Pd(II)-catalyzed annulation of N-benzyl-N-aroylmethyl-2-alkynamides with arylboronic acids: An efficient synthesis of highly substituted α-alkylidene-β-hydroxy-γ-lactams

Article abstract of DOI:10.1016/j.tet.2010.09.090

A simple palladium(II)-catalyzed intramolecular addition of vinylpalladium species to ketones initiated by the carbopalladation of alkynamides under mild conditions without a Pd(II)/Pd(0) redox system was developed. This cascade reaction provides a new approach for the synthesis of highly substituted α-alkylidene-β-hydroxy-γ-lactams.

Full text of DOI:10.1016/j.tet.2010.09.090

Tetrahedron 66 (2010) 9129e9134
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Pd(II)-catalyzed annulation of N-benzyl-N-aroylmethyl-2-alkynamides
with arylboronic acids: an efficient synthesis of highly substituted
a
-alkylidene-
b
-hydroxy-
g
-lactams
*
*
Huan Wang, Xiuling Han , Xiyan Lu
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 15 August 2010
Received in revised form 27 September 2010
Accepted 29 September 2010
Available online 16 October 2010
A simple palladium(II)-catalyzed intramolecular addition of vinylpalladium species to ketones initiated
by the carbopalladation of alkynamides under mild conditions without a Pd(II)/Pd(0) redox system was
developed. This cascade reaction provides a new approach for the synthesis of highly substituted
kylidene- -hydroxy- -lactams.
a-al-
b
g
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
Palladium(II)
Ketone
Arylboronic acid
Lactam
Carbopalladation
1. Introduction
Recently, we reported some Pd(II)-catalyzed addition reactions
to carbon-heteroatom multiple bonds10,11aec initiated by carbo-
palladation of alkynes with arylboronic acids.11 In all of these re-
actions, palladium(II) complexes were used as catalysts and no
redox system was required. Inspired by these works, we wonder if
Biologically active substances possessing lactam units are found
common in natural sources.1,2 According to some recent researches,
the
g-lactam skeleton shows cytotoxicity, antitumor, and antiin-
flamation activities and are less toxic compared to the corre-
we can construct the a-alkylidene-g-lactam unit in one-step
through the similar route (Scheme 1). Recently, Corey reported the
total synthesis of Salinosporamide A and its analogues with
sponding lactones.3 Especially highly substituted lactams possess
different biological activities.4 In addition, the
g-lactam function-
ality is a prevalent theme in various natural product synthesis and
serves as a crucial intermediate for numerous natural products.5
Although different methods have been developed to construct
this kind of structures,6 much more attention can never be enough.
the similar
a
-methylene-
b
-hydroxy-
g
-butyrolactam structure as
the intermediate.5
R1
O
Ar2
OH
As a potential precursor for synthesis of natural products,
lidene- -lactams attracted our interest. In earlier work, our group
has constructed this kind of unit in different ways.6o-q
a-alky-
Ar1
Ar1
R1
Ar2B(OH)2
g
+
N
O
N
O
The addition of specific carbon nucleophiles to carbon-hetero-
atom multiple bond, such as C]O,7 C]N,8 CN9 is an attractive syn-
thetic methodology for forming CeC bonds. Compared to Rh species,
organopalladium(II) species are more electrophilic and can easily
react with some nucleophiles, such as carbon, oxygen or nitrogen
anions. Although a few papers have reported the nucleophilic reac-
tions,7c,d,9b most of these reactions were catalyzed by Pd(0) species,
and involved a Pd(II)/Pd(0) redox system. Thus, it is a challenge to
accomplish a nucleophilic addition reaction for Pd(II) species.
R2
R2
Scheme 1. The proposed reaction.
2. Results and discussion
To begin the study of the annulation reaction, the effect of dif-
ferent catalysts was first surveyed using N-benzyl-N-benzoyl-
methyl-but-2-ynamide (1a) as the substrate. It was found that the
reaction did work when using some neutral or cationic Pd(II)/dppp
(or bpy) species to give
the product. Cationic palladium species and Pd(CF3COO)2 can only
a-alkylidene-b-hydroxy-g-butyrolactams as
* Corresponding authors. Tel.: þ86 21 54925158; fax: þ86 21 64166128; e-mail
address: xylu@mail.sioc.ac.cn (X. Lu).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.09.090

9130
H. Wang et al. / Tetrahedron 66 (2010) 9129e9134
give moderate yields of the product in dioxane (or DCE) and H2O
(Table 1, entries 1e8) at 80 ꢀC orelevated temperature. Pd(OAc)2/bpy
can provide the product in good yield (Table 1, entry 9). The reaction
did not occur in the absence of the ligand (Table 1, entry 10).
