New cationic bisoxazoline-Au(III) complex catalyzed cycloisomerization of 1-allenyl-1-ethynyl acetate

Article abstract of DOI:10.1055/s-2008-1072655

Treatment of 1-allenyl-1-diethynyl acetates in the presence of a Au or Pt catalyst (5 mol%) in toluene at room temperature, followed by methanolysis, gave 4-methylene-2-cyclopentenones. The new cationic bisoxazoline (box)-Au(III) complex {(S,S)-Ph-box- or [(R,R)-Bnbox AuCl₂]SbF₆} accelerated the reaction, providing the products in moderate yield (60-69%). Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2008-1072655

LETTER
1081
New Cationic Bisoxazoline–Au(III) Complex Catalyzed Cycloisomerization of
1-Allenyl-1-ethynyl Acetate
C
ycloisomerizatio
e
nof 1-Alle
i
t
s
hynyl
A
ce
u
tate ke Kato,*a Takuya Kobayashi,a Takeo Fujinami,a Satoshi Motodate,a Taichi Kusakabe,a Tomoyuki Mochida,b
Hiroyuki Akita*a
a
Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
Fax +81(474)721825; E-mail: kkk@phar.toho-u.ac.jp
Department of Chemistry, Faculty of Science, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan
b
Received 17 January 2008
ety to 3, followed by desilylation, and subsequent
Abstract: Treatment of 1-allenyl-1-diethynyl acetates in the pres-
ence of a Au or Pt catalyst (5 mol%) in toluene at room temperature,
followed by methanolysis, gave 4-methylene-2-cyclopentenones.
The new cationic bisoxazoline (box)–Au(III) complex {(S,S)-Ph-
box- or [(R,R)-Bnbox AuCl2]SbF6} accelerated the reaction, pro-
viding the products in moderate yield (60–69%).
acetylation afforded 1 in moderate to good yields. When
the substrate 3f, containing a benzoyl group, was em-
ployed in the reaction, a complex mixture was obtained.
As the starting point in this study, we selected 1a as a stan-
dard substrate to search for potential catalysts and sol-
vents (Scheme 3 and Table 1). Treatment of 1a in the
presence of HAuCl4·3H2O (5 mol%) in MeCN at room
temperature for 96 hours gave the 4-methylene-2-cyclo-
pentenone (2a) in 24% yield (entry 1). Among the sol-
vents investigated, toluene produced the desired 2a with
the best yield (entries 2 and 3). Commercially available
AuCl3, PtCl4, and LiAuCl4 exhibited similar catalytic ac-
tivity, while Ph3PAuCl/AgSbF62g yielded a complex mix-
ture (entries 4–7). Thin-layer chromatography suggested
Key words: 1-allenyl-1-diethynyl acetates, 4-alkylidene-2-cyclo-
pentenones, cationic box–Au(III) complex
The transition-metal-catalyzed reaction of unsaturated
systems has recently proven to be a powerful method for
the construction of a variety of carbo- and heterocycles.1
A large number of reactions of propargylic esters mediat-
ed by gold and platinum catalysts have been recently re-
ported.2 Rautenstrauch3a and Toste et al.3b reported on
palladium- and gold-catalyzed cycloisomerization of pro-
O
MeO
O
pargylic acetates having
a
1,4-enyne structure
Au(III) cat.
O
O
(Scheme 1). Recently, we have reported on the gold-cata-
lyzed double Wacker-type reaction4a of propargylic ace-
tates having a 1,4-diyne structure, and also on a
bisoxazoline (Phbox)–palladium complex catalyzed car-
bonylative cyclization4b of the same substrates
(Scheme 2).
During the course of our study,4a–d we became interested
in the transition-metal-catalyzed reaction of propargylic
acetates having a 1,5-allenyne structure. Herein, we report
a cycloisomerization of 1-allenyl-1-ethynyl acetates 1 us-
ing new cationic box–Au(III) complexes, [(S,S)-
+
R
OAc
R
R
PhboxPd(II)
CO, MeOH
O
MeO
MeO
O
R
Scheme 2 1,4-Diynes: Kato et al.4a,b
Au(III) cat.
