Palladium-catalyzed reactions of vinylidenecyclopropanes with acetic acid

Article abstract of DOI:10.1016/j.tet.2006.07.052

Pd(PPh₃)₄-catalyzed reactions of vinylidenecyclopropanes 1 with acetic acid proceeded smoothly at 80 °C in toluene to give the corresponding acetylated dienes 2 in moderate to good yields in the presence of DPEphos ligand. The plausi

Full text of DOI:10.1016/j.tet.2006.07.052

Tetrahedron 62 (2006) 9115–9122
Palladium-catalyzed reactions of vinylidenecyclopropanes
with acetic acid
*
Jian-Mei Lu and Min Shi
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry,
Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
Received 30 May 2006; revised 17 July 2006; accepted 18 July 2006
Available online 4 August 2006
Abstract—Pd(PPh3)4-catalyzed reactions of vinylidenecyclopropanes 1 with acetic acid proceeded smoothly at 80 ꢀC in toluene to give the
corresponding acetylated dienes 2 in moderate to good yields in the presence of DPEphos ligand. The plausible mechanism is proposed on the
basis of the control and deuterium labeling experiments.
Ó 2006 Elsevier Ltd. All rights reserved.
1. Introduction
are summarized in Table 1. As shown in Table 1, Pd(PPh3)4
can catalyze the reaction of vinylidenecyclopropane 1a with
acetic acid in toluene to produce 2a in moderate yields as
mixtures of E- and Z-isomers (Table 1). The structure of
Vinylidenecyclopropanes 11 are one of the most remarkable
organic compounds known. They have an allene moiety
connected by a cyclopropane ring and yet they are thermally
stable and reactive substances. Thermal and photochemical
skeletal conversions of vinylidenecyclopropanes 1 have
attracted much attention from mechanistic, theoretical, spec-
troscopic and synthetic viewpoints.2,3 Vinylidenecyclopro-
panes 1 also undergo a variety of unique addition reactions
with electrophiles to give novel products sometimes along
with the formation of cyclopropane ring-opened products.4
Previously, we reported the palladium-catalyzed isomeriza-
tion of a variety of methylenecyclopropanes (MCPs),
another kind of molecules having surprising stability along
with a high level of strain, in acetic acid to give the corre-
sponding 1-substituted or 1,1-disubstituted dienes in good
yields.5 However, to the best of our knowledge, there has
been no report on the palladium-catalyzed reactions of vinyl-
idenecyclopropanes 1 until now. In this context, we wish to
disclose the first example of palladium-catalyzed reactions
of vinylidenecyclopropanes with acetic acid to give the cor-
responding acetylated dienes 2 in moderate to good yields.
1
product 2a was determined by H and 13C NMR spectro-
scopic data, HRMS and NOESY analytic data (Supplemen-
tary data). The NOESY of 2a is shown in Figure 1, which
clearly indicates that the major isomer has E-configuration.
Other palladium catalysts, such as PdCl2(PPh3)2, Pd(OAc)2,
PdCl2(dppf) and Pd(dba)2, did not catalyze the reaction
under identical conditions (Table 1, entries 5, 8–10). Avariety
of phosphine ligands, such as PPh3, AsPh3, tri-2-furyl-
phosphine (TFP), bis[(2-diphenylphosphino)phenyl]ether
(DPEphos), 1,4-bis(diphenylphosphino)butane (dppb) and
1,3-bis(diphenylphosphino)propane (dppp), were also
examined for this reaction to improve the yield of 2a. We found
that when Pd(PPh3)4 (10 mol %) and DPEphos (40 mol %)
were utilized in this reaction, 2a can be obtained in 58%
yield as mixtures of E- and Z-isomers (E:Z¼6:1) (Table 1,
entry 16). Using Pd(OAc)2 or Pd(dba)2 as a catalyst, 2a
was still obtained in lower yield even in the presence of
AsPh3 or DPEphos ligand (Table 1, entries 6, 11 and 12).
Using Pd(PPh3)4 (10 mol %) and DPEphos (40 mol %) as
the catalyst, solvent effects were also examined upon heating
or under reflux. The results are summarized in Table 1 as
entries 16–20. As can be seen from these experiments, toluene
is the best solvent for this reaction at 80 ꢀC (Table 1, entries
16–20). We found that the employed amount of DPEphos
slightly affected the yield of product 2a in toluene at 80 ꢀC
(Table 1, entries 21–23). When Pd(PPh3)4 (10 mol %) and
DPEphos (20 mol %) were used, 2a was obtained in 64%
yield, which is the highest yield in this reaction (Table 1,
entry 22).
2. Results and discussion
As an initial examination, the reaction of vinylidenecyclo-
propane 1a with acetic acid (2.0 equiv) was carried out
with a variety of catalysts in toluene at 80 ꢀC. The results
Keywords: Palladium catalyst; Vinylidenecyclopropanes; Acetic acid;
Acetylated dienes; Deuterium labeling experiment.
* Corresponding author. Fax: +86 21 64166128; e-mail: mshi@pub.sioc.
ac.cn
0040–4020/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.07.052

9116
J.-M. Lu, M. Shi / Tetrahedron 62 (2006) 9115–9122
Table 1. Optimization of the reaction condition of 1a with acetic acid
C6H5
C6H5
C6H5
H
C6H5
C6H5
Catalyst
C6H5
H
+
HOAc
solvent, temp.