arylboronic acids was explored. As shown in Table 3, this reaction
proceeded well with various substrates, and some different kinds of
electronically and sterically diverse functional groups can be tol-
erated. Substrates with methyl, n-propyl, TMS at the end of the
Table 1
Screening of catalystsa
Ph
OH
Ph
O
Ph
PhB(OH)2
+
O
N
O
N
Bn
Bn
1a
2a
3aa
Entry
Catalyst
Solvent (v/v)
Temperature (ꢀC)
Time (h)
Yieldb (%)
1c
2c
3c
4
[dpppPd(H2O)2]2þ(BF4ꢁ)2
[dpppPd(H2O)2]2þ(OTfꢁ)2
[dpppPd(H2O)2]2þ(OTfꢁ)2
[dpppPd(H2O)2]2þ(OTfꢁ)2
[bpyPd(H2O)2]2þ(OTfꢁ)2
Pd (CF3COO)2/dppp
Pd (CF3COO)2/bpy
Pd(CF3COO)2/NO2-bpy
Pd (OAc)2/bpy
Pd (OAc)2
Dioxane/H2O (10/1)
Dioxane/H2O (10/1)
Dioxane/H2O (10/1)
DCE/H2O (20/1)
DCE/H2O (20/1)
DCE/H2O (20/1)
DCE/H2O (20/1)
DCE/H2O (20/1)
DCE/H2O (20/1)
DCE/H2O (20/1)
80
80
Reflux
80
80
80
80
80
Reflux
Reflux
14
14
8
40
8
48
40
72
2
48
41
52
42
52
39
75
57
88
d
5
6d
7d
8d
9d
10d
72
a
Reaction conditions: 1a (0.1 mmol), phenylboronic acid (1.3 equiv), catalyst (5 mol %), solvent/H2O (2 mL/0.1 mL).
Isolated yield.
Solvent/H2O (1 mL/0.1 mL).
Catalyst (5 mol %)/ligand (6 mol %).
b
c
d
Then the effect of solvent to the reaction was studied as shown in
triple bond all can gave corresponding products in moderate to
excellent yields (Table 3, entries 1, 2, and 18). It is worth noting that
the substrate 1k with the terminal triple bond can also gave the
expected product in excellent yield (Table 3, entry 19). The reaction
did not occur for phenyl substituted alkynamides (Table 3, entry 3).
Changing the substituent on the nitrogen atom from methyl to
ethyl or benzyl made no difference in reactivity, and they all pro-
ceeded with good yields (Table 3, entries 1, 4, and 5). For substrate
with 4-tolyl group on the nitrogen atom, the reaction did not occur
(Table 3, entry 6). Different arylboronic acids with various sub-
stituents, such as F, Cl, NO2, OMe, etc., all proceeded well with
substrate 1a (Table 3, entries 10e17).
Table 2. Itwasfoundthat thereaction canproceed smoothlyin DCE or
benzene at reflux, giving the product in excellent yields in 3 h or 16 h,
respectively (Table 2, entries 4 and 8). The water also has some in-
fluence to the reaction. The reaction gave a lower yield of the product
in the absence of water (Table 2, entry 9). Finally, DCE was chosen as
the best solvent in consideration of its shorter reaction time. The
effect of temperature on the reaction was investigated (Table 2, en-
tries 10e13). The reaction gave the best yield at reflux, and lower
temperature made the reaction time longer and yield lower.
Table 2
Screening of solvents and temperaturea
The stereochemistry of the exocyclic double bond in all the prod-
ucts was assigned as (E)-configuration on the basis of the lower field
chemical shift of the methyl group resulting from the deshielding
effect of the same side carbonyl group in 1H NMR spectra and com-
pared with the data in the literatures.12 In addition, the stereochem-
istry of product 3aa was confirmed by X-ray crystallography.13
To study further the utility of the reaction, the substrate di-
methyl 2-(but-20-ynyl)-2-benzoylmethylmalonate (1l) was sub-
jected to the optimal reaction condition. It can also give the
expected product 3la in 49% yield. A moderate yield (66%) could be
obtained when the reaction was carried out in the presence of KF
(Scheme 2).
Entry
Solvent
Temperature (ꢀC)
Time (h)
Yieldb (%)
1
2
3
4
5
6
7
8
Dioxane
Toluene
CHCl3
DCE
80
80
60
60
60
3
72
15
3
16
4
2
5
64
46
87
20
73
77
88
76
87
75
79
62
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
90
THF
CH3CN
CH2Cl2
Benzene
DCE
DCE
DCE
9c
10
11
12
13
80
68
rt
2
7
48
DCE
DCE
Subsequently the possible mechanism is proposed for the re-
action: first, bpyPd(OAc)2 is formed in situ from Pd(OAc)2 and bpy,
followed by transmetalation with arylboronic acids 2 to produce
the arylpalladium species A. Then intermediate B may be formed
by the coordination of arylpalladium species with the triple bond
and the carbonyl group of substrate 1. The insertion of the triple
bond to arylpalladium species in B affords vinylpalladium in-
termediate C. 1,2-Addition of the vinylpalladium species to the
carbonyl group in C generates D, and finally the product 3 is
formed by protonolysis of the palladium alkoxide intermediate D
with the regeneration of the palladium(II) species to complete the
catalytic cycle (Scheme 3).
a
Reaction conditions: 1a (0.1 mmol), phenylboronic acid (1.3 equiv), Pd(OAc)2
(5 mol %)/bpy (6 mol %), solvent/H2O (2 mL/0.1 mL).
b
Isolated yield.
Reaction in DCE in the absence of water.
c
On the basis of the above screening procedure, the optimal
condition for this tandem annulation reaction was as follows:
substrate (0.1 mmol), phenylboronic acid (1.3 equiv), Pd(OAc)2
(5 mol %), bpy (6 mol %), DCE (2 mL), H2O (0.1 mL) at reflux.
