, 0.574 g), DTBP
(10 mmol, 1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 4x as
pale yellow liquid. Yield: 0.398 g, 70%; 1H NMR (400 MHz,
CDCl3): d 0.87 (s, 3H), 0.88 (s, 3H), 2.39–2.45 (m, 1H), 3.72 (s,
3H), 3.76 (s, 2H), 6.62 (d, J ¼ 10.4 Hz, 1H), 7.22 (dd, J ¼ 8.4 Hz &
2.0 Hz, 2H), 7.32 (dd, J ¼ 8.4 Hz & 2.0 Hz, 2H); 13C NMR (100
MHz, CDCl3): d 22.1, 28.4, 31.6, 52.0, 125.6, 128.9, 133.2, 134.4,
152.3, 167.2; HRMS (ESI) exact mass calcd for C14H17ClO2S + Na
(M + Na), 307.0535; found: 307.0539.
Methyl-(Z)-2-((benzylthio)methyl)-3-(4-chlorophenyl)acrylate
(4t). The title compound was prepared following the general
procedure for Table 2, using allyl iodide 1b i.e. methyl-(Z)-3-(4-
chlorophenyl)-2-(iodomethyl)acrylate (2.0 mmol, 0.673 g),
dibenzyl disulde (2.0 mmol, 0.492 g), DTBP (10 mmol, 1.46 g,
1.8 mL) and CH3CN (2.0 mL), providing 4t as pale yellow liquid.
General procedure for Table 3
To a stirred solution of allyl bromide 5 (2.0 mmol) and disulde
1
Yield: 0.493 g, 74%; H NMR (400 MHz, CDCl3): d 3.52 (s, 2H),
(2.0 mmol) in CH3CN (2.0 mL) was added DTBP (10.0 mmol),
3.74 (s, 2H), 3.82 (s, 3H), 7.22–7.32 (m, 9H), 7.65 (s, 1H); 13C
NMR (100 MHz, CDCl3): d 28.3, 37.4, 52.4, 127.1, 128.5, 128.94,
128.99, 129.0, 129.5, 131.0, 133.2, 135.0, 138.1, 139.5, 167.7;
HRMS (ESI) exact mass calcd for C18H17ClO2S + Na (M + Na),
355.0535; found: 355.0529.
ꢀ
then the reaction mixture was stirred for 48 h at 80 C under
nitrogen atmosphere. The solvent was then removed under
reduced pressure and the crude product thus obtained was
puried by column chromatography (silica gel, 1% EtOAc in
hexanes) to provide the allyl thioether 6.
(E)-3-Phenyl-2-((phenylthio)methyl)acrylonitrile (6a).10c The
title compound was prepared following the general procedure
for Table 3, using allyl iodide 5a i.e. (E)-2-(iodomethyl)-3-
phenylacrylonitrile (2.0 mmol, 0.538 g), diphenyl disulde
(2.0 mmol, 0.436 g), DTBP (10 mmol, 1.46 g, 1.8 mL) and CH3CN
(2.0 mL), providing 6a as pale yellow liquid. Yield: 0.426 g, 85%;
1H NMR (400 MHz, CDCl3): d 3.73 (s, 2H), 6.65 (s, 1H), 7.27–7.35
Methyl-(Z)-2-((methylthio)methyl)-3-phenylacrylate
(4u).13
The title compound was prepared following the general proce-
dure for Table 2, using allyl iodide 1a i.e. methyl-(Z)-2-
(iodomethyl)-3-phenylacrylate (2.0 mmol, 0.604 g), dimethyl
disulde (2.0 mmol, 0.188 g), DTBP (10 mmol, 1.46 g, 1.8 mL)
and CH3CN (2.0 mL), providing 4u as colourless oil. Yield:
0.293 g, 66%; 1H NMR (400 MHz, CDCl3): d 2.01 (s, 3H), 3.55 (s,
2H), 3.76 (s, 3H), 7.25–7.34 (m, 3H), 7.40 (d, J ¼ 7.6 Hz, 2H), 7.68
(s, 1H); 13C NMR (100 MHz, CDCl3): d 16.1, 30.4, 52.2, 128.6,
128.8, 129.3, 129.5, 134.9, 140.6, 167.9.