OAc
2a
1a
Entrya
Catalyst/ligand/mol %
Solvent
Temp/ꢀC
Time/h
2a Yieldb/% (E:Z)c
1
2
3
4
5
6
7
8
—
Pd(PPh3)4 (10)
Pd(PPh3)4/PPh3 (10/40)
Pd(PPh3)4/AsPh3 (10/40)
Pd(OAc)2
Pd(OAc)2/AsPh3 (10/40)
Pd(PPh3)4/TFP (10/40)
PdCl2(PPh3)2/PPh3 (10/40)
PdCl2(dppf)/dppf (10/20)
Pd(dba)2 (10)
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Dioxane
CH3CN
THF
80
80
80
80
80
80
80
80
80
80
80
80
80
80
80
80
110
100
80
66
80
80
80
48
5
6
N.R
44 (6:1)
37 (6:1)
50 (6:1)
Complex
14 (9:1)
38 (6:1)
N.R
6
12
18
6
20
24
9
18
18
33
33
17
20
11
9
9
N.R
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Complex
42 (8:1)
36 (7:1)
34 (11:1)
32 (5:1)
36 (6:1)
58 (6:1)
26 (9:1)
10 (11:1)
21 (9:1)
14 (12:1)
36 (>40:1)
64 (7:1)
60 (8:1)
Pd(dba)2/DPEphos (10/20)
Pd(OAc)2/DPEphos (10/20)
Pd(PPh3)4/dppp (10/40)
Pd(PPh3)4/dppb (10/40)
Pd(PPh3)4/(o-CH3C6H4)3P (10/40)
Pd(PPh3)4/DPEphos (10/40)
Pd(PPh3)4/DPEphos (10/40)
Pd(PPh3)4/DPEphos (10/40)
Pd(PPh3)4/DPEphos (10/40)
Pd(PPh3)4/DPEphos (10/40)
Pd(PPh3)4/DPEphos (20/60)
Pd(PPh3)4/DPEphos (10/20)
Pd(PPh3)4/DPEphos (10/10)
9
33
36
18
12
Toluene
Toluene
Toluene
a
All reactions were carried out using 1a (0.3 mmol), AcOH (0.6 mmol) and catalysts in a variety of solvents (2.0 mL).
Isolated yields.
b
c
Determined from 1H NMR spectroscopic data and NOESY.
Under these optimized conditions, we next examined a vari-
For arylvinylidenecyclopropane 1c (R1¼C6H5 and R2¼
p-ClC6H4), the corresponding E- and Z-isomers can be
separated by silica gel chromatograph. In other cases, the
corresponding E- and Z-isomers are inseparable. For alkyl-
vinylidenecyclopropanes 1i and 1j (R1¼alkyl, R2¼aryl), the
corresponding acetylated dienes 2i and 2j were also formed
in 36 and 61% yields, respectively (Table 2, entries 8 and 9).
ety of vinylidenecyclopropanes 1 with acetic acid for the
reaction generality. The results are summarized in Table 2.
With respect to the electron-rich and electron-poor aryl-
vinylidenecyclopropanes 1 (R1, R2¼aryl), they reacted with
acetic acid smoothly to provide the corresponding acetylated
dienes 2 in moderate to good yields (Table 2, entries 1–7).
NOE
C6H5
C6H5
H
C6H5
H
H
H
OAc
NOE
Figure 1.

J.-M. Lu, M. Shi / Tetrahedron 62 (2006) 9115–9122
9117
Table 2. Palladium-catalyzed reactions of vinylidenecyclopropanes 1 with
acetic acid in toluene
C-1, along with the regeneration of palladium(0) catalyst.
Previously, Yamamoto and co-workers reported that alkynes
can be allylated by carbon pronucleophiles in the presence
of palladium/acetic acid catalyst via a p-allyl-palladium
intermediate.7 However, we found that no such allylation
occurred in our system when malononitrile [CH2(CN)2]
(2.0 equiv) and diethyl malonate [CH2(COOEt)2]
(2.0 equiv) were used as the carbon pronucleophiles in the
presence of Pd(PPh3)4 (10 mol %)/DPEphos (20 mol %)/
AcOH (20 mol %). This result suggests that the reaction
mechanism is not involved in the nucleophilic attack of
AcOH to p-allyl intermediates C-1 and C-2 to produce 2.
In addition, it should also be noted here that when formic
acid was used instead of acetic acid in this case, many
unidentified products were formed.8
R2
Pd(PPh3)4 (10 mol%)
DPEphos (20 mol%)
R1
R1
H
R1
R1
R2
H
+
AcOH
toluene, 80 °C, 18 h
1
OAc
2
Entrya
1 (R1/R2)
2 Yieldb/% (E:Z)c
1
2
3
4
5
6
7
8
9
1b (C6H5/p-MeC6H4)
1c (C6H5/p-CIC6H4)
1d (C6H5/p-MeOC6H4)
1e (p-MeC6H4/C6H5)
1f (p-FC6H4/C6H5)
1g (p-MeOC6H4/C6H5)
1h (p-CIC6H4/C6H5)
1i (nBu/C6H5)
2b, 67 (8:1)
2c, 67 (7:1)
2d, 78 (19:1)
2e, 75 (8:1)
2f, 67 (11:1)
2g, 70 (14:1)
2h, 65 (8:1)
2i, 36 (5:1)
2j, 61 (5:1)
1j (CH3/C6H5)
a
In order to clarify the mechanism of this reaction, the reac-
tion of 1c in deuterated acetic acid AcOD (D content 99%)
was carried out under identical conditions (Scheme 2).5
Based on the observed 1H NMR spectral data, we confirmed
that besides the olefinic protons at C2 (D content: 37% in
E-2c-d1 and 41% in Z-2c-d1), deuterium incorporation also
occurred at the olefinic protons of C4 (D content 53% in
E-2c-d1 and 55% in Z-2c-d1) and at the allylic protons of
All reactions were carried out using 1 (0.3 mmol), AcOH (0.6 mmol),
Pd(PPh3)4 (10 mol %) and DPEphos (20 mol %) in toluene (2.0 mL).
Isolated yields.
b
c
Determined from 1H NMR spectroscopic data and NOESY.
It should be noted that for alkylvinylidenecyclopropanes 1i
and 1j, other complicated products were also formed pre-
sumably due to the b-hydride elimination from aliphatic
R1 group. In addition, we found that vinylidenecyclopro-
panes 1 are labile under the reaction conditions, partially
leading to the formation of 2 in moderate yields.