With the effective catalytic system in hand, the application
scope of this reaction with various substituted ynamides and

Table 3
Synthesis of substituted
a
-alkylidene-
b
-hydroxy-
g
-lactamsa
R1
Ar2
OH
Ar1
O
Ar1
Pd(OAc)2/bpy
R1
Ar2B(OH)2
+
DCE/H2O (20/1)
reflux
O
O
N
N
R2
1a-k
R2
3aa-ka
2a-i
Entry
1
Ar2
Time (h)
3
Yieldb (%)
R1
R2
Ar1
1
1
2
3
4
5
6
7
8
Me
nPr
Ph
Bn
Bn
Bn
Me
Et
Ph
Ph
Ph
Ph
Ph
Ph
1a
Ph (2a)
Ph (2a)
Ph (2a)
Ph (2a)
Ph (2a)
Ph (2a)
Ph (2a)
Ph (2a)
Ph (2a)
4-MeeC6H4 (2b)
3-MeeC6H4 (2c)
4-MeOeC6H4 (2d)
4-FeC6H4 (2e)
4-CleC6H4 (2f)
4-PheC6H4 (2g)
3-NO2eC6H4 (2h)
2-Naphthyl (2i)
Ph (2a)
2
0.5
48
2
1.25
48
1.5
2
0.5
2
2
2
8
5
4
4
4
2
1
3aa
3ba
3ca
3da
3ea
3fa
3ga
3ha
3ia
3ab
3ac
3ad
3ae
3af
3ag
3ah
3ai
88
91
N.R.
77
90
N.R.
79
89
88
92
78
100
77
73
94
87
58
85
100
1b
1c
1d
1e
1f
1g
1h
1i
1a
1a
1a
1a
1a
1a
1a
1a
1j
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
TMS
H
4-MeeC6H4
Bn
Bn
Bn
Bn
Bn
Bn
Bn
Bn
Bn
Bn
Bn
Bn
Bn
4-CleC6H4
4-BreC6H4
4-MeOeC6H4
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
9
10
11
12
13
14
15
16
17
18
19
3ja
3ka
4-CleC6H4
1k
Ph (2a)
a
Reaction conditions: substrate 1 (0.1 mmol), arylboronic acid (1.3 equiv), Pd(OAc)2 (5 mol %)/bpy (6 mol %), DCE/H2O (2 mL/0.1 mL), reflux.
Isolated yield.
b
3. Conclusion
Ph
Pd(OAc)2 (5mol%)
bpy (6mol%)
OH
Ph
O
Ph
KF (1.3 equiv)
In conclusion, we have demonstrated an efficient approach to
synthesize the highly substituted -alkylidene- -hydroxy- -lac-
tams using Pd(OAc)2/bpy as the catalyst. This is a tandem reaction
involving carbopalladation of alkyne/1,2-addition to carbonyl
groups. The asymmetric version of this cascade cyclization reaction
is in progress in our group.
+
PhB(OH)2
a
b
g
DCE/H2O
80oC
MeO2C CO2Me
MeO2C CO2Me
3la
1l
2a
Scheme 2. Reaction of 1l.
Pd(OAc)2 + bpy
Pd(OAc)2(bpy)
4. Experimental section
4.1. General methods
R1
O
Ar2
Ar1
NMR spectra were recorded on a Varian Mercury Vꢂ300 or
Vꢂ400 spectrometers. Infrared spectra were obtained on a Bio-Rad
FTS-185 machine. Mass spectra were provided on Agilent 5973 or
Agilent 1100 instruments. Elemental analyses were carried out on
Elementar Vario EL instruments. Palladium acetate was purchased
from Aldrich. 2,2-Bipyridine was purchased from Sinopharm
Chemical Reagent Co., LtdS. All solvents were dried and distilled
before use according to the standard methods. All melting
points were uncorrected. BEP (2-bromo-1-ethyl-pyridinium
R1
OH
Ar1
Ar2B(OH)2
N
O
R2
1
O
2
N
R2
Ar2Pd(OAc)L
A
3
Ar2B(OH)2
H2O
Ar2
tetrafluoroborate),14 substituted
u u-(N-
-bromoacetophenone,15
R1
L
Pd
substituted amino)-acetophenone hydrochloride,16 1-phenyl-2-(p-
tolylamino)ethanone,17 but-2-ynoic acid,18 1-bromobut-2-yne,19
dimethyl 2-(but-2-ynyl)malonate20 were synthesized employing
the literature procedures.
O
Ar1
N
O
L
R2
B
Ar2
Pd
R1
O
O
Ar1
4.2. General procedure for the synthesis of N-benzyl-N-
L
aroylmethyl-2-alkynamides (1)14a
N
R2
insertion into
C-Pd bond
Ar2
Ar1
Pd O
DIEA (N,N-diisopropylethylamine, 3.2 equiv) was added
D
R1
1,2-addition
at ꢁ10 ꢀC to a cooled mixture of
u-(N-substituted amino)aceto-
N
O
phenone hydrochloride (1.1 equiv), alkynoic acid (1 mmol), BEP
(1.5 equiv) in CH2Cl2 (10 mL) under N2 atmosphere. The mixture
was stirred at ꢁ10 ꢀC for 10 min and then reacted at room tem-
perature until the consumption of alkynoic acid as monitored by
L = bpy
R2
C
Scheme 3. Proposed mechanism.

