Gold-catalyzed intramolecular [3+2] cycloadditions of 1-Aryl-1-allene-6- enes

Article abstract of DOI:10.1002/chem.200900580

Treatment of 1-aryl-1-allen-6-enes with [PPh₃AuCl]/AgSbF ₆ (5 mol%) in CH₂Cl₂ at 25°C led to intramolecular [3+2] cycloadditions, giving cis-fused dihydrobenzo[a]fluorene products efficiently and selectively. The reactions proceeded with initial formation of trans/cis mixtures of 2-alkyl-1-isopropy1-2-phenyl-1,2- dihydronaphthalene cations B, which were convertible into the desired cis-fused cycloadducts through the combined action of a gold catalyst and a Bronsted acid. Theoretic calculation supports the participation of the trans-B cation as reaction intermediate. Although HOTf showed similar activity towards several 1-aryl-1-allen-6-enes, it lacks generality for this cycloaddition reaction.

Full text of DOI:10.1002/chem.200900580

FULL PAPER
DOI: 10.1002/chem.200900580
Gold-Catalyzed Intramolecular [3+2] Cycloadditions of 1-Aryl-1-allene-6-
enes
Rupsha Chaudhuri,[a] Hsin-Yi Liao,[b] and Rai-Shung Liu*[a]
Abstract: Treatment of 1-aryl-1-allen-6-
enes with [PPh3AuCl]/AgSbF6
(5 mol%) in CH2Cl2 at 258C led to in-
tramolecular [3+2] cycloadditions,
giving cis-fused dihydrobenzo[a]fluo-
ACHTUNGTRENNUNGrene products efficiently and selective-
ly. The reactions proceeded with initial
formation of trans/cis mixtures of 2-
alkyl-1-isopropyl-2-phenyl-1,2-dihydro-
naphthalene cations B, which were con-
vertible into the desired cis-fused cy-
cloadducts through the combined
action of a gold catalyst and a Brønsted
acid. Theoretic calculation supports the
participation of the trans-B cation as
reaction intermediate. Although HOTf
showed similar activity towards several
1-aryl-1-allen-6-enes, it lacks generality
for this cycloaddition reaction.
Keywords: allenes · cycloaddition ·
gold · heterogeneous catalysis
Introduction
Cycloadditions are powerful tools for accessing complex mo-
lecular frameworks.[1] Gold complexes are prominent cata-
lysts for activation of alkynes, allenes, and alkenes towards
nucleophilic attack under ambient conditions.[2–4] Such nu-
cleophilic enhancement enables gold catalysts to effect cy-
cloadditions of novel types, including [4+2] or [3+2] enyne/
alkene cycloadditions[5] and [3+2] enyne/alkyne cycloaddi-
tions.[6] Recently, gold-activated cycloadditions of allene-ene
functionalities have become particularly notable because
they provide useful carbocyclic frameworks that are difficult
to obtain by conventional methods.[7–9] Equations (1–3) show
model gold-catalyzed [2+2] and [3+2] cycloadditions of al-
lenes with tethered alkenes.[7–9] The versatility of such reac-
tions is also reflected in a tandem reaction sequence involv-
ing an initial rearrangement of starting alkynyl acetates to
allenyl acetates followed by [2+2] or [3+2] cycloaddition
with tethered alkene components.[9]
of 1-aryl-1-allen-6-enes with their tethered alkene compo-
nents to give cis-fused dihydrobenzo[a]fluoACTHUNRTGNEUNGrene products ef-
ficiently [(Eq. (4)].
In a search for new carbocyclic frameworks, we have iden-
tified stereocontrolled intramolecular [3+2] cycloadditions
[a] R. Chaudhuri, Prof. Dr. R.-S. Liu
Department of Chemistry
National Tsing-Hua University
Hsinchu (Taiwan, ROC)
E-mail: rsliu@mx.nthu.edu.tw
[b] Prof. Dr. H.-Y. Liao
Results and Discussion
Department of Science Education
National Taipei University of Education, Taipei (Taiwan, ROC)
Table 1 shows catalyst screening with commonly used Lewis
acids including various gold, silver, and platinum catalysts,
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.200900580.
Chem. Eur. J. 2009, 15, 8895 – 8901
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Table 1. Screening of catalyst activities with various p-allene activators.[a]
external water (entries 8–9).
The most efficient catalyst
composition appears to be
[PPh3AuCl]/AgSbF6/H2O in a
1:1:2 ratio.
We prepared 1-aryl-1-allen-
6-enes 5–13 with alteration of
the R1 and phenyl R2 substitu-
ents; the results are summar-
ized in Table 2. These cycload-
Entry
Catalyst
Additive
t [h]
Products (Yield [%])[b]
NR[c]
2 (45), 4 (34)
2 (42), 3/4 (1:1.1, 33)
3/4 (1:1.2, 46)
1
2
3
4
5
6
7
8
9
PhCl2
AgSbF6
AgOTf
–
–
–
–
–
–
8.5
3.5
8.5
3.5
3
0.5
12
1
T
[e]
–
ditions
were
run
with
N
2 (72)[f]
[PPh3AuCl]/AgSbF6 (5 mol%)
in CH2Cl2 (258C) and went to
completion in 0.3–0.5 h. The
resulting [3+2] cycloadducts
14–22 were obtained with cis
configurations, and the struc-
tures of representative com-
pounds 15 and 19 were deter-
mined from their 1H NOE
N
MS (4 ꢁ)
H2O (0.15 equiv)
H2O (1.2 equiv)
3/4 (1:1, 4)[c]
2 (69), 4 (4)
N
N
12
2 (2), 3/4 (1:1.1, 13)[c]
[a] [Substrate]=0.2m. [b] Isolated yields are reported after chromatography. [c] Recovered 1 is obtained in 81,
79, and 71% yield in entries 1, 6 and 9, respectively. [d] HOTf (0.3 and 5 mol%) was used. [e] Complex mix-
tures of products were obtained in entry 5. [f] This set of conditions includes 0.11 equiv water according to GC
analysis.
