An odorless thia-Michael addition using Bunte salts as thiol surrogates

Article abstract of DOI:10.1039/c5ra01381j

A newly developed C-S bond formation process via acid-catalyzed thia-Michael addition has been demonstrated. The protocol, in which Bunte salts generated from odorless and inexpensive sodium thiosulfate and organic halides are used as the thiol precursors, provides an efficient approach for the synthesis of β-sulfido carbonyl compounds.

Full text of DOI:10.1039/c5ra01381j

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An odorless thia-Michael addition using Bunte salts
as thiol surrogates†
Cite this: RSC Adv., 2015, 5, 27107
Ya-mei Lin, Guo-ping Lu,* Chun Cai and Wen-bin Yi
Received 23rd January 2015
Accepted 6th March 2015
A newly developed C–S bond formation process via acid-catalyzed thia-Michael addition has been
demonstrated. The protocol, in which Bunte salts generated from odorless, inexpensive sodium
thiosulfate and organic halides are used as the thiol precursors, provides an efficient approach for the
synthesis of b-sulfido carbonyl compounds.
DOI: 10.1039/c5ra01381j
www.rsc.org/advances
odorless S-alkylisothiouronium salts in place of thiols, which
Introduction
9c,10
are formed by organic halides and thiourea.
Although
Bunte salts are conveniently prepared by the reaction of odor- various electron-decient alkenes could proceed smoothly
less and inexpensive sodium thiosulfate with alkyl halides, under odorless and mild conditions, more sterically hindered
which are easy to handle crystalline solids, even with highly substrates such as chalcone fail to yield the desired products,
1
10
lipophilic organic moieties, and generally have little to no odor.
and a stoichiometric amount of base is required.
More recently, various attempts have been made to employ
Grignard reagents could react with Bunte salts to yield disul- odorless disuldes and N-(organothio)succinimides for the
des, trisuldes, thiocyanates and suldes respectively. Mean- synthesis of sulfocompound, but these reagents should be pre-
2
3
4
Various nucleophiles such as thiols, Na S, cyanide or
2
1c

11
while, these compounds also exhibit nucleophilicity under generated from thiols. Iranpoor's and our group have reported
acidic conditions to produce thiols. Therefore, we envisage that several transformations for C–S bonds formation using thiourea
electrophiles such as a,b-unsaturated ketones can be attacked as an odorless sulfur source, meanwhile a series of sulfur
by thiol in situ formed by the hydrolysis of Bunte salts under transfer reactions by in situ formation of Bunte salts from
5
12
acidic conditions (Scheme 1).
sodium thiosulfate and organic halides have also been ach-
In the last decades, sulfur-based compounds have ieved. With our interest in exploring novel odorless means for
13
received wide-spread attention due to their potential as novel construction of C–S bonds, we found odorless Bunte salts could
6
pharmaceutical, agricultural and chemical agents. More- react with steric a,b-unsaturated ketones under acidic condi-
over, organic sulfur compounds are essential in materials tions with good yields.
science, in which the sulfur constituent can have profound
effects on the physical, electronic, and surface properties of
the resultant materials. The construction of sulfur-
Results and discussion
7
containing compounds via simple C–S bond-forming reac- As a representative example, the sulfur-Michael addition of 1a
tions is of utmost importance in synthetic and catalytic and 2a was chosen to optimize the reaction conditions (Table 1).
8
research elds. The thia-Michael addition is one of most Aer screening different solvent, methanol emerged as the best
useful approaches for the construction of C–S bonds, so there choice (entry 4). No reaction took place without acid (entry 9).
have been signicant efforts towards the development of Various Brønsted acids were employed to further improve the
9
methodologies for this transformation.
2
yield. Both HN(Tf) (triuoromethanesulfonimide) and TsOH
Nevertheless, most of these strategies require malodorous (p-toluenesulfonic acid) were equally effective in this model
and expensive thiols as starting materials. Because of their reaction (entries 4 and 13). TsOH is much cheaper than HN(Tf)
,
2
potent stench and air sensitivity, the use of thiol as the starting so TsOH was selected as the catalyst for further studies. The
materials, particularly on a large scale operation, is highly amount of TsOH was also optimized, and 20 mol% of TsOH was
undesirable. In order to solve the issue, several odorless the best option (entry 15). Finally, satisfactory yield could be
ꢀ
protocols have been reported through the in situ generation of obtained via heating the reaction to 80 C.