O
PhboxAuCl2]SbF6
(Scheme 3).
or
[(R,R)-Bnbox
AuCl2]SbF6
O
R
O
R
1-Allenyl-1-ethynyl acetates 1 were prepared from the
corresponding allenyl ketones 35 by a three-step proce-
dure (Scheme 4). Addition of the lithiated acetylene moi-
Me
2
1
Scheme 3 1,5-Allenynes: this work
R2
R2
R3
R2
R3
Pd(II) cat. or
R3
O
OCOR1
Au(I) cat.
OCOR1
Scheme 1 1,4-Enynes: Rautenstrauch3a and Toste et al.3b
SYNLETT 2008, No. 7, pp 1081–1085
x
x.
x
x.
2
0
0
8
Advanced online publication: 28.03.2008
DOI: 10.1055/s-2008-1072655; Art ID: U00408ST
© Georg Thieme Verlag Stuttgart · New York

1082
K. Kato et al.
LETTER
+
–
Li (3 equiv)
TMS
1)
Ac2O
pyridine
R
O
2) K2CO3, MeOH
R
OAc
R
OH
1a 99%
3a R = PhCH2CH2
3b R = Bn
3c R = nonyl
3d R = octyl
3e R = Me2C=CH(CH2)2CHMeCH2
(racemic)
4a 77%
4b 68%
4c 60%
4d 74%
4e 92%
1b 99%
1c 94%
1d 92%
1e 99%
n-hexyl
R
OAc
1a'
3f R = Ph
4f complex mixture
Scheme 4
Table 2 Cycloisomerization of 1: Two-Step Procedure (Scheme 5)
Table 1 Cycloisomerization of 1a: One-Step Procedure (Scheme 3)
Entry Catalyst
(5 mol%)
R
Time
(1 → A)
Yield of 2
(%)
Entry Catalyst (5 mol%)
Solvent
MeCN
CH2Cl2
toluene
toluene
toluene
toluene
toluene
Time (h) Yield (%)
1
2
3
4
5
6
7
HAuCl4·3H2O
HAuCl4·3H2O
HAuCl4·3H2O
AuCl3
96
0.5
0.5
48
24
35
40
43
49
36
1
2
3
4
5
AuCl3
AuCl
Ph(CH2)2
Ph(CH2)2
Ph(CH2)2
Ph(CH2)2
Ph(CH2)2
1 h
48 h
1 h
49
36
52
56
60
KAuCl4
PtCl4
9 h
PtCl4
48
20
[(S,S)-Phbox
10 min
LiAuCl4
AuCl2]SbF6
Ph3PAuCl/AgSbF6
0.5
complex
mixture
6
7
[(R,R)-Bnbox
AuCl2]SbF6
Ph(CH2)2
PhCH2
Nonyl
10 min
10 min
30 min
10 min
60
69
66
63
60
[(R,R)-Bnbox
that the fulvene derivative A is an intermediate in the
transformation 1 → 2 (Scheme 5).3a,b In 1H NMR and 13C
NMR experiments, the spectra of A could barely be ob-
served, and the spectra became increasingly complex after
15 minutes because of the instability of the compound. To
increase the efficiency of the cleavage (A → 2), we at-
tempted methanolysis of the intermediates A (two-step
procedure, Scheme 5, Table 2). A mixture of the substrate
1a and catalyst in toluene was monitored by TLC until all
of the substrate had been consumed (1 → A), then K2CO3
and methanol were added, and the mixture was stirred for
30 minutes. The yield of 2a was slightly improved
(Table 2, entry 1).
AuCl2]SbF6
8
[(R,R)-Bnbox
AuCl2]SbF6
9
[(R,R)-Bnbox
Octyl
AuCl2]SbF6
10
[(R,R)-Bnbox
Me2C=CH(CH2)2 10 min
CHMeCH2
AuCl2]SbF6
ported to date.7 This prompted us to prepare new cationic
box–Au(III) complexes. The complexes were prepared
from a commercially available box ligand [(S,S)-Phbox or
(R,R)-Bnbox], KAuCl4, and AgSbF6. The use of [(S,S)-
Phbox AuCl2]SbF6 or [(R,R)-Bnbox AuCl2]SbF6 gave the
best results overall, providing 2a in 60% yield (entries 5
and 6). Next, substrates 1b–e were tested for the reaction
using 5 mol% of [(R,R)-Bnbox AuCl2]SbF6 as catalyst;
the corresponding products 2b–e were afforded in 60–
69% yield (entries 7–10). The use of internal acetylene 1a¢
resulted in no reaction.