each at 5 mol% loading. These catalysts were selected be-
cause of their capabilities to increase the electrophilicity of
the allene moiety through p coordination (A), which is best
represented by the resonance form A’ [Eq. (5)]. Use of
PtCl2 in CH2Cl2 at 258C gave disappointing results, with ex-
clusive recovery of unreacted 1. Use of AgSbF6 improved
the cyclization efficiency, giving the trans-cyclohexenyl com-
pound 4 (34%) and the cis-fused dihydrobenzo[a]fluorene
product 2 (45%) containing a quaternary carbon (their
spectra.[10] The reactions worked well with substrate 5 (R1 =
propyl), which gave cycloadduct 14 in 70% yield. For spe-
cies 6 and 7, each bearing a toluyl group (R2 =CH3), the cy-
cloadducts 15 and 16 were produced more efficiently (81
and 82% yields) than compounds 17 and 18, which were ob-
tained in 45 and 56% yields from 1-allen-6-enes 8 and 9,
each bearing a 4-methoxyphenyl group. The low yields of
cycloadducts 17 and 18 were presumably the consequences
of undesired Nazarov cyclizations of the 1-aryl-1-allene
functionalities, favored by the presence of the electron-rich
aryl group.[11] The presence of the same catalysis with sub-
1
structures were determined from their H NOE spectra[10]).
Use of AgOTf and [PPh3AuCl]/AgOTf did not improve the
chemoselectivity, with the formation of the additional cis-cy-
clohexenyl compound 3, which was inseparable from its
trans isomer 4. Although use of HOTf (0.3 or 5 mol%) led
to complete consumption of starting 1, we obtained only
complex mixtures of unknown species.
strates 10–13, bearing 4-fluoro- or 4-chloACHTNUGTRENNUGroACHTUGTNERNNUGphenyl groups,
gave cycloadducts 19–22 in moderate yields (58–63%). In
the case of species 12 we also obtained the trans-cyclohexen-
yl compound 23, which was inseparable from cycloadduct
21. Use of a long reaction time (6.5 h) failed to convert this
species into the desired 21.
Through control experiments, we also found that HOTf
(0.3 mol%) showed similar activity for 1-aryl-1-allen- 6-enes
including 5, 7, 9, 11, and 13 (R1 =propyl), efficiently produc-
ing the corresponding cycloadducts 14 (65%), 16 (75%), 18
(60%), 20 (70%), and 22 (65%). The use of HOTf
(2 mol%) with substrate 5 gave a low yield of cycloadduct
14 (34%). We were unable to obtain these products in sig-
nificant yields with use of other Brønsted acids including p-
toluenesulfonic acids, CF3CO2H, and HBF4 in various pro-
portions (0.3–5 mol%). Notably, HOTf was not catalytically
active for those 1-allen- 6-enes with R1 =methyl, as depicted
in Table 2. The success of HOTf in the [3+2] cycloaddition
relies on the stability of the resulting allylic cationic
intermediates.[12]
We also prepared substrates 24–27 (Table 3), bearing
fluoro and methoxy groups at their C(3)- and C(4)-positions,
and their gold catalysis gave cycloadducts 28–30 in 79–82%
yields. The failure in the case of substrate 27 is presumably
the result of an undesired Nazarov cyclization of the 1-aryl-
1-allene functionality favored by the presence of the para-
In careful control experiments, however, use of HOTf in
small quantities (0.3 mol%) resulted in the [3+2] cycloaddi-
tions of 1-allen-6-enes of particular types (see Table 2,
below). Gratifyingly, the use of [PPh3AuCl]/AgSbF6 led to
exclusive formation of cycloadduct 2 in 72% yield (Table 1,
entry 6); the short reaction time (0.5 h) makes it unlikely
that the cycloaddition was caused by AgSbF6 residues. From
GC analysis, this reaction solution contains water in very
small proportions (0.11 equiv). Entry 7 shows the crucial
role of water, which proved to be indispensable for this cy-
cloaddition; we obtained unreacted 1 in 79% recovery yield
when MS (4 ꢁ) were present in the system. We observed a
gradual loss of catalytic activity with increasing amounts of
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Gold-Catalyzed Cycloadditions
FULL PAPER
Table 2. AuI-catalyzed [3+2] cycloadditions of phenylallene-enes.
Entry Substrate[a]
t [h] Product Yield [%][b]
5 {Au}/{Ag} 0.3 HOTf
1
2
3
4
5
6
7
8
R1 =nPr, R2 =H (5)
0.5
0.3
0.3
14
15
16
17
18
19
20
21/23
70
81
65 (34)[c]
[d]
R1 =Me, R2 =Me (6)
R1 =nPr, R2 =Me (7)
–
82
45
75
–
R1 =Me, R2 =OMe (8) 0.5
R1 =nPr, R2 =OMe (9) 0.5
56
58
60
–
R1 =Me, R2 =F (10)
R1 =nPr, R2 =F (11)
R1 =Me, R2 =Cl (12)
0.3
0.3
0.5
63
67
74
–
(21/23 1.6)
64
(21/23 1.4)
62
6.5
0.5
21/23
9
R1 =nPr, R2 =Cl (13)
22
65
[a] [Substrate]=0.2m, {Au}=[Ph3PAuCl], {Ag}=AgSbF6. [b] Isolated
yield after silica chromatography. [c] This yield was obtained with
2 mol% HOTf. [d] Complex mixtures were obtained in entries 2, 4, 6,
and 8 when HOTf was used as catalyst.
Table 3. Effects of the phenyl substituents of substrates.
Entry
Substrate[a]
Products (Yield [%])[b]
Scheme 1. ACTHNUGRTNEUNG[3+2] Cycloadducts with new skeletons.