With the optimized conditions in hands, a series of Bunte
salts and various a,b-unsaturated ketones were applied in the
Chemical Engineering College, Nanjing University of Science & Technology, Nanjing,
reaction to establish the scope and generality of the protocol
Jiangsu 210094, P. R. China. E-mail: glu@njust.edu.cn
(
Scheme 2). Steric a,b-unsaturated ketones including chalcones,
†
Electronic supplementary information (ESI) available: More experimental
1
13
benzylidene acetone and (E)-4-(thiophen-2-yl)but-3-en-2-one
could react with different Bunte salts to afford corresponding
entails, characterization data and copies of H NMR, C NMR spectra of all
products. See DOI: 10.1039/c5ra01381j
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Scheme 1 Working hypothesis: thia-Michael addition using Bunte salts as the thiol equivalents.
products. Excellent yields would be gained using electron- Michael addition of ethyloxycarbonylmethyl Bunte salt with N-
decient terminal alkenes to yield the addition products (3d, benzyl maleimide, following a transesterication with MeOH.
ꢀ
3
e) at lower temperature (40 C). Benzyl, allyl and cyclohexyl
To further optimize the reaction conditions, attempts were
Bunte salts were also employed in the protocol successfully, and also made to realize thia-Micheal additions via a one-pot
the cyclohexyl Bunte salt leaded to a lower yield (46%) due to process from benzyl chloride, Na and a,b-unsaturated
2 2 3
S O
sterically hindered effects (3g). It should be noted that ethyl- ketones (Scheme 4). Although the results were also satisfactory,
oxycarbonylmethyl Bunte salt did not result in the desired the one-pot process required excess benzyl chloride (3 equiv.)
product, but generate 3h via an additionally transesterication and Na S O (4 equiv.) which leaded to unnecessary waste of
2
2 3
with MeOH. The substituented groups on chalcones had no substrates.
obvious inuence on the reaction (3k–m). Finally, a proposed mechanism for the reaction was also
Because sodium S-aryl sulfothioate can't be hydrolyzed illustrated in Scheme 5. TsOH may play a dual role in the
under optimized conditions, no desired product was found reaction: (i) TsOH promotes the hydrolysis of Bunte salts to
5a
when aryl Bunte salts such as phenyl and 4-toluene Bunte salts, form thiol in situ; (ii) TsOH actives a,b-unsaturated ketones to
were employed in the protocol. To further broaden the scope of form carbonium ion intermediate I, following a nucleophilic
the approach, thia-Michael additions of Bunte salts with N- attack by thiol to afford the nal product.
substituented maleimides were achieved under optimized
conditions (Scheme 3). N-Benzyl, methyl and ethyl maleimide
reacted smoothly with Bunte salts in good to excellent yields. In Conclusions
the case of N-phenyl maleimide, no Michael addition occurred.
In summary, we have described an efficient and odorless thia-
Undesired products generated from the ring-opening of N-
Michael addition by in situ formation of thiols from the
phenyl maleimide was observed. Similarly, 3q was formed via
hydrolysis of Bunte salts under acidic conditions. Steric a,b-
unsaturated ketones can also be applied in the system
successfully. The procedure uses odorless, inexpensive and easy
a
to handle Bunte salts instead of thiols, making it more suitable
for large-scale operations.
Table 1 Optimization of the reaction conditions
Experimental section
General
b
All chemical reagents are obtained from commercial suppliers
Entry
Solvent
Acid
Yield (%)
and used without further purication. All known compounds
are identied by appropriate technique such as MS, H NMR,
1
1
2
3
4
5
6
7
8
9
CH
MeCN
2
Cl
2
TsOH
TsOH
TsOH
TsOH
TsOH
TsOH
TsOH
TsOH
—
Trace
63
nr
71
68
nr
nr
16
nr
27
38
52
76
72
and compared with previously reported data. All unknown
H
2
O
1
13
compounds are characterized by H NMR, C NMR, MS and
elemental analyses. Analytical thin-layer chromatography are
performed on glass plates precoated with silica gel impregnated
with a uorescent indicator (254 nm), and the plates are visu-
alized by exposure to ultraviolet light. Mass spectra are taken on
a Finnigan TSQ Quantum-MS instrument in the electrospray
MeOH
EtOH
DMSO
DMF
Toluene
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
10
11
12
13
14
15
16
HCl
1
13
ionization (ESI) mode. H NMR and C NMR spectra are
recorded on an AVANCE 500 Bruker spectrometer operating at
HClO
SO
4
4
H
2
HN(Tf)
2
3
500 MHz and 125 MHz in CDCl , respectively, and chemical
c
TsOH
shis are reported in ppm. Elemental analyses are performed
on a Yanagimoto MT3CHN recorder. GC analyses are performed
on an Agilent 7890A instrument (column: Agilent 19091J-413: 30
d
e
TsOH
69 (88)
34
f
TsOH
a
Reaction conditions: 1a 0.60 mmol, 2a 0.50 mmol, acid 0.50 mmol,
m ꢁ 320 mm ꢁ 0.25 mm, carrier gas: H , FID detection). GC/MS
ꢀ
b
c
2
solvent 1 mL, 6 h, 50 C. GC yields. 0.5 equiv. of TsOH was used.
