Gold-catalyzed cascade friedel-crafts/furan-yne cyclization/heteroenyne metathesis for the highly efficient construction of phenanthrene derivatives

Article abstract of DOI:10.1002/adsc.201000644

A rapid access to highly substituted phenanthrenyl ketones through gold-catalyzed cyclization of 1,6-diyn-4-en-3-ols with furans has been developed. Gold catalysts are effective to catalyze three cascade processes involving Friedel-Crafts/furan-yne cyclization/heteroenyne metathesis through C-O bond and alkyne activation. This method offers several advantages such as high selectivities and easily accessible starting materials.

Full text of DOI:10.1002/adsc.201000644

FULL PAPERS
DOI: 10.1002/adsc.201000644
Gold-Catalyzed Cascade Friedel–Crafts/Furan-Yne Cyclization/
Heteroenyne Metathesis for the Highly Efficient Construction of
Phenanthrene Derivatives
Yifeng Chen,a Guijie Li,a and Yuanhong Liua,*
a
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of
Sciences, 345 Lingling Lu, Shanghai 200032, Peopleꢀs Republic of China
Fax : (+86)-21-6416-6128; e-mail: yhliu@mail.sioc.ac.cn
Received: August 17, 2010; Revised: November 7, 2010; Published online: February 16, 2011
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.201000644.
À
Abstract: A rapid access to highly substituted phe- through C O bond and alkyne activation. This
nanthrenyl ketones through gold-catalyzed cycliza- method offers several advantages such as high selec-
tion of 1,6-diyn-4-en-3-ols with furans has been de- tivities and easily accessible starting materials.
veloped. Gold catalysts are effective to catalyze
three cascade processes involving Friedel–Crafts/ Keywords: annulation; cascade reactions; gold catal-
furan-yne
cyclization/heteroenyne
metathesis ysis; heteroenyne metathesis; phenanthrene
Introduction
the alkyne moiety located on the proximal reaction
site through a p-complex. This would eventually lead
Transition metal-catalyzed cascade reactions are to the polycyclic aromatic ketones such as phenan-
among the most powerful strategic tools for the rapid threnyl ketone 4, which are very important subunits
assembly of complex structures.[1] These processes in material science[7] and which occur in numerous
enable multiple bond-forming and bond-cleaving natural products.[8] The alkyne-carbonyl metathesis is
events to occur in one sequence which greatly enhan- an attractive method for the construction of cyclic
ces the synthetic efficiency, while producing less waste enones, it also serves as an alternative to the Wittig
and minimizing handling. Although much progress reaction in carbonyl olefinations due to the efficient
À
À
has been achieved in this field, metal-catalyzed cas- construction of new C C bond and C O bonds at the
cades involving three or more than three reactions
are still a major challenge in synthetic organic chemis-
try. In recent years, gold complexes and salts are
emerging as promising catalysts due to their unique
ability to activate alkynes, allenes, and alkenes to-
wards nucleophilic attack.[2] Recently, we have devel-
oped a new domino approach for the synthesis of (Z)-
enones with excellent stereoselectivity through
gold(I)-catalyzed reactions of enynols with furans.[3,4]
The gold catalyst was found to be quite efficient to
catalyze both the Friedel–Crafts and the furan/
alkyne[5,6] cyclization reactions in a highly regioselec-
tive manner of endo-cyclization. The resulting Z-
enones enable the possibility of further facile cycliza-
tions with unsaturated moieties. We envisioned that if
an alkynyl group was introduced at the alcoholic posi-
tion in enynol substrates such as diyne 1 shown in
Scheme 1, the newly formed (Z)-enone 3 might un-
dergo further heteroenyne metathesis reactions with Scheme 1. Proposed formation of phenanthrene derivatives.