1
2
3
4
R1 =F, R2 =H (24)
28 (82)
29 (79)
30 (81)
R1 =H, R2 =F (25)
R1 =OMe, R2 =H (26)
R1 =H, R2 =OMe (27)
[c]
–
trans/cis 1.6:1) and the naphthalene 48 (23%); subsequent
treatment of species 47 (trans/cis 1.6:1) with [PPh3AuCl]/
AgSbF6 gave the naphthalene 48 in 86% yield. Treatment of
disubstituted alkene species 38 with [PPh3AuCl]/AgSbF6 re-
sulted in complex product mixtures. We tried to implement
HOTf-catalyzed [3+2] cycloadditions of allen-1-enes 32 and
34, each bearing a propyl group, but we again obtained com-
plex mixtures of unknown species. The use of the Brønsted
acid in the cycloaddition is severely limited by a lack of
generality.
[a] [Substrate]=0.2m, 5 mol% catalyst. [b] Product yields after silica
column separation. [c] Complex mixture of products.
methoxy group;[11] the same explanation has also been given
for previous substrates such as 8 and 9.
Scheme 1 shows our efforts to produce new cycloadduct
skeletons. 1-Phenyl-1-allen-6-enes 31 and 32, each bearing a
cyclopentylidene ring, were treated with 5 mol%
[PPh3AuCl]/AgSbF6 in CH2Cl2 (258C), giving the desired cy-
cloadducts 39 and 41 in 49 and 51% yield together with un-
cyclized 40 and 42 in 19 and 20% yield. For substrates 33
and 34, each bearing an ethynylthiophene moiety, we ob-
tained their cycloadducts 43 and 44 in moderate yields (42
and 53%). This approach was applicable to the allenene 35,
bearing a cyclohexenyl group, which provided cycloadduct
45 in 61% yield. The catalysis, however, shows substrate-de-
pendent chemoselectivity: allenene 36, with a 1-methylvinyl
group, underwent the formation of the naphthalene deriva-
tive 46 in 64% yield through a Nazarov/aromatization cas-
cade.[4d,13–14] Treatment of the disubstituted allenene 37 with
the gold catalyst gave the cyclohexenyl species 47 (61%,
To examine the role of the Brønsted acid in gold catalysis,
the trans-cyclohexenyl species
4
was treated with
[PPh3AuCl]/AgSbF6 (5 mol%) in CH2Cl2 (258C, 0.5 h) to
give the cycloadduct 2, with epimerization of the CH stereo-
center, in 69% yield (Table 4). In the presence of MS (4 ꢁ),
[PPh3AuCl]/AgSbF6 became inactive, with exclusive recov-
ery of unreacted 4 (92%). The use of basic MgO additive
also led to inactivity of gold catalyst. Use of a Brønsted acid
such as HOTf (0.3 or 5 mol%) gave complex mixtures of
products. Accordingly, we envisage that catalytic transfor-
mation of 4 into 2 is actually catalyzed by both [PPh3AuCl]/
AgSbF6 and small amounts of Brønsted acid[15] such as
Chem. Eur. J. 2009, 15, 8895 – 8901
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R.-S. Liu et al.
much smaller than that (17.4 kcalmolꢀ1) of the trans-B!
trans-G transformation; the energy profiles are depicted in
Figure 1. This information suggests that the transformation
of trans-B cation into the cis-cycloadduct 2 is inevitable; the
process requires both [PPh3AuSbF6] and water to generate a
Table 4. The role of the Brønsted acid.
Brønsted acid such as [PPh3AuACHTNUGTRNEUNG(H2O)SbF6] according to the
control experiments outlined in Table 3.
Entry Substrate[a]
Additive
–
t [h] Product (Yield [%])[b]
1
2
3
4
[PPh3AuCl]/AgSbF6
ACHTUNGTRENNUNG[PPh3AuCl]/AgSbF6 MS (4 ꢁ) 2.5
E
0.5
2 (69)
n.r.[c]
n.r.[c]
2.5
0.3
[e]
–
–
[a] [4]=0.2m, 5 mol% catalyst. [b] Isolated yields are those obtained
after column chromatography. [c] Unreacted 4 was obtained in 92 and
91% recovery yields for entries 2 and 3, respectively. [d] HOTf (0.3 and
5 mol%) used. [e] A complex mixture of products was obtained in
entry 4.
[PPh3AuACHTUNGTRENNUNG(H2O)SbF6] generated by [PPh3AuSbF6] with resid-
ual water.
Accordingly, we propose a plausible mechanism as shown
in Scheme 2 to explain the catalytic transformation of 1-
allen-6-ene 1 into cycloadduct 2. With isolation of com-
pounds 4, 23, and trans-47 after use of [PPh3AuCl]/AgX
(X=OTf, SbF6), we envisage that an intramolecular 6-endo-
dig cyclization of AuI-coordinated allene A inevitably gave a
trans/cis mixture of 2-alkyl-1-isopropyl-2-phenyl-1,2-dihydro-
naphthalene cations B. This hypothesis was supported by
calculations (B3LYP/LANL2DZ), which indicate that the
trans-B cation is 1.6 kcalmolꢀ1 lower in energy than the cis-
B cation. Activation energies are nearly equal—that is,
12.5 kcalmolꢀ1 and 12.4 kcalmolꢀ1—for 1!cis-B and 1!
trans-B, respectively. Furthermore, the cis-B species should
be more active than trans-B in the intramolecular aryla-
tion,[16] because the resulting cis-cycloadduct 2 is 9.15 kcal
molꢀ1 lower in energy than its trans-annulation isomer. This
assessment is supported by calculations, which indicate that
the activation energy for cis-B!cis-G is 7.1 kcalmolꢀ1,
Figure 1. Energy profiles for the transformation of species A!B!G
(units: kcalmolꢀ1).