d
e
ꢀ
.2 equiv. of TsOH was used. The reaction temperature is 80 C,
f
data was recorded on a 5975C Mass Selective Detector, coupled
with a 7890A Gas Chromatograph (Agilent Technologies).
0
isolated yield. 0.1 equiv. of TsOH was used.
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a,b a
Scheme 2 The thia-Michael addition of Bunte salts and a,b-unsaturated ketones.
Reaction conditions: 1 0.60 mmol, 2 0.50 mmol, TsOH 0.10
ꢀ
b
c
ꢀ
mmol, MeOH 1 mL, 6 h, 80 C. Isolated yields. Reaction conditions: 1 0.60 mmol, 2 0.50 mmol, TsOH 0.10 mmol, CH
Cl
2 2
1 mL, 6 h, 40 C.
Scheme 3 The thia-Michael additions of Bunte salts with N-substituented maleimide.
1
c
ꢀ
General procedures for the synthesis of Bunte salts
60 C to remove the MeOH and water. The resultant solid is
ꢀ
treated with MeOH (100 mL), heated to 50 C (most solid
A ask is charged with organic halides (50 mmol), sodium
thiosulfate pentahydrate (60 mmol), water (10.0 mL) and
MeOH (50 mL). The reaction mixture is stirred and heated to
5 C. Aer 16 h at 65 C, the reaction mixture is cooled to rt,
and then concentrated on a rotovap at a bath temperature of
dissolves), and ltered to remove excess sodium thiosulfate
and sodium bromide. The ltrate is concentrated to a white
solid, following trituration of this solid with hexanes, ltra-
tion, and drying under vacuum at 50 C to afford the corre-
sponding Bunte salts.
ꢀ
ꢀ
6
ꢀ
Scheme 4 Thia-Micheal additions via a one-pot process through in situ formation of Bunte salts.
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3 2 2
30.7 (1C, CH ), 35.2 (1C, SCH ), 44.2 (1C, CH), 49.9 (1C, CH C]
O), 123.7 (2C, Ar-C), 127.8 (1C, Ar-C), 128.0 (2C, Ar-C), 129.8 (2C,
Ar-C), 141.1 (1C, Ar-C), 146.0 (1C, Ar-C), 147.0 (1C, Ar-C), 205.0
+
(
1C, C]O). MS (ESI) m/z: 314.98 [M + H] . Anal. calcd for
C
17
H
17NO
3
S: C, 64.74%; H, 5.43%; N, 4.44%. Found: C, 64.38%;
H, 5.29%; N, 4.75%.
-(4-Methoxyphenyl)-3-((4-nitrobenzyl)thio)-1-phenylpropan-
3
1
1-one 3k. H NMR (500 MHz, CDCl
3
) d 3.42 (d, J ¼ 7.0 Hz, 2H),
3
.51–3.60 (dd, J ¼ 32, 14 Hz, 2H), 3.79 (s, 3H), 4.39–4.42 (t, J ¼ 7.0
Hz, 1H), 6.84 (d, J ¼ 8.5 Hz, 2H), 7.19–7.36 (m, 7H), 7.81 (d, J ¼
1
3
8
.5 Hz, 2H), 8.04 (d, J ¼ 8.5 Hz, 2H). C NMR (125 MHz, CDCl ) d
3
35.4 (1C, SCH ), 44.7 (1C, CH), 44.9 (1C, CH C]O), 55.6 (1C,
2
2
3
OCH ), 113.9 (2C, Ar-C), 123.7 (2C, Ar-C), 127.7 (1C, Ar-C), 128.1
(
1
2C, Ar-C), 128.8 (2C, Ar-C), 129.7 (1C, Ar-C), 129.8 (2C, Ar-C),
30.5 (2C, Ar-C), 141.6 (1C, Ar-C), 146.1 (1C, Ar-C), 146.9 (1C,
Scheme 5 A proposed mechanism for thia-Micheal additions with
Bunte salts.