0
C3 (D content: 54% in E-2c-d1 and 58% in Z-2c-d1). The
37% D content at C2 is due to the generation of AcO–Pd–H
species via b-hydride elimination during the reaction,
which can initiate the same reaction to give the acetylated
diene 2c without deuterium incorporation even in AcOD
(Scheme 1).5,9
A plausible mechanism for the formation of acetylated
dienes 2 is outlined in Scheme 1 on the basis of previous
investigations.5,6 The initial step is a regioselective hydro-
palladation of vinylidenecyclopropane 1 with hydridopalla-
dium species A, generated from oxidative addition of Pd(0)
with acetic acid, to afford intermediate B, which undergoes
b-carbon elimination to give two p-allyl-palladium interme-
diates C-1 and C-2. Intermediate C-1 should be the major
conformer because of the steric repulsion between R2 group
and palladium metal center in intermediate C-2. Reductive
elimination of intermediates C-1 and C-2 gives the corre-
sponding product 2 as mixtures of E- and Z-isomers, leading
to the formation of E-2 as major product from intermediate
(37%)
Pd(PPh3)4 (10 mol%)
DPEphos (20 mol%)
D
C6H5
C6H4Cl-p
AcOD
C6H5
C6H5
1
2
C6H4Cl-p
4
3
+
C6H5
D
toluene, 80 °C, 46 h
3'
(53%)
D
5 equiv
(54%)
1c
OAc
(D)H
E-2c-d1, 58%
(41%)
D
C6H5
1
2
(55%)
D
3
+
4
C6H
5 D
3'
C6H4Cl-p
(58%)
(D)H
OAc
Z-2c-d1, 15%
Scheme 2. Reaction of vinylidenecyclopropane 1c with AcOD (5.0 equiv)
under these optical conditions.
R1
R1
H
H
R2
The control experiment confirmed that deuterium incorpora-
0
OAc
Z-2, minor
tion at the olefinic protons of C4 and the allylic protons of C3
is derived from the scrambling of E-2c with AcOD catalyzed
by Pd(0) as shown in Scheme 3 because similar D contents at
Pd(0)
OAc
AcOH
OAc
Pd
0
C4 and C3 were observed in the reaction of E-2c with AcOD
Pd
R1
in the presence of Pd(0) catalyst and no reaction occurred in
the absence of Pd(0) catalyst as in the previously reported
example.5
R2
R1
R1
R1
R1
AcO-Pd-H
A
.
R2
H
H
R2
C-1
C-2
R1
R1
The control experiment of the transformation of E-2c to
E- and Z-regioisomers in the presence of Pd(0) catalyst
was also examined under the standard conditions. The result
is shown in Scheme 4, which clearly indicates that E- and
Z-isomerization independently takes place through the
corresponding p-allyl intermediates C-1 and C-2 and it is
not related with HOAc in the reaction system. A plausible
mechanism for the formation of E-2c-d2 and Z-2c-d2 is
shown in Scheme 5. The initial step is a palladium-catalyzed
1
2 3
R2
R1
R1
1
H
R2
H
R1
PdOAc
H
B
OAc
E-2, major
Scheme 1. Plausible mechanism for the reactions of vinylidenecyclopro-
panes 1 with acetic acid in the presence of palladium(0) catalyst.

9118
J.-M. Lu, M. Shi / Tetrahedron 62 (2006) 9115–9122
Pd(PPh3)4 (10 mol%)
DPEphos (20 mol%)
C6H5
C6H
H
C6H4Cl-p
(40%)
5 D
toluene, 80 °C, 46 h
D
(45%)
OAc
(D)H
E-2c-d2, 86%
C6H5
C6H5
H
C6H4Cl-p
H
AcOD
C6H5
C6H5
+
(44%)
D
H
5 equiv
OAc
+
D
E-2c
C6H4Cl-p
(44%)
(D)H
OAc
Z-2c-d2, 14%
toluene, 80 °C
46 h
N.R
Scheme 3. Reactions of E-2c with AcOD (5 equiv).
C6H5
H
C6H5
C6H5
H
C6H5
C6H5
H
H
Pd(PPh3)4 (10 mol%)
DPEphos (20 mol%)
C6H4Cl-p
C6H4Cl-p
C6H5
+
C6H4Cl-p
H
H
toluene, 80 °C, 14 h
OAc
E-2c, 73%
OAc
OAc
E-2c
Scheme 4. Isomerization of E-2c in the presence of Pd(0).
Z-2c, 9%
R1
R1
H
R1
R1
R1
R1
H
H
1 2
1
2
R2
H
1
2
R2
H
D(H)PdOAc
4
Pd(0)
3
4
3
3
PdOAc
3'
4
E
3'
D(H)
3'
OAc
AcO
OAc
D
H
R2
E-2c
-H(D) elimination
-H(D)PdOAc
R
1 = C6H5, R2 = p-ClC6H4
R1
R1
H
H
1
2
1 2
D(H)
D(H)
R2
4
3
3
4
R2
R1
R1
M
F
3'
3'
H
H
OAc
OAc
D(H)PdOAc
D(H)PdOAc
H
2
R1
R1
R1
R1
H
1
1
2
PdOAc
4
PdOAc
4
3
3
H
H 3'
D(H)
D(H)
3'
G
N
D(H)
H
H
(H)D
2
OAc
OAc
R2
R
-H(D) elimination
-H(D)PdOAc
-H elimination
-HPdOAc
R1
R1
H
R1
R1
H
1
2
D(H)
1
2
J
D(H)
R2
R2
3
4
3
4
H
O
3'
H
D(H)
3'
H
(H)D
OAc
OAc
D(H)PdOAc
H
D(H)PdOAc
H
3
R1
R1
R1
R1
1
2
1
2
PdOAc
PdOAc
D(H)
3
H
D(H)
4
4
I
P
3'
3'
(H)D
H
(H)D
D(H)
R2
-H(D) elimination
R2
OAc
(H)D
OAc
D(H)PdOAc
-H(D) elimination
-H(D)PdOAc
-H(D)PdOAc
R1
R1
H
2
R1
H
R1
R1
H
1
1
2
D(H)
1
2
D(H)
3
4
D(H)
3
4
R2
D(H)
3
4
H
R1
R2
Q
3'
(H)D
R2
3'
3'
(H)D
(H)D
OAc
OAc
OAc
(H)D
K
J
R1
H
2
1
D(H)PdOAc
PdOAc
-H(D) elimination
-H(D)PdOAc
3
R1
(H)D
D(H)
4
3'
D(H)
R2
L
OAc
(H)D
Scheme 5. Plausible mechanism for the formation of E-2c-d and Z-2c-d in the presence of palladium(0) catalyst.

