Synthesis of allenamides by Pd-catalyzed coupling of 3-alkoxycarbonyloxy ynamides or 1-alkoxycarbonyloxy allenamides with arylboronic acids

Article abstract of DOI:10.1039/c2ob26727f

An efficient palladium-catalyzed method is reported for the synthesis of multi-substituted allenamides by Suzuki-Miyaura cross-coupling reaction between easily prepared 3-alkoxycarbonyloxy ynamides or 1-alkoxycarbonyloxy allenamides and arylboronic acids.

Full text of DOI:10.1039/c2ob26727f

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PAPER
Synthesis of allenamides by Pd-catalyzed coupling of 3-alkoxycarbonyloxy
ynamides or 1-alkoxycarbonyloxy allenamides with arylboronic acids†
Jian Cao,* Yulong Kong, Yuan Deng, Guoqiao Lai,* Yuming Cui, Ziqiang Hu and Guanhai Wang
Received 1st September 2012, Accepted 15th October 2012
DOI: 10.1039/c2ob26727f
An efficient palladium-catalyzed method is reported for the synthesis of multi-substituted allenamides
by Suzuki–Miyaura cross-coupling reaction between easily prepared 3-alkoxycarbonyloxy ynamides or
1-alkoxycarbonyloxy allenamides and arylboronic acids.
Introduction
Allenes represent a versatile functional group that has been
widely investigated because of its high reactivity.1 Allenamides,
a special class of functionalized allenes, have recently received
much attention in the synthetic community.2 Various nitrogen-
containing building blocks including nitrogen heterocycles were
successfully synthesized from allenamides.3 However, there are
only a few methods to prepare allenamides, such as sigmatropic
rearrangement of propargylic imidates,4 base-catalyzed isomeri-
zation of propargylic amides,5 and recently reported copper-cata-
lyzed coupling of allenyl halides with amides.6 From the view of
the types and locations of substituents and availability of starting
materials, more efficient strategies are still needed.
Scheme 1
for the synthesis of allenamides via Pd-catalyzed coupling reac-
tion of 3-alkoxycarbonyloxy ynamides with arylboronic acids.
Since Tsuji’s first report in 1985,7 the palladium-catalyzed
reaction of propargylic carbonates has become a powerful tool
for constructing different kinds of allene, alkene, alkyne, and
enyne derivatives.8 Ynamides, an important subclass of alkynes,
have emerged as important synthons in modern organic synthesis
in the past 15 years.9 An array of synthetic targets, including
enamides,10 amidines,11 2-amidofuran,12 and amidocyclo-
butenes,13 have been constructed from ynamides. We are recently
interested in transition metal catalyzed reactions of alkynes,
especially ynamides.14 Enlightened by the chemistry of pro-
pargylic carbonates, we expect that in the presence of a Pd(0)
catalyst, 3-alkoxycarbonyloxy ynamides would react with the
organometallic reagents or nucleophiles to afford nitrogen substi-
tuted allenes or alkenes via allenylpalladium intermediates
(Scheme 1). Considering ynamides can be easily prepared since
the copper-catalyzed amides cross-coupling reaction was esta-
blished,15 we anticipate that this strategy might be an efficient
route to construct allenamides. Herein, we report a novel reaction
Results and discussion
3-Alkoxycarbonyloxy ynamides were prepared from amides and
alkynyl bromides in moderate to good yield by Hsung’s
method15a–d,16 (Table 1).
Interestingly, the reaction gave 1-alkoxycarbonyloxy allena-
mides 2 as main products when R2 and R3 were both alkyl
groups, and expected ynamides were not found (Scheme 2).
Probably due to the high steric hindrance, spontaneous sigmatro-
pic rearrangement occurred after 3-alkoxycarbonyloxy ynamides
were formed under the conditions of coupling reaction. Fortu-
nately, we were able to obtain single crystals of 2a, which un-
ambiguously confirmed the proposed structure via X-ray
diffraction study17 (Fig. 1).