Ar-C), 163.8 (1C, Ar-C), 195.0 (1C, C]O). MS (ESI) m/z: 407.13 [M
+
3
+
H] . Anal. calcd for C23
.44%. Found: C, 67.81%; H, 5.32%; N, 3.74%.
-(4-Bromophenyl)-3-((4-nitrobenzyl)thio)-3-phenylpropan-
4
H21NO S: C, 67.79%; H, 5.19%; N,
General procedures for thia-Michael additions with Bunte
salts and a,b-unsaturated ketones
1
1
1
-one 3l. H NMR (500 MHz, CDCl ) d 3.41–3.42 (dd, J ¼ 7.0, 1.0
3
A mixture of Bunte salts 1 0.60 mmol, a,b-unsaturated ketones 2 Hz, 2H), 3.50–3.59 (dd, J ¼ 32.5, 13.5 Hz, 2H), 4.34–4.37 (t, J ¼
0
ꢀ
.50 mmol, TsOH 0.10 mmol in MeOH (1.0 mL) is stirred at 80 7.0 Hz, 1H), 7.19–7.32 (m, 7H), 7.51 (d, J ¼ 8.5 Hz, 2H), 7.67 (d, J
13
C for 6 h. Upon completion, the reaction mixture is diluted ¼ 8.5 Hz, 2H), 8.06 (d, J ¼ 8.5 Hz, 2H). C NMR (125 MHz,
with EtOAc (4.0 mL), ltered through a bed of silica gel layered CDCl
3
) d 35.4 (1C, SCH ), 44.4 (1C, CH), 45.2 (1C, CH C]O),
2
2
over Celite, The volatiles are removed in vacuo to afford the 123.7 (2C, Ar-C), 127.8 (1C, Ar-C), 128.1 (2C, Ar-C), 128.7 (1C, Ar-
crude product. Further column chromatography on silica gel C), 128.8 (2C, Ar-C), 129.7 (2C, Ar-C), 129.8 (2C, Ar-C), 132.0 (2C,
affords the pure desired product 3.
Ar-C), 135.4 (1C, Ar-C), 141.2 (1C, Ar-C), 145.9 (1C, Ar-C), 147.0
+
(
1C, Ar-C), 195.5 (1C, C]O). MS (ESI) m/z: 455.18 [M + H] . Anal.
calcd for C22 18BrNO S: C, 57.90%; H, 3.98%; N, 3.07%. Found:
C, 57.68%; H, 4.17%; N, 2.86%.
-((4-Nitrobenzyl)thio)-3-phenyl-1-(p-tolyl)propan-1-one 3m.
H NMR (500 MHz, CDCl
) d 2.38 (s, 3H), 3.45–3.47 (dd, J ¼ 7.0,
.5 Hz, 2H), 3.53–3.62 (dd, J ¼ 32, 14 Hz, 2H), 4.40–4.43 (t, J ¼
.0 Hz, 1H), 7.19–7.25 (m, 3H), 7.29–7.36 (m, 6H), 7.75 (d, J ¼ 8.5
H
3
General procedures for thia-Michael additions via a one-pot
process from benzyl chloride, Na
ketones
2 2 3
S O and a,b-unsaturated
3
1
3
A mixture of benzyl chloride 1.5 mmol and Na
2
S
2
O
3
2.0 mmol in
1
7
ꢀ
MeOH (1.0 mL) is stirred at 80 C for 2 h. Then, a,b-unsaturated
ketones 0.50 mmol and TsOH 0.10 mmol are added to the
mixture. The reaction proceeds at the same temperature for
additionally 6 h. Upon completion, the reaction mixture is
diluted with EtOAc (4.0 mL), ltered through a bed of silica gel
layered over Celite, the volatiles are removed in vacuo to afford
the crude product. Further column chromatography on silica
gel affords the pure desired product.