9132
H. Wang et al. / Tetrahedron 66 (2010) 9129e9134
TLC. Then the reaction mixture was concentrated and purified by
flash chromatography on silica gel to afford the desired product.
For the characterization data of product 1aek, please see
Supplementary data.
126.0, 76.0, 61.2, 46.6, 21.9; IR (KBr): n 3263, 1663, 1634, 1492, 1433,
1265, 708, 697 cmꢁ1; MS (m/z, EI): 405 (37Cl, Mþ), 403 (35Cl, Mþ),
388, 221, 120, 91 (100); calcd for C25H22ClNO2: C, 74.34%; H, 5.49%;
N, 3.47%; found: C, 74.26%; H, 5.58%; N, 3.33%.
4.3. General procedure for the synthesis of
hydroxy- -lactams
a
-alkylidene-
b-
4.3.6. Compound 3ha. Solid; mp 222e223 ꢀC; 1H NMR (400 MHz,
CDCl3): d 7.26e7.23 (m, 7H), 7.13e7.10 (m, 3H), 6.94e6.92 (m, 2H),
g
6.74 (d, J¼6.8 Hz, 2H), 4.59 (s, 2H), 3.43 (d, J¼10 Hz, 1H), 3.23 (d,
Pd(OAc)2 (5 mol %), bpy (6 mol %), and DCE (2 mL) was added
into a Schlenk tube, then the mixture was stirred at reflux for
10 min. The substrate (0.1 mmol), arylboronic acid (1.3 equiv), and
H2O (0.1 mL) were added subsequently, then the mixture was
reacted at reflux until the consumption of substrate as monitored
by TLC. Then the reaction mixture was concentrated and purified by
flash chromatography on silica gel using ethyl acetate/petroleum
ether as the eluent to afford the desired product.
J¼10.8 Hz, 1H), 2.65 (s, 3H), 2.28 (s, 1H); 13C NMR (100 MHz, CDCl3):
d
167.5, 150.9, 146.0, 141.2, 135.8, 134.0, 131.0, 128.7, 128.2, 127.7,
127.6,126.6,126.4,120.8, 76.0, 61.1, 46.6, 21.9; IR (KBr): n 3273, 3057,
2915, 1663, 1633, 1490, 1433, 760, 698 cmꢁ1; MS (m/z, EI): 449 (81Br,
Mþ), 447 (79Br, Mþ), 434, 432, 278, 221, 91 (100); calcd for
C25H22BrNO2: C, 66.97%; H, 4.95%; N, 3.12%; found: C, 67.24%; H,
4.94%; N, 3.08%.
4.3.7. Compound 3ia. Solid; mp 191e193 ꢀC; 1H NMR (400 MHz,
4.3.1. Compound 3aa. Solid; mp 158e160 ꢀC; 1H NMR (400 MHz,
CDCl3):
d
7.30e7.20 (m, 5H), 7.16e7.01 (m, 3H), 7.03 (d, J¼8.8 Hz,
CDCl3):
d
7.29e7.22 (m, 5H), 7.15e7.06 (m, 8H), 6.73 (d, J¼6.8 Hz,
2H), 6.78 (d, J¼6.4 Hz, 2H), 6.76 (d, J¼8.8 Hz, 2H), 4.62 (d, J¼14.8 Hz,
1H), 4.55 (d, J¼14.4 Hz, 1H), 3.77 (s, 3H), 3.44 (d, J¼10 Hz, 1H), 3.23
(d, J¼10 Hz, 1H), 2.66 (s, 3H), 2.08 (s, 1H); 13C NMR (100 MHz,
2H), 4.64 (d, J¼14.8 Hz,1H), 4.57 (d, J¼14.8 Hz,1H), 3.45 (d, J¼10 Hz,
1H), 3.27 (d, J¼10 Hz, 1H), 2.66 (s, 3H), 2.18 (s, 1H); 13C NMR
(100 MHz, CDCl3):
d
167.7, 150.1, 147.3, 141.3, 136.0, 134.4, 128.7,
CDCl3): d 167.8, 158.5, 149.7, 141.4, 139.7, 136.0， 134.3, 128.7, 128.6,
128.2, 128.0, 127.6, 127.5, 126.9, 126.6, 124.4, 76.4, 61.0, 46.6, 21.8; IR
128.2, 128.1, 127.6, 127.5, 126.6, 125.7, 113.4, 76.3, 61.0, 55.3, 46.5,
(KBr):
n
3285, 3062, 2915, 1659, 1492, 1431, 757, 694 cmꢁ1; MS (m/z,
21.8; IR (KBr): n 3332, 3057, 2915, 1662, 1627, 1512, 1435, 1242,
EI): 369 (Mþ), 354, 292, 278, 91 (100); calcd for C25H23NO2: C,
81.27%; H, 6.27%; N, 3.79%; found: C, 81.27%; H, 6.28%; N, 3.62%.