392
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 392 – 400

Gold-Catalyzed Cascade Friedel–Crafts/Furan-Yne Cyclization/Heteroenyne Metathesis
same time.[9,10] However, incorporation of this meta- accessible 3-phenyl-1-(2-(phenylethynyl)phenyl)prop-
thesis strategy into a cascade sequence is quite 2-yn-1-ol 1a, which has previously been shown to un-
rare.[10o] In this contribution, we report our study of dergo gold-catalyzed intramolecular 6-endo-dig cycli-
this novel transformation as shown in Scheme 1 di- zation without addition of any nucleophiles to form
rectly from the readily available 1,6-diyn-4-en-3-ols naphthyl ketones (Table 1).[11a] An initial study was
and furans catalyzed by gold, which involves the three conducted by treatment of 1a and 2 equivalents of 2-
key steps of Friedel–Crafts/furan-yne cyclization/het- methylfuran in DCE with 5 mol% of PPh3AuNTf2. It
eroenyne metathesis, affording multi-substituted phe- was found that enone 3a was obtained in 48% yield
nanthrenyl ketones in a one-pot procedure.
with a high level of (Z)-olefin selectivity (Z/E=
100:3), together with 23% of the naphthyl ketone de-
rived by intramolecular 6-endo-dig cyclization[11a]
(Table 1, entry 1). To our delight, performing the re-
action at 808C resulted in the formation of the target
Results and Discussion
In the proposed process, three independent reactions phenanthren-4-one 4a in 53% yield (entry 2).
should occur sequentially by a single-set catalyst, and PPh3AuSbF6 was also effective to afford a moderate
how to avoid the undesired side reactions becomes a yield of 4a at 808C (entry 3). The use of AuCl3 afford-
big challenge. We began our investigations with easily ed mainly Friedel–Crafts product 2a at room tempera-
Table 1. Optimization studies for the formation of phenanthrenyl ketones.
[a]
Isolated yields.
[b]
Z/E=100:3. Phenyl(2-phenylnaphthalen-1-yl)methanone was also ob-
tained in 23% yield.
In a sealed tube.
NMR yield. The product 2a of a Friedel–Crafts reaction was also ob-
[c]
[d]
tained in 60% NMR yield.
A mixture of cis/trans isomers was obtained in a ratio of 2.5:1.
The reaction was stirred at room temperature for 1–1.5 h with AuCl3
[e]
[f]
until most of 1a was converted to Friedel–Crafts product 2a, then
AgSbF6 was added and the mixture was heated up to 808C.
Containing 12% of impurity. In addition, 2a was also obtained in 35%
[g]
yield.
[h]
HCl was used as a 2.1M solution in ether. 1a was recovered quantita-
tively.
Adv. Synth. Catal. 2011, 353, 392 – 400
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
393

Yifeng Chen et al.
FULL PAPERS
Table 2. Synthesis of phenanthrenyl ketones through cascade reactions.
[a]
Isolated yields. Unless noted, all the reactions were carried out with 2-methyl-
furan. Conditions A: AuCl3 (5 mol%), room temperature, 1.0–2.5 h, then
AgSbF6 (15 mol%) and heated up to 808C. Conditions B: 5 mol% PPh3AuCl
and 5 mol% AgSbF6.
PPh3AuNTf2 (5 mol%) and 5 equiv. of furan were used.
2,3-Dimethylfuran was used.
[b]
[c]
394
asc.wiley-vch.de
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 392 – 400

Gold-Catalyzed Cascade Friedel–Crafts/Furan-Yne Cyclization/Heteroenyne Metathesis
ture,[12] and enone 3a as a mixture of Z/E isomers in a
ratio of 2.5:1 at 808C, respectively (entries 4 and 5).
Further screening of catalysts and reaction conditions
revealed that stepwise addition of AuCl3 and AgSbF6
was the optimal set of conditions, in which the yield
of 4a could be improved to 65% (entry 12). The re-
sults indicated that to achieve good reaction yields, it
is crucial to first complete the Friedel–Crafts alkyla-
tion of 2-methylfuran before the sequential cycliza-
tion/metathesis reactions (compare entry 7 and
entry 12). When 10% HCl was used, the desired prod-
ucts were not observed (entry 14).