13
Hz, 2H), 8.08 (d, J ¼ 8.5 Hz, 2H). C NMR (125 MHz, CDCl ) d
3
2
1.7 (1C, Ar-CH ), 35.4 (1C, CH S), 44.6 (1C, CH), 45.2 (1C,
3 2
2
CH C]O), 123.7 (2C, Ar-C), 127.7 (1C, Ar-C), 128.1 (2C, Ar-C),
128.3 (2C, Ar-C) 128.8 (2C, Ar-C), 129.4 (2C, Ar-C), 129.8 (2C,
Ar-C), 134.2 (1C, Ar-C), 141.5 (1C, Ar-C), 144.4, 146.1, 147.0,
+
1
96.0. MS (ESI) m/z: 391.20 [M + H] . Anal. calcd for
S: C, 70.56%; H, 5.41%; N, 3.58%. Found: C, 70.29%;
H, 5.17%; N, 3.96%.
-(Benzylthio)-1-ethylpyrrolidine-2,5-dione 3p. H NMR (500
) d 1.18–1.21 (t, J ¼ 7.0 Hz, 3H), 2.39–2.43 (dd, J ¼
23 3
C H21NO
Characterization data for unknown compounds
1
3
1
4
-((4-Methylbenzyl)thio)-4-phenylbutan-2-one 3i. H NMR MHz, CDCl
3
(500 MHz, CDCl
3
) d 2.02 (s, 3H), 2.33 (s, 3H), 2.92–2.94 (m, 2H), 18.5, 1.5 Hz, 1H), 2.94–2.99 (dd, J ¼ 9.0, 4.0 Hz, 1H), 3.49–3.51
3
7
.41–3.51 (dd, J ¼ 37.0, 8.5 Hz, 2H), 4.19–4.22 (t, J ¼ 7.5 Hz, 1H), (dd, J ¼ 9.0, 3.5 Hz, 1H), 3.55–3.59 (q, J ¼ 7.5 Hz, 2H), 3.87 (d, J ¼
1
3
1
3
.09 (brs, 4H), 7.24–7.26 (m, 1H), 7.32–7.33 (m, 4H). C NMR 13.5 Hz, 1H), 4.24 (d, J ¼ 13.5 Hz, 1H), 7.29–7.42 (m, 5H).
) d 21.2 (1C, Ar-CH ), 30.6 (1C, O]CCH ), 35.5 NMR (125 MHz, CDCl ) d 13.0 (1C, CH ), 34.1 (1C, CH N), 35.6
), 44.0 (1C, CH), 50.1 (1C, CH C]O), 127.5 (1C, Ar-C), (1C, CH C]O), 36.0 (1C, SCH ), 37.4 (1C, CH), 127.7 (1C, Ar-C),
28.1 (2C, Ar-C), 128.7 (2C, Ar-C), 128.9 (2C, Ar-C), 129.3 (2C, Ar- 128.8 (2C, Ar-C), 129.3 (2C, Ar-C), 136.9 (1C, Ar-C), 174.7 (1C, C]
C
(
(
125 MHz, CDCl
1C, SCH
3
3
3
3
3
2
2
2
2
2
1
+
C), 134.8 (1C, Ar-C), 136.7 (1C, Ar-C), 141.7 (1C, Ar-C), 205.5 (1C, O), 176.8 (1C, C]O). MS (ESI) m/z: 249.18 [M + H] . Anal. calcd
+
C]O). MS (ESI) m/z: 284.25 [M + H] . Anal. calcd for C18H
2
20OS: for C13H15NO S: C, 62.62%; H, 6.06%; N, 5.62%. Found: C,
C, 76.01%; H, 7.09%. Found: C, 76.36%; H, 7.45%.
62.38%; H, 5.87%; N, 5.37%.
1
4-((4-Nitrobenzyl)thio)-4-phenylbutan-2-one 3j. H NMR (500
Methyl 2-((1-benzyl-2,5-dioxopyrrolidin-3-yl)thio)acetate 3q.
1
MHz, CDCl ) d 2.02 (s, 3H), 2.93 (d, J ¼ 7.0 Hz, 2H), 3.48–3.57
H NMR (500 MHz, CDCl
3
) d 2.50–2.54 (dd, J ¼ 19.0, 4.0 Hz, 1H),
3
(
(
dd, J ¼ 34.0, 8.0 Hz, 2H), 4.17–4.19 (t, J ¼ 7.5 Hz, 1H), 7.21–7.31 3.11–3.17 (q, J ¼ 9.5 Hz, 1H), 3.34–3.37 (d, J ¼ 16.0 Hz, 1H), 3.74
13
m, 7H), 8.08 (d, J ¼ 8.5 Hz, 2H). C NMR (125 MHz, CDCl
3
) d (s, 3H), 3.90–3.93 (d, J ¼ 16.0 Hz, 1H), 4.01–4.04 (dd, J ¼ 9.5, 3.5
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1
3
Hz, 1H), 4.62–4.70 (q, J ¼ 9.0 Hz, 2H), 7.28–7.37 (m, 5H).