J.-M. Lu, M. Shi / Tetrahedron 62 (2006) 9115–9122
9119
isomerization of E-2c to produce intermediate D as mixtures
4. Experimental
4.1. General methods
of E- and Z-isomers. Regioselective deuteropalladation
or hydropalladation of D with deuteropalladium species or
hydridopalladium species, generated from the oxidative
addition of Pd(0) with deuterated acetic acid (AcOD) and
b-hydride elimination during the reaction, respectively, to
afford intermediate E.5 Intermediate E undergoes b-hydride
(b-H) or b-deuterium (b-D) elimination to give inter-
mediates F and M. Intermediate F undergoes the same pro-
cesses (deuteropalladation or hydropalladation, b-hydride
or b-deuterium elimination and the repeated processes) to
afford intermediates J and Q via intermediates G, H, I, K
and L, successively. Regioselective deuteropalladation or
hydropalladation of J regenerates intermediate I. From the
same processes (deuteropalladation or hydropalladation,
b-hydride or b-deuterium elimination and the repeated pro-
cesses), intermediates J and Q would be also formed from
intermediate M via intermediates N, O and P, respectively
(Scheme 5). Then, palladium-catalyzed isomerization of
intermediate Q gives the corresponding E-isomer as the major
product because of the different steric effect between inter-
mediates R-1 and R-2 as that described above (Scheme 6).
1H and 13C NMR spectra were recorded at 300 and 75 MHz,
respectively. Mass spectra were recorded by EI and MALDI
methods, and HRMS was measured on Kratos Analytical
Concept mass spectrometer (EI), Bruker FT mass spectro-
meter (ESI), and IonSpec 4.7 Tesla FTMS (MALDI).
Organic solvents used were dried by standard methods
when necessary. Commercially obtained reagents were used
without further purification. All reactions were monitored by
TLC with Yinlong GF254 silica gel coated plates. Flash col-
umn chromatography was carried out using 300–400 mesh
silica gel at increased pressure.
4.2. General procedure for palladium-catalyzed reac-
tion of vinylidenecyclopropanes with acetic acid
Under an argon atmosphere, vinylidenecyclopropanes 1
(0.3 mmol), Pd(PPh3)4 (10 mol %), DPEphos (20 mol %),
toluene (2.0 mL) and acetic acid (0.6 mmol) were added
into a Schlenk tube. The mixture was stirred at 80 ꢀC for
18 h. Then the solvent was removed under reduced pressure
and the residue was purified by a flash column chromato-
graphy.
OAc
OAc
D(H)
Pd
D(H)
Pd
R1
R1
H
3
1
2
(H)D
R1
D(H)
R2
D(H)
R2
(H)D
R1
R2
D(H)
4
+
Pd(0)
.
.
3'
(H)D
(H)D
R1
H
R-2
1
R1
4.2.1. Compound 2a. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 1.99 (s, 3H, CH3), 4.29 (s, 2H,
CH2), 6.62 (s, 1H), 6.71 (d, J¼1.2 Hz, 1H), 7.19–7.32 (m,
OAc
Q
H
R-1
R1 = C6H5, R2 = p-ClC6H4
1
13H, Ar), 7.41–7.44 (m, 2H, Ar). (Z-isomer): H NMR
R1
H
2
R1
H
(CDCl3, 300 MHz, TMS) d 1.99 (s, 3H, CH3), 4.61 (s, 2H,
CH2), 6.64 (s, 2H), 7.05–7.08 (m, 2H, Ar), 7.19–7.32 (m,
13H, Ar). (E-isomer): 13C NMR (CDCl3, 75 MHz, TMS)
d 20.9, 66.8, 124.9, 127.5, 127.65, 127.67, 128.0, 128.1,
128.19, 128.24, 129.3, 129.7, 132.6, 133.5, 136.7, 140.1,
142.5, 144.9, 170.7. IR (CH2Cl2) n 3056, 3024, 2922,
2850, 1739, 1597, 1493, 1444, 1373, 1232, 1075, 1030,
763, 699 cmꢁ1. MS (%) m/z 354 (M+, 2), 294 (100), 293
(40), 43 (27), 352 (26), 295 (25), 203 (22), 217 (20), 91
(20). HRMS (MALDI) calcd for C25H22O2Na: 377.1512,
found: 377.1522 (M+Na+).
1
1
2
R2
3
4
D(H)
3
4
R1
(H)D
+
R1
(H)D
R2
3'
3'
D(H)
OAc
(H)D
OAc
(H)D
Z-2c-d2, minor
E-2c-d2,
major
Scheme 6. Isomerization of intermediate Q to form E-2c-d2 and Z-2c-d2.
