Tandem decarboxylative allylation and fragmentation of allyl benzocyclobutenyl carbonates: Access to ortho-functionalized aryls from aryl bromides

Article abstract of DOI:10.1055/s-0031-1290943

Allyl benzocyclobutyl carbonates yield ortho-allyl α-aryl ketones through a palladium-catalyzed decarboxylative allylation, fragmentation, and cross-coupling process. Georg Thieme Verlag Stuttgart · New York.

Full text of DOI:10.1055/s-0031-1290943

SPECIAL TOPIC
▌1885
special topic
Tandem Decarboxylative Allylation and Fragmentation of Allyl Benzocyclo-
butenyl Carbonates: Access to ortho-Functionalized Aryls from Aryl Bromides
Decarboxylative Allylation of Benzocyclobutenols
David Rosa, Andrei Chtchemelinine, Arturo Orellana*
Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
Fax +1(416)7365936; E-mail: aorellan@yorku.ca
Received: 19.03.2012; Accepted: 22.03.2012
ized aryl rings bearing allyl and ketone groups.7 A
Abstract: Allyl benzocyclobutyl carbonates yield ortho-allyl α-
plausible catalytic cycle for this transformation would in-
aryl ketones through a palladium-catalyzed decarboxylative al-
volve palladium-catalyzed ionization of the allyl benzo-
cyclobutenyl carbonate, followed by decarboxylation to
generate an ion pair consisting of a cationic allylpalladium
intermediate and an alkoxide anion (I to II, Scheme 2).
Coordination of palladium to the alkoxide oxygen (II to
lylation, fragmentation, and cross-coupling process.
Key words: benzocyclobutenol, decarboxylative allylation, palla-
dium, fragmentation, strain release
III), selective β-carboelimination (III to IV), and reduc-
Due to their inherent reactivity, highly strained carbocy-
tive elimination (IV to V) would furnish the allylated
clic systems provide unusual opportunities for synthesis.
product.
Transition-metal catalysts are capable of modulating the
reactivity of such systems, thereby furnishing useful prod-
ucts with a good degree of selectivity and in good yields.
We have been interested in developing reactions in which
LnPd
O
O
the palladium-catalyzed β-carboelimination1 of tertiary
alcohols is a key design element.2 Recently we reported
the selective and high-yielding cross-coupling reaction of
benzocyclobutenols with aryl bromides3 (Scheme 1, equa-
tion 1). Here we extend this chemistry to the use of allyl
benzocyclobutenyl carbonates, and show that these sub-
strates undergo a decarboxylative allylation and fragmen-
tation reaction to yield ortho-allyl α-arylated ketones
(Scheme 1, equation 2).
O
O
CO2
( )n
( )n
H
II
H
I
PdLn
O
LnPd(0)
( )n
H
III
R1
R1
PdLn
R2
OH
( )n
Pd2dba3
O
DavePhos
R2
V
+
(1)
Ag2CO3
toluene, 65 °C
( )n Br
( )n
H
O
IV
( )n
O
O
O
Scheme 2 Plausible catalytic cycle for the proposed tandem decar-
boxylative allylation and fragmentation reaction
O
(2)
this work
Benzocyclobutenols8 have featured in complex molecule
synthesis9 and a number of synthetic methods. Their gen-
eration via nucleophilic addition to the corresponding
benzocyclobutenone is a common preparative method,
however the preparation of the benzocyclobutenone10
moiety itself suffers from lengthy reaction sequences that
often require the use of ortho-difunctionalized aryl sub-
strates.11 With the aim of developing a streamlined syn-
thetic method, we decided to prepare substrates for the
proposed reaction from the corresponding bromoben-
zenes. Durst has shown that treatment of bromo- and io-
dobenzenes with a strong, non-nucleophilic base in the
presence of a ketone results in the formation of benzocy-
clobutenols.12,13 Addition of the ketone enolate to the ben-
zyne generated in situ results in the formation of an aryl
anion that undergoes a subsequent 1,2-addition to the ke-
( )n
( )n
O
H
Scheme 1
We envisioned that allyl benzocyclobutenyl carbonates
would participate in a tandem reaction combining the pal-
ladium-catalyzed decarboxylative allylation chemistry of
allyl carbonate4 functions with the selective, palladium-
catalyzed cleavage5 of benzocyclobutenols.6 Such a pro-
cess would result in the preparation of ortho-functional-
SYNTHESIS 2012, 44, 1885–1891
Advanced online publication: 08.05.2012
DOI: 10.1055/s-0031-1290943; Art ID: SS-2012-C0279-ST
© Georg Thieme Verlag Stuttgart · New York
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X

1886
D. Rosa et al.
SPECIAL TOPIC
tone function. Simply quenching the reaction mixture (Scheme 3). Curiously, consistent with Durst’s report we
with allyl chloroformate or allyl imidazolide14 results in were able to prepare benzocyclobutenols using cyclopen-
the formation of the desired substrates (Scheme 3).
tanone and cyclohexanone, however attempts to prepare
the corresponding allyl benzocyclobutenyl carbonates 1a
and 2a in one or two steps failed. In contrast, the use of cy-
cloheptanone in combination with a variety of substituted
bromobenzenes provided the desired benzocyclobutenols
3a–11a. Similarly, the use of a cyclooctanone and an acy-
clic ketone provided the desired substrates 12a and 13a,
respectively, in practical yields. We also prepared sub-
strates bearing 1,1-dimethylallyl 8a, crotyl 9a, and meth-
allyl groups 10a and 11a on the carbonate function by
simply quenching the corresponding alkoxide anions with
the corresponding allyl imidazolides. It is clear that in a
number of cases the yields of allylbenzocyclobutenyl car-
bonates are poor, nevertheless this unoptimized protocol
provided access to practical amounts of substrates for the
present study.