Subsequently, reaction conditions were screened for the coup-
ling reaction of 3-alkoxycarbonyloxy ynamides and arylboronic
acid. Pd(PPh3)4 proved to be the best catalyst, and Pd(OAc)2,
PdCl2(PPh3)2, and Pd2(dba)3·CHCl3 were not effective. The
reaction proceeds well in dioxane, though other common sol-
vents such as toluene and THF could also be used. The tempera-
ture is important for this reaction: at 100 °C the reaction runs
smoothly, while lowering the temperature results in lower yield.
Thus the reaction conditions were chosen as: ynamide 1.0 equiv.,
Key Laboratory of Organosilicon Chemistry and Material Technology of
Ministry of Education, Hangzhou Normal University, Wenyi Road 222,
Hangzhou 310012, P. R. China. E-mail: caojianhznu@yahoo.cn
†Electronic supplementary information (ESI) available. CCDC 898714,
898715. For ESI and crystallographic data in CIF or other electronic
format see DOI: 10.1039/c2ob26727f
9556 | Org. Biomol. Chem., 2012, 10, 9556–9561
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Table 1 Synthesis of 3-alkoxycarbonyloxy ynamides 1a
Table 2 Optimization of the reaction conditionsa
Entry
EWG
R1
R2
R3
R4
Yield (%)
Temp
Time
Yield of 3a
Entry
Catalyst
Solvent
(°C)
(h)
(%)
1
2
3
4
Ts
Ts
Ts
Ms
Bn
Bn
n-Pr
Bn
H
H
H
H
H
Me
H
Me
Me
n-Pr
n-Pr
59 (1a)
67 (1b)
52 (1c)
50 (1d)
1
2
3
4
5
6
7
8
Pd(OAc)2
Dioxane
Dioxane
Dioxane
Dioxane
THF
Toluene
Dioxane
Dioxane
100
100
100
100
65
100
rt
1
1
1
0.5
3
0.5
3
3
NRb
NRb
NRb
75
PdCl2(PPh3)2
Pd2(dba)3·CHCl3
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
H
5
H
H
Me
45 (1e)
57
33
NDc
66
a Unless otherwise specified, the reaction was carried out using amide
(1.0 equiv.), alkynyl bromide (1.1 equiv.), CuSO4·5H2O (0.1 equiv.),
1,10-phen (0.2 equiv.), and K2CO3 (2.0 equiv.) in toluene at 75 °C
under N2.
60
a Unless otherwise specified, the reaction was carried out using 1a (1.0
equiv.), arylboronic acid (1.5 equiv.), and catalyst (0.05 equiv.) under
N2. b No reaction. c Not determined. The reaction was too slow to
observe.
Scheme 2
Scheme 3
alkoxycarbonyloxy ynsulfonamides 1 and 1-alkoxycarbonyloxy
allensulfonamides 2 underwent the coupling reaction well to
afford di-, tri-, and tetrasubstituted allensulfonamides 3.
However, oxazolidinone 1e failed to produce any allenamide.
The structures of all these products were confirmed with the help
of spectral and analytical data, and the structure of 3a was
further established by X-ray diffraction analysis18 (Fig. 2).
Interestingly, a cyclic product was obtained when 2-hydroxy-
phenylboronic acid was used. It is reasonable to propose that
spontaneous cyclization occurred after allenamide was formed to
afford 4-amino-2H-chromene 4 (Scheme 4).
The following plausible mechanism was proposed for the
coupling-reaction as shown in Scheme 5: (i) 3-alkoxycarbonyl-
oxy ynamide 1 or 1-alkoxycarbonyloxy allenamide 2 (may be
interconverted to 1 at 100 °C) reacts with Pd(0) to afford the
intermediate 4; (ii) subsequently, transmetalation reaction with
arylboronic acid gives 5; (iii) finally, reductive elimination gives
the product allenamide 3.
Fig. 1 ORTEP representation of 2a.
arylboronic acid 1.5 equiv., Pd(PPh3)4 0.05 equiv. in dioxane at
100 °C for 30 min (Table 2).
1-Alkoxycarbonyloxy allenamide 2 could also undergo a
coupling reaction under the same conditions and gave the corre-
sponding allenamide in high yield. As far as we know, this is the
first report that allenyl carbonate participates in a Suzuki–
Miyaura reaction (Scheme 3).