C
8 (a) Y. Dong, B. Liu, P. Chen, Q. Liu and M. Wang, Angew.
Chem., Int. Ed., 2014, 53, 3442; (b) Q. Jiang, B. Xu, J. Jia,
A. Zhao, Y.-R. Zhao, Y.-Y. Li, N.-N. He and C.-C. Guo, J. Org.
Chem., 2014, 79, 7372; (c) C. Shen, P. Zhang, Q. Sun, S. Bai,
T. S. A. Hor and X. Liu, Chem. Soc. Rev., 2015, 44, 291.
9 (a) W.-Z. Lee, T.-L. Wang, H.-C. Chang, Y.-T. Chen and
T.-S. Kuo, Organometallics, 2012, 31, 4106; (b) G. Sharma,
R. Kumar and A. K. Chakraborti, Tetrahedron Lett., 2008,
49, 4272; (c) N. Azizi, Z. Yadollahy and A. Rahimzadeh-
Oskooee, Tetrahedron Lett., 2014, 55, 1722; (d) I. Alt,
P. Rohse and B. Plietker, ACS Catal., 2013, 3, 3002; (e)
A. Barakat, A. M. Al-Majid, H. J. Al-Najjar, Y. N. Mabkhot,
H. A. Ghabbour and H.-K. Fun, RSC Adv., 2014, 4, 4909; (f)
N. Fu, L. Zhang, S. Luo and J.-P. Cheng, Org. Lett., 2014,
16, 4626; (g) N. Azizi, A. Khajeh-Amiri, H. Ghafuri and
M. Bolourtchian, Green Chem. Lett. Rev., 2009, 2, 43.
NMR (125 MHz, CDCl ) d 33.0 (1C, SCH ), 35.5 (1C, CHCH C]
O), 38.4 (1C, CH), 42.8 (1C, Ph-CH ), 52.8 (1C, OCH ), 128.2 (1C,
Ar-C), 128.8 (4C, Ar-C), 135.2 (1C, Ar-C), 170.1 (1C, O–C]O),
74.1 (1C, N–C]O), 176.1 (1C, N–C]O). MS (ESI) m/z: 293.22
S: C, 57.32%; H, 5.15%; N,
.77%. Found: C, 57.65%; H, 5.41%; N, 4.59%.
-Benzyl-3-((4-methylbenzyl)thio)pyrrolidine-2,5-dione 3s.
H NMR (500 MHz, CDCl
) d 2.34 (s, 3H), 2.40–2.45 (dd, J ¼ 19.0,
.5 Hz, 1H), 2.95–3.00 (dd, J ¼ 9.0, 4.0 Hz, 1H), 3.81 (d, J ¼ 13.5
Hz, 1H), 4.17 (d, J ¼ 13.5 Hz, 1H), 4.63–4.71 (q, J ¼ 9.0 Hz, 2H),
3
2
2
2
3
1
+
[M + H] . Anal. calcd for C14
H
15NO
4
4
1
1
3
1
1
3
7
.13–7.14 (d, J ¼ 8.0 Hz, 2H), 7.25–7.40 (m, 7H). C NMR (125
MHz, CDCl ) d 21.2 (1C, CH ), 35.6 (1C, CH C]O), 35.7 (1C,
CH S), 37.6 (1C, CH), 42.7 (1C, NCH ), 128.1 (1C, Ar-C), 128.8
4C, Ar-C), 129.2 (2C, Ar-C), 129.5 (2C, Ar-C), 133.7 (1C, Ar-C),
35.5 (1C, Ar-C), 137.4 (1C, Ar-C), 174.5 (1C, C]O), 176.6 (1C,
C]O). MS (ESI) m/z: 325.12 [M + H] . Anal. calcd for 10 (a) H. Firouzabadi, N. Iranpoor and M. Abbasi, Adv. Synth.
3
3
2
2
2
(
1
+
C H NO S: C, 70.12%; H, 5.88%; N, 4.30%. Found: C, 70.42%;
H, 6.01%; N, 4.41%.
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