Table 3 DTBP-promoted C–S bond formation between allyl iodides 5
and disulfides 2a,b
Methyl-(Z)-2-((methylthio)methyl)-3-(p-tolyl)acrylate
(4v).
The title compound was prepared following the general proce-
dure for Table 2, using allyl iodide 1c i.e. methyl-(Z)-2-(iodo-
methyl)-3-(p-tolyl)acrylate (2.0 mmol, 0.632 g), dimethyl
disulde (2.0 mmol, 0.188 g), DTBP (10 mmol, 1.46 g, 1.8 mL)
and CH3CN (2.0 mL), providing 4v as colourless oil. Yield:
0.297 g, 63%; 1H NMR (400 MHz, CDCl3): d 2.09 (s, 3H), 2.35 (s,
3H), 3.63 (s, 2H), 3.82 (s, 3H), 7.19 (d, J ¼ 8.0 Hz, 2H), 7.38 (d, J ¼
8.0 Hz, 2H), 7.72 (s, 1H); 13C NMR (100 MHz, CDCl3): d 16.1,
21.3, 30.5, 52.1, 128.3, 129.3, 129.6, 132.0, 139.0, 140.7, 168.0;
HRMS (ESI) exact mass calcd for C13H16O2S + K (M + K),
275.0508; found: 275.0501.
Methyl-(E)-4-methyl-2-((phenylthio)methyl)pent-2-enoate (4w).
The title compound was prepared following the general proce-
dure for Table 2, using allyl iodide 1d i.e. methyl-(E)-2-
(iodomethyl)-4-methylpent-2-enoate (2.0 mmol, 0.536 g), diphenyl
disulde (2.0 mmol, 0.436 g), DTBP (10 mmol, 1.46 g, 1.8 mL) and
CH3CN (2.0 mL), providing 4w as pale yellow liquid. Yield:
1
0.360 g, 72%; H NMR (400 MHz, CDCl3): d 0.84 (s, 3H), 0.85 (s,
3H), 2.39–2.45 (m, 1H), 3.71 (s, 3H), 3.79 (s, 2H), 6.60 (d, J ¼
10.4 Hz, 1H), 7.18–7.26 (m, 3H), 739–7.41 (m, 2H); 13C NMR (100
MHz, CDCl3): d 19.1, 22.1, 28.4, 31.4, 52.0, 125.9, 127.1, 128.8,
128.9, 131.9, 135.9, 152.0, 167.4; HRMS (ESI) exact mass calcd for
C14H18O2S + Na (M + Na), 273.0925; found: 273.0920.
a
Reaction conditions: allyl iodide 5 (2.0 mmol), disulde 2 (2.0 mmol)
and DTBP (10.0 mmol) were reacted in CH3CN (2.0 mL) at 80 ꢀC for 48 h.
b
Isolated yields are based on allyl iodide 5.
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(m, 6H), 7.44–7.46 (m, 2H), 7.58–7.59 (m, 2H); 13C NMR (100 disulde (2.0 mmol, 0.752 g), DTBP (10 mmol, 1.46 g, 1.8 mL)
MHz, CDCl3): d 41.1, 107.7, 118.2, 128.1, 128.8, 128.9, 129.3, and CH3CN (2.0 mL), providing 6f as pale yellow liquid. Yield:
130.5, 132.9, 133.1, 133.5, 144.9.
0.587 g, 89%; 1H NMR (400 MHz, CDCl3): d 3.74 (s, 2H), 6.76 (s,
(E)-2-(((4-Chlorophenyl)thio)methyl)-3-phenylacrylonitrile (6b). 1H), 7.11 (t, J ¼ 8.0 Hz, 1H), 7.21–7.41 (m, 5H), 7.56 (s, 1H), 7.61–
The title compound was prepared following the general proce- 7.66 (m, 2H); 13C NMR (100 MHz, CDCl3): d 40.6, 107.2, 118.0,
dure for Table 3, using allyl iodide 5a i.e. (E)-2-(iodomethyl)-3- 122.9, 128.9, 129.05, 129.06, 130.7, 130.8, 130.9, 132.9, 134.5,
phenylacrylonitrile (2.0 mmol, 0.538 g), bis(4-chlorophenyl) 136.1, 145.4; HRMS (ESI) exact mass calcd for C16H12BrNS + Na
disulde (2.0 mmol, 0.574 g), DTBP (10 mmol, 1.46 g, 1.8 mL) (M + Na), 351.9772; found: 351.9625.