Conclusions
With the optimized reaction conditions in hand, the scope of
this Pd-catalyzed reaction was further investigated, and the
results are summarized in Table 3.
Various arylboronic acids gave good results, either with an
electron-donating or electron-withdrawing group. Both 3-
In summary, we have described an efficient palladium-catalyzed
method for the synthesis of multi-substituted allenamides by
Suzuki–Miyaura cross-coupling reaction between 3-alkoxycarbo-
nyloxy ynamides or 1-alkoxycarbonyloxy allenamides and aryl-
boronic acids.
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Table 3 Synthesis of allenamides 3a
Entry
1
1/2
Product, yield (%)
Entry
7
1/2
Product, yield (%)
1a
2a
2
1c
8
2a
3
4
1a
1b
9
2a
2a
10
5
6
1d
1e
11
12
2a
2b
a Unless otherwise specified, the reaction was carried out using 1a (1.0 equiv.), arylboronic acid (1.5 equiv.), and catalyst (0.05 equiv.) under N2.
General procedures for synthesis of 3-alkoxycarbonyloxy
Experimental
ynamides 1 and 1-alkoxycarbonyloxy allenamides 215c
General
To a mixture of an amide (1.0 equiv.), K2CO3 (2.0 equiv.),
CuSO4·5H2O (0.10 equiv.), and 1,10-phenanthroline (0.20
equiv.) in a reaction vial was added a solution of a respective
1-bromoalkyne (1.1 equiv.) in toluene. The reaction mixture was
capped and heated at 75 °C while being monitored with TLC
All reactions were performed under a N2 atmosphere. All sol-
vents were purified and dried according to standard methods
1
prior to use. All H NMR and 13C NMR spectra were measured
in CDCl3 with TMS as the internal standard. Chemical shifts are
expressed in ppm and J values are given in Hz.
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(4H, m), 0.95 (3H, t, J = 7.6 Hz), 0.88 (3H, t, J = 7.6 Hz); 13C
NMR (100 MHz, CDCl3): δ 154.7, 144.7, 134.6, 129.8, 127.6,
80.8, 69.9, 65.6, 56.0, 53.0, 22.0, 21.7, 21.2, 10.8, 10.2; IR
(film, cm−1): 2969, 2246, 1747, 1365, 1258, 1172, 581; HRMS
(m/z) Calcd for C17H23NNaO5S (M + Na)+: 376.1195, Found:
376.1182.
1d Yield: 50%. Oil. 1H NMR (400 MHz, CDCl3): δ
7.36–7.41 (5H, m), 4.85 (2H, s), 4.62 (2H, s), 4.11 (2H, d, J =
6.8 Hz), 2.87 (3H, s), 1.70 (2H, m), 0.96 (3H, d, J = 7.2 Hz);
13C NMR (100 MHz, CDCl3): δ 154.7, 134.4, 128.9, 128.87,
128.81, 80.7, 70.0, 66.8, 55.9, 55.7, 39.2, 22.0, 10.2; IR (film,
cm−1): 2970, 2247, 1747, 1360, 1258, 1165, 929, 539; HRMS
(m/z) Calcd for C15H19NNaO5S (M + Na)+: 348.0882, Found:
348.0877.
Fig. 2 ORTEP representation of 3e.
1
1e Yield: 45%. Solid, mp: 106–108 °C. H NMR (400 MHz,
CDCl3): δ 4.89 (2H, s), 4.44 (2H, t, J = 8.0 Hz), 3.92 (2H, t, J =
8.0 Hz), 3.79 (3H, s); 13C NMR (100 MHz, CDCl3): δ 155.9,
155.2, 77.5, 66.0, 63.2, 55.9, 55.1, 46.6; IR (KBr, cm−1): 3442,
2263, 1758, 1428, 1258, 1117, 754; HRMS (m/z) Calcd for
C8H9NNaO5 (M + Na)+: 222.0378, Found: 222.0373.