We suggest that [PPh3AuACHTNUTRGNE(UNG H2O)SbF6] catalysis caused un-
cyclized trans-B to undergo a 1,2-shift of the C=C bond
through sequential deprotonation and demetalation reac-
tions, giving its isomeric species C. A final arylation at the =
CMe2 carbon of species C is then achieved through coordi-
nation of [PPh3Au+] to this olefin opposite its phenyl group,
generating the gold-containing intermediate E, and ulti-
mately giving the desired cis-fused cycloadduct 2 through
hydrodemetalation. Notably, the presence of the Brønsted
acid in large quantities would be expected to give thermody-
namically favorable tertiary benzyl cation F, and thus be un-
suitable for this arylation. Because HOTf in small quanti-
ties[17] was also effective for this [3+2] cycloaddition in the
Scheme 2. Proposed reaction mechanism.
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Gold-Catalyzed Cycloadditions
FULL PAPER
2) Synthesis of {4-[2-(2-methylprop-1-enyl)phenyl]buta-2,3-dien-2-yl}ben-
zene (1): Magnesium turnings (111.3 mg, 4.5 mmol) were weighed into a
round-bottomed flask together with catalytic amounts of iodine and were
activated in THF (5 mL) with stirring. A Grignard reagent was prepared
by addition of bromobenzene (0.4 mL, 3.7 mmol), and this mixture was
stirred for 0.5 h at 258C, after which a THF solution of ZnCl2 (490.6 mg,
cases of the modified 1-aryl-1-allen-6-enes 5 and 7. We do
not exclude the possibility that the arylation process C!
D!E can also be achieved by HOTf and [PPh3Au
as shown by species D’.
(H2O)+],
ACHTUNGTRENNUNG
3.6 mmol) was added. After 20 min stirring, [PdACTHNUTRGNE(UNG PPh3)4] (13.8 mg,
0.012 mmol) and compound II (0.3 g, 1.2 mmol) were added to this mix-
ture, and the resulting solution was stirred for 5 min before being
quenched with water. The organic layer was extracted with diethyl ether,
(10 mL), dried over MgSO4, and concentrated under reduced pressure.
The residue was eluted through a silica column to afford compound 1
(0.28 g, 1.1 mmol, 87%) as an orange-yellow liquid.
Conclusion
In summary, we report new gold-catalyzed intramolecular
[3+2] cycloadditions of 1-aryl-1-allen-6-enes in CH2Cl2 at
258C, selectively giving cis-fused [4.3.0] carbocyclic com-
pounds. The reactions are initiated by 6-endo cyclizations to
give mixtures of cis and trans-2-alkyl-1-isopropyl-2-phenyl-
1,2-dihydronaphthalene cations B, which are convertible
into the desired cis-fused cycloadducts through the com-
bined action of the gold catalyst and the Brønsted acid. The-
oretic calculations support the involvement of the trans-B
cation as a reaction intermediate. This mechanistic feature
enables a completely cis-stereoselective [3+2] cycloaddition.
Although the Brønsted acid showed similar activity towards
several 1-aryl-1-allen-6-enes, it lacks generality for this cy-
cloaddition reaction. Efforts to identify new cycloadditions
of allenenes are currently in progress.
Standard procedure for catalytic operations—synthesis of cycloadduct 2:
Dry dichloromethane (1.0 mL) was added to a long tube containing
[PPh3AuCl] (9.5 mg, 0.019 mmol) and AgSbF6 (6.6 mg, 0.019 mmol), and
the mixture was stirred for 5 min. A dichloromethane solution (1.0 mL)
of allenene 1 (100 mg, 0.38 mmol) was added to this solution, and the re-
sulting suspension was stirred for 0.5 h. The solution was concentrated
and then eluted through a silica column (hexane) to afford compound 2
(72 mg, 0.27 mmol, 72%) as a white crystalline solid.
Spectral data for compounds 1, 2, 14–22, 28–30, 39, 41, and 43–46 are
listed below. Spectral data for the remaining compounds, together with
copies of 1H and 13C NMR spectra of all compounds, are given in the
Supporting Information.
1
Spectral data for compound 1: H NMR (400 MHz, CDCl3): d=7.52–7.45
(m, 3H), 7.36 (t, J=7.6 Hz, 2H), 7.25 (t, J=7.2 Hz, 1H), 7.22–7.18 (m,
3H), 6.69 (q, J=3.2 Hz, 1H), 6.40 (s, 1H), 2.26 (d, J=2.8 Hz, 3H), 1.91
(d, J=1.2 Hz, 3H), 1.75 ppm (d, J=1.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3): d=207.3, 136.8, 136.6, 136.2, 132.4, 130.1, 128.3 (2ꢂCH), 127.1,
126.7, 126.5, 126.4, 125.7 (2ꢂCH), 123.5, 103.5, 94.6, 25.9, 19.3, 16.8 ppm;
IR (neat): n˜ =3035, 2105, 1632, 1377, 1372, 1365, 1256, 1221, 1201, 976,
688 cmꢀ1; HRMS: m/z: calcd for C20H20: 260.1565; found: 260.1564.
Spectral data for compound 2: 1H NMR (400 MHz, CDCl3): d=7.35 (d,
J=6.8 Hz, 1H), 7.30–7.22 (m, 6H), 7.12 (t, J=4.1 Hz, 1H), 6.26 (d, J=
9.5 Hz, 1H), 5.73 (d, J=9.5 Hz, 1H), 3.03 (s, 1H), 1.45 (s, 3H), 1.37 (s,
3H), 0.70 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=152.1, 147.5,
136.1, 133.9, 132.9, 129.1, 127.2, 126.9, 126.8, 126.6 (2ꢂCH), 124.1, 123.0,
122.5, 60.2, 48.6, 46.6, 28.4, 26.8, 25.1 ppm; IR (neat): n˜ =3033, 1632,
1379, 1370, 1368, 1262, 1220, 1201, 981, 688 cmꢀ1; HRMS: m/z: calcd for
C20H20: 260.1565; found: 260.1564.