Having established the effective catalytic system for
this novel cascade annulation reaction, we proceeded
to explore the scope of this method under the optimal
reaction conditions (Table 2). In addition to 2-methyl-
furan, furan and 2,3-dimethylfuran could also be used,
furnishing the corresponding phenanthrenes 4b and
Scheme 2. Determination and transformation of the inter-
mediates.
4c in the same yield of 72% (Table 2, entries 2 and 3). uct 2a, we screened various acid catalysts. Gratifying-
It is noted that the reaction with furan was found to ly, we found that 2a could be formed cleanly using
be efficient only with PPh3AuNTf2. Next, the diyne 30 mol% TsOH·H2O. Treatment of 2a with gold cata-
substrates containing different R1 and R2 groups at lyst resulted in the formation of 3a and 4a in 16%
the alkyne terminus were examined. The reaction tol- and 59% yields, respectively.
erated both electron-rich and electron-poor aryl sub-
The intramolecular alkyne-carbonyl metathesis of
stituents as R1 and R2, furnishing the corresponding 3a catalyzed by AuCl3/AgSbF6 proceeded smoothly to
phenanthrenyl ketones 4d–4f, 4h and 4i in 51–67% provide the same product 4a as observed in the
yields (entries 4–6, 8 and 9). As the aryl substituent tandem process [Scheme 2, Eq. (3)]. These results
R1 became more electron-deficient (4f, entry 6), the strongly supported our assumption that phenanthrene
reaction efficiency decreased, this might due to the was formed through the tandem sequence involving
lower stability of the cationic intermediate formed in the key intermediates 2a and 3a.
the metathesis step. A thienyl group as R1 was also
To our delight, we found that when Friedel–Crafts
suitable in this domino reaction, producing 4g in 54% product 2a was used as a starting material, the phe-
yield (entry 7). The reaction with the alkyl (R2)-sub- nanthrenyl ketone 4a could be obtained in a high
stituted diyne 1j was also satisfactory, as it afforded yield of 90% in the presence of 5 mol%
desired 4j in 73% yield (entry 10). In addition, the (PPh3)AuNTf2 (Scheme 3). The results clearly indicate
substituted parent phenyl rings with F or OR func- that the domino furan/yne and carbonyl-yne cycliza-
tionalities were compatible for this transformation, tion reactions are highly efficient under gold catalysis.
and moderate yields were realized for all cases (en-
Based on the above results, we propose the follow-
tries 11–13), especially, the reaction of the diyne 1m ing reaction mechanism for this cascade sequence
substituted with a strong electron-donating methy- (Scheme 4).[3,5o] The reaction is initiated by gold-cata-
ACHTUNGTRENNUNGlenedioxy group afforded the ketone 4m without lyzed Friedel–Crafts reaction with 2-substituted furan
problems in 52% yield (entry 13). The structure of 4m through the nucleophilic attack of furan C-5 on the
was unambiguously determined by X-ray crystallogra- benzyl cationic intermediate[14] to afford the arylated
phy.[13] The reaction has also been successfully extend- diyne 2. Intramolecular furan/yne cyclization takes
ed to enynols without the fused aromatic rings. place in a highly regioselective 7-endo-dig manner to
Enynol 1n fused with a 5-membered carbocycle readi- form a cyclopropyl gold carbenoid 6.[15] Rearrange-
ly participated in this domino reaction to generate the ment of 6 followed by aromatization/deauration via 8
naphthyl ketone 4n in a good yield of 76% (entry 14).
A trisubstituted (Z)-enynol underwent cyclization
smoothly with 2-methylfuran to give the desired
ketone 4o in 48% yield (entry 15). It was noted that,
in some cases, the use of PPh3AuSbF6 afforded better
results than those with AuCl3/AgSbF6.
To understand the mechanism, the Friedel–Crafts
product 2a and enone 3a were isolated under con-
trolled reaction conditions [Scheme 2, Eq. (1) and Eq.
(2)]. In order to obtain the pure Friedel–Crafts prod- Scheme 3. Gold-catalyzed tandem reaction of 2a.