Scheme 4
1
2a Yield: 63%. Solid, mp: 101–103 °C. H NMR (400 MHz,
CDCl3): δ 7.80 (2H, d, J = 8.4 Hz), 7.29–7.33 (7H, m), 4.40
(2H, s), 3.74 (3H, s), 2.44 (3H, s), 1.53 (6H, s); 13C NMR
(100 MHz, CDCl3): δ 191.2, 153.0, 143.9, 135.5, 135.2, 129.5,
128.5, 128.4, 128.1, 127.8, 117.4, 113.4, 55.2, 53.1, 21.6, 20.7;
IR (KBr, cm−1): 2930, 1763, 1275, 1170, 1153, 669; HRMS
(m/z) Calcd for C21H23NNaO5S (M + Na)+: 424.1188, Found:
424.1195.
1
2b Yield: 71%. Solid, mp: 95–97 °C. H NMR (400 MHz,
CDCl3): δ 7.81 (2H, d, J = 8.4 Hz), 7.24–7.33 (7H, m), 4.40
(2H, s), 3.75 (3H, s), 2.43 (3H, s), 1.84–1.92 (4H, m), 1.40–1.52
(4H, m), 1.22–1.27 (2H, m); 13C NMR (100 MHz, CDCl3): δ
187.6, 153.0, 143.8, 135.6, 134.9, 129.4, 128.4, 128.3, 128.2,
127.7, 120.2, 117.2, 55.1, 53.4, 31.4, 27.1, 25.5, 21.6; IR (KBr,
cm−1): 2928, 1765, 1277, 1169, 1149, 670; HRMS (m/z) Calcd
for C24H27NNaO5S (M + Na)+: 464.1508, Found: 464.1503.
Scheme 5
analysis. Upon reaction completion, the mixture was filtered over
a plug of silica gel (washed with ethyl acetate), and the filtrate was
concentrated. The residue was purified by flash chromatography
(eluent: hexane–ethyl acetate = 9 : 1–6 : 1) to afford 1 or 2.
1a Yield: 59%. Oil. 1H NMR (400 MHz, CDCl3): δ 7.73 (2H,
d, J = 8.4 Hz), 7.26–7.31 (7H, m), 4.78 (2H, s), 4.49 (2H, s),
3.77 (3H, s), 2.43 (3H, s); 13C NMR (100 MHz, CDCl3): δ
155.1, 144.9, 134.5, 134.2, 129.8, 128.7, 128.6, 128.4, 127.7,
81.2, 86.3, 56.2, 55.4, 55.1, 21.7; IR (film, cm−1): 2957, 2247,
1755, 1361, 1261, 1168, 544; HRMS (m/z) Calcd for
C19H19NNaO5S (M + Na)+: 396.0882, Found: 396.0876.
1b Yield: 67%. Oil. 1H NMR (400 MHz, CDCl3): δ 7.73 (2H,
d, J = 8.0 Hz), 7.26–7.31 (7H, m), 5.53 (1H, t, J = 6.8 Hz), 4.52
(1H, d, J = 13.6 Hz), 4.42 (1H, d, J = 13.6 Hz), 3.75 (3H, s),
2.43 (3H, s), 1.40 (3H, d, J = 6.8 Hz); 13C NMR (100 MHz,
CDCl3): δ 154.7, 144.8, 134.4, 134.2, 129.7, 128.9, 128.5,
128.4, 127.8, 79.6, 70.1, 64.9, 55.4, 54.8, 21.7, 21.2; IR (film,
cm−1): 2956, 2247, 1749, 1367, 1264, 1170, 1090, 545; HRMS
(m/z) Calcd for C20H21NNaO5S (M + Na)+: 410.1038, Found:
410.1030.
General procedures for synthesis of allenamides 3 and 4
A vial was charged with 1 or 2 (0.5 mmol), arylboronic acid
(0.75 mmol) and Pd(PPh3)4 (28.9 mg, 0.025 mmol). The vial
was evacuated under high vacuum and backfilled with N2.
Dioxane (3 mL) was next added and the solution was stirred at
100 °C for 30 min. Upon reaction completion, the mixture was
concentrated and the residue was purified by flash chromato-
graphy on silica gel (eluent: hexane–ethyl acetate = 9 : 1–6 : 1) to
afford 3 or 4.