O
O
O
Br
H
O
LTMP
O
+
( )n
( )n
H
1 or 2 steps
O
X
O
O
O
H
O
O
O
H
1a (–a)
2a (–b)
O
Optimization of the reaction was conducted with substrate
3a (Table 1). We were happy to observe that treatment of
a toluene solution of this substrate with 10% palladium(II)
acetate and triphenylphosphine provided the desired prod-
uct 3b in 75% yield (entry 1). The use of tris(dibenzylide-
neacetone)dipalladium(0) (Pd2dba3, 10% Pd basis) and
triphenylphosphine provided similar yield of the coupled
product along with some of the corresponding benzocy-
clobutenol 3c (entry 2). Increased yields of the desired
product 3b were obtained with a range of biarylphosphine
(Buchwald) ligands and Pd2dba3, with S-Phos providing
the best result (entries 3–6). The use of bidentate phos-
phine ligands provided diminished yields of the coupled
product along with the benzocyclobutenol 3c (entries 7–
9). Reduction of the palladium loading to 5% and 2% did
not affect the isolated yields significantly (entries 10 and
11). While the use of tetrahydrofuran and acetonitrile as
solvents gave similar results (entries 12 and 13), more po-
lar solvents provided diminished yields of the coupled
product, along with significant amounts of the free alco-
hol (entries 14–17). An excellent yield of the coupled
product was also obtained at reduced temperature (entry
18).
O
R
OMe
O
O
O
H
O
MeO
MeO
( )2
( )2
H
3a, R = H (65%)c
4a, R = Me (28%)d
5a, R = Ph (36%)d
6a, R = OMe (36%)d
7a (16%)
O
O
O
O
O
O
( )2
( )2
H
H
8a (60%)d,e
9a (67%)d,e
O
O
OMe
O
O
O
O
( )2
( )2
H
H
10a (64%)d,e
11a (56%)d,e
O
O
With optimized reaction conditions in hand we set out to
test the scope of the reaction (Scheme 4). Substrates 3a–
7a, bearing an allyl carbonate function and a fused cyclo-
heptane ring provided the coupled products 3b–7b in uni-
formly excellent yields.
O
O
O
O
t-Bu
( )3
H
13a (19%)c
12a (60%)c
Substrates 8a and 9a, bearing 1,1-dimethylallyl and crotyl
carbonate functions respectively, failed to provide any of
the possible coupled products, i.e. 8b/8c or 9b/9c. In con-
trast, substrates 10a and 11a, bearing methallyl carbon-
ates, provided the expected coupled product in excellent
yields. Similar yields were observed with substrates 12a
and 13a.
Scheme 3 Preparation of allyl benzocyclobutenyl carbonates from
a
aryl bromides. Not isolated; the corresponding benzocyclobutenol
was isolated in 36% yield. b Not isolated; the corresponding benzocy-
c
clobutenol was isolated in 53% yield. Overall yield for a one-pot
d
e
process. Prepared in two steps, overall yield. Prepared using the
corresponding allyl imidazolide.
Although the desired carbonates could all be prepared in
a one-pot process, in most cases it was difficult to isolate
them from the reaction mixture. This required us to isolate
the benzocyclobutenol and install the allyl carbonate
function in a separate operation in the case of 4a–11a
Finally, in order to explore the mechanism proposed in
Scheme 2, we conducted a cross-over experiment under
optimized conditions using substrates 3a and 11a
(Scheme 5). Analysis of the crude reaction mixture by 1H
Synthesis 2012, 44, 1885–1891
© Georg Thieme Verlag Stuttgart · New York

SPECIAL TOPIC
Decarboxylative Allylation of Benzocyclobutenols
1887
Table 1 Reaction Optimizationa
O
O
O
Pd2dba3 (1 mol%)
S-Phos (5 mol%)
( )2
O
( )2
toluene, 60 °C
O
( )2
Pd source
ligand
O
3b (93%)
H
3a
O
O
3b
solvent
temperature
OH
Ph
( )2
H
3a
( )2
H
3c
( )2
( )2
O
O
Yieldb (%)
Entry Pd source Ligand
Solvent, temp
4b (91%)
5b (88%)
OMe
OMe
3b
3c
MeO
MeO
1c
2d
Pd(OAc)2 Ph3P
toluene, 80 °C
toluene, 80 °C
toluene, 80 °C
toluene, 80 °C
toluene, 80 °C
75
72
88
82
93
88
53
57
78
93
96
88
93
29
41
23
93
–
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Pd2dba3
Ph3P
15
–
( )2
( )2
O
O
7b (87%)
3d
DavePhos
X-Phos
S-Phos
6b (87%)
4d
–
5d
–
6d
t-Bu-X-Phos toluene, 80 °C
–
( )2
( )2
O
O
7e
8b (–a)
8c (–a)
Me
dppe
toluene, 80 °C
toluene, 80 °C
toluene, 80 °C
toluene, 80 °C
toluene, 80 °C
THF, 60 °C
39
21
9
8e
dppp
9e
dppf
10f
11g
12g
13g
14g
16g
17g
18g
S-Phos
S-Phos
S-Phos
S-Phos
S-Phos
S-Phos
S-Phos
S-Phos
–
( )2
( )2
O
O
9b (–a)
9c (–a)
–
MeO
–
MeCN, 80 °C
NMP, 80 °C
DME, 80 °C
DMA, 80 °C
toluene, 60 °C
–
53
39
55
–
( )2
( )2
O
O
10b (90%)
11b (85%)
a All reactions were conducted at 0.1 M concentration.
b Isolated yields.
( )3
O
O
t-Bu
12b (94%)
13b (92%)
c 10 mol% Pd and 40 mol% Ph3P.
d 10 mol% Pd and 20 mol% ligand.
e 10 mol% Pd and 10 mol% ligand.
f 5 mol% Pd and 10 mol% ligand.
g 2 mol% Pd and 5 mol% ligand.
Scheme 4 Substrate scope study. a Not isolated.
benzocyclobutenols can be incorporated into a tandem re-
action leading to ortho-functionalized aryl rings. While
there is significant room for improvement in the prepara-
tion of substrates, the cross-coupling reaction works in ex-
cellent yields with allyl and methallyl carbonates. The
effect of polar solvents on product distribution, and the re-
sults of a cross-over experiment are consistent with a re-
action occurring through a solvent separated ion pair.
NMR and GC-MS revealed that the expected products
(i.e., 3b and 11b) and the cross-over products (i.e., 6b and
10b) were formed in this process, and suggests that the re-
action takes place via a solvent separated ion pair (cf. II,
Scheme 2).
We have shown that the palladium-catalyzed decarboxyl-
ative allylation and the selective β-carboelimination of
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 1885–1891

1888
D. Rosa et al.
SPECIAL TOPIC
column chromatography (1% EtOAc–hexanes) to afford carbonate
3a (0.480 g, 1.8 mmol, 65%) as a clear oil.