695 cmꢁ1; MS (m/z, EI): 399 (Mþ), 384, 252, 237, 135, 91 (100);
HRMS-EI calcd for C26H25NO3： 399.1834; found: 399.1837.
4.3.2. Compound 3ba. Solid; mp 154e155 ꢀC; 1H NMR (400 MHz,
4.3.8. Compound 3ja. Solid; mp 81e83 ꢀC; 1H NMR (300 MHz,
CDCl3):
d
7.29e7.20 (m, 5H), 7.16e7.04 (m, 8H), 6.70 (d, J¼7.2 Hz,
CDCl3): d 7.33e7.23 (m, 6H), 7.17e7.15 (m, 3H), 7.01e6.99 (m, 4H),
2H), 4.64 (d, J¼14.4 Hz,1H), 4.54 (d, J¼14.4 Hz,1H), 3.44 (d, J¼10 Hz,
1H), 3.45e3.38 (m, 1H), 3.24 (d, J¼10 Hz, 1H), 2.91e2.89 (m, 1H),
2.08 (s, 1H), 1.45e1.39 (m, 2H), 0.97 (t, J¼6.8 Hz, 3H); 13C NMR
6.77 (s, 1H), 5.98 (s, 1H), 4.75 (d, J¼20 Hz, 1H), 4.53 (d, J¼20 Hz, 1H),
3.54 (d, J¼12 Hz, 1H), 3.28 (d, J¼12 Hz, 1H), 2.19 (s, 1H), 0.14 (s,
9H)； 13C NMR (75 MHz, CDCl3):
d 166.7, 156.5, 147.4, 147.2, 140.7,
(100 MHz, CDCl3):
d
167.4, 154.4, 147.7, 139.8, 136.0, 134.5, 128.6,
135.8, 128.7, 128.1, 128.0, 127.6, 126.9, 126.2, 125.8, 123.9, 76.0; IR
128.1, 128.0, 127.5, 127.4, 127.2, 126.9, 124.3, 76.3, 60.9, 46.5, 35.7,
(KBr): n 3388, 3059, 3026, 2902, 1664, 1592, 1486, 1439, 1293,
21.3, 14.0; IR (KBr):
n
3391, 3026, 2956, 2871, 1656, 1632, 1486, 1438,
1243 cmꢁ1; MS (m/z, EI): 427 (Mþ), 412 (100), 105, 91, 73, 65;
758, 695 cmꢁ1; MS (m/z, EI): 397 (Mþ), 380, 354, 278, 91 (100);
calcd for C27H27NO2: C, 81.58%; H, 6.85%; N, 3.52%; found: C, 81.40%;
H, 6.88%; N, 3.45%.
HRMS-EI calcd for C27H29NO2Si: 427.1968; found: 427.1971.
4.3.9. Compound 3ka. Solid; mp 196e198 ꢀC; 1H NMR (400 MHz,
CDCl3):
d 7.66 (s, 1H), 7.37e7.24 (m, 7H), 7.17e7.10 (m, 7H), 4.70 (d,
4.3.3. Compound 3da. Solid; mp 180e182 ꢀC; 1H NMR (400 MHz,
J¼14.4 Hz, 1H), 4.27 (d, J¼14.8 Hz, 1H), 4.16 (s, 1H), 3.61 (d,
CDCl3):
d
7.16e7.06 (m, 8H), 6.73 (d, J¼6.8 Hz, 2H), 3.57 (d, J¼10 Hz,
J¼10.4 Hz,1H), 3.36 (d, J¼10.4 Hz,1H)； 13C NMR (100 MHz, CDCl3):
1H), 3.41 (d, J¼10.4 Hz, 1H), 2.97 (s, 3H), 2.61 (s, 3H), 2.17 (s, 1H); 13C
d 168.0, 142.0, 137.5, 135.5, 133.1, 132.7, 131.0, 129.5, 128.8, 128.4,
NMR (100 MHz, CDCl3):
d
168.0, 149.7, 147.1, 141.4, 134.3, 128.1,
128.1, 127.8, 126.4, 74.8, 63.4, 47.1; IR (KBr): n 3286, 3052, 3029,
128.0, 127.3, 126.8, 126.7, 124.5, 76.1, 64.0, 29.8, 21.6; IR (KBr):
n
2952, 2922, 1667, 1627, 1432, 739, 699 cmꢁ1; MS (m/z, EI): 391 (Mþ,
37Cl), 389 (Mþ, 35Cl), 327, 298, 286, 242,155,127, 85, 71, 57 (100), 43,
41; HRMS-EI calcd for C24H20ClNO2: 389.1183; found: 389.1182.
3300, 3059, 3022, 2937, 1670, 1658, 1492, 1450, 1281, 1213, 756,
693 cmꢁ1; MS (m/z, EI): 293 (Mþ), 278, 250, 207,105 (100); calcd for
C19H19NO2: C, 77.49%; H, 6.53%; N, 4.77%; found: C, 77.61%; H,
6.49%; N, 4.68%.