1
3a Yield: 75%. Solid, mp: 164–166 °C. H NMR (400 MHz,
CDCl3): δ 7.72 (2H, d, J = 8.4 Hz), 7.21–7.34 (9H, m), 6.78
(2H, d, J = 8.4 Hz), 5.01 (2H, s), 4.40 (2H, s), 3.76 (3H, s), 2.46
(3H, s); 13C NMR (100 MHz, CDCl3): δ 208.5, 159.2, 143.7,
135.5, 134.1, 129.4, 129.2, 128.3, 128.2, 127.8, 127.2, 126.6,
113.6, 112.7, 84.9, 55.3, 54.5, 21.6; IR (KBr, cm−1): 3447,
2971, 1607, 1509, 1347, 1251, 1165, 598; HRMS (m/z) Calcd
for C24H23NNaO3S (M + Na)+: 428.1296, Found: 428.1300.
3b Yield: 49%. Oil. 1H NMR (400 MHz, CDCl3): δ 7.68 (2H,
d, J = 8.0 Hz), 7.49 (2H, d, J = 8.8 Hz), 7.29 (2H, d, J =
8.0 Hz), 6.89 (2H, d, J = 8.8 Hz), 5.00 (2H, s), 3.81 (3H, s),
1c Yield: 52%. Oil. 1H NMR (400 MHz, CDCl3): δ 7.78 (2H,
d, J = 8.0 Hz), 7.33 (2H, d, J = 8.0 Hz), 4.86 (2H, s), 4.10 (2H,
t, J = 6.8 Hz), 3.26 (2H, t, J = 7.2 Hz), 2.44 (3H, s), 1.63–1.70
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3.22 (2H, t, J = 7.2 Hz), 2.43 (3H, s), 1.50–1.56 (2H, m), 0.89
(3H, t, J = 7.2 Hz); 13C NMR (100 MHz, CDCl3): δ 207.9,
159.3, 143.5, 134.3, 129.2, 128.1, 127.2, 126.9, 113.8, 112.7,
84.9, 55.3, 52.9, 21.6, 21.4, 11.4; IR (film, cm−1): 3447, 2969,
1606, 1508, 1340, 1246, 1165, 837; HRMS (m/z) Calcd for
C20H23NNaO3S (M + Na)+: 380.1296, Found: 380.1294.
NMR (100 MHz, CDCl3): δ 201.1, 163.3, 160.8, 143.6, 136.0,
134.9, 132.3, 132.2, 129.4, 128.9, 128.3, 128.2, 127.8, 127.78,
127.73, 115.0, 114.8, 109.3, 106.9, 54.4, 21.6, 20.1; IR (KBr,
cm−1): 3448, 2964, 1598, 1507, 1340, 1158, 589; HRMS (m/z)
Calcd for C25H24FNNaO2S (M + Na)+: 444.1409, Found:
444.1403.
1
1
3c Yield: 64%. Solid, mp: 165–167 °C. H NMR (400 MHz,
3k Yield: 90%. Solid, mp: 144–146 °C. H NMR (400 MHz,
CDCl3): δ 7.73 (2H, d, J = 8.0 Hz), 7.22–7.34 (9H, m), 7.07
(2H, d, J = 8.0 Hz), 5.03 (2H, s), 4.41 (2H, s), 2.47 (3H, s), 2.29
(3H, s); 13C NMR (100 MHz, CDCl3): δ 208.7, 143.7, 137.5,
135.5, 134.0, 131.4, 129.4, 129.2, 128.9, 128.3, 128.2, 127.9,
125.9, 113.0, 85.0, 54.5, 21.7, 21.2; IR (KBr, cm−1): 3447,
3036, 1342, 1160, 1067, 814, 661; HRMS (m/z) Calcd for
C24H23NNaO3S (M + Na)+: 412.1347, Found: 412.1355.
CDCl3): δ 7.73 (2H, d, J = 8.0 Hz), 7.17–7.34 (11H, m), 4.42
(2H, s), 2.46 (3H, s), 1.54 (6H, s); 13C NMR (100 MHz,
CDCl3): δ 201.3, 143.6, 135.9, 134.9, 134.6, 132.8, 129.4,
128.7, 128.4, 128.2, 128.1, 127.8, 127.4, 109.3, 107.2, 54.4,
21.6, 20.0; IR (KBr, cm−1): 3441, 2923, 1488, 1337, 1164,
1090, 673, 549; HRMS (m/z) Calcd for C25H24ClNNaO2S
(M + Na)+: 460.1114, Found: 460.1108.