and CH3CN (2.0 mL), providing 6b as pale yellow liquid. Yield:
(E)-2-(((2-Bromophenyl)thio)methyl)-3-phenylacrylonitrile (6g).
0.433 g, 76%; 1H NMR (400 MHz, CDCl3): d 3.71 (s, 2H), 6.68 (s, The title compound was prepared following the general proce-
1H), 7.24 (dd, J ¼ 8.8 Hz & 2.0 Hz, 2H), 7.35–7.37 (m, 5H; dure for Table 3, using allyl iodide 5a i.e. (E)-2-(iodomethyl)-3-
multiplet conations one doublet at d 7.36, J ¼ 8.4 Hz, 2H and phenylacrylonitrile (2.0 mmol, 0.538 g), bis(2-bromophenyl)
multiplet for 3H), 7.58–7.61 (m, 2H); 13C NMR (100 MHz, disulde (2.0 mmol, 0.752 g), DTBP (10 mmol, 1.46 g, 1.8 mL)
ꢀ
CDCl3): d 41.2, 107.5, 118.0, 128.8, 128.9, 129.4, 130.7, 132.0, and CH3CN (2.0 mL), providing 6g as yellow solid. Mp: 79 C;
132.9, 134.2, 134.3, 145.1, HRMS (ESI) exact mass calcd for yield: 0.574 g, 87%; H NMR (400 MHz, CDCl3): d 3.81 (s, 2H),
1
C
16H12ClNS + Na (M + Na), 308.0277; found: 308.0092.
(E)-2-(((4-Bromophenyl)thio)methyl)-3-phenylacrylonitrile (6c). & 1.2 Hz, 1H), 7.31–7.37 (m, 3H), 7.45 (dd, J ¼ 8.0 Hz & 1.6 Hz,
6.74 (s, 1H), 7.10 (td, J ¼ 7.6 Hz & 1.6 Hz, 1H), 7.21 (td, J ¼ 7.6 Hz
The title compound was prepared following the general proce- 2H), 7.53–7.62 (m, 3H); 13C NMR (100 MHz, CDCl3): d 39.5,
dure for Table 3, using allyl iodide 5a i.e. (E)-2-(iodomethyl)-3- 106.8, 118.1, 127.3, 128.2, 128.8, 128.9, 129.3, 130.7, 133.0,
phenylacrylonitrile (2.0 mmol, 0.538 g), bis(4-bromophenyl) 133.5, 133.6, 134.5, 145.4; HRMS (ESI) exact mass calcd for
disulde (2.0 mmol, 0.752 g), DTBP (10 mmol, 1.46 g, 1.8 mL)
C
16H12BrNS + Na (M + Na), 351.9772; found: 351.9713.
(E)-2-((Phenylthio)methyl)-3-(p-tolyl)acrylonitrile (6h).10c The
ꢀ
and CH3CN (2.0 mL), providing 6c as yellow solid. Mp: 83 C;
1
yield: 0.475 g, 72%; H NMR (400 MHz, CDCl3): d 3.72 (s, 2H), title compound was prepared following the general procedure
6.70 (s, 1H), 7.28 (d, J ¼ 8.4 Hz, 2H), 7.36–7.40 (m, 5H, multiplet for Table 3, using allyl iodide 5b i.e. (E)-2-(iodomethyl)-3-(p-tolyl)
contains one doublet at d 7.37, J ¼ 8.4 Hz, 2H and one multiplet acrylonitrile (2.0 mmol, 0.566 g), diphenyl disulde (2.0 mmol,
for 3H), 7.59–7.61 (m, 2H); 13C NMR (100 MHz, CDCl3): d 41.0, 0436 g), DTBP (10 mmol, 1.46 g, 1.8 mL) and CH3CN (2.0 mL),
107.4, 118.0, 122.3, 128.8, 129.0, 130.7, 132.3, 132.7, 132.9, providing 6h as pale yellow liquid. Yield: 0.482 g, 91%; 1H NMR
134.3, 145.1; HRMS (ESI) exact mass calcd for C16H12BrNS + Na (400 MHz, CDCl3): d 2.33 (s, 3H), 3.71 (s, 2H), 6.63 (s, 1H), 7.14
(M + Na), 351.9772; found: 351.9749.