4.3.10. Compound 3ab. Solid; mp 139e140 ꢀC; 1H NMR (300 MHz,
CDCl3):
d
7.26e7.11 (m, 10H), 6.99 (d, J¼7.8 Hz, 2H), 6.63 (d,
4.3.4. Compound 3ea. Solid; mp 129e130 ꢀC; 1H NMR (300 MHz,
J¼8.1 Hz, 2H), 4.64 (d, J¼14.7 Hz, 1H), 4.54 (d, J¼14.7 Hz, 1H), 3.45
(d, J¼9.9 Hz,1H), 3.24 (d, J¼9.9 Hz,1H), 2.64 (s, 3H), 2.24 (s, 3H), 2.17
CDCl3):
d
7.16e7.10 (m, 8H), 6.72 (d, J¼8.8 Hz, 2H), 3.56 (d,
J¼13.2 Hz, 1H), 3.60e3.38 (m, 2H), 3.39 (d, J¼13.6 Hz, 1H), 2.60 (s,
(s, 1H); 13C NMR (75 MHz, CDCl3):
d 167.9, 149.9, 147.7, 138.4, 137.4,
3H), 2.34 (s, 1H), 1.13 (t, J¼8 Hz, 3H); 13C NMR (75 MHz, CDCl3):
136.0, 134.2, 128.9, 128.6, 128.1, 127.5, 126.9, 126.5, 124.5, 76.5, 60.8,
d
167.5, 149.5, 147.4, 141.3, 134.7, 128.1, 128.2, 128.0, 127.4, 126.8,
46.5, 21.8, 21.1; IR (KBr): n 3416, 3058, 3026, 2910, 1657, 1633, 1510,
126.6, 124.3, 76.3, 61.1, 37.2, 21.6, 12.2; IR (KBr):
n
3367, 3025, 2978,
1482, 1440, 697 cmꢁ1; MS (m/z, EI): 383 (Mþ, 100), 368, 292, 221,
105, 91; calcd for C26H25NO2: C, 81.43%; H, 6.57%; N, 3.65%; found:
C, 81.40%; H, 6.67%; N, 3.56%.
2938, 1658, 1631, 1601, 1485, 1448, 1431, 1283, 758, 700 cmꢁ1; MS
(m/z, EI): 307 (Mþ), 292, 222, 207, 105, 58 (100); calcd for
C20H21NO2: C, 78.15%; H, 6.89%, N, 4.56%; found: C, 78.10%; H, 6.82%;
N, 4.57%.
4.3.11. Compound 3ac. Solid; mp 134e137 ꢀC; 1H NMR (400 MHz,
CDCl3):
d 7.30e7.23 (m, 5H), 7.17e7.14 (m, 3H), 7.08e7.06 (m, 2H),
4.3.5. Compound 3ga. Solid; mp 222e223 ꢀC; 1H NMR (400 MHz,
7.03 (t, J¼7.6 Hz, 1H), 6.93 (d, J¼7.6 Hz, 1H), 6.61 (d, J¼7.6 Hz, 1H),
6.38 (s, 1H), 4.64 (d, J¼14.8 Hz, 1H), 4.57 (d, J¼14.8 Hz, 1H), 3.45 (d,
J¼9.6 Hz, 1H), 3.27 (d, J¼10 Hz, 1H), 2.64 (s, 3H), 2.21 (s, 1H), 2.05 (s,
CDCl3):
d 7.28e7.26 (m, 5H), 7.14e7.07 (m, 5H), 6.99e6.98 (m, 2H),
6.74 (dd, J¼1.2 and 7.8 Hz, 2H), 4.62 (d, J¼14.8 Hz, 1H), 4.57 (d,
J¼14.8 Hz, 1H), 3.43 (d, J¼10 Hz, 1H), 3.24 (d, J¼10.4 Hz, 1H), 2.65 (s,
3H); 13C NMR (100 MHz, CDCl3):
d 167.8, 150.2, 147.7, 141.1, 137.9,
3H), 2.39 (s, 1H)； 13C NMR (100 MHz, CDCl3):
d
167.5, 150.9, 145.4,
136.0, 134.3, 128.6, 128.2, 128.1, 127.9, 127.5, 127.4, 126.8, 124.3,
123.4, 76.2, 60.8, 46.5, 21.7, 21.2; IR (KBr): 3385, 3051, 3030, 2914,
141.2, 135.8, 134.0, 132.6, 128.7, 128.2, 128.0, 127.7, 127.6, 126.6,
n

H. Wang et al. / Tetrahedron 66 (2010) 9129e9134
9133
1668, 1635, 1496, 1483, 705, 699 cmꢁ1; MS (m/z, EI) 383 (Mþ), 368,
221, 159, 105, 91 (100); HRMS-EI calcd for C26H25NO2: 383.1885;
found: 383.1887.
128.2, 128.1, 128.0, 127.6, 127.5, 126.9, 126.4, 126.3, 125.6, 124.6,
124.4, 76.4, 60.9, 46.6, 21.6; IR (KBr): n 3365, 3059, 3026, 2935, 2910,
1668, 1645, 1481, 1430, 1286, 1264, 747, 700 cmꢁ1; MS (m/z, EI): 419
(Mþ), 404, 195, 91 (100); calcd for C29H25NO2: C, 83.03%; H, 6.01%;
N, 3.34%; found: C, 82.97%; H, 6.18%; N, 3.10%.