Adv. Synth. Catal. 2011, 353, 392 – 400
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
395

Yifeng Chen et al.
FULL PAPERS
Scheme 4. Proposed mechanism for the gold-catalyzed domino reaction.
leads to Z-enone 9. Addition of the carbonyl oxygen
ACHTUNGTRENeNGNU nyne metathesis to form phenanthrenyl ketones with
to the gold-alkyne complex in 9 results in the forma- high diversity and in a regioselective manner. Gold
tion of oxetene intermediate 12 via oxonium 10 and catalysts are effective to catalyze all the three pro-
À
cationic gold species 11. Ring opening of 12 give the cesses through C O bond and alkyne activation. A
final product 4.
variety of diyne substrates turned out to be applicable
We also tried the gold-catalyzed reaction of 2 in the to this catalytic system. Further studies to extend the
presence of I2 (Scheme 5). It was found that the iodi- scope and synthetic utility of this Au-catalyzed cas-
nated phenanthrenyl ketones 13 were formed in 39– cade reactions are in progress in our laboratory.
63% yields. This result supports the formation of a
naphthyl gold intermediate 8 in the domino process.
Experimental Section
Typical Procedure for Gold-Catalyzed Cascade
Reaction for the Synthesis of Phenanthrenyl Ketone
Derivatives
Method A: All the reactions were carried out on a 0.2 or
0.3 mmol scale. To a solution of 3-phenyl-1-[2-(phenyleth-
AHCTUNGTREGyNNNU nyl)phenyl]prop-2-yn-1-ol (1a) (92.5 mg, 0.3 mmol) and 2-
methylfuran (49.3 mg, 54 mL, 0.6 mmol) in DCE (3 mL) was
added AuCl3 (0.3 mL, 0.015 mmol, used as a 0.05M solution
in MeCN). The resulting solution was stirred at room tem-
perature for 1.5 h until most of the diyne 1a was converted
to Friedel–Crafts product as monitored by thin-layer chro-
matography. Then AgSbF6 (0.9 mL, 0.045 mmol, used as a
0.05M solution in MeCN) was added. The flask was sealed
and immersed in an oil bath at 808C. After stirring for 2 h,
the mixture was cooled down. The solvent was evaporated
Scheme 5. Formation of iodinated phenanthrenes.
Conclusions
In conclusion, we have developed a gold-catalyzed
tandem Friedel–Crafts/furan-yne cyclization/hetero- under the reduced pressure and the residue was purified by
396
asc.wiley-vch.de
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 392 – 400

Gold-Catalyzed Cascade Friedel–Crafts/Furan-Yne Cyclization/Heteroenyne Metathesis
chromatography on silica gel (petroleum ether:dichlorome-
thane=2:1) to afford (3-methyl-10-phenylphenanthren-4-
yl)-(phenyl)methanone 4a as a yellow solid; yield: 72.4 mg
7.2 Hz, 2H), 8.35 (d, J=8.4 Hz, 1H); 13C NMR (100.6 MHz,
CDCl3, Me4Si): d=16.95, 20.73, 125.96, 126.21, 126.63,
126.68, 127.34, 128.08, 128.32, 128.38, 128.61, 128.84, 128.86,
129.50, 130.06, 130.30, 132.37, 132.92, 133.62, 135.82, 136.82,
137.80, 138.36, 140.96, 203.07; HR-MS (EI): m/z=386.1669,
calcd. for C29H22O: 386.1671.
1
(65%); mp 178–1798C. H NMR (400 MHz, CDCl3, Me4Si):
d=2.32 (s, 3H), 7.24–7.28 (m, 1H), 7.34 (t, J=7.6 Hz, 2H),
7.39–7.54 (m, 8H), 7.64 (s, 1H), 7.78 (d, J=8.0 Hz, 1H),
7.83 (d, J=7.2 Hz, 2H), 7.92 (d, J=8.8 Hz, 1H), 8.38 (d, J=
8.4 Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si): d=
20.28, 126.02, 126.67, 126.95, 127.41, 127.88, 127.93, 128.32,
128.41, 128.65, 128.82, 128.85, 129.06, 129.46, 130.06, 130.34,
132.70, 133.64, 133.80, 136.69, 137.46, 138.68, 140.76, 202.32;
HR-MS (EI): m/z=372.1513, calcd. for C28H20O: 372.1514.