IR (thin film): 3079, 2923, 1743, 1648, 1454 cm–1.
O
O
O
OMe
O
O
O
1H NMR (400 MHz, CDCl3): δ = 7.44 (d, J = 7.2 Hz, 1 H), 7.34 (t,
J = 7.2 Hz, 1 H), 7.26 (t, J = 7.2 Hz, 1 H), 7.15 (d, J = 7.2 Hz, 1 H),
5.95 (dddd, J = 16.4, 10.4, 5.6 Hz, 1 H), 5.36 (dd, J = 16.4, 1.2 Hz,
1 H), 5.27 (d, J = 10.4 Hz, 1 H), 4.65 (dd, J = 12.8, 5.6 Hz, 1 H),
4.60 (dd, J = 12.8, 5.6 Hz, 1 H), 3.81 (dd, J = 10.0, 4.0 Hz, 1 H),
2.70 (m, 1 H), 2.17 (m, 1 H), 2.03 (m, 1 H), 1.75–1.67 (m, 4 H),
1.57–1.41 (m, 3 H).
+
( )2
( )2
H
3a
H
11a
Pd2dba3
S-Phos
toluene
60 °C
MeO
13C NMR (100 MHz, CDCl3): δ = 153.6, 145.8, 144.3, 131.7, 129.9,
127.4, 124.4, 122.4, 118.6, 90.7, 67.9, 56.7, 32.4, 31.7, 30.0, 27.0,
23.8.
HRMS (EI): m/z [M]+ calcd for C17H20O3: 272.1412; found:
272.1416.
( )2
O
3b
( )2
O
11b
OMe
Carbonate 12a
Chromatography (2% EtOAc–hexanes); colorless oil; yield: 465
mg (1.6 mmol, 60%).
IR (thin film): 3068, 3023, 2926, 1745, 1649, 1460, 951 cm–1.
( )2
( )2
O
10b
O
6b
1H NMR (400 MHz, CDCl3): δ = 7.45 (d, J = 7.6 Hz, 1 H), 7.33 (t,
J = 7.6 Hz, 1 H), 7.25 (t, J = 7.6 Hz, 1 H), 7.15 (d, J = 7.6 Hz, 1 H),
5.95 (dddd, J = 17.2, 10.4, 5.2 Hz, 1 H), 5.36 (dd, J = 17.2, 1.6 Hz,
1 H), 5.27 (d, J = 10.4 Hz, 1 H), 4.66 (dd, J = 13.2, 5.2 Hz, 1 H),
4.60 (dd, J = 13.2, 5.2 Hz, 1 H), 3.51 (d, J = 11.6 Hz, 1 H), 2.90 (dt,
J = 15.6, 3.6 Hz, 1 H), 2.02 (d, J = 14.8 Hz, 1 H), 1.82–1.54 (m, 8
H), 1.41 (m, 1 H), 1.03 (s, 1 H).
Scheme 5 Cross-over study
13C NMR (100 MHz, CDCl3): δ = 153.7, 146.4, 145.0, 131.7, 129.9,
127.5, 124.3, 121.9, 118.6, 88.6, 67.9, 56.2, 29.1, 28.8, 27.7, 25.7,
25.4, 25.1.
HRMS (EI): m/z [M]+ calcd for C18H22O3: 286.1569; found:
286.1561.
Reactions were conducted in flame- or oven-dried glassware under
an atmosphere of argon using freshly distilled solvents unless spec-
ified otherwise. Commercial reagents were used as received. Tolu-
ene and MeCN were distilled from CaH2 prior to use. THF was
distilled from Na/benzophenone. TLC was performed on Merck sil-
ica gel 60 F254 plates. Visualization was carried out using UV light
and/or KMnO4, anisaldehyde or (NH4)2Ce(NO3)6 solns. ACS grade
hexanes and EtOAc were used as received. Flash column chroma-
tography was carried out using Dynamic Absorbents Inc. Flash sil-
Carbonate 13a
Chromatography (2% EtOAc–hexanes); colorless oil; yield: 136
mg (0.52 mmol, 19%).
1
ica gel (32–63 μm). H and 13C NMR spectra were recorded on a
IR (thin film): 3065, 2926, 1743, 1645, 1380 cm–1.
Bruker 400 AV or 300 AV spectrometer in CDCl3 (99.8% deuterat-
ed). Spectra recorded using CDCl3 were calibrated to δ = 7.28 (1H)
and 77.23 (13C). Infrared spectra were recorded as thin films (neat)
in NaCl cells using a Mattson Genesis II FT-IR instrument. Mass
spectrometry was conducted at the Mass Spectrometry Facility of
Queen’s University on either a Waters/Micromass GC-TOF instru-
ment with an EI source or an Applied Biosystems/MDS Sciex QStar
XL QqTOF instrument with and ESI source.
1H NMR (400 MHz, CDCl3): δ = 7.30–7.23 (m, 3 H), 7.16 (d, J =
6.9 Hz, 1 H), 5.95 (dddd, J = 17.1, 10.5, 6.0 Hz, 1 H), 5.34 (dd, J =
17.1, 1.2 Hz, 1 H), 5.26 (d, J = 10.5 Hz, 1 H), 4.55 (d, J = 6.0 Hz, 2
H), 3.58 (d, J = 14.1 Hz, 1 H), 3.47 (d, J = 14.1 Hz, 1 H), 1.04 (s, 9
H).
13C NMR (100 MHz, CDCl3): δ = 153.4, 144.7, 141.7, 131.9, 129.6,
126.8, 123.8, 122.7, 118.6, 92.7, 67.8, 39.5, 37.0, 25.2.
HRMS (EI): m/z [M]+ calcd for C16H20O3: 260.1412; found:
260.1405.