K2CO3
catalyst
OAc
O
O
MeOH
solvent
R
r.t., 30 min
r.t., time
R
O
R
2
Me
1
A
Scheme 5
Next, we screened catalysts with a two-step procedure
(entries 2–4). Among the catalysts investigated, PtCl4
gave the best yield (entry 4). Recently, we reported the
first examples of asymmetric cyclization–carbonylation
of meso-2-alkyl-2-propargylcyclohexane-1,3-diol and 2-
methyl-2-propargylcyclohexane-1,3-dione catalyzed by
several kinds of box–palladium complexes.6 To the best
of our knowledge, box–Au(III) complex has not been re-
LnAu 2+
AuLn3+
AuLn2+
+
O
+
O
OAc
O
OAc
R
R
R
R
R
O
O
AuLn3+
1
2
B
C
A
Scheme 6
Synlett 2008, No. 7, 1081–1085 © Thieme Stuttgart · New York

LETTER
Cycloisomerization of 1-Allenyl-1-ethynyl Acetate
1083
H, m), 2.27 (1 H, br s), 2.55 (1 H, s), 5.01 (2 H, d, J = 6.4 Hz), 5.11
(1 H, t, J = 6.8 Hz), 5.38 (1 H, t, J = 6.4 Hz). 13C NMR (100 MHz,
CDCl3): d (major diastereomer) = 17.7, 21.1, 25.4, 25.7, 29.2, 38.2,
49.0, 68.9, 73.0, 79.8, 85.8, 98.3, 124.8, 131.2, 205.9. IR (neat):
3419, 3306, 1957, 847 cm–1. HRMS (EI): m/z [M+] calcd for
C15H22O: 218.1671; found: 218.1669.
A plausible mechanism of the present reaction is proposed
as shown in Scheme 6.3b 5-exo-dig Cyclization of 1-alle-
nyl-1-ethynyl acetates 1 via nucleophilic attack of the
alkyne by a carbonyl oxygen in accordance with Mark-
ovnikov’s rule generates vinyl gold species B. Cyclization
of vinyl gold species B produces cationic intermediate C,
which upon elimination of cationic gold(III), affords ful-
vene derivative A. Methanolysis of A gives the product 2.
General Procedure for the Preparation of Substrates 1
To a solution of 4 (5 mmol) in pyridine (2 mL) and Ac2O (1.5 mL)
was added 4-dimethylaminopyridine (20 mg) and the mixture was
stirred for 1.5–3 h at r.t. The mixture was diluted with H2O (50 mL)
and EtOAc (50 mL). The layers were separated, the aqueous layer
was extracted with EtOAc (50 mL), and the combined organic lay-
ers were washed with 10% HCl aq, sat. NaHCO3 aq, and H2O. The
organic layers were dried with MgSO4 and concentrated in vacuo.
The product was pure enough to use for further reaction.
Compound 1a: colorless oil. 1H NMR (400 MHz, CDCl3): d = 2.04
(3 H, s), 2.16–2.23 (1 H, m), 2.31–2.38 (1 H, m), 2.70 (1 H, s), 2.82–
2.90 (2 H, m), 5.00–5.06 (2 H, m), 5.68 (1 H, t, J = 6.8 Hz), 7.17–
7.31 (5 H, m). 13C NMR (100 MHz, CDCl3): d = 21.7, 30.6, 42.1,
74.6, 74.9, 79.6, 81.6, 94.1, 126.0, 128.4 (2 C), 128.5 (2 C), 141.3,
169.0, 207.5. IR (neat): 1954, 1747, 1231 cm–1. HRMS (EI): m/z
[M+] calcd for C16H16O2: 240.1150; found: 240.1147.