Spectral data for compound 14: 1H NMR (400 MHz, CDCl3): d=7.31–
7.20 (m, 7H), 7.10–7.08 (m, 1H), 6. 33 (d, J=8.0 Hz, 1H), 5.65 (d, J=
8.0 Hz, 1H), 3.14 (s, 1H), 1.81 (t, J=4.0 Hz, 1H), 1.58 (t, J=4.0 Hz, 1H),
1.45 (s, 3H), 1.25–1.04 (m, 2H), 0.79 (t, J=8.0 Hz, 3H), 0.69 ppm (s,
3H); 13C NMR (100 MHz, CDCl3): d=152.1, 147.0, 135.3, 134.8, 133.3,
128.7, 128.3, 127.1, 126.9, 126.6, 126.6, 126.5, 125.2, 123.2, 122.5, 57.1,
50.4, 48.8, 43.4, 28.6, 25.8, 16.9, 14.6 ppm; IR (neat): n˜ =3037, 1640, 1449,
1374, 1373, 1370, 1220, 1219, 1201, 963, 694 cmꢀ1; HRMS: m/z: calcd for
C22H24: 288.1878; found: 288.1876.
Experimental Section
Procedures for theoretical calculations: All geometries (reactants, inter-
mediates, transition states, and products) were fully optimized by the
B3LYP method[18–19] with the LANL2DZ basis set[20] (B3LYP/
LANL2DZ). Density Functional Theory (DFT) is recognized as a valua-
ble tool for the study of transition states and reaction intermediates. The
vibrational frequencies, at the same level of theory, were computed to
characterize the stationary points either as true minima or as saddle
points on the potential energy hypersurfaces. All of the calculations were
performed with the Gaussian 03 package.[21] The unscaled zero-point vi-
brational energies (ZPEs) are included in the reported energies.
Experimental procedures for the synthesis of allene (1)
a) General: Unless otherwise noted, all reactions were carried out under
nitrogen in oven-dried glassware with standard syringes and other appa-
ratus. Diethyl ether, tetrahydrofuran, and hexane were dried with sodium
benzophenone and distilled before use. Dichloromethane was distilled
over CaH2 before use. All spectra were run at 400/500/600 MHz
(1H NMR) or 100/125/150 MHz (13C NMR) in CDCl3 solution.
b) Typical procedure for the synthesis of allenene (1):
Spectral data for compound 15: 1H NMR (400 MHz, CDCl3): d=7.32–
7.28 (m, 4H), 7.18 (d, J=8.0 Hz, 2H), 7.10 (s, 1H), 6.32 (d, J=8.0 Hz,
1H), 5.80 (d, J=9.2 Hz, 1H), 3.11 (s, 1H), 2.45 (s, 3H), 1.51 (s, 3H), 1.43
(s, 3H), 0.78 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=152.2, 144.7,
136.2 (2ꢂCH), 134.0, 133.0, 129.1, 128.1, 126.9, 126.8, 126.6, 124.0, 123.2,
122.7, 60.4, 48.5, 46.2, 28.4, 26.9, 25.1, 21.3 ppm ; IR (neat): n˜ =3033,
1640, 1377, 1374, 1372, 1227, 1219, 1208, 963, 694 cmꢀ1; HRMS: m/z:
calcd for C21H22: 274.1722; found: 274.1722.
Spectral data for compound 16: 1H NMR (400 MHz, CDCl3): d=7.30–
7.24 (m, 4H), 7.16–7.13 (m, 2H), 7.08 (s, 1H), 6.38 (d, J=9.6 Hz, 1H),
5.70 (q, J=9.1 Hz, 1H), 3.20 (s, 1H), 2.43 (s, 3H), 1.87 (t, J=12.8 Hz,
1H), 1.63 (t, J=13.4 Hz, 1H), 1.53 (s, 3H), 1.32–1.24 (m, 2H), 1.15 (t,
J=4.9 Hz, 3H), 1.12 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=
152.2, 144.2, 136.1, 135.3, 135.0, 133.4, 128.2, 128.1, 126.9, 126.6, 126.5,
125.1, 123.2, 122.9, 57.4, 50.0, 48.7, 43.5, 28.6, 25.8, 21.3, 17.0, 14.7 ppm;
IR (neat): n˜ =3033, 1640, 1440, 1377, 1375, 1372, 1371, 1227, 1219, 1208,
963, 694 cmꢀ1; HRMS: m/z: calcd for C23H26: 302.2035; found: 302.2032.
1) Synthesis of 1-[2-(2-methylprop-1-enyl)phenyl]but-2-ynylacetate (II):
Acetyl chloride (0.6 mL, 8.6 mmol) and Et3N (1.8 mL) were added at
08C to alcohol I (860 mg, 4.3 mmol),[22] and the resulting mixture was
stirred for 2 h. The reaction mixture was quenched with water and ex-
tracted with diethyl ether (25 mL). The extract was washed with brine so-
lution, dried over MgSO4, and concentrated under reduced pressure. The
residue was eluted through a silica column to afford compound II (0.9 g,
3.7 mmol, 86%) as a yellow liquid.
Chem. Eur. J. 2009, 15, 8895 – 8901
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8899

R.-S. Liu et al.