4.3.12. Compound 3ad. Solid; mp 147e148 ꢀC; 1H NMR (400 MHz,
CDCl3):
d
7.29e7.11 (m, 10H), 6.68 (d, J¼8.4 Hz, 2H), 6.60 (d,
4.4. Synthesis of dimethyl 2-(but-20-ynyl)-2-(benzoylmethyl)
malonate (1l)
J¼8.4 Hz, 2H), 4.63 (d, J¼14.8 Hz,1H), 4.55 (d, J¼14.8 Hz,1H), 3.72 (s,
3H), 3.45 (d, J¼10 Hz, 1H), 3.25 (d, J¼10 Hz, 1H), 2.64 (s, 3H), 2.24 (s,
1H); 13C NMR (100 MHz, CDCl3):
d 167.9, 158.9, 149.7, 147.6, 136.0,
134.2, 133.6, 128.6, 128.2, 128.1, 128.0, 127.5, 126.9, 124.5, 113.6, 76.5,
To the solution of NaH (4.5 mmol) in THF (10 mL), dimethyl 2-(2-
but ynyl)malonate (2.3 mmol) was added dropwise at ꢁ10 ꢀC. After
60.9, 55. 2, 46.5, 21.9; IR (KBr): n 3398, 3034, 2914, 2837, 1656, 1627,
1510, 1440, 1247, 697 cmꢁ1; MS (m/z, EI): 399 (Mþ), 384, 175, 120,
105, 91(100); calcd for C26H25NO3: C, 78.14%; H, 6.31%; N, 3.51%;
found: C, 78.10%; H, 6.48%; N, 3.27%.
the reaction was stirred for 20 min the solution of
u-bromoaceto-
phenone (2.4 mmol) in THF was added dropwise. Then the mixture
was refluxed for 5 h as monitored by TLC. The reaction was
quenched by 5 mL of saturated aqueous solution of ammonium
chloride. The aqueous phase was extracted with diethylether sev-
eral times. The combined organic layer was dried by MgSO4. The
mixture was concentrated and purified by flash chromatography on
silica gel using ethyl acetate/petroleum ether as the eluent to afford
the desired product in 50% yield.
4.3.13. Compound 3ae. Solid; mp 137e138 ꢀC; 1H NMR (400 MHz,
CDCl3):
d 7.31e7.23 (m, 5H), 7.13e7.11 (m, 3H), 7.06e7.05 (m, 2H),
6.72 (d, J¼7.2 Hz, 4H), 4.63 (d, J¼14.8 Hz, 1H), 4.63 (d, J¼14.8 Hz,
1H), 3.44 (d, J¼10.4 Hz,1H), 3.34 (d, J¼10.4 Hz,1H), 2.63 (s, 3H), 2.52
(s, 1H); 13C NMR (100 MHz, CDCl3):
d 167.6, 163.0, 160.5, 149.6,
146.4, 137.3, 135.9, 134.9, 128.7, 128.6, 128.2, 128.0, 127.6, 126.9,
124.5, 115.0, 114.8, 76.2, 61.6, 46.6, 21.9; 19F NMR(MHz, CDCl3):
4.5. Synthesis of (Z)-dimethyl 3-hydroxy-3-phenyl-4-
d
ꢁ114.1 to ꢁ112.2 (m); IR (KBr):
n 3408, 3028, 2912, 1658, 1635,
(1-phenylethylidene) cyclopentane-1,1-dicarboxylate (3la)
1508, 1484, 1440, 1225, 698 cmꢁ1; MS (m/z, EI): 387 (Mþ), 372, 225,
120, 91 (100), 372; calcd for C25H22FNO2: C, 77.50%; H, 5.72%; N,
3.62%; found: C, 77.67%; H, 5.79%; N, 3.53%.
Pd(OAc)2 (5 mol %), bpy (6 mol %), and DCE (2 mL) was added
into a dried Schlenk tube, then the mixture was stirred at 80 ꢀC for
10 min. The substrate 3la (0.1 mmol), phenylboronic acid
(1.3 equiv), KF (1.5 equiv), and H2O (0.1 mL) were added sub-
sequently, then reacted at 80 ꢀC oil bath until the consumption of
3la as monitored by TLC. Then the reaction mixture was concen-
trated and purified by flash chromatography on silica gel using
ethyl acetate/petroleum ether as the eluent to afford the desired
product in 66% yield.
4.3.14. Compound 3af. Solid; mp 163e164 ꢀC; 1H NMR (400 MHz,
CDCl3):
d 7.32e7.23 (m, 5H), 7.15e7.13 (m, 3H), 7.07e7.04 (m, 2H),
7.01(d, J¼8.4 Hz, 2H), 6.67 (d, J¼8.4 Hz, 2H), 4.64 (d, J¼15.2 Hz, 1H)
4.57 (d, J¼15.2 Hz, 1H), 3.44 (d, J¼10.2 Hz, 1H), 3.34 (d, J¼10 Hz, 1H),
2.62 (s, 3H), 2.19 (s, 1H)； 13C NMR (100 MHz, CDCl3):
d 167.4, 149.3,
146.3, 139.8, 135.8, 135.0, 133.3, 128.7, 128.2, 128.1, 128.0, 127.6,
126.9, 124.5, 76.2, 61.5, 46.6, 21.7; IR (KBr): n 3414, 3059, 2912, 1658,
1636, 1488, 1450, 1298, 701, 695 cmꢁ1; MS (m/z, EI): 405 (37Cl, Mþ),
403 (35Cl, Mþ), 388, 120, 105, 91 (100); calcd for C25H22ClNO2: C,
74.34%; H, 5.49%; N, 3.47%; found: C, 74.16%; H, 5.63%; N, 3.28%.