Compound 1b: colorless oil. 1H NMR (400 MHz, CDCl3): d = 2.02
(3 H, s), 2.64 (1 H, s), 3.21 (1 H, d, J = 13.6 Hz), 3.33 (1 H, d,
J = 13.6 Hz), 4.92–5.02 (2 H, m), 5.57 (1 H, t, J = 6.8 Hz), 7.25–
7.31 (5 H, m). 13C NMR (100 MHz, CDCl3): d = 21.7, 46.4, 74.8,
75.8, 79.6, 81.4, 94.1, 127.1, 127.8 (2 C), 131.1 (2 C), 135.0, 168.9,
207.4. IR (neat): 3284, 2120, 1957, 1743, 1216 cm–1. HRMS (EI):
m/z [M+] C15H14O2: 226.0994; found: 226.0992.
Compound 1c: colorless oil. 1H NMR (400 MHz, CDCl3): d = 0.88
(3 H, t, J = 6.8 Hz), 1.25–1.32 (12 H, m), 1.46–1.55 (2 H, m), 1.85–
1.93 (1 H, m), 1.97–2.03 (1 H, m), 2.04 (3 H, s), 2.62 (1 H, s), 4.94–
5.03 (2 H, m), 5.60 (1 H, t, J = 6.6 Hz). 13C NMR (100 MHz,
CDCl3): d = 14.1, 21.7, 22.7, 24.1, 29.3, 29.4, 29.5, 29.6, 31.9, 40.4,
74.4, 75.1, 79.3, 81.9, 94.3, 169.0, 207.5. IR (neat): 2925, 2120,
1957, 1746, 1226 cm–1. HRMS (EI): m/z [M+] C17H26O2: 262.1933;
found: 262.1933.
In conclusion, we have reported the cycloisomerization of
1-allenyl-1-ethynyl acetates 1 using new cationic box–
Au(III) complexes, [(S,S)-PhboxAuCl2]SbF6 or [(R,R)-
Bnbox AuCl2]SbF6 afforded 4-methylene-2-cyclopenten-
ones 2 in 60–69% yield. An application of the complexes
to an asymmetric reaction is now in progress.
General Procedure for the Preparation of 4
To a solution of trimethylsilyl acetylene (3.81g, 38.8 mmol) in THF
(30 mL) under Ar was added n-BuLi (12.8 mL of 2.6 M in hexane,
33.3 mmol) at –78 °C and the mixture was stirred for 0.5 h at 0 °C.
After the solution was cooled to –78 °C, the corresponding alle-
nylketone 3 (11.1 mmol) in THF (3 × 8 mL) was added slowly drop-
wise. The mixture was stirred at –15 °C for 12 h and quenched with
H2O (80 mL) and EtOAc (80 mL). The layers were separated, the
aqueous layer was extracted with EtOAc (50 mL), and combined or-
ganic layers were dried with MgSO4 and concentrated in vacuo. The
crude product was purified by column chromatography on silica
gel. The fraction eluted with hexane–EtOAc (100:1 to 50:1) afford-
ed 4.
Compound 4a: colorless oil. 1H NMR (400 MHz, CDCl3): d = 2.07–
2.12 (2 H, m), 2.39 (1 H, br s), 2.60 (1 H, s), 2.85–2.90 (2 H, m),
5.03 (2 H, d, J = 6.9 Hz), 5.43 (1 H, t, J = 6.9 Hz), 7.17–7.30 (5 H,
m). 13C NMR (100 MHz, CDCl3): d = 30.8, 44.1, 68.8, 73.2, 80.0,
85.0, 97.4, 125.9, 128.4 (2 C), 128.4 (2 C), 141.6, 206.1. IR (neat):
3390, 2114, 1956, 852 cm–1. HRMS (EI): m/z [M+] calcd for
C14H14O: 198.1045; found: 198.1039.
Compound 1d: colorless oil. 1H NMR (400 MHz, CDCl3): d = 0.89
(3 H, t, J = 6.8 Hz), 1.25–1.34 (10 H, m), 1.45–1.55 (2 H, m), 1.85–
1.93 (1 H, m), 1.97–2.03 (1 H, m), 2.04 (3 H, s), 2.62 (1 H, s), 4.94–
5.03 (2 H, m), 5.60 (1 H, t, J = 6.8 Hz). 13C NMR (100 MHz,
CDCl3): d = 14.1, 21.8, 22.7, 24.1, 29.2, 29.4, 29.5, 31.9, 40.4, 74.4,
75.1, 79.2, 82.0, 94.3, 169.0, 207.5. IR (neat): 2954, 2120, 1957,
1746, 1227 cm–1. HRMS (EI): m/z [M+] C16H24O2: 248.1776; found:
248.1775.