(d, J ¼ 8.0 Hz, 2H), 7.26–7.29 (m, 3H), 7.44 (d, J ¼ 8.0 Hz, 2H),
(E)-2-(((4-Methoxyphenyl)thio)methyl)-3-phenylacrylonitrile 7.52 (d, J ¼ 8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3): d 21.6, 41.1,
(6d). The title compound was prepared following the general 106.3, 118.4, 128.0, 128.9, 129.3, 129.6, 130.4, 132.8, 133.7,
procedure for Table 3, using allyl iodide 5a i.e. (E)-2- 141.0, 144.9.
(iodomethyl)-3-phenylacrylonitrile (2.0 mmol, 0.538 g), bis(4-
(E)-2-(((4-Chlorophenyl)thio)methyl)-3-(p-tolyl)acrylonitrile (6i).
methoxyphenyl)disulde (2.0 mmol, 0.556 g), DTBP (10 mmol, The title compound was prepared following the general proce-
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 6d as pale yellow dure for Table 3, using allyl iodide 5b i.e. (E)-2-(iodomethyl)-3-
liquid. Yield: 0.488 g, 87%; 1H NMR (400 MHz, CDCl3): d 3.60 (s, (p-tolyl)acrylonitrile (2.0 mmol, 0.566 g), bis(4-chlorophenyl)
2H), 3.71 (s, 3H), 6.47 (s, 1H), 6.79 (d, J ¼ 8.8 Hz, 2H), 7.32–7.34 disulde (2.0 mmol, 0.574 g), DTBP (10 mmol, 1.46 g, 1.8 mL)
(m, 3H), 7.38 (d, J ¼ 8.8 Hz, 2H), 7.53–7.55 (m, 2H); 13C NMR and CH3CN (2.0 mL), providing 6i as yellow solid. Mp: 73 C;
ꢀ
1
(100 MHz, CDCl3): d 42.7, 55.4, 108.0, 114.8, 118.2, 123.5, 128.7, yield: 0.551 g, 92%; H NMR (400 MHz, CDCl3): d 2.35 (s, 3H),
128.9, 130.4, 133.1, 136.3, 144.7, 160.1; HRMS (ESI) exact mass 3.71 (s, 2H), 6.65 (s, 1H), 7.17 (d, J ¼ 8.0 Hz, 2H), 7.24 (d, J ¼
calcd for C17H15NOS + K (M + K), 320.0511; found: 320.0517.
8.4 Hz, 2H), 7.36 (d, J ¼ 8.8 Hz, 2H), 7.52 (d, J ¼ 8.4 Hz, 2H); 13
C
(E)-2-(((3-Chlorophenyl)thio)methyl)-3-phenylacrylonitrile (6e). NMR (100 MHz, CDCl3): d 22.7, 41.3, 106.1, 118.1, 128.8, 129.3,
The title compound was prepared following the general proce- 129.6, 130.2, 132.1, 134.20, 134.29, 141.2, 145.0; HRMS (ESI)
dure for Table 3, using allyl iodide 5a i.e. (E)-2-(iodomethyl)-3- exact mass calcd for C17H14ClNS + K (M + K), 338.0173; found:
phenylacrylonitrile (2.0 mmol, 0.538 g), bis(3-chlorophenyl) 338.0179.
disulde (2.0 mmol, 0.574 g), DTBP (10 mmol, 1.46 g, 1.8 mL)
(E)-2-(((3-Chlorophenyl)thio)methyl)-3-(p-tolyl)acrylonitrile (6j).