Overall, on the basis of the control and deuterium labeling
experiments, the initial step of this reaction should indeed
proceed through the hydropalladation of the C1 and C2 ole-
finic moieties of 1 via the hydridopalladium species as
shown in Scheme 1. The repeated deuteropalladation or
hydropalladation and b-hydride or b-deuterium elimination
between the C3 and C4 olefinic moieties in 2 catalyzed by
Pd(0) in AcOD caused the scrambling at C4 protons and at
1
4.2.2. Compound 2b. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 1.98 (s, 3H, CH3), 2.31 (s, 3H,
CH3), 4.27 (s, 2H, CH2), 6.60 (s, 1H), 6.72 (s, 1H), 7.09
(d, J¼8.1 Hz, 2H, Ar), 7.19–7.34 (m, 12H, Ar). (Z-isomer):
1H NMR (CDCl3, 300 MHz, TMS) d 1.98 (s, 3H, CH3), 2.31
(s, 3H, CH3), 4.60 (s, 2H, CH2), 6.63 (s, 1H), 6.64 (s, 1H),
6.97 (d, J¼8.1 Hz, 2H, Ar), 7.19–7.34 (m, 12H, Ar). (E-iso-
mer): 13C NMR (CDCl3, 75 MHz, TMS) d 20.9, 21.2, 66.8,
125.1, 127.6, 127.90, 127.92, 128.1, 128.2, 129.0, 129.3,
129.8, 132.7, 132.8, 133.9, 137.4, 140.1, 142.5, 144.4,
170.4. IR (CH2Cl2) n 3054, 3023, 2962, 2920, 2850, 1738,
1597, 1509, 1493, 1444, 1374, 1260, 1229, 1029, 868,
806, 758, 699 cmꢁ1. MS (%) m/z 368 (M+, 1), 43 (100),
308 (43), 293 (32), 330 (33), 91 (29), 105 (29), 57 (28),
215 (19). HRMS (MALDI) calcd for C26H24O2Na:
391.1669, found: 391.1674 (M+Na+).
0
the allylic protons of C3 as shown in Scheme 2.
3. Conclusion
We have disclosed the first example of palladium(0)-cata-
lyzed reactions of vinylidenecyclopropanes 1 with acetic
acid to give the corresponding acetylated dienes 2 under
mild conditions. On the basis of the control and deuterium
labeling experiments, we found that this reaction process
is involved in the regioselective hydropalladation of
vinylidenecyclopropanes 1 with AcO–Pd–H as shown in
Scheme 1. Efforts are underway to elucidate the mechanistic
details of this reaction and to disclose its scope and limita-
tions. Work along this line is currently in progress.
1
4.2.3. Compound 2c. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 2.01 (s, 3H, CH3), 4.31 (s, 2H,
CH2), 6.53 (s, 1H), 6.62 (d, J¼1.5 Hz, 1H), 7.16–7.34 (m,

9120
J.-M. Lu, M. Shi / Tetrahedron 62 (2006) 9115–9122
1
14H, Ar). (Z-isomer): H NMR (CDCl3, 300 MHz, TMS)
d 2.01 (s, 3H, CH3), 4.57 (s, 2H, CH2), 6.55 (s, 1H), 6.62
(d, J¼0.9 Hz, 1H), 6.99 (d, J¼9.0 Hz, 2H, Ar), 7.24–7.35
(m, 12H, Ar). (E-isomer): 13C NMR (CDCl3, 75 MHz,
TMS) d 20.9, 66.6, 124.3, 127.85, 127.93, 128.0, 128.18,
128.20, 128.4, 129.7, 130.4, 130.9, 133.1, 134.3, 135.2,
139.8, 142.3, 145.5, 170.4. (Z-isomer): 13C NMR (CDCl3,
75 MHz, TMS) d 21.0, 62.1, 127.6, 127.7, 128.19, 128.24,
128.44, 128.47, 128.7, 129.9, 130.2, 133.3, 134.1, 134.7,
135.4, 140.1, 142.9, 143.9, 170.6. (E-isomer): IR (CH2Cl2)
n 3056, 3025, 2962, 2846, 1740, 1594, 1498, 1444, 1372,
1228, 1091, 1030, 1013, 868, 763, 699 cmꢁ1. (Z-isomer):
IR (CH2Cl2) n 3056, 3025, 2961, 2920, 1740, 1597, 1489,
1444, 1374, 1232, 1092, 1028, 1014, 970, 829, 807, 763,
700 cmꢁ1. (E-isomer): MS (%) m/z 388 (M+, 1), 43 (100),
328 (73), 293 (62), 215 (35), 330 (25), 202 (24), 329 (23),
292 (22). (Z-isomer): MS (%) m/z 388 (M+, 3), 43 (100),
293 (63), 328 (43), 215 (35), 91 (27), 57 (26), 292 (20),
202 (20). (E-isomer): HRMS (MALDI) calcd for
C25H21O2ClNa: 411.1122, found: 411.1140 (M+Na+).
(Z-isomer): HRMS (MALDI) calcd for C25H21O2ClNa:
411.1122, found: 411.1133 (M+Na+).
75 MHz, TMS) d 20.9, 66.8, 115.0 (d, J¼11.0 Hz), 115.3
(d, J¼11.8 Hz), 125.0, 127.5, 128.2, 129.1, 129.5 (d,
J¼8.0 Hz), 131.3 (d, J¼8.1 Hz), 132.7, 133.1, 135.7
(d, J¼3.9 Hz), 136.5, 138.5 (d, J¼3.9 Hz), 142.9, 162.4 (d,
J¼246.4 Hz), 162.6 (d, J¼246.8 Hz), 170.4. IR (CH2Cl2)
n 3050, 3019, 2919, 2850, 1740, 1600, 1508, 1446, 1371,
1275, 1226, 1158, 1095, 1029, 838, 764, 751, 698 cmꢁ1
.
MS (%) m/z 390 (M+, 0.31), 49 (100), 84 (54), 51 (29), 86
(28), 43 (27), 47 (13), 127 (11), 330 (10). HRMS (MALDI)
calcd for C25H20O2F2Na: 413.1324, found: 413.1333
(M+Na+).