Compound 4b: colorless oil. 1H NMR (400 MHz, CDCl3): d = 2.30
(1 H, s), 2.56 (1 H, s), 3.06 (1 H, d, J = 13.6 Hz), 3.10 (1 H, d,
J = 13.6 Hz), 4.98 (2 H, d, J = 6.7 Hz), 5.43 (1 H, t, J = 6.7 Hz),
7.25–7.35 (5 H, m). 13C NMR (100 MHz, CDCl3): d = 48.4, 68.8,
74.0, 79.9, 84.8, 97.0, 127.1, 128.0 (2 C), 131.0 (2 C), 135.3, 206.1.
IR (neat): 3403, 1958, 699 cm–1. HRMS (EI): m/z [M+] calcd for
C13H12O: 184.0888; found: 184.0882.
Compound 4c: colorless oil. 1H NMR (400 MHz, CDCl3): d = 0.88
(3 H, t, J = 7.2 Hz), 1.24–1.33 (12 H, m), 1.46–1.56 (2 H, m), 1.75–
1.80 (2 H, m), 2.25 (1 H, br s), 2.53 (1 H, s), 5.01 (2 H, d, J = 6.4
Hz), 5.37 (1 H, t, J = 6.4 Hz). 13C NMR (100 MHz, CDCl3): d =
14.1, 22.7, 24.3, 29.3, 29.5, 29.5, 29.5, 31.9, 42.5, 69.1, 72.7, 79.7,
85.4, 97.5, 206.1. IR (neat): 3387, 3309, 2923, 2116, 1958 cm–1.
HRMS (EI): m/z [M+] calcd for C15H24O: 220.1827; found:
220.1831.
Compound 4d: colorless oil. 1H NMR (400 MHz, CDCl3): d = 0.88
(3 H, t, J = 6.8 Hz), 1.25–1.35 (10 H, m), 1.47–1.57 (2 H, m), 1.71–
1.83 (2 H, m), 2.32 (1 H, br s), 2.53 (1 H, s), 5.00 (2 H, d, J = 6.6
Hz), 5.37 (1 H, t, J = 6.6 Hz). 13C NMR (100 MHz, CDCl3): d =
14.1, 22.7, 24.3, 29.3, 29.5, 29.6, 31.9, 42.5, 69.1, 72.7, 79.7, 85.4,
97.5, 206.1. IR (neat): 3399, 3309, 1958, 1738, 988 cm–1. HRMS
(EI): m/z [M+] calcd for C14H22O: 206.1671; found: 206.1671.
1
Compound 1e: colorless oil (diastereomeric mixture, dr = 6:5). H
NMR (400 MHz, CDCl3): d = 1.01 and 1.03 (total 3 H, each as d,
J = 6.8 Hz), 1.20–1.31 (1 H, m), 1.41–1.52 (1 H, m), 1.61 (3 H, s),
1.68 (3 H, s), 1.77–1.90 (3 H, m), 1.95–2.07 (2 H, m), 2.04 (3 H, s),
2.64 (1 H, s), 4.94–5.03 (2 H, m), 5.10 (1 H, t, J = 6.8 Hz), 5.58–
5.62 (1 H, m). 13C NMR (100 MHz, CDCl3): d (major diastereo-
mer) = 17.7, 21.1, 21.8, 25.3, 25.7, 29.1, 38.0, 47.1, 74.7, 75.1, 79.4,
82.1, 94.9, 124.7, 131.2, 168.9, 207.3. IR (neat): 2918, 1957, 1746,
1225 cm–1. HRMS (EI): m/z [M+] C17H24O2: 260.1776; found:
260.1770.