and CH3CN (2.0 mL), providing 6e as pale yellow liquid. Yield: The title compound was prepared following the general proce-
0.502 g, 88%; 1H NMR (400 MHz, CDCl3): d 3.75 (s, 2H), 6.76 (s, dure for Table 3, using allyl iodide 5b i.e. (E)-2-(iodomethyl)-3-
1H), 7.07–7.22 (m, 2H), 7.24–7.44 (m, 5H), 7.55–7.65 (m, 2H); (p-tolyl)acrylonitrile (2.0 mmol, 0.566 g), bis(3-chlorophenyl)
13C NMR (100 MHz, CDCl3): d 40.5, 107.2, 118.0, 128.0, 128.9, disulde (2.0 mmol, 0.574 g), DTBP (10 mmol, 1.46 g, 1.8 mL)
ꢀ
129.0, 130.2, 130.3, 130.7, 131.7, 132.9, 134.8, 135.7, 145.3; and CH3CN (2.0 mL), providing 6j as yellow solid. Mp: 70 C;
1
HRMS (ESI) exact mass calcd for C16H12ClNS + Na (M + Na), yield: 0.539 g, 90%; H NMR (400 MHz, CDCl3): d 2.31 (s, 3H),
308.0277; found: 308.0091.
3.74 (s, 2H), 6.75 (s, 1H), 7.13 (d, J ¼ 7.6 Hz, 2H), 7.16–7.17 (m,
(E)-2-(((3-Bromophenyl)thio)methyl)-3-phenylacrylonitrile (6f). 2H), 7.22–7.31 (m, 1H), 7.39 (s, 1H), 7.46–7.56 (m, 2H); 13C NMR
The title compound was prepared following the general proce- (100 MHz, CDCl3): d 21.6, 40.5, 105.8, 118.3, 127.8, 128.9, 129.7,
dure for Table 3, using allyl iodide 5a i.e. (E)-2-(iodomethyl)-3- 130.0, 130.2, 130.3, 131.4, 134.7, 136.0, 141.2, 145.4; HRMS (ESI)
phenylacrylonitrile (2.0 mmol, 0.538 g), bis(3-bromophenyl)
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exact mass calcd for C17H14ClNS + Na (M + Na), 322.0433; found:
322.0439.
Acknowledgements
(E)-2-(((3-Bromophenyl)thio)methyl)-3-(p-tolyl)acrylonitrile
(6k). The title compound was prepared following the general
procedure for Table 3, using allyl iodide 5b i.e. (E)-2-(iodo-
methyl)-3-(p-tolyl)acrylonitrile (2.0 mmol, 0.566 g), bis(3-
bromophenyl)disulde (2.0 mmol, 0.752 g), DTBP (10 mmol,
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 6k as yellow
solid. Mp: 79 ꢀC; yield: 0.605 g, 88%; 1H NMR (400 MHz, CDCl3):
d 2.35 (s, 3H), 3.75 (s, 2H), 6.73 (s, 1H), 7.10–7.20 (m, 3H), 7.30–
7.39 (m, 2H), 7.52–7.58 (m, 3H); 13C NMR (100 MHz, CDCl3):
d 21.6, 40.7, 105.8, 118.2, 122.8, 128.9, 129.7, 130.1, 130.5, 130.7,
130.8, 134.5, 136.1, 141.3, 145.4; HRMS (ESI) exact mass calcd
for C17H14BrNS + K (M + K), 381.9667; found: 381.9666.
(E)-2-(((2-Bromophenyl)thio)methyl)-3-(p-tolyl)acrylonitrile
(6l). The title compound was prepared following the general
procedure for Table 3, using allyl iodide 5b i.e. (E)-2-(iodo-
methyl)-3-(p-tolyl)acrylonitrile (2.0 mmol, 0.566 g), bis(2-
bromophenyl)disulde (2.0 mmol, 0.752 g), DTBP (10 mmol,
1.46 g, 1.8 mL) and CH3CN (2.0 mL), providing 6l as yellow solid.