1
4.2.7. Compound 2g. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 2.00 (s, 3H, CH3), 3.78 (s, 3H,
OCH3), 3.81 (s, 3H, OCH3), 4.32 (s, 2H, CH2), 6.56 (s,
1H), 6.58 (s, 1H), 6.81–6.88 (m, 4H, Ar), 7.13–7.30 (m,
1
7H, Ar), 7.44 (d, J¼7.2 Hz, 2H, Ar). (Z-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 1.99 (s, 3H, CH3), 3.80 (s, 6H,
2OCH3), 4.62 (s, 2H, CH2), 6.50 (s, 1H), 6.64 (s, 1H),
6.81–6.88 (m, 4H, Ar), 7.07–7.30 (m, 9H, Ar). (E-isomer):
13C NMR (CDCl3, 75 MHz, TMS) d 20.9, 55.13, 55.19,
66.8, 113.4, 113.5, 122.8, 127.3, 128.2, 129.16, 129.19,
130.9, 131.7, 132.5, 134.0, 135.4, 136.9, 144.1, 159.30,
159.32, 170.5. IR (CH2Cl2) n 3028, 3001, 2954, 2934,
2836, 1739, 1605, 1573, 1511, 1463, 1443, 1369, 1287,
1247, 1175, 1110, 1033, 974, 919, 834, 754, 738,
699 cmꢁ1. MS (%) m/z 414 (M+, 18), 354 (100), 135 (70),
353 (42), 242 (34), 323 (29), 355 (27), 341 (27), 84 (25).
HRMS (MALDI) calcd for C27H26O4Na: 437.1723, found:
437.1724 (M+Na+).
1
4.2.4. Compound 2d. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 1.97 (s, 3H, CH3), 3.75 (s, 3H,
OCH3), 4.26 (s, 2H, CH2), 6.57 (s, 1H), 6.71 (d, J¼1.5 Hz,
1H), 6.80–6.83 (m, 2H, Ar), 7.21–7.39 (m, 12H, Ar). (Z-iso-
1
mer): H NMR (CDCl3, 300 MHz, TMS) d 1.99 (s, 3H,
CH3), 3.78 (s, 3H, OCH3), 4.60 (s, 2H, CH2), 6.62 (s, 1H),
6.64 (s, 1H), 7.02 (d, J¼8.7 Hz, 4H, Ar), 7.21–7.39 (m,
10H, Ar). (E-isomer): 13C NMR (CDCl3, 75 MHz, TMS)
d 20.9, 55.1, 66.9, 113.6, 125.2, 127.5, 127.8, 127.9,
128.07, 128.13, 129.4, 129.7, 130.6, 131.5, 132.5, 140.1,
142.5, 144.3, 159.0, 170.4. IR (CH2Cl2) n 3056, 3026,
2932, 2836, 1738, 1605, 1509, 1444, 1374, 1252, 1176,
1032, 756, 700 cmꢁ1. MS (%) m/z 384 (M+, 7), 43 (100),
49 (79), 57 (58), 324 (57), 51 (45), 84 (44), 105 (39), 207
(30). HRMS (MALDI) calcd for C26H24O3Na: 407.1618,
found: 407.1626 (M+Na+).
1
4.2.8. Compound 2h. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 2.02 (s, 3H, CH3), 4.37 (s, 2H,
CH2), 6.63 (s, 2H), 7.07–7.36 (m, 13H, Ar). (Z-isomer):
1H NMR (CDCl3, 300 MHz, TMS) d 2.02 (s, 3H, CH3),
4.65 (s, 2H, CH2), 6.59 (s, 2H), 7.07–7.36 (m, 13H, Ar).
(E-isomer): 13C NMR (CDCl3, 75 MHz, TMS) d 20.9,
66.8, 125.9, 127.7, 128.3, 128.4, 128.6, 128.9, 129.1,
131.0, 132.9, 133.3, 133.9, 134.0, 136.5, 138.0, 140.6,
142.6, 170.4. IR (CH2Cl2) n 3019, 2920, 2846, 1740, 1590,
1491, 1368, 1275, 1260, 1227, 1091, 1014, 831, 764, 750,
697 cmꢁ1. MS (%) m/z 422 (M+, 9), 327 (100), 277 (73),
362 (62), 278 (47), 292 (46), 364 (41), 215 (40), 43 (37).
HRMS (MALDI) calcd for C25H20O2Cl2Na: 445.0733,
found: 445.0745 (M+Na+).
1
4.2.5. Compound 2e. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 1.99 (s, 3H, CH3), 2.34 (s, 3H,
CH3), 2.36 (s, 3H, CH3), 4.29 (s, 2H, CH2), 6.60 (s, 1H),
6.65 (s, 1H), 7.08–7.30 (m, 11H, Ar), 7.44 (d, J¼7.5 Hz,
1
2H, Ar). (Z-isomer): H NMR (CDCl3, 300 MHz, TMS)
d 1.98 (s, 3H, CH3), 2.35 (s, 6H, 2CH3), 4.60 (s, 2H, CH2),
6.60 (s, 1H), 6.65 (s, 1H), 7.08–7.30 (m, 13H, Ar). (E-iso-
mer): 13C NMR (CDCl3, 75 MHz, TMS) d 20.9, 21.1,
21.3, 66.8, 123.9, 127.4, 127.9, 128.2, 128.8, 128.9, 129.3,
129.7, 132.1, 133.9, 136.8, 137.2, 137.5, 137.7, 139.9,
144.8, 170.5. IR (CH2Cl2) n 3023, 2920, 2853, 1740, 1067,
1
4.2.9. Compound 2i. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 0.77 (t, J¼6.6 Hz, 3H, CH3),
0.92 (t, J¼6.9 Hz, 3H, CH3), 1.12–1.15 (m, 4H, 2CH2),
1.26–1.41 (m, 4H, 2CH2), 1.85 (t, J¼7.5 Hz, 2H, CH2),
2.07 (t, J¼6.3 Hz, 2H, CH2), 2.09 (s, 3H, CH3), 4.65 (s,
2H), 5.74 (s, 1H), 6.48 (s, 1H), 7.15–7.34 (m, 3H, Ar),
7.41 (d, J¼7.8 Hz, 2H). (Z-isomer): 1H NMR (CDCl3,
300 MHz, TMS) d 0.88–0.95 (m, 6H, 2CH3), 1.26–1.41
(m, 8H, 4CH2), 2.07–2.13 (m, 2H, CH2), 2.09 (s, 3H,
CH3), 2.27 (t, J¼7.8 Hz, 2H, CH2), 4.74 (s, 2H, CH2),
5.77 (s, 1H), 6.58 (s, 1H), 7.15–7.34 (m, 5H, Ar). (E-isomer):
13C NMR (CDCl3, 75 MHz, TMS) d 13.9, 14.0, 21.0, 22.5,
22.8, 29.5, 29.9, 30.8, 35.8, 68.7, 120.3, 126.9, 127.9,
128.5, 128.9, 133.9, 137.1, 145.2, 170.7. (Z-isomer): 13C
NMR (CDCl3, 75 MHz, TMS) d 13.9, 14.0, 20.9, 22.4,
22.8, 30.3, 30.4, 30.8, 36.7, 63.6, 124.8, 127.0, 128.1,
128.3, 128.7, 132.1, 136.7, 145.2, 170.7. IR (CH2Cl2)
1509, 1493, 1445, 1369, 1228, 1023, 822, 752, 700 cmꢁ1
.