Allyl 5,6,7,8,9,9a-Hexahydro-4bH-benzo[3,4]cyclobuta[1,2]cy-
clohepten-4b-yl Carbonate (3a); Typical Procedure 1 for the
One-Step Preparation of 3a, 12a, and 13a
Following a procedure published by Durst et al.,12 an oven-dried,
25-mL round-bottomed flask equipped with a stir bar was charged
with 2,2,6,6-tetramethylpiperdine (0.724 g, 0.907 mL, 5.4 mmol,
2.0 equiv) and capped with a rubber septum. The reaction vessel
was flushed with argon for 10 min at r.t. prior to the addition of THF
(8 mL). The resulting soln was cooled to –40 °C using dry
ice/EtOH–H2O (2:1). Once cold, 1.7 M t-BuLi soln (5.4 mmol, 2.0
equiv) was added dropwise via syringe. The mixture was stirred for
30 min before a soln of cycloheptanone (0.300 g, 0.315 mL, 2.7
mmol, 1.0 equiv) in THF (2 mL) was added. This was followed by
a soln of bromobenzene (0.424 g, 0.284 mL, 2.7 mmol, 1.0 equiv)
in THF (2 mL). The reaction was stirred at –40 °C for a further 4 h
before neat allyl chloroformate (0.976 g, 0.861 mL, 3.0 equiv) was
introduced. After the reaction had warmed to r.t. it was quenched
with sat. NH4Cl soln. The layers were separated and the aqueous
layer was extracted with EtOAc (2 ×). The combined organic layers
were washed with brine and dried (MgSO4). Filtration and concen-
tration in vacuo gave the crude product, which was purified by flash
Allyl 4-Methyl-5,6,7,8,9,9a-hexahydro-4bH-benzo[3,4]cyclobu-
ta[1,2]cyclohepten-4b-yl Carbonate (4a); Typical Procedure 2
for the Two-Step Preparation of 4a–11a
The required benzocyclobutenols were prepared from the corre-
sponding bromobenzenes and cycloheptanone according to the pro-
cedure reported by Durst.12 An oven-dried, 25-mL round-bottomed
flask equipped with a stir bar was capped with a rubber septum and
flushed with argon for 10 min at r.t. The flask was charged with i-
Pr2NH (0.081 g, 0.81 mmol, 1.3 equiv) and THF (6 mL). The result-
ing soln was cooled to 0 °C prior to the addition of n-BuLi (0.81
mmol, 1.3 equiv) to prepare LDA. After stirring at 0 °C for 30 min,
a soln of the required benzocyclobutenol (0.125 g, 0.62 mmol, 1.0
equiv) in THF (2 mL) was added dropwise via syringe. The temper-
ature was maintained at 0 °C for a 2 h, after which neat allyl chlo-
roformate (0.149 g, 1.2 mmol, 2.0 equiv) was added. The resulting
mixture was warmed to r.t. over 16 h. Sat. NH4Cl soln was added
and the aqueous layer was extracted with EtOAc (2 ×). The com-
bined organic layers were washed with brine and dried (MgSO4).
Synthesis 2012, 44, 1885–1891
© Georg Thieme Verlag Stuttgart · New York

SPECIAL TOPIC
Decarboxylative Allylation of Benzocyclobutenols
1889
Filtration and concentration in vacuo gave the crude product which
was purified by flash column chromatography (1% EtOAc–hex-
anes) to afford carbonate 4a (0.148 g, 0.52 mmol, 28% overall yield
in 2 steps from the bromobenzene) as a clear oil. This protocol was
followed for the preparation of substrates 4a–7a. A similar protocol
was followed for substrates 8a–11a using the corresponding allyl
imidazolide instead of allyl chloroformate. All reported yields are
for the two-step process.
3 H), 3.81 (s, 3 H), 2.65 (dd, J = 13.6, 12.0 Hz, 1 H), 2.19–2.07 (m,
3 H), 1.73–1.62 (m, 3 H), 1.27 (m, 2 H), 0.93 (m, 1 H).
13C NMR (100 MHz, CDCl3): δ = 156.4, 153.6, 149.7, 140.7, 137.6,
131.6, 119.8, 118.7, 99.8, 91.2, 67.9, 60.9, 58.9, 56.2, 54.4, 35.1,
31.4, 28.3, 25.2, 24.1.
HRMS (EI): m/z [M]+ calcd for C20H26O6: 362.1729; found:
362.1738.
IR (thin film): 3063, 3025, 2915, 1747, 1640, 1365, 877 cm–1.
Carbonate 8a
1H NMR (400 MHz, CDCl3): δ = 7.24 (t, J = 7.6 Hz, 1 H), 7.04 (d,
J = 7.6 Hz, 1 H), 6.96 (d, J = 7.6 Hz, 1 H), 5.95 (dddd, J = 17.2, 10.4,
5.2 Hz, 1 H), 5.37 (d, J = 17.2 Hz, 1 H), 5.27 (d, J = 10.4 Hz, 1 H),
4.64 (dd, J = 13.6, 5.2 Hz, 1 H), 4.60 (dd, J = 13.6, 5.2 Hz, 1 H),
3.98 (dd, J = 6.8, 3.2 Hz, 1 H), 2.64 (t, J = 12.4 Hz, 1 H), 2.32 (s, 3
H), 2.23 (m, 2 H), 2.06 (m, 1 H), 1.58–1.76 (m, 3 H), 1.36 (m, 2 H),
0.96 (m, 1 H).
13C NMR (100 MHz, CDCl3): δ = 153.8, 145.3, 142.0, 133.6, 131.7,
129.9, 128.6, 119.8, 118.6, 91.9, 67.8, 56.2, 32.8, 31.8, 28.9, 25.9,
24.0, 17.2.
Chromatography (1% CH2Cl2–toluene); colorless oil; yield: 120 mg
(0.40 mmol, 60%).
IR (thin film): 3043, 2971, 1745, 1642, 1456, 1083 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.42 (d, J = 7.2 Hz, 1 H), 7.32 (t,
J = 7.2 Hz, 1 H), 7.24 (t, J = 7.2 Hz, 1 H), 7.14 (d, J = 7.2 Hz, 1 H),
6.13 (dd, J = 17.6, 10.8 Hz, 1 H), 5.22 (d, J = 17.6 Hz, 1 H), 5.14 (d,
J = 10.4 Hz, 1 H), 3.80 (dd, J = 9.2, 3.6 Hz, 1 H), 2.70 (m, 1 H), 2.16
(m, 1 H), 2.03 (m, 1 H), 1.69 (m, 3 H), 1.57 (s, 3 H), 1.55 (s, 3 H),
1.47–1.28 (m, 4 H).
13C NMR (100 MHz, CDCl3): δ = 152.1, 145.8, 144.6, 142.0, 129.7,
127.3, 124.4, 122.3, 113.1, 90.2, 64.0, 56.6, 32.4, 31.7, 29.8, 26.8,
26.7, 26.0, 23.7.
HRMS (EI): m/z [M]+ calcd for C18H22O3: 286.1569; found:
286.1575.