Method B: To a solution of 3-(4-bromophenyl)-1-[2-(phe-
nylethynyl)-phenyl]prop-2-yn-1-ol (1f) (116.2 mg, 0.3 mmol)
and 2-methylfuran (49.3 mg, 54 mL, 0.6 mmol) in DCE
(3 mL) were added PPh3AuCl (7.4 mg, 0.015 mmol) and
AgSbF6 (0.3 mL, 0.015 mmol, used as a 0.05M solution in
MeCN) subsequently. The flask was sealed and immersed in
an oil bath at 808C. After stirring for 4 h, the mixture was
cooled down. The solvent was evaporated under reduced
pressure and the residue was purified by chromatography on
silica gel (petroleum ether: dichloromethane=2:1) to afford
(4-bromophenyl)(3-methyl-10-phenylphenanthren-4-yl)me-
thanone 4f as a sticky yellow oil; yield: 69.5 mg (51%).
1H NMR (400 MHz, CDCl3, Me4Si): d=2.32 (s, 3H), 7.25–
7.30 (m, 1H), 7.40–7.52 (m, 9H), 7.64 (s, 1H), 7.65 (d, J=
8.4 Hz, 2H), 7.79 (dd, J=1.6, 8.0 Hz, 1H), 7.93 (d, J=
8.4 Hz, 1H), 8.30 (dd, J=0.8, 8.4 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si): d=20.24, 126.10, 126.75, 126.82,
127.47, 128.01, 128.10, 128.32, 128.34, 128.49, 128.91, 128.99,
129.13, 130.04, 130.33, 130.88, 132.21, 132.71, 133.84, 135.96,
136.24, 138.68, 140.61, 201.22; HR-MS (EI): m/z=450.0616,
calcd. for C28H19OBr: 450.0619.
(3-Methyl-10-phenylphenanthren-4-yl)
methanone (4d)
ACHTUNGTRENUN(NG p-tolyl)-
Method A and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a sticky yellow oil; yield: 63%. 1H NMR (300 MHz,
CDCl3, Me4Si): d=2.31 (s, 6H), 7.13 (d, J=7.8 Hz, 2H),
7.26 (t, J=7.8 Hz, 1H), 7.37–7.52 (m, 7H), 7.62 (s, 1H), 7.75
(t, J=8.7 Hz, 3H), 7.90 (d, J=8.7 Hz, 1H), 8.40 (d, J=
8.7 Hz, 1H); 13C NMR (75.5 MHz, CDCl3, Me4Si): d=20.24,
21.68, 126.00, 126.60, 126.95, 127.37, 127.73, 127.88, 128.29,
128.33, 128.67, 128.78, 129.02, 129.57, 129.60, 130.03, 130.30,
132.65, 133.71, 135.07, 136.91, 138.65, 140.76, 144.61, 202.00;
HR-MS (EI): m/z=386.1667, calcd. for C29H22O: 386.1671.
(4-Chlorophenyl)(3-methyl-10-phenylphenanthren-4-
yl)methanone (4e)
Method A and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
1
as sticky yellow oil; yield: 67%. H NMR (300 MHz, CDCl3,
Me4Si): d=2.31 (s, 3H), 7.27 (dt, J=1.8, 7.8 Hz, 1H), 7.38–
7.51 (m, 9H), 7.64 (s, 1H), 7.65 (d, J=8.7 Hz, 2H), 7.78 (d,
J=8.1 Hz, 1H), 7.93 (d, J=9.0 Hz, 1H), 8.31 (d, J=8.4 Hz,
1H); 13C NMR (75 MHz, CDCl3, Me4Si): d=20.23, 126.08,
126.70, 126.78, 127.44, 127.98, 128.06, 128.27, 128.32, 128.43,
128.89, 128.98, 129.11, 130.00, 130.27, 130.85, 132.17, 132.67,
133.80, 135.91, 136.16, 138.62, 140.55, 201.22; HR-MS (EI):
m/z=406.1122, calcd. for C28H19OCl: 406.1124.