General procedure for the cycloisomerization reaction of 1
To a solution of 1 (50 mg) in toluene (5 mL) was added the catalyst
(5 mol%) and the mixture was stirred at r.t. The mixture was moni-
tored by TLC until all the substrate had been consumed (1 → A),
then K2CO3 (86 mg, 0.62 mmol) and MeOH (3 mL) were added.
After stirring for 30 min, the mixture was diluted with EtOAc (20
mL), and washed with 3% NaHCO3 aq (20 mL). The layers were
separated, the aqueous layer was extracted with EtOAc (20 mL),
1
Compound 4e: colorless oil (diastereomeric mixture, dr = 6:5). H
NMR (400 MHz, CDCl3): d = 1.02 and 1.04 (total 3 H, each as d,
J = 6.5 Hz), 1.18–1.28 (1 H, m), 1.39–1.53 (1 H, m), 1.60 (3 H, s),
1.63–1.66 (1 H, m), 1.68 (3 H, s), 1.78–1.86 (2 H, m), 1.91–2.03 (2
Synlett 2008, No. 7, 1081–1085 © Thieme Stuttgart · New York

1084
K. Kato et al.
LETTER
and the combined organic layers were dried with MgSO4 and con-
centrated in vacuo. The crude product was purified by column chro-
matography on silica gel. The fraction eluted with hexane–EtOAc
(100:1 to 50:1) afforded 2.
lographic data (excluding structure factors) for the structure have
been deposited with the Cambridge Crystallographic Data Centre as
supplementary publication no. 645186.
Compound 2a: colorless oil. 1H NMR (400 MHz, CDCl3): d = 2.61
(2 H, t, J = 7.6 Hz), 2.84 (2 H, t, J = 7.6 Hz), 2.99 (2 H, s), 5.15 (1
H, s), 5.25 (1 H, s), 7.17–7.30 (5 H, m), 7.34 (1 H, s). 13C NMR (100
MHz, CDCl3): d = 26.5, 33.7, 39.8, 111.0, 126.1, 128.4 (2 C), 128.4
(2 C), 141.1, 142.9, 148.2, 154.2, 205.9. IR (CCl4): 3027, 1698,
1638 cm–1. HRMS (EI): m/z [M+] calcd for C14H14O: 198.1045;
found: 198.1043.
Compound 2b: colorless oil. 1H NMR (400 MHz, CDCl3): d = 3.02
(2 H, t, J = 1.2 Hz), 3.59 (2 H, s), 5.15 (1 H, s), 5.22 (1 H, s), 7.20–
7.33 (6 H, m). 13C NMR (100 MHz, CDCl3): d = 31.3, 39.9, 111.5,
126.5, 128.6 (2 C), 129.0 (2 C), 138.3, 142.8, 148.6, 154.6, 205.29.
IR (CCl4): 3028, 1699, 1639 cm–1. HRMS (EI): m/z [M+] calcd for
C13H12O: 184.0888; found: 184.0889.
Figure 1 X-ray crystal structure of [(R,R)-Bnbox AuCl2]SbF6
1
[(S,S)-Phbox AuCl2]SbF6: yellow needles. H NMR (400 MHz,
Compound 2c: colorless oil. 1H NMR (400 MHz, CDCl3): d = 0.88
(3 H, t, J = 7.1 Hz), 1.23–1.32 (12 H, m), 1.47–1.55 (2 H, m), 2.26
(2 H, t, J = 7.1 Hz), 2.98 (2 H, t, J = 1.2 Hz), 5.14 (1 H, s), 5.26 (1
H, s), 7.41 (1 H, s). 13C NMR (100 MHz, CDCl3): d = 14.1, 22.7,
24.8, 27.7, 29.3, 29.4, 29.4, 29.5, 31.9, 39.9, 110.5, 143.1, 149.6,
153.5, 206.2. IR (neat): 2923, 1704, 1639 cm–1. HRMS (EI): m/z
[M+] calcd for C15H24O: 220.1827; found: 220.1824.