MS: m/z [M – C5H9 – CO2]+ calcd for C12H13O:173.0966; found:
Carbonate 5a
173.13. [M]+ was not observed.
Chromatography (1% CH2Cl2–toluene); colorless oil; yield: 184 mg
(0.53 mmol, 36%).
Carbonate 9a
IR (thin film): 3063, 3042, 2910, 1739, 1647, 1412, 928 cm–1.
Chromatography (1% CH2Cl2–toluene); colorless oil; yield: 126 mg
(0.44 mmol, 67%).
1H NMR (400 MHz, CDCl3): δ = 7.74 (d, J = 7.6 Hz, 2 H), 7.46 (m,
4 H), 7.37 (t, J = 7.6 Hz, 1 H), 7.13 (m, 1 H), 5.95 (dddd, J = 17.2,
10.4, 5.2 Hz, 1 H), 5.40 (d, J = 17.2 Hz, 1 H), 5.30 (d, J = 10.4 Hz,
1 H), 4.70 (dd, J = 13.2, 5.2 Hz, 1 H), 4.65 (dd, J = 13.2, 5.2 Hz, 1
H), 4.15 (m, 1 H), 2.43 (t, J = 12.8 Hz, 1 H), 2.19 (m, 2 H), 2.07 (m,
1 H), 1.61 (m, 1 H), 1.45 (m, 1 H), 1.30–1.20 (m, 3 H), 0.56 (m, 1
H).
13C NMR (100 MHz, CDCl3): δ = 153.8, 146.1, 140.8, 137.7, 137.4,
131.8, 130.4, 128.5, 128.0, 127.5, 126.3, 121.6, 118.6, 92.0, 67.9,
55.9, 32.1, 31.6, 28.6, 25.4, 24.1.
IR (thin film): 3067, 2925, 1748, 1633, 1426 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.44 (d, J = 7.2 Hz, 1 H), 7.33 (t,
J = 7.2 Hz, 1 H), 7.26 (t, J = 7.2 Hz, 1 H), 7.14 (d, J = 7.2 Hz, 1 H),
5.83 (m, 1 H), 5.63 (m, 1 H), 4.55 (m, 2 H), 3.80 (dd, J = 10.0, 4.0
Hz, 1 H), 2.70 (m, 1 H), 2.17 (m, 1 H), 2.05 (m, 1 H), 1.69 (m, 7 H),
1.61–1.41 (m, 4 H).
13C NMR (100 MHz, CDCl3): δ = 153.7, 145.8, 144.4, 132.0, 129.8,
127.4, 124.6, 124.4, 122.3, 90.6, 67.9, 56.7, 32.4, 31.7, 30.0, 27.0,
23.8, 17.7.
HRMS (EI): m/z [M]+ calcd for C23H24O3: 348.1725; found:
348.1733.
MS: m/z [M – C4H7 – CO2]+ calcd for C12H13O: 173.0966; found:
173.11. [M]+ was not observed.
Carbonate 6a
Carbonate 10a
Chromatography (8% EtOAc–hexanes); colorless oil; yield: 148
mg (0.49 mmol, 36%).
Chromatography (1% CH2Cl2–toluene); colorless oil; yield: 182 mg
(0.64 mmol, 64%).
IR (thin film): 3058, 2921, 1743, 1642, 1235 cm–1.
IR (thin film): 3054, 2956, 1742, 1637, 1409, 1076 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.31 (t, J = 7.6 Hz, 1 H), 6.75 (d,
J = 7.6 Hz, 1 H), 6.74 (d, J = 7.6 Hz, 1 H), 5.95 (ddt, J = 16.8, 10.4,
5.6 Hz, 1 H), 5.36 (d, J = 16.8 Hz, 1 H), 5.27 (d, J = 10.4 Hz, 1 H),
4.62 (d, J = 5.6 Hz, 2 H), 4.00 (dd, J = 5.2, 3.2 Hz, 1 H), 3.87 (s, 3
H), 2.59 (t, J = 12.8 Hz, 1 H), 2.26 (dd, J = 13.6, 8.0 Hz, 1 H), 2.12
(m, 2 H), 1.73–1.57 (m, 3 H), 1.29 (m, 2 H), 0.92 (m, 1 H).
13C NMR (100 MHz, CDCl3): δ = 154.4, 153.8, 147.1, 131.7, 131.6,
128.4, 118.5, 115.1, 111.6, 91.1, 67.8, 56.1, 55.8, 33.8, 31.6, 28.5,
25.5, 24.3.
1H NMR (400 MHz, CDCl3): δ = 7.43 (d, J = 7.2 Hz, 1 H), 7.33 (t,
J = 7.2 Hz, 1 H), 7.26 (t, J = 7.2 Hz, 1 H), 7.14 (d, J = 7.2 Hz, 1 H),
5.02 (s, 1 H), 4.96 (s, 1 H), 4.57 (d, J = 12.8 Hz, 1 H), 4.50 (d, J =
12.8 Hz, 1 H), 3.81 (dd, J = 10.0, 4.0 Hz, 1 H), 2.70 (m, 1 H), 2.17
(m, 1 H), 2.03 (m, 1 H), 1.78 (s, 3 H), 1.74–1.63 (m, 3 H), 1.58–1.43
(m, 3 H), 0.96 (m, 1 H).
13C NMR (100 MHz, CDCl3): δ = 153.7, 145.8, 144.3, 139.4, 129.8,
127.4, 124.4, 122.4, 113.2, 90.7, 70.5, 56.7, 32.3, 31.7, 30.0, 26.9,
23.7, 19.3.
HRMS (EI): m/z [M]+ calcd for C18H22O4: 302.1526; found:
302.1518.
HRMS (EI): m/z [M]+ calcd for C18H22O3: 286.1569; found:
286.1577.
Carbonate 7a
Carbonate 11a
Chromatography (13% EtOAc–hexanes); colorless oil; yield: 175
mg (0.47 mmol, 16%).
Chromatography (2% EtOAc–hexanes); colorless oil; yield: 0.153
g (0.48 mmol, 56%).
IR (thin film): 3061, 2987, 1730, 1648, 1606, 1241, 1045 cm–1.
IR (thin film): 3061, 2946, 1725, 1641, 1218, 1046 cm–1.