Phenyl(10-phenylphenanthren-4-yl)methanone (4b)
To a solution of 3-phenyl-1-[2-(phenylethynyl)phenyl]prop-
2-yn-1-ol (1a) (61.7 mg, 0.2 mmol) and furan (68.1 mg,
1 mmol) in DCE (2 mL) was added PPh3AuNTf2 (7.4 mg,
0.01 mmol). The flask was sealed and immersed in an oil
bath at 808C. After stirring for 2 h, the mixture was cooled
down. The solvent was evaporated under the reduced pres-
sure and the residue was purified by chromatography on
silica gel (petroleum ether:ethyl acetate=50:1) to afford 4b
(3-Methyl-10-phenylphenanthren-4-yl)(thien-2-yl)-
methanone (4g)
Method B and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a sticky yellow oil; yield: 54%. 1H NMR (400 MHz,
CDCl3, Me4Si): d=2.45 (s, 3H), 6.87 (t, J=4.0 Hz, 1H), 7.06
(d, J=2.4 Hz, 1H), 7.35 (t, J=7.2 Hz, 1H), 7.40–7.53 (m,
7H), 7.62 (d, J=4.2 Hz, 1H), 7.64 (s, 1H), 7.80 (d, J=
7.6 Hz, 1H), 7.91 (d, J=8.4 Hz, 1H), 8.56 (d, J=8.4 Hz,
1H); 13C NMR (100.6 MHz, CDCl3, Me4Si): d=20.21,
126.15, 126.77, 126.81, 127.43, 127.92, 128.13, 128.16, 128.30,
128.33, 128.66, 128.76, 128.99, 130.06, 130.27, 132.63, 134.23,
134.77, 135.14, 136.25, 138.55, 140.68, 145.31, 194.49; HR-
MS (EI): m/z=378.1074, calcd. for C26H18OS: 378.1078.
1
as a yellow oil; yield: 51.5 mg (72%). H NMR (400 MHz,
CDCl3, Me4Si): d=7.29 (t, J=7.6 Hz, 1H), 7.35 (t, J=
7.6 Hz, 2H), 7.43–7.55 (m, 9H), 7.71 (s, 1H), 7.81 (d, J=
7.6 Hz, 1H), 7.87 (d, J=7.2 Hz, 2H), 8.04 (t, J=4.8 Hz,
1H), 8.19 (d, J=8.4 Hz, 1H); 13C NMR (100.6 MHz, CDCl3,
Me4Si): d=125.37, 126.03, 126.98, 127.10, 127.44, 127.51,
128.33, 128.36, 128.57, 128.66, 128.71, 128.84, 130.06, 130.24,
132.15, 132.44, 133.49, 137.07, 138.21, 138.62, 140.51, 200.36;
HR-MS (EI); m/z=358.1360, calcd. for C27H18O: 358.1358.
(3-Methyl-10-p-tolylphenanthren-4-yl)ACTHNUTRGENUG(N phenyl)-
methanone (4h)
(2,3-Dimethyl-10-phenylphenanthren-4-yl)
methanone (4c)
ACHTUNGTRENN(UNG phenyl)-
Method A and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a sticky yellow oil; yield: 62%. 1H NMR (400 MHz,
CDCl3, Me4Si): d=2.32 (s, 3H), 2.45 (s, 3H), 7.24 (t, J=
8.0 Hz, 1H), 7.30–7.48 (m, 9H), 7.62 (s, 1H), 7.76 (d, J=
7.2 Hz, 1H), 7.83 (d, J=8.0 Hz, 2H), 7.95 (d, J=8.4 Hz,
1H), 8.37 (d, J=8.4 Hz, 1H); 13C NMR (100.6 MHz, CDCl3,
Method A and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a sticky yellow oil; yield: 72%. 1H NMR (400 MHz,
CDCl3, Me4Si): d=2.22 (s, 3H), 2.37 (s, 3H), 7.24 (t, J=
8.0 Hz, 1H), 7.33–7.41 (m, 3H), 7.46–7.53 (m, 6H), 7.61 (s,
1H), 7.76 (d, J=7.6 Hz, 1H), 7.80 (s, 1H), 7.86 (d, J=
Adv. Synth. Catal. 2011, 353, 392 – 400
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
397

Yifeng Chen et al.