MS (%) m/z 382 (M+, 3), 43 (100), 322 (82), 307 (73), 215
(36), 105 (35), 91 (30), 323 (28), 229 (28). HRMS (MALDI)
calcd for C27H26O2Na: 405.1825, found: 405.1845
(M+Na+).
1
4.2.6. Compound 2f. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 2.02 (s, 3H, CH3), 4.36 (s, 2H,
CH2), 6.59 (s, 1H), 6.60 (s, 1H), 6.95–7.38 (m, 13H, Ar).
(Z-isomer): H NMR (CDCl3, 300 MHz, TMS) d 2.02 (s,
1
3H, CH3), 4.65 (s, 2H, CH2), 6.55 (s, 1H), 6.59 (s, 1H),
6.95–7.38 (m, 13H, Ar). (E-isomer): 13C NMR (CDCl3,

J.-M. Lu, M. Shi / Tetrahedron 62 (2006) 9115–9122
9121
1976, 41, 2408–2411; (c) Sasaki, T.; Eguchi, S.; Ogawa, T.
J. Org. Chem. 1974, 39, 1927–1930; (d) Sasaki, T.; Eguchi, S.;
Ogawa, T. Heterocycles 1975, 3, 193–196; (e) Eguchi, S.;
Arasaki, M. J. Chem. Soc., Perkin Trans. 1 1988, 1047–1050;
(f) Sugita, H.; Mizuno, K.; Mori, T.; Isagawa, K.; Otsuji, Y.
Angew. Chem., Int. Ed. Engl. 1991, 30, 984–986; (g) Patrick,
T. B. Tetrahedron Lett. 1974, 15, 1407–1408; (h) Al-Dulayymi,
J. R.; Baird, M. S. J. Chem. Soc., Perkin Trans. 1 1994, 1547–
1548; (i) Patrick, T. B. J. Org. Chem. 1977, 42, 3354–3356; (j)
Hartzler, H. D. J. Am. Chem. Soc. 1971, 93, 4527–4531.
n 3059, 3025, 2956, 2930, 2871, 1743, 1599, 1494, 1456,
1376, 1228, 1027, 966, 915, 803, 751, 696 cmꢁ1. MS (%)
m/z 314 (M+, 1), 91 (100), 43 (74), 155 (40), 197 (37), 41
(36), 141 (28), 115 (27), 211 (26). HRMS (EI) calcd for
C21H30O2: 314.2246, found: 314.2252.
1
4.2.10. Compound 2j. A yellow oil, (E-isomer): H NMR
(CDCl3, 300 MHz, TMS) d 1.44 (d, J¼0.6 Hz, 3H, CH3),
1.78 (d, J¼1.2 Hz, 3H, CH3), 2.10 (s, 3H, CH3), 4.66 (s,
2H), 5.76 (s, 1H), 6.48 (s, 1H), 7.15–7.41 (m, 5H, Ar). (Z-
1
2. (a) Poutsma, M. L.; Ibarbia, P. A. J. Am. Chem. Soc. 1971, 93,
440–450; (b) Smadja, W. Chem. Rev. 1983, 83, 263–320; (c)
Paulson, D. R.; Crandall, J. K.; Bunnell, C. A. J. Org. Chem.
1970, 35, 3708–3714; (d) Hendrick, M. E.; Hardie, J. A.;
Jones, M. J. Org. Chem. 1971, 36, 3061–3062; (e) Patrick,
T. B.; Haynie, E. C.; Probst, W. J. J. Org. Chem. 1972, 37,
1553–1556; (f) Aue, D. H.; Meshishnek, M. J. J. Am. Chem.
Soc. 1977, 99, 223–231; (g) Sasaki, T.; Eguchi, S.; Ogawa, T.
J. Am. Chem. Soc. 1975, 97, 4413–4414; (h) Sadler, I. H.;
Stewart, J. A. G. J. Chem. Soc., Perkin Trans. 2 1973, 3, 278–
288; (i) Sugita, H.; Mizuno, K.; Saito, T.; Isagawa, K.; Otsuji,
Y. Tetrahedron Lett. 1992, 33, 2539–2542; (j) Mizuno, K.;
Sugita, H.; Kamada, T.; Otsuji, Y. Chem. Lett. 1994, 449–452;
(k) Akasaka, T.; Misawa, Y.; Ando, W. Tetrahedron Lett.
1990, 31, 1173–1176; (l) Mizuno, K.; Sugita, H.; Isagawa, K.;
Goto, M.; Otsuji, Y. Tetrahedron Lett. 1993, 34, 5737–5738;
(m) Mizuno, K.; Nire, K.; Sugita, H.; Otsuji, Y. Tetrahedron
Lett. 1993, 34, 6563–6566; (n) Mizuno, K.; Sugita, H.; Hirai,
T.; Maeda, H. Chem. Lett. 2000, 1144–1145; (o) Mizuno, K.;
Nire, K.; Sugita, H.; Maeda, H. Tetrahedron Lett. 2001, 42,
2689–2692; (p) Mizuno, K.; Maeda, H.; Sugita, H.; Nishioka,
S.; Hirai, T.; Sugimoto, A. Org. Lett. 2001, 3, 581–584; (q)
Mizuno, K.; Sugita, H.; Hirai, T.; Maeda, H.; Otsuji, Y.;
Yasuda, M.; Hashiguchi, M.; Shima, K. Tetrahedron Lett.