1H NMR (400 MHz, CDCl3): δ = 6.41 (s, 1 H), 5.95 (dddd, J = 17.2,
13.2, 10.4, 6.0 Hz, 1 H), 5.36 (dd, J = 17.2, 1.6 Hz, 1 H), 5.28 (d,
J = 10.4 Hz, 1 H), 4.65 (dd, J = 13.2, 6.0 Hz, 1 H), 4.59 (dd, J = 13.2,
6.0 Hz, 1 H), 4.00 (s, 3 H), 3.93 (dd, J = 5.6, 3.2 Hz, 1 H), 3.87 (s,
1H NMR (400 MHz, CDCl3): δ = 7.31 (t, J = 8.0 Hz, 1 H), 6.76 (d,
J = 8.0 Hz, 1 H), 6.75 (d, J = 8.0 Hz, 1 H), 5.02 (s, 1 H), 4.95 (s, 1
H), 4.54 (m, 2 H), 4.00 (m, 1 H), 3.88 (s, 3 H), 2.60 (t, J = 12.8 Hz,
1 H), 2.26 (dd, J = 12.8, 8 Hz, 1 H), 2.13 (m, 2 H), 1.78 (s, 3 H),
1.73–1.62 (m, 3 H), 1.29 (m, 2 H), 0.95 (m, 1 H).
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 1885–1891

1890
D. Rosa et al.
SPECIAL TOPIC
2-(2-Allyl-3-methoxyphenyl)cycloheptanone (6b)
Chromatography (2% EtOAc–hexanes); colorless oil; yield: 34 mg
(0.13 mmol, 87%).
13C NMR (100 MHz, CDCl3): δ = 154.4, 153.9, 147.1, 139.5, 131.6,
128.4, 115.1, 113.1, 111.6, 91.1, 70.4, 56.1, 55.8, 33.8, 31.6, 28.5,
25.5, 24.3, 19.3.
IR (thin film): 2925, 1695, 1637, 1461, 1257, 1065 cm–1.
HRMS (EI): m/z [M]+ calcd for C19H24O4: 316.1675; found:
1H NMR (400 MHz, CDCl3): δ = 7.23 (t, J = 8.0 Hz, 1 H), 6.85 (d,
J = 8.0 Hz, 1 H), 6.80 (d, J = 8.0 Hz, 1 H), 5.95 (ddt, J = 17.2, 10.4,
6.0 Hz, 1 H), 5.00 (d, J = 10.4 Hz, 1 H), 5.01 (dd, J = 17.2, 1.2 Hz,
1 H), 4.07 (dd, J = 10.8, 2.8 Hz, 1 H), 3.82 (s, 3 H), 3.55 (dd, J =
15.6, 6.0 Hz, 1 H), 3.44 (dd, J = 15.6, 6.0 Hz, 1 H), 2.71 (m, 2 H),
2.08–1.93 (m, 5 H), 1.71 (m, 1 H), 1.54–1.42 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 213.6, 157.3, 141.4, 136.9, 127.0,
125.7, 120.1, 114.4, 108.8, 55.6, 53.5, 43.8, 32.9, 29.8, 29.7, 29.6,
24.6.
316.1683.
2-(2-Allylphenyl)cycloheptanone (3b); Typical Procedure 3 for
Palladium-Catalyzed Decarboxylative Allylation and Fragmen-
tation
An oven-dried 15-mL test tube equipped with a stir bar was charged
Pd2dba3 (0.002 g, 0.002 mmol, 0.01 equiv) and S-Phos (0.003 g,
0.008 mmol, 0.05 equiv). The reaction vessel was sealed with a sep-
tum and flushed with argon for 10 min at r.t. Toluene was added (1.0
mL) and the resulting soln stirred at r.t.. To the reaction vessel was
added a soln of carbonate 3a (0.040 g, 0.15 mmol, 1.0 equiv) in tol-
uene (0.5 mL); the vessel was heated to 60 °C (TLC monitoring).
Upon completion, the reaction mixture was filtered through a pad of
silica gel (EtOAc). The filtrate was concentrated in vacuo and the
crude product purified by flash column chromatography (4%
EtOAc–hexanes) to give ketone 3b (33 mg, 0.014 mmol, 93%) as a
clear oil.
HRMS (EI): m/z [M]+ calcd for C17H22O2: 258.1620; found:
258.1611.
2-(2-Allyl-3,4,5-trimethoxyphenyl)cycloheptanone (7b)
Chromatography (17% EtOAc–hexanes); colorless oil; yield: 42
mg (0.13 mmol, 87%).
IR (thin film): 3051, 2920, 1700, 1648, 1232, 1215, 1046 cm–1.
1H NMR (400 MHz, CDCl3): δ = 6.57 (s, 1 H), 5.95 (ddt, J = 17.2,
10.0, 5.2 Hz, 1 H), 5.02 (d, J = 10.0 Hz, 1 H), 4.88 (dd, J = 17.2, 1.6
Hz, 1 H), 4.03 (dd, J = 11.2, 2.4 Hz, 1 H), 3.87 (s, 6 H), 3.84 (s, 3
H), 3.45 (dd, J = 15.2, 5.2 Hz, 1 H), 3.37 (dd, J = 15.2, 5.2 Hz, 1 H),
2.67 (m, 2 H), 2.04 (m, 4 H), 1.91 (m, 1 H), 1.72 (m, 1 H), 1.55 (m,
1 H), 1.41 (m, 1 H).
13C NMR (100 MHz, CDCl3): δ = 213.3, 161.6, 151.6, 140.8, 137.5,
135.7, 123.2, 114.7, 107.6, 61.1, 60.6, 55.9, 53.0, 43.9, 33.3, 30.0,
29.7, 29.4, 24.2.
IR (thin film): 3068, 3021, 2921, 1702, 1637, 1602, 1454 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.22–7.18 (m, 4 H), 5.98 (ddt, J =
17.2, 10.4, 6.4 Hz, 1 H), 5.09 (d, J = 10.4 Hz, 1 H), 4.98 (d, J = 17.2
Hz, 1 H), 3.98 (dd, J = 11.2, 2.8 Hz, 1 H), 3.50 (dd, J = 16.4, 6.4 Hz,
1 H), 3.39 (dd, J = 16.4, 6.4 Hz, 1 H), 2.69 (m, 2 H), 2.08–1.95 (m,
5 H), 1.72 (m, 1 H), 1.63–1.44 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 213.5, 139.8, 137.2, 136.9, 129.9,
127.8, 126.7, 126.5, 115.7, 53.4, 43.7, 37.7, 32.7, 29.7, 29.6, 24.6.