Spectral data for compound 17: 1H NMR (400 MHz, CDCl3): d=7.23–
7.18 (m, 4H), 7.10 (d, J=3.6 Hz, 1H), 6.82 (dq, J=5.7, 2.5 Hz, 1H), 6.74
(d, J=2.5 Hz, 1H), 6.22 (d, J=9.6 Hz, 1H), 5.70 (dq, J=8.4, 0.8 Hz, 1H),
3.80 (s, 3H), 3.02 (d, J=0.5 Hz, 1H),1.42 (s, 3H), 1.33 (s, 3H), 0.68 ppm
(s, 3H); 13C NMR (150 MHz, CDCl3): d=159.0, 153.7, 139.7, 136.3, 133.9,
133.0, 129.1, 126.8, 126.7, 126.6, 123.8, 123.5, 113.0, 108.1, 60.6, 55.4, 48.6,
45.9, 28.3, 27.0, 25.0 ppm; IR (neat): n˜ =3042, 2851, 2122, 1632, 1364,
1363, 1360, 1256, 1222, 1201, 989, 688 cmꢀ1; HRMS: m/z: calcd for
C21H22O: 290.1671; found: 290.1670.
Spectral data for compound 18: 1H NMR (400 MHz, CDCl3): d=7.22–
7.05 (m, 5H), 6.81 (dq, J=6.1, 2.2 Hz, 1H), 6.72 (d, J=2.0 Hz, 1H), 6.29
(d, J=9.6 Hz, 1H), 5.61 (d, J=9.6 Hz, 1H), 3.80 (s, 3H), 3.11 (s, 1H),
1.80–1.70 (m, 2H), 1.42 (s, 3H), 1.07–0.96 (m, 2H), 0.77 (t, J=7.2 Hz,
3H), 0.65 ppm (s, 3H); 13C NMR (150 MHz, CDCl3): d=158.8, 153.7,
139.2, 135.3, 135.0, 133.5, 128.2, 126.7, 126.6, 126.5, 124.9, 123.8, 113.0,
108.0, 57.5, 55.3, 50.0, 48.8, 43.6, 28.5, 25.7, 16.9, 14.6 ppm; IR (neat): n˜ =
3041, 2853, 2122, 1632, 1447, 1369, 1363, 1361, 1256, 1222, 1201, 990,
690 cmꢀ1;HRMS: m/z: calcd for C23H26O: 318.1984; found: 318.1982.
Spectral data for compound 19: 1H NMR (400 MHz, CDCl3): d=7.26–
7.17 (m, 4H), 7.13–7.10 (m, 1H), 6.97–6.92 (m, 1H), 6.86 (dd, J=9.2,
2.8 Hz, 1H), 6.25 (d, J=9.6 Hz, 1H), 5.68 (dd, J=9.6, 1.2 Hz, 1H), 3.04
(s, 1H), 1.41 (s, 3H), 1.34 (s, 3H), 0.68 ppm (s, 3H); 13C NMR (100 MHz,
CDCl3): d=162.3 (d, JC,F =242.0 Hz), 154.4 (d, JC,F =7.0 Hz), 143.0, 135.8,
133.6, 132.8, 129.0, 127.1, 127.0, 126.7, 124.2, 124.0 (d, JC,F =8.0 Hz), 114.1
(d, JC,F =23.0 Hz), 109.5 (d, JC,F =22.0 Hz), 60.5, 48.6, 46.1, 28.3, 27.0,
24.9 ppm; IR (neat): n˜ =3041, 2126, 1633, 1376, 1371, 1361, 1350, 1255,
1221, 1203, 990, 692 cmꢀ1; HRMS: m/z: calcd for C20H19F: 278.1471;
found: 278.1472.
Spectral data for compound 20: 1H NMR (400 MHz, CDCl3): d=7.23–
7.17 (m, 3H), 7.14–7.09 (m, 2H), 6.95 (dt, J=8.0, 2.4 Hz, 1H), 6.87 (dd,
J=9.6, 2.4 Hz, 1H), 6.34 (d, J=9.6 Hz, 1H), 5.61 (dd, J=8.0, 0.8 Hz,
1H), 3.16 (s, 1H), 1.79 (dt, J=12.0, 4.4 Hz, 1H), 1.55 (dt, J=16.0, 4.4 Hz,
1H), 1.43 (s, 3H), 1.24–1.15 (m, 1H), 1.08 ~0.99 (m, 1H), 0.81 (t, J=
8.0 Hz, 3H), 0.66 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=162.2 (d,
J=9.5 Hz, 1H), 5.69 (d, J=9.6 Hz, 1H), 2.99 (s, 1H), 1.44 (s, 3H), 1.35
(s, 3H), 0.70 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=161.7 (d,
J
C,F =244.0 Hz), 151.7, 147.2, 136.4 (d, JC,F =7.0 Hz), 135.3, 129.2, 127.9
(d, JC,F =8.0 Hz), 127.3, 126.7, 126.1, 123.0 (d, JC,F =3.0 Hz), 122.5, 116.0
(d, JC,F =21.0 Hz), 113.4 (d, JC,F =21.0 Hz), 60.4, 48.7, 46.3, 28.4, 26.8,
25.1 ppm; IR (neat): n˜ =3044, 2129, 1633, 1379, 1371, 1363, 1350, 1258,
1223, 1203, 991, 695 cmꢀ1; HRMS: m/z: calcd for C20H19F: 278.1471;
found: 278.1472.
Spectral data for compound 30: 1H NMR (400 MHz, CDCl3): d=7.34–
7.18 (m, 4H), 7.13 (d, J=8.2 Hz, 1H), 6.78 (dd, J=8.2, 2.5 Hz, 1H), 6.68
(d, J=2.6 Hz, 1H), 6.21 (d, J=9.4 Hz, 1H), 5.74 (d, J=9.6 Hz, 1H), 3.81
(s, 3H), 2.98 (s, 1H), 1.41 (s, 3H), 1.35 (s, 3H), 0.68 ppm (s, 3H);
13C NMR (100 MHz, CDCl3): d=158.6, 152.2, 147.5, 136.8, 133.9, 129.9,
127.2, 126.6, 126.1, 124.2, 123.0, 122.5, 112.3, 112.1, 59.6, 55.2, 48.5, 46.8,
28.4, 26.8, 25.1 ppm; IR (neat): n˜ =3040, 2855, 2122, 1632, 1363, 1363,
1360, 1257, 1225, 1201, 989, 688 cmꢀ1; HRMS: m/z: calcd for C21H22O:
290.1671; found: 290.1670.