1
1
3d Yield: 82%. Solid, mp: 141–143 °C. H NMR (400 MHz,
3l Yield: 93%. Solid, mp: 119–121 °C. H NMR (400 MHz,
CDCl3): δ 7.74 (2H, d, J = 8.0 Hz), 7.19–7.34 (9H, m), 6.79
(2H, d, J = 8.8 Hz), 5.47 (1H, t, J = 6.8 Hz), 4.47 (1H, d, J =
13.6 Hz), 4.36 (1H, d, J = 13.6 Hz), 3.76 (3H, s), 2.46 (3H, s),
1.49 (3H, d, J = 7.2 Hz); 13C NMR (100 MHz, CDCl3): δ 203.7,
159.0, 143.6, 135.8, 134.3, 129.4, 129.0, 128.33, 128.27, 127.8,
127.3, 113.5, 111.8, 96.4, 55.3, 54.4, 21.7, 14.0; IR (KBr,
cm−1): 3440, 2917, 1607, 1510, 1348, 1248, 1164, 594; HRMS
(m/z) Calcd for C25H25NNaO3S (M + Na)+: 442.1453, Found:
442.1448.
CDCl3): δ 7.75 (2H, d, J = 8.4 Hz), 7.21–7.34 (9H, m), 6.81
(2H, d, J = 8.8 Hz), 4.46 (2H, s), 3.77 (3H, s), 2.45 (3H, s),
1.84–1.98 (4H, m), 1.47–1.59 (4H, m), 1.28–1.35 (2H, m); 13C
NMR (100 MHz, CDCl3): δ 196.9, 158.8, 143.4, 136.3, 134.6,
129.4, 128.8, 128.7, 128.3, 128.2, 127.6, 127.3, 113.5, 113.4,
109.5, 55.3, 54.5, 31.1, 27.5, 25.7, 21.6; IR (KBr, cm−1): 3447,
2926, 2914, 1606, 1510, 1342, 1159, 1038; HRMS (m/z) Calcd
for C29H31NNaO3S (M + Na)+: 496.1922, Found: 496.1918.
1
4 Yield: 75%. Solid, mp: 109–111 °C. H NMR (400 MHz,
3e Yield: 40%. Oil. 1H NMR (400 MHz, CDCl3): δ 7.29–7.36
(7H, m), 6.84 (2H, d, J = 8.8 Hz), 5.41 (2H, s), 4.57 (2H, s),
3.78 (3H, s), 2.84 (3H, s); 13C NMR (100 MHz, CDCl3): δ
208.5, 159.6, 135.6, 129.4, 128.5, 128.2, 127.4, 125.4, 114.0,
112.1, 84.8, 55.3, 53.7, 38.6; IR (film, cm−1): 2933, 1725, 1606,
1510, 1336, 1250, 1149, 835; HRMS (m/z) Calcd for
C18H19NNaO3S (M + Na)+: 352.0983, Found: 352.0976.
CDCl3): δ 7.76 (2H, d, J = 8.4 Hz), 7.22–7.31 (7H, m),
7.05–7.08 (2H, m), 6.70–6.78 (2H, m), 5.05 (1H, s), 4.59 (2H,
s), 2.43 (3H, s), 1.27 (6H, s); 13C NMR (100 MHz, CDCl3): δ
153.5, 143.8, 135.63, 135.57, 131.8, 131.4, 129.8, 129.5, 129.4,
128.3, 128.1, 128.0, 124.0, 120.6, 119.9, 116.4, 76.6, 53.9, 27.2,
21.6; IR (KBr, cm−1): 3447, 2972, 1637, 1451, 1352, 1163, 760,
661; HRMS (m/z) Calcd for C25H25NNaO3S (M + Na)+:
442.1453, Found: 442.1447.