Mp: 69 ꢀC; yield: 0.537 g, 78%; 1H NMR (400 MHz, CDCl3): d 2.34
(s, 3H), 3.80 (s, 2H), 6.71 (s, 1H), 7.10 (td, J ¼ 7.6 Hz & 1.6 Hz,
1H), 7.15 (d, J ¼ 8.0 Hz, 2H), 7.21 (td, J ¼ 7.6 Hz, & 1.2 Hz, 1H),
7.43 (dd, J ¼ 8.0 Hz & 1.6 Hz, 1H), 7.49 (d, J ¼ 8.0 Hz, 2H), 7.58
(dd, J ¼ 8.0 Hz & 1.6 Hz, 1H); 13C NMR (100 MHz, CDCl3): d 21.6,
39.5, 105.5, 118.3, 127.5, 128.1, 128.8, 129.3, 129.6, 130.2, 133.4,
133.9, 141.2, 145.4; HRMS (ESI) exact mass calcd for
SERB-DST, New Delhi (YSS/2015/001870) and UGC-India (Start-
up grant) are gratefully acknowledged for nancial support. P.
S. and R. C. thanks the UGC and R. B. thanks the SERB-DST for
their fellowships. S. S. B. is DST INSPIRE Faculty (IFA-2014/CH-
167), DST-India. We thank MRC-MNIT Jaipur for NMR and USIC
University of Rajasthan, Jaipur for HRMS & GCMS data
collection.
Notes and references
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C
17H14BrNS + K (M + K), 381.9667; found: 381.9673.
(E)-2-((benzylthio)methyl)-3-(p-tolyl)acrylonitrile (6m). The
title compound was prepared following the general procedure
for Table 3, using allyl iodide 5b i.e. (E)-2-(iodomethyl)-3-(p-tolyl)
acrylonitrile (2.0 mmol, 0.566 g), dibenzyl disulde (2.0 mmol,
0.492 g), DTBP (10 mmol, 1.46 g, 1.8 mL) and CH3CN (2.0 mL),
providing 6m as yellow liquid; yield: 0.441 g, 79%; 1H NMR (400
MHz, CDCl3): d 2.40 (s, 3H), 3.31 (s, 2H), 3.76 (s, 2H), 6.83 (s,
1H), 7.24 (d, J ¼ 8.0 Hz, 2H), 7.31–7.35 (m, 5H), 7.67 (d, J ¼
8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3): d 21.6, 35.4, 36.2, 106.7,
118.5, 127.4, 128.8, 129.0, 129.1, 129.7, 130.3, 137.2, 141.2,
144.6; HRMS (ESI) exact mass calcd for C18H17NS + K (M + K),
318.0719; found: 318.0726.
Methyl
(E)-3-phenyl-2-(((2,2,6,6-tetramethylpiperidin-1-yl)
oxy)methyl)acrylate (7). To a stirred solution of allyl iodide 1a
i.e. methyl-(Z)-2-(iodomethyl)-3-phenylacrylate (2.0 mmol, 0.604
g) in CH3CN (2.0 mL) was added TEMPO (2.0 mmol, 0.312 g)
and then the reaction mixture was stirred for 80 ꢀC under
nitrogen atmosphere for 48 h. The solvent was then removed
under reduced pressure and the crude product thus obtained
was puried by column chromatography (silica gel, 1% EtOAc in
hexanes) to provide the allyl thioether 7 as pale yellow colour
liquid. Yield: 0.543 g, 82%; 1H NMR (400 MHz, CDCl3): d 1.06 (s,
6H), 1.09 (s, 6H), 1.40–1.42 (m, 6H), 3.82 (s, 3H), 4.67 (s, 2H),
7.34–7.68 (m, 3H), 7.47–7.49 (m, 2H), 7.83 (s, 1H); 13C NMR (100
MHz, CDCl3): d 17.1, 20.2, 32.9, 40.0, 52.0, 59.9, 70.8, 128.3,
128.9, 129.5, 135.1, 143.6, 168.5; HRMS (ESI) exact mass calcd
for C20H29NO3 + K (M + K), 370.1785; found: 370.1778.
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