HRMS (EI): m/z [M]+ calcd for C16H20O: 228.1514; found:
HRMS (EI): m/z [M]+ calcd for C19H26O4: 318.1831; found:
228.1519.
318.1843.
2-(2-Allyl-3-methylphenyl)cycloheptanone (4b)
Chromatography (3% EtOAc–hexanes); colorless oil; yield: 33 mg
(14 mmol, 91%).
IR (thin film): 3057, 2942, 1701, 1648, 1422 cm–1.
2-(2-Methallylphenyl)cycloheptanone (10b)
Chromatography (5% EtOAc–hexanes); colorless oil; yield: 33 mg
(0.14 mmol, 90%).
IR (thin film): 3072, 2968, 1695, 1649, 1489, 1450, 741 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.16 (t, J = 7.6 Hz, 1 H), 7.09 (d,
J = 7.6 Hz, 1 H), 7.08 (d, J = 7.6 Hz, 1 H), 5.95 (ddt, J = 17.2, 10.0,
5.6 Hz, 1 H), 5.09 (dd, J = 10.0, 1.6 Hz, 1 H), 4.84 (d, J = 17.2 Hz,
1 H), 4.04 (dd, J = 11.2, 3.2 Hz, 1 H), 3.50 (dd, J = 16.8, 5.6 Hz, 1
H), 3.41 (dd, J = 16.8, 5.6 Hz, 1 H), 2.70 (m, 2 H), 2.31 (s, 3 H),
2.31–1.94 (m, 5 H), 1.70 (m, 1 H), 1.48 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 213.8, 140.2, 136.9, 135.8, 135.0,
128.7, 126.2, 125.5, 115.2, 53.7, 43.7, 33.1, 33.0, 29.8, 29.6, 24.7,
20.3.
1H NMR (400 MHz, CDCl3): δ = 7.25 (m, 2 H), 7.21–7.14 (m, 2 H),
4.84 (s, 1 H), 4.52 (s, 1 H), 4.07 (dd, J = 10.8, 3.2 Hz, 1 H), 3.43 (d,
J = 16.0 Hz, 1 H), 3.32 (dd, J = 16.0 Hz, 1 H), 2.66 (m, 2 H), 2.00
(m, 5 H), 1.75 (s, 3 H), 1.73 (m, 1 H), 1.49 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 213.3, 144.9, 140.2, 136.7, 130.4,
128.0, 126.5, 126.4, 111.9, 53.1, 43.7, 42.0, 32.9, 29.7, 29.6, 24.5,
22.6.
HRMS (EI): m/z [M]+ calcd for C17H22O: 242.1671; found:
242.1665.
HRMS (EI): m/z [M]+ calcd for C17H22O: 242.1671; found:
242.1681.
2-(2-Methallyl-3-methoxyphenyl)cycloheptanone (11b)
Chromatography (5% EtOAc–hexanes); colorless oil; yield: 35 mg
(0.13 mmol, 85%).
IR (thin film): 2928, 2852, 1698, 1635, 1218, 1032 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.23 (t, J = 8.0 Hz, 1 H), 6.88 (d,
J = 8.0 Hz, 1 H), 6.80 (d, J = 8.0 Hz, 1 H), 4.74 (s, 1 H), 4.38 (s, 1
H), 4.03 (dd, J = 10.8, 2.4 Hz, 1 H), 3.81 (s, 3 H), 3.49 (d, J = 16.4
Hz, 1 H), 3.38 (d, J = 16.4 Hz, 1 H), 2.67 (m, 2 H), 2.00 (m, 5 H),
1.80 (s, 3 H), 1.67 (m, 1 H), 1.45 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 213.4, 157.4, 144.8, 141.8, 126.9,
125.8, 120.3, 110.1, 108.8, 55.7, 53.2, 43.8, 33.3, 33.0, 29.7, 29.6,
24.5, 22.9.
2-(2-Allylbiphenyl-3-yl)cycloheptanone (5b)
Chromatography (2% EtOAc–hexanes); colorless oil; yield: 40 mg
(0.13 mmol, 88%).
IR (thin film): 3059, 2925, 1697, 1642, 1468 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.40–7.27 (m, 7 H), 7.15 (dd, J =
6.8, 1.6 Hz, 1 H), 5.96 (ddt, J = 17.2, 10.0, 5.2 Hz, 1 H), 5.09 (dd,
J = 10.0, 1.6 Hz, 1 H), 4.82 (dd, J = 17.2, 1.6 Hz, 1 H), 4.17 (dd, J =
10.8, 2.0 Hz, 1 H), 3.40 (dd, J = 16.8, 5.2 Hz, 1 H), 3.32 (dd, J =
16.8, 5.2 Hz, 1 H), 2.70 (m, 2 H), 2.09–1.98 (m, 5 H), 1.74 (m, 1 H),
1.61–1.45 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 213.5, 143.0, 142.4, 140.9, 137.7,
133.7, 129.0, 128.6, 127.7, 127.4, 126.7, 126.0, 115.7, 53.3, 43.9,
34.1, 33.4, 29.8, 29.6, 24.4.
HRMS (EI): m/z [M]+ calcd for C18H24O2: 272.1776; found:
272.1785.
HRMS (EI): m/z [M]+ calcd for C22H24O: 304.1827; found:
304.1836.
2-(2-Allylphenyl)cyclooctanone (12b)
Chromatography (5% EtOAc–hexanes); colorless oil; yield: 34 mg
(0.14 mmol, 94%).
Synthesis 2012, 44, 1885–1891
© Georg Thieme Verlag Stuttgart · New York

SPECIAL TOPIC
Decarboxylative Allylation of Benzocyclobutenols
1891
IR (thin film): 3072, 3027, 2968, 1695, 1648, 1450 cm–1.
Fleming, I., Eds.; Pergamon: Oxford, 1991, 441.
(j) Kuwajima, I.; Nakamura, I. Top. Curr. Chem. 1990, 155,
1. (k) Kuwajima, I. Pure Appl. Chem. 1988, 60, 115.
(2) (a) Rosa, D.; Orellana, A. Chem. Commun. 2012, 48, 1922.
(b) Rosa, D.; Orellana, A. Org. Lett. 2011, 13, 110.