4.5.1. Compound 3la21. Solid; mp 86e88 ꢀC; 1H NMR (400 MHz,
CDCl3): d 7.01e6.98 (m, 5H), 6.95e6.91 (m, 3H), 6.68e6.65 (m, 2H),
3.82 (s, 3H), 3.70 (s, 3H), 3.65 (dq, J¼17 and 0.8 Hz, 1H), 3.16 (dq,
J¼16.8 and 2 Hz, 1H), 2.78e2.69 (m, 2H), 2.45 (s, 1H), 2.01 (q,
4.3.15. Compound 3ag. Solid; mp 159e160 ꢀC; 1H NMR (400 MHz,
J¼1.2 Hz, 3H)； 13C NMR (100 MHz, CDCl3):
d 172.8, 171.8, 146.2,
141.9, 141.5, 134.9, 127.7, 127.6, 127.2, 126.1, 125.9, 125.3, 82.0, 57.5,
CDCl3):
d
7.46 (d, J¼7.2 Hz, 2H), 7.40 (t, J¼7.2 Hz, 2H), 7.34e7.24 (m,
8H), 7.11e7.10 (m, 5H), 6.81 (d, J¼8 Hz, 2H), 4.61 (s, 2H), 3.46 (d,
53.2, 53.0, 52.9, 40.5, 23.9; IR (KBr): n 3567, 3057, 2955, 2852, 1733,
J¼10.4 Hz,1H), 3.32 (d, J¼10.4 Hz,1H), 2.70 (s, 3H), 2.46 (s,1H)； 13C
1600, 1494, 1436, 1257, 761, 699 cmꢁ1; MS (m/z, ESI): 362
(MþꢁH2O), 302 (100); HRMS-ESI calcd for C23H22O4 (MþꢁH2O):
362.1518; found: 362.1523.
NMR (100 MHz, CDCl3):
d 167.7, 150.0, 146.8, 140.3, 140.1, 135.9,
134.6,128.7, 128.6, 128.1, 127.9, 127.6,127.4, 127.1,126.9, 126.8, 126.6,
124.6, 76.3, 61.3, 46.6, 21.7; IR (KBr): n 3358, 3050, 3028, 2897, 2848,
1658, 1612, 1478, 1264, 769, 755, 701 cmꢁ1; MS (m/z, EI): 445 (Mþ),
430, 221, 120, 105, 91 (100); calcd for C31H27NO2: C, 83.57%; H,
6.11%; N, 3.14%; found: C, 83.48%; H, 6.32%; N, 3.00%.
Acknowledgements
The National Basic Research Program of China 2006CB806105 is
acknowledged. We also thank the National Natural Science Foun-
dation of China (20732005, 20872158) and Chinese Academy of
Sciences for financial support.
4.3.16. Compound 3ah. Solid; mp 184e189 ꢀC; 1H NMR (400 MHz,
CDCl3):
d 7.87 (s, 1H), 7.58 (s, 1H), 7.26e7.35 (m, 5H), 7.16e7.19 (m,
2H), 6.97 (d, J¼6.4 Hz, 5H), 4.72 (d, J¼14.4 Hz, 1H), 4.57 (d,
J¼14.8 Hz, 1H), 3.49 (d, J¼11.2 Hz, 1H), 3.44 (d, J¼11.2 Hz, 1H), 3.12
Supplementary data
(s, 1H), 2.65 (s, 3H)； 13C NMR (100 MHz, CDCl3):
d 167.2, 149.0,
147.2,144.1,142.8,136.0, 135.7,133.2,128.8,128.4,128.2,127.8,127.7,
The spectroscopic and analytic data of the new compounds are
included in the Supplementary data. Supplementary data associ-
ated with this article can be found in online version at doi:10.1016/
j.tet.2010.09.090. These data include MOL files and InChIKeys of the
most important compounds described in this article.
126.7, 124.7, 122.6, 121.8, 75.7, 62.8, 46.8, 21.5; IR (KBr):
n 3439,
3081, 3028, 2919, 2866, 1658, 1637, 1525, 1348, 1265, 699 cmꢁ1; MS
(m/z, EI): 414 (Mþ), 399, 120, 105, 91 (100); calcd for C25H22N2O4: C,
72.45%; H, 5.35%; N, 6.76%; found: C, 72.10%; H, 5.38%; N, 6.68%.
4.3.17. Compound 3ai. Solid; mp 147e148 ꢀC; 1H NMR (400 MHz,
References and notes
CDCl3):
d
7.72 (d, J¼7.2 Hz, 1H), 7.59 (d, J¼8.4 Hz, 1H), 7.42e7.39 (m,
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d 167.8, 149.8, 147.7, 138.6, 135.9, 134.9, 132.4, 132.2, 128.7,

9134
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