Compound 2d: colorless oil. 1H NMR (400 MHz, CDCl3): d = 0.88
(3 H, t, J = 6.8 Hz), 1.25–1.34 (10 H, m), 1.47–1.55 (2 H, m), 2.26
(2 H, t, J = 7.4 Hz), 2.99 (2 H, t, J = 1.2 Hz), 5.15 (1 H, s), 5.27 (1
H, s), 7.41 (1 H, s). 13C NMR (100 MHz, CDCl3): d = 14.1, 22.7,
24.8, 27.7, 29.2, 29.4, 29.4, 31.9, 39.9, 110.5, 143.1, 149.6, 153.5,
206.2. IR (neat): 2924, 1704, 1639 cm–1. HRMS (EI): m/z [M+]
calcd for C14H22O: 206.1671; found: 206.1671.
Compound 2e: colorless oil. 1H NMR (400 MHz, CDCl3): d = 0.87
(3 H, d, J = 6.8 Hz), 1.12–1.21 (1 H, m), 1.31–1.40 (1 H, m), 1.60
(3 H, s), 1.68 (3 H, s), 1.68–1.78 (1 H, m), 1.91–2.05 (2 H, m), 2.10
(1 H, dd, J = 7.2, 14.8 Hz), 2.23 (1 H, dd, J = 7.2, 14.8 Hz), 2.99 (2
H, t, J = 1.2 Hz), 5.06–5.11 (1 H, m), 5.16 (1 H, s), 5.27 (1 H, s),
7.40 (1 H, s). 13C NMR (100 MHz, CDCl3): d = 17.7, 19.5, 25.5,
25.7, 31.6, 32.2, 36.9, 39.8, 110.5, 124.6, 131.4, 143.1, 148.2,
154.6, 206.2. IR (neat): 2914, 1704, 1638 cm–1. HRMS (EI): m/z
[M+] calcd for C15H22O: 218.1671; found: 218.1673.
Fulvene intermediate A [R = Ph(CH2)2]: 1H NMR (400 MHz,
CDCl3): d = 2.21 (3 H, s), 2.60 (2 H, t, J = 7.8 Hz), 2.89 (2 H, t,
J = 7.8 Hz), 5.68 (1 H, s), 5.73 (1 H, s), 5.93 (1 H, s), 6.14 (1 H, s),
7.18–7.31 (5 H, m). 13C NMR (100 MHz, CDCl3): d = 21.2, 28.7,
34.4, 106.9, 119.3, 121.5, 126.0, 128.4 (2 C), 128.4 (2 C), 141.8,
143.2, 147.8, 154.3, 167.8.
CD2Cl2): d = 2.10 (6 H, s), 4.75 (2 H, dd, J = 5.0, 9.6 Hz), 5.27 (2
H, t, J = 9.6 Hz), 6.02 (2 H, dd, J = 5.0, 9.6 Hz), 7.24–7.27 (4 H, m),
7.41–7.50 (6 H, m). 13C NMR (100 MHz, CD2Cl2): d = 26.0 (2 C),
42.8, 69.7 (2 C), 80.3 (2 C), 126.5 (4 C), 130.0 (2 C), 130.1 (4 C),
137.7 (2 C), 176.4 (2 C).
References
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(g) Asao, N. Synlett 2006, 1645.
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Chem. Soc. 2006, 128, 1442. (e) Zhao, J.; Hughes, C. O.;
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L. J. Am. Chem. Soc. 2005, 127, 16804. (g) Johansson, M.
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X.; Gorin, D. J.; Toste, F. D. J. Am. Chem. Soc. 2005, 127,
5802.
1
[(R,R)-Bnbox AuCl2]SbF6: yellow needles. H NMR (400 MHz,
(4) (a) Kato, K.; Teraguchi, R.; Kusakabe, T.; Motodate, S.;
Yamamura, S.; Mochida, T.; Akita, H. Synlett 2007, 63.
(b) Kato, K.; Teraguchi, R.; Yamamura, S.; Mochida, T.;
Akita, H.; Peganova, T. A.; Vologdin, N. V.; Gusev, O. V.
Synlett 2007, 638. (c) Kato, K.; Yamamoto, Y.; Akita, H.
Tetrahedron Lett. 2002, 43, 6587. (d) Kato, K.; Nouchi, H.;
Ishikura, K.; Takaishi, S.; Motodate, S.; Tanaka, H.;
Okudaira, K.; Mochida, T.; Nishigaki, R.; Shigenobu, K.;
Akita, H. Tetrahedron 2006, 62, 2545.