1
3g Yield: 94%. Solid, mp: 136–138 °C. H NMR (400 MHz,
CDCl3): δ 7.78 (2H, d, J = 8.0 Hz), 7.23–7.37 (9H, m), 6.83
(2H, d, J = 8.8 Hz), 4.49 (2H, s), 3.77 (3H, s), 2.45 (3H, s), 1.56
(6H, s); 13C NMR (100 MHz, CDCl3): δ 200.8, 158.9, 143.5,
136.3, 134.9, 129.4, 128.8, 128.6, 128.4, 128.1, 127.7, 127.5,
113.5, 109.8, 106.6, 55.3, 54.3, 21.6, 20.2; IR (KBr, cm−1):
3440, 2924, 1600, 1517, 1341, 1155, 1034; HRMS (m/z) Calcd
for C26H27NNaO3S (M + Na)+: 456.1609, Found: 456.1605.
Acknowledgements
We are grateful to the National Natural Science Foundation of
China (Project No. 21102029) for financial support.
1
3h Yield: 86%. Solid, mp: 145–147 °C. H NMR (400 MHz,
Notes and references
CDCl3): δ 7.80 (2H, d, J = 8.4 Hz), 7.44 (2H, d, J = 7.6 Hz),
7.20–7.38 (10H, m), 4.52 (2H, s), 2.47 (3H, s), 1.59 (6H, s); 13C
NMR (100 MHz, CDCl3): δ 201.6, 143.6, 136.3, 136.2, 135.1,
129.5, 128.8, 128.4, 128.2, 128.1, 127.8, 127.2, 126.3, 109.9,
106.6, 54.3, 21.7, 20.1; IR (KBr, cm−1): 3445, 3031, 1597,
1350, 1167, 767, 662, 598; HRMS (m/z) Calcd for
C25H25NNaO2S (M + Na)+: 426.1504, Found: 426.1498.
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1
3i Yield: 80%. Solid, mp: 153–155 °C. H NMR (400 MHz,
CDCl3): δ 7.89 (2H, d, J = 8.4 Hz), 7.43 (2H, d, J = 8.4 Hz),
7.19–7.40 (9H, m), 4.44 (2H, s), 3.88 (3H, s), 2.46 (3H, s), 1.57
(6H, s); 13C NMR (100 MHz, CDCl3): δ 202.5, 167.0, 143.6,
141.1, 135.8, 134.8, 129.4, 129.3, 128.8, 128.5, 128.4, 128.2,
127.8, 126.0, 109.5, 107.2, 54.4, 52.0, 21.6, 19.9; IR (KBr,
cm−1): 3416, 1716, 1343, 1274, 1174, 1101, 665; HRMS (m/z)
Calcd for C27H27NNaO4S (M + Na)+: 484.1558, Found:
484.1545.
1
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3j Yield: 82%. Solid, mp: 167–169 °C. H NMR (400 MHz,
CDCl3): δ 7.74 (2H, d, J = 8.0 Hz), 7.23–7.34 (9H, m),
6.90–6.94 (2H, m), 4.44 (2H, s), 2.45 (3H, s), 1.55 (6H, s); 13C
9560 | Org. Biomol. Chem., 2012, 10, 9556–9561
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17 Crystal data for 2a: C21H23NO5S, MW = 401.46, triclinic, space group
ˉ
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data), R1 = 0.1179, wR2 = 0.1939; a = 10.8478(12) Å, b = 11.5786(13)
Å, c = 17.841(2) Å, α = 80.352(2), β = 80.707(2), γ = 76.854(2), V =
2133.5(4) Å3, T = 296(2) K, Z = 4. Supplementary crystallographic data
have been deposited at the Cambridge Crystallographic Data Centre,
CCDC 898714.
18 Crystal data for 3e: C48H48N2O7S2, MW = 829.00, triclinic, space group
ˉ
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= 15.9530(9) Å, α = 61.7910(10), β = 76.5350(10), γ = 86.7540(10), V =
2125.4(2) Å3, T = 296(2) K, Z = 2. Supplementary crystallographic data
have been deposited at the Cambridge Crystallographic Data Centre,
CCDC 898715.
This journal is © The Royal Society of Chemistry 2012
Org. Biomol. Chem., 2012, 10, 9556–9561 | 9561