Spectral data for compound 39: 1H NMR (400 MHz, CDCl3): d=7.33–
7.31 (m, 1H), 7.31–7.14 (m, 6H), 7.13–7.12 (m, 1H), 6.28 (d, J=
9.5 Hz,1H), 5.71 (d, J=12.0 Hz, 1H), 3.21 (s, 1H), 2.14–211 (m, 2H),
1.81–1.74 (m, 1H), 1.63–1.56 (m, 2H), 1.36 (s, 3H), 1.35–1.26 ppm (m.
3H); 13C NMR (100 MHz, CDCl3): d=153.7, 147.5, 136.2, 133.9, 133.6,
129.4, 127.0, 126.8, 126.8, 126.6, 126.4, 124.2, 122.7, 122.6, 59.3, 58.8, 46.7,
39.0, 35.6, 25.6 ppm (1ꢂCH2, 1ꢂCH3); IR (neat): n˜ =3043 (s), 1668 (s),
1449, 1442, 1384, 1377, 1374, 1369, 1263, 1223, 1206, 973, 688 cmꢀ1
;
HRMS: m/z: calcd for C22H22: 286.1722; found: 286.1714.
Spectral data for compound 41: 1H NMR (400 MHz, CDCl3): d=7.36 (t,
J=7.1 Hz, 2H), 7.23–7.18 (m, 6H), 6.35 (d, J=9.5 Hz, 1H), 5.63 (d, J=
8.7 Hz, 1H), 3.32 (s, 1H), 2.17–2.10 (m, 2H), 1.81–1.73 (m, 2H), 1.63–
1.56 (m, 3H), 1.24–0.97 (m. 5H), 0.78 ppm (t, J=7.2 Hz, 3H); 13C NMR
(100 MHz, CDCl3): d=153.9, 146.8, 141.2, 135.2, 135.0, 128.5, 127.1,
126.8, 126.7, 126.5, 126.4, 125.2, 122.9, 122.7, 59.0, 56.2, 50.4, 42.3, 39.3,
36.3, 25.6, 25.2, 17.0, 14.7 ppm; IR (neat): n˜ =3049, 1660, 1455, 1442,
1384, 1377, 1370, 1369, 1263, 1221, 1206, 973, 689 cmꢀ1; HRMS: m/z:
calcd for C24H26: 314.2035; found: 314.2036.
J
C,F =236.0 Hz), 154.4 (d, JC,F =7.0 Hz), 142.4, 134.9, 134.5, 133.3, 128.5
(d, JC,F =8.0 Hz), 128.2, 127.0, 126.7 (d, JC,F =12.0 Hz), 125.3, 115.6 (d,
C,F =22.0 Hz), 114.1 (d, JC,F =23.0 Hz), 109.5 (d, JC,F =21.0 Hz), 57.4,
Spectral data for compound 43: 1H NMR (400 MHz, CDCl3): d=7.22–
7.18 (m, 2H), 7.17 (d, J=3.7 Hz,1H), 7.16–7.15 (m, 2H), 6.80 (d, J=
4.8 Hz, 1H), 6.25 (d, J=9.5 Hz, 1H), 5.78 (dd, J=11.0, 0.9 Hz, 1H), 3.3
(s, 1H), 1.41 (s, 3H), 1.39 (s, 3H), 0.67 ppm (s, 3H); 13C NMR (100 MHz,
CDCl3): d=154.1, 146.8, 134.6, 133.6, 132.9, 128.6, 127.3, 127.0, 127.0,
126.7, 123.9, 120.9, 64.9, 46.9, 45.8, 28.7, 27.8, 24.1 ppm; IR (neat): n˜ =
J
49.9, 48.7, 43.5, 28.4, 25.6, 16.9, 14.6 ppm; IR (neat): n˜ =3045, 2126, 1638,
1447, 1376, 1371, 1361, 1350, 1255, 1221, 1208, 991, 692 cmꢀ1; HRMS:
m/z: calcd for C22H23F: 306.1784; found: 306.1786.
Spectral data for compound 21: 1H NMR (400 MHz, CDCl3): d=7.51–
7.24 (7H), 6.32 (d, J=9.6 Hz, 1H), 5.76 (d, J=9.6 Hz, 1H), 3.08 (s, 1H),
1.48 (s, 3H), 1.30 (s, 3H), 0.72 ppm (s, 3H); 13C NMR (100 MHz, CDCl3):
d=154.1, 146.1, 135.2, 132.9, 132.7, 132.7, 129.0–124.4 (8ꢂCH), 60.2, 48.7,
46.3, 28.3, 26.8, 24.9 ppm; IR (neat): n˜ =3051, 2133, 1636, 1378, 1374,
1370, 1256, 1221, 1203, 1025, 991, 692 cmꢀ1; HRMS: m/z: calcd for
C20H19Cl: 294.1175; found: 294.1177.
3053, 1666, 1380, 1372, 1370, 1369, 1263, 1224, 1203, 967, 694 cmꢀ1
;
HRMS: m/z: calcd for C18H18S: 266.1129; found: 266.1128.