2001, 42, 3363–3366; (r) Maeda, H.; Zhen, L.; Hirai, T.;
Mizuno, K. ITE Lett. Batteries, New Technol. Med. 2002, 3,
485–491; (s) Sydnes, L. K. Chem. Rev. 2003, 103, 1133–1150.
3. For recent contributions from our group, see: (a) Shi, M.; Lu, J.-M.
J. Org. Chem. 2006, 71, 1920–1923; (b) Shi, M.; Lu, J.-M. Synlett
2005, 2352–2356; (c) Xu, G.-C.; Liu, L.-P.; Lu, J.-M. J. Am.
Chem. Soc. 2005, 127, 14552–14553; (d) Shi, M.; Ma, M.;
Shao, L.-X. Tetrahedron Lett. 2005, 46, 7609–7613; (e) Xu,
G.-C.; Ma, M.; Liu, L.-P. Synlett 2005, 1869–1872; (f) Shi, M.;
Lu, J.-M.; Xu, G.-C. Tetrahedron Lett. 2005, 46, 4745–4748.
4. For the reactions of vinylidenecyclopropanes with carbenes and
carbene complexes, see: (a) Crandall, J. K.; Paulson, D. R.;
Bunnell, C. A. Tetrahedron Lett. 1969, 48, 4217–4220; (b)
Hwu, C.-C.; Wang, F.-C.; Yeh, M.-C. P. J. Organomet. Chem.
1994, 474, 123–128; (c) Billups, W. E.; Haley, M. M.; Boese,
R.; Blaser, D. Tetrahedron 1994, 50, 10693–10700; (d)
Maeda, H.; Hirai, T.; Sugimoto, A.; Mizuno, K. J. Org. Chem.
2003, 68, 7700–7706; (e) Bloch, R.; Perchec, P. L.; Conia, J.-
M. Angew. Chem., Int. Ed. Engl. 1970, 9, 798–799; (f) Pasto,
D. J.; Yang, S. H. J. Org. Chem. 1986, 51, 1676–1680; For the
addition reactions of vinylidenecyclopropanes, see: (g) Pasto,
D. J.; Miles, M. F. J. Org. Chem. 1976, 41, 2068–2611; (h)
Pasto, D. J.; Chen, A. F.-T.; Binsch, G. J. Am. Chem. Soc.
1973, 95, 1553–1562; (i) Pasto, D. J.; Chen, A. J. Am. Chem.
Soc. 1971, 93, 2562–2564; (j) Pasto, D. J.; Borchardt, J. K.;
Fehlner, T. P.; Baney, H. F.; Schwartz, M. E. J. Am. Chem.
Soc. 1976, 98, 526–529; (k) Pasto, D. J.; Fehlner, T. P.;
Schwartz, M. E.; Baney, H. F. J. Am. Chem. Soc. 1976, 98,
530–534; (l) Pasto, D. J.; Miles, M. F. J. Org. Chem. 1976, 41,
isomer): H NMR (CDCl3, 300 MHz, TMS) d 1.86 (s, 3H,
CH3), 1.87 (d, J¼1.2 Hz, 3H, CH3), 2.07 (s, 3H, CH3),
4.74 (s, 2H, CH2), 5.79 (d, J¼1.2 Hz, 1H), 6.59 (s, 1H),
7.15–7.41 (m, 5H, Ar). (E-isomer): 13C NMR (CDCl3,
75 MHz, TMS) d 19.6, 21.0, 25.7, 68.5, 120.7, 126.8,
128.0, 128.7, 128.8, 133.6, 137.1, 137.5, 170.8. (Z-isomer):
13C NMR (CDCl3, 75 MHz, TMS) d 19.6, 21.0, 26.8, 63.6,
125.2, 127.1, 128.3, 128.7, 133.1, 133.6, 136.5, 136.8,
171.0. IR (CH2Cl2) n 3059, 3019, 2968, 2920, 1741, 1488,
1446, 1374, 1228, 1029, 965, 920, 751, 696 cmꢁ1. MS (%)
m/z 230 (M+, 4), 43 (100), 155 (81), 91 (51), 170 (32), 115
(29), 129 (19), 128 (18), 77 (17). HRMS (EI) calcd for
C15H18O2: 230.1307, found: 230.1304.
4.3. General procedure for palladium-catalyzed
reaction of vinylidenecyclopropane 1c with
deuterated acetic acid
Under an argon atmosphere, vinylidenecyclopropane 1c
(0.3 mmol), Pd(PPh3)4 (10 mol %), DPEphos (20 mol %),
toluene (2.0 mL) and deuterated acetic acid (1.5 mmol)
were added into a Schlenk tube. The mixture was stirred at
80 ꢀC for 46 h. Then the solvent was removed under reduced
pressure and the residue was purified by a flash column chro-
matography.
Acknowledgements
We thank the State Key Project of Basic Research (Project
973) (No. G2000048007), Shanghai Municipal Committee
of Science and Technology (04JC14083), Chinese Academy
of Sciences (KGCX2-210-01), and the National Natural Sci-
ence Foundation of China for financial support (20472096,
203900502 and 20272069).
Supplementary data
1H and 13C NMR spectroscopic data and analytic data for
compounds 2a–2j. This material is available free of charge
via the Internet. Supplementary data associated with this
article can be found in the online version, at doi:10.1016/
j.tet.2006.07.052.
References and notes
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Sasaki, T.; Eguchi, S.; Ohno, M.; Nakata, F. J. Org. Chem.

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