(5) (a) Compound 3a: Denichoux, A.; Ferreira, F.; Chemla, F.
Org. Lett. 2004, 6, 3509. (b) Compound 3b: Lucas, S.;
Kazmaier, U. Synlett 2006, 255. (c) Compound 3c: Yoo,
B.-W.; Lee, S.-J.; Choi, K.-H.; Keum, S.-R.; Ko, J.-J.; Choi,
K.-I.; Kim, J.-H. Tetrahedron Lett. 2001, 42, 7287.
(d) Compound 3d:Ma, S.; Yu, S.; Yin, S. J. Org. Chem.
2003, 68, 8996. (e) Compounds 3e and 3f: Hashmi, A. S. K.;
Ruppert, T. L.; Knofel, T.; Bats, J. W. J. Org. Chem. 1997,
62, 7295.
CD2Cl2): d = 1.61 (6 H, s), 2.99 (2 H, dd, J = 10.0, 13.6 Hz), 3.56 (2
H, dd, J = 2.8, 13.6 Hz), 4.76 (2 H, t, J = 9.4 Hz), 4.81 (2 H, dd,
J = 3.6, 9.4 Hz), 5.21–5.27 (2 H, m), 7.29–7.38 (10 H, m). 13C NMR
(100 MHz, CD2Cl2): d = 25.1 (2 C), 39.7 (2 C), 42.2, 67.2 (2 C),
76.3 (2 C), 128.2 (2 C), 129.6 (4 C), 130.0 (4 C), 134.5 (2 C), 175.9
(2 C). X-ray crystallographic analysis (Figure 1): X-ray diffraction
data were collected on a Bruker SMART APEX II CCD diffracto-
meter equipped with a graphite crystal and incident beam mono-
chromator using MoKa radiation (l = 0.71073 Å) at 173 K. The
structure was solved by direct method8 and expanded using Fourier
techniques. The non-hydrogen atoms were refined anisotropically.
Crystallographic
parameters:
C23H26Au1Cl2F6N2O2Sb1,
MW = 866.07, orthorhombic, space group P212121, with unit cell
a = 8.9774(6) Å, b = 14.5518(10) Å, c = 21.3864(15) Å and
V = 2793.9(3) Å3. Z = 4, Dcalcd = 2.059
g >
cm–3, R1 [I
2s(I)] = 0.0747, wR2 = 0.1669, R1 (all data) = 0.0875,
wR2 = 0.1729, 6915 independent reflections [R (int) = 0.1409], 337
parameters refined on F2. The flack parameter was 0.03(2). Crystal-
Synlett 2008, No. 7, 1081–1085 © Thieme Stuttgart · New York

LETTER
Cycloisomerization of 1-Allenyl-1-ethynyl Acetate
1085
(6) (a) Kato, K.; Tanaka, M.; Yamamoto, Y.; Akita, H.
Tetrahedron Lett. 2002, 43, 1511. (b) Kato, K.; Matsuba,
C.; Kusakabe, T.; Takayama, H.; Yamamura, S.; Mochida,
T.; Akita, H.; Peganova, T. A.; Vologdin, N. V.; Gusev, O.
V. Tetrahedron 2006, 62, 9988. (c) Kato, K.; Tanaka, M.;
Yamamura, S.; Yamamoto, Y.; Akita, H. Tetrahedron Lett.
2003, 44, 3089. (d) Kusakabe, T.; Kato, K.; Takaishi, S.;
Yamamura, S.; Mochida, T.; Akita, H.; Peganova, T. A.;
Vologdin, N. V.; Gusev, O. V. Tetrahedron 2008, 64, 319.
(7) Au(III)–Bipyridine complex: Cinellu, M. A.; Minghetti, G.;
Pinna, M. V.; Stoccoro, S.; Zucca, A.; Manassero, M.;
Sansoni, M. J. Chem. Soc., Dalton Trans. 1998, 1735.
(8) SHELXL97. Program for the Solution of Crystal Structures;
Sheldrick, G. M., Ed.; University of Göttingen: Germany,
1997.
Synlett 2008, No. 7, 1081–1085 © Thieme Stuttgart · New York

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