Spectral data for compound 44: 1H NMR (400 MHz, CDCl3): d=7.19–
7.15 (m, 3H), 7.11–7.10 (m, 1H), 7.08–7.07 (m, 1H), 6.79 (d, J=
4.8 Hz,1H), 6.29 (d, J=9.6 Hz, 1H), 5.73 (dq, J=9.0, 0.7 Hz, 1H), 3.38
(s, 1H), 1.69–1.60 (m, 2H), 1.40 (s, 3H), 1.28–1.22 (m, 2H), 0.81 (t, J=
7.3 Hz, 3H), 0.64 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=154.2,
145.9, 134.6, 133.3, 133.2, 128.0, 127.3, 127.0, 126.8, 126.7, 125.0, 120.7,
62.9, 49.6, 46.7, 44.5, 28.9, 24.4, 17.6, 14.6 ppm; IR (neat): n˜ =3042, 1660,
Spectral data for compound 22: 1H NMR (400 MHz, CDCl3): d=7.24–
7.08 (m, 6H), 7.10–7.08 (m, 1H), 6.33 (d, J=9.6 Hz, 1H), 5.59 (d, J=
9.6 Hz, 1H), 3.14 (s, 1H), 1.77 (dt, J=26.1, 13.1 Hz, 1H), 1.54 (dt, J=
26.0, 13.4 Hz, 1H), 1.43 (s, 3H), 1.23–1.14 (m, 2H), 1.05 (t, J=6.1 Hz,
3H), 0.65 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=154.1, 145.5,
138.3, 134.7, 134.1, 133.7, 129.0, 128.2, 128.1, 127.3, 127.1, 126.8, 126.7,
122.9, 57.1, 50.1, 48.8, 43.2, 28.4, 25.6, 16.9, 14.6 ppm; IR (neat): n˜ =3054,
1450, 1442, 1378, 1376, 1370, 1366, 1262, 1221, 1203, 964, 689 cmꢀ1
;
HRMS: m/z: calcd for C20H22S: 294.1442; found: 294.1438.
Spectral data for compound 45: 1H NMR (400 MHz, CDCl3): d=7.18–
7.10 (m, 3H), 7.06–7.04 (m, 1H), 6.19 (d, J=9.6 Hz,1H), 5.70 (d, J=
9.6 Hz, 1H), 2.67 (s, 1H), 2.09–1.99 (m, 3H), 1.66–1.61 (m, 5H), 1.10 (s,
3H), 1.03 (s, 3H), 0.45 ppm (s. 3H); 13C NMR (100 MHz, CDCl3): d=
143.3, 135.4, 135.0, 133.6, 133.0, 128.9, 126.5, 126.3, 126.2, 123.2, 59.4,
50.8, 47.9, 27.0, 25.3, 23.2, 23.1, 21.8, 21.2, 21.1 ppm; IR (neat): n˜ =3049,
2133, 1639, 1452, 1378, 1376, 1370, 1256, 1222, 1203, 1025, 991, 692 cmꢀ1
;
HRMS: m/z: calcd for C22H23Cl: 322.1488; found: 322.1494.
Spectral data for compound 28: 1H NMR (400 MHz, CDCl3): d=7.27–
7.14 (m, 5H), 6.91 (dt, J=6.0, 2.6 Hz, 1H), 6.83 (dd, J=9.3, 2.6 Hz, 1H),
6.20 (d, J=9.5 Hz, 1H), 5.79 (d, J=9.5 Hz, 1H), 3.01 (s, 1H), 1.43 (s,
3H), 1.36 (s, 3H), 0.69 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=
161.9 (d, JC,F =242.0 Hz), 152.0, 147.1, 137.5, 134.7 (d, JC,F =11.4 Hz),
130.2 (d, JC,F =8.0 Hz), 129.5, 127.3, 126.8, 123.4, 123.0, 122.5, 113.4 (d,
1660, 1454, 1441, 1381, 1374, 1370, 1368, 1263, 1221, 1209, 970, 684 cmꢀ1
;
HRMS: m/z: calcd for C20H24: 264.1878; found: 264.1875.
Spectral data for compound 46: 1H NMR (400 MHz, CDCl3): d=8.01
(dq, J=6.1, 1.1 Hz, 1H), 7.83 (d, J=7.0 Hz, 1H), 7.37–7.34 (m, 3H), 3.51
(s, 2H), 2.68 (s, 3H), 2.62 (s, 3H), 2.31 (d, J=0.7 Hz, 3H), 2.11 ppm (s,
3H); 13C NMR (100 MHz, CDCl3): d=143.1, 138.1, 136.6, 134.4, 130.2,
130.0, 128.3 (2ꢂ48C), 124.7, 124.5, 123.9, 123.7, 41.1, 16.6, 15.2, 14.7,
14.1 ppm; IR (neat): n˜ =3053, 1670, 1380, 1372, 1370, 1369, 1263, 1224,
1203, 967, 694 cmꢀ1; HRMS: m/z: calcd for C17H18: 222.1409; found:
222.1413.
J
C,F =12.0 Hz), 113.2 (d, JC,F =12.0 Hz), 59.6, 48.5, 46.7, 28.3, 26.7,
25.1 ppm; IR (neat): n˜ =3044, 2126, 1633, 1379, 1371, 1361, 1350, 1255,
1221, 1203, 991, 692 cmꢀ1; HRMS: m/z: calcd for C20H19F: 278.1471;
found: 278.1472.
Spectral data for compound 29: 1H NMR (400 MHz, CDCl3): d=7.38–
7.19 (m, 5H), 7.07 (dd, J=8.1, 2.2 Hz, 1H), 6.95–6.90 (m, 1H), 6.21 (d,
8900
www.chemeurj.org
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 8895 – 8901

Gold-Catalyzed Cycloadditions
FULL PAPER
[13] Formation of naphthalenes proceeds via initial gold-catalyzed Naza-
rov cyclization of allenene[4d,14] to form gold-carbenoid, followed by
attacked of its tethered alkene group. This reaction is closely related
to a recent reported by Malacria.[14b]
Acknowledgements
The authors wish to thank the National Science Council, Taiwan for sup-
porting this work.
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trans-isomer 4 required 5 h to complete its conversion to cycload-
duct 2.
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Received: March 4, 2009
Published online: July 23, 2009
Chem. Eur. J. 2009, 15, 8895 – 8901
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8901