(3) Rosa, D.; Chtchemelinine, A.; Orellana, A. J. Org. Chem.
2011, 76, 9157.
(4) Recent review: Weaver, J. D.; Recio, A.; Grenning, A. J.;
Tunge, J. A. Chem. Rev. 2011, 111, 1846.
(5) The base-catalyzed cleavage of benzocyclobutenols is
generally not selective. Seminal report: Cava, M. P.; Muth,
K. J. Am. Chem. Soc. 1960, 82, 652.
(6) For a related process see: Schulz, S. R.; Blechert, S. Angew.
Chem. Int. Ed. 2007, 46, 3966.
(7) This functional group disposition is found in some natural
products. Shirataki, Y.; Yoshida, S.; Sugita, Y.; Yokoe, I.;
Komatsu, M.; Ohyama, M.; Tanaka, T.; Iinuma, M.
Phytochemistry 1997, 44, 715.
(8) For selected examples of benzocyclobutenol synthesis, see:
(a) Photochemical synthesis: Ito, Y.; Takahashi, H.;
Hasegawa, J.-Y.; Turro, N. J. Tetrahedron 2009, 65, 677.
(b) Intramolecular reaction of o-acylbenzyllithiums:
Kobayashi, K.; Kawakita, M.; Uchida, M.; Nishimura, K.;
Mannami, T.; Irisawa, S.; Morikawa, O.; Konishi, H. J. Org.
Chem. 1999, 64, 3557. (c) Intramolecular addition of
aryllithiums to ketones: Aidhen, I. S.; Narasimhan, N. S.
Tetrahedron Lett. 1991, 32, 2171. (d) Pb(OAc)4-mediated
decarboxylation of the corresponding carboxylic acids:
Macdonald, D. I.; Durst, T. Tetrahedron Lett. 1986, 27,
2235. (e) Metalation of o-halostyrene oxides: Akguen, E.;
Glinski, M. B.; Dhawan, K. L.; Durst, T. J. Org. Chem.
1981, 46, 2730.
1H NMR (400 MHz, CDCl3): δ = 7.44 (t, J = 8.0 Hz, 1 H), 7.36 (d,
J = 8.0 Hz, 1 H), 7.25 (m, 2 H), 5.82 (dddd, J = 17.6, 10.4, 6.4 Hz,
1 H), 5.09 (d, J = 17.6 Hz, 1 H), 4.97 (d, J = 10.4 Hz, 1 H), 3.45 (m,
1 H), 3.19 (m, 1 H), 2.57 (m, 1 H), 2.48–2.40 (m, 2 H), 1.75–1.49
(m, 5 H), 1.40–1.22 (m, 3 H), 1.16 (m, 1 H), 0.59 (m, 1 H).
13C NMR (100 MHz, CDCl3): δ = 210.6, 142.4, 141.5, 137.1, 130.4,
126.7, 125.1, 115.7, 44.3, 39.7, 36.1, 35.0, 28.0, 22.7, 21.8, 21.7.
HRMS (EI): m/z [M]+ calcd for C17H22O: 242.1671; found:
242.1663.
1-(2-Allylphenyl)-3,3-dimethylbutan-2-one (13b)
Chromatography (2% EtOAc–hexanes); colorless oil; yield: 28 mg
(0.14 mmol, 92%).
IR (thin film): 3065, 2957, 1703, 1623, 1438 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.24–7.18 (m, 3 H), 7.05 (d, J =
7.6 Hz, 1 H), 5.98 (ddt, J = 17.2, 10.0, 6.0 Hz, 1 H), 5.09 (d, J = 10.0
Hz, 1 H), 4.99 (dd, J = 17.2, 1.6 Hz, 1 H), 3.89 (s, 2 H), 3.30 (d, J =
6.0 Hz, 2 H), 1.27 (s, 9 H).
13C NMR (100 MHz, CDCl3): δ = 212.7, 138.2, 136.8, 133.5, 130.6,
129.6, 127.1, 126.3, 115.8, 44.4, 40.8, 37.4, 26.6.
HRMS (EI): m/z [M]+ calcd for C15H20O: 216.1514; found:
216.1519.
Acknowledgment
We gratefully acknowledge the support of this work by York Uni-
versity and the Natural Sciences and Engineering Research Council
of Canada. We also thank Professor Michael Organ (York Univer-
sity) for generous sharing of resources.
(9) Selected examples: (a) Tambar, U. K.; Ebner, D. C.; Stoltz,
B. J. Am. Chem. Soc. 2006, 128, 11752. (b) Macdonald, D.
I.; Durst, T. J. Org. Chem. 1988, 53, 3663.
(10) For a leading reference on the synthesis of benzocyclo-
butenones, see: Alvares-Bercedo, P.; Flores-Gaspar, A.;
Correa, A.; Martin, R. J. Am. Chem. Soc. 2010, 132, 466.
(11) For an example of this strategy in complex molecule
synthesis, see: Takemura, I.; Imura, K.; Matsumoto, T.;
Suzuki, K. Org. Lett. 2004, 6, 2503.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synthesis.onmorinIfatgnonmSorti
i
npfurotIangSiuptor
References
(1) For recent reviews on transition-metal-catalyzed β-carbo-
elimination reactions see: (a) Seiser, T.; Saget, T.; Tran, D.
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(b) Murakami, M.; Matsuda, T. Chem. Commun. 2011, 47,
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Cramer, N. Org. Biomol. Chem. 2009, 7, 2835. (e) Satoh, T.;
Miura, M. Top. Organomet. Chem. 2007, 24, 61.
(12) Tripathy, S.; Reddy, R.; Durst, T. Can. J. Chem. 2003, 81,
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(13) For early reports of a similar transformation, see:
(a) Gregoire, B.; Carre, M.-C.; Caubere, P. J. Org. Chem.
1986, 51, 1419. (b) Carre, M.-C.; Gregoire, B.; Caubere, P.
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(f) Murakami, M.; Makino, M.; Ashida, S.; Matsuda, T.
Bull. Chem. Soc. Jpn. 2006, 79, 1315. (g) Satoh, T.; Miura,
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Uemura, S. Synlett 2004, 201. (i) Kuwajima, I.; Nakamura,
E. In Comprehensive Organic Synthesis, Vol. 2; Trost, B.;
(14) Bertolini, G.; Pavich, G.; Vergani, B. J. Org. Chem. 1998,
63, 6031.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 1885–1891