FULL PAPERS
Me4Si): d=20.24, 21.23, 125.90, 126.61, 126.90, 127.85,
127.92, 128.38, 128.55, 128.77, 128.82, 128.99, 129.01, 129.43,
129.91, 130.44, 132.73, 133.61, 133.70, 136.63, 137.08, 137.42,
137.75, 138.64, 202.35; HR-MS (EI): m/z=386.1674, calcd.
for C29H22O: 386.1671.
(6,7-Dimethoxy-3-methyl-10-phenylphenanthren-4-
yl)ACTHNUGRTNEUNG(phenyl)methanone (4l)
Method A and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a sticky yellow oil; yield: 46%. 1H NMR (400 MHz,
CDCl3, Me4Si): d=2.32 (s, 3H), 3.52 (s, 3H), 3.94 (s, 3H),
7.16 (s, 1H), 7.34–7.58 (m, 10H), 7.68 (s, 1H), 7.90–7.92 (m,
3H); 13C NMR (100.6 MHz, CDCl3, Me4Si): d=20.18, 55.35,
55.72, 108.35, 108.50, 123.14, 127.01, 127.23, 127.89, 128.00,
128.06, 128.09, 128.26, 128.98, 129.47, 129.54, 130.16, 133.28,
133.92, 135.80, 137.10, 137.43, 140.99, 148.22, 148.87, 202.44;
HR-MS (EI): m/z=432.1726, calcd. for C30H24O3: 432.1725.
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
Method A and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a sticky yellow oil; yield: 66%. It could be solidified as a
foamy solid by the treatment with hot hexane; mp 151–
1
1528C. H NMR (400 MHz, CDCl3, Me4Si): d=2.31 (s, 3H),
(2-Methyl-5-phenylphenanthro
yl)(phenyl)methanone (4m)
ACHTUGTNREN[UNG 2,3-d]AHCUTNGTREN[NUGN 1,3]dioxol-1-
7.25 (t, J=7.2 Hz, 1H), 7.32 (t, J=7.2 Hz, 2H), 7.38–7.45
(m, 7H), 7.58 (s, 1H), 7.75 (d, J=7.6 Hz, 1H), 7.81–7.84 (m,
3H), 8.38 (d, J=8.8 Hz, 1H); 13C NMR (100.6 MHz, CDCl3,
Me4Si): d=20.24, 126.22, 126.75, 126.91, 127.49, 128.01,
128.41, 128.51, 128.70, 128.84, 129.18, 129.40, 130.01, 131.33,
132.50, 133.45, 133.66, 133.98, 136.78, 137.35, 137.37, 139.12,
202.13; HR-MS (EI): m/z=406.1128, calcd. for C28H19OCl:
406.1124.
AHCTUNGTRENNUNG
Method A and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) to afford the title prod-
uct as a sticky yellow oil; yield: 52%. It could be solidified
as a foamy solid by the treatment with hot hexane; mp 226–
1
2278C. H NMR (400 MHz, CDCl3, Me4Si): d=2.30 (s, 3H),
5.59 (s, 1H), 5.93 (s, 1H), 7.12 (s, 1H), 7.36 (q, J=8.0 Hz,
3H), 7.45–7.54 (m, 7H), 7.78 (s, 1H), 7.83 (d, J=7.2 Hz,
2H), 7.89 (d, J=8.4 Hz, 1H); 13C NMR (100.6 MHz, CDCl3,
Me4Si): d=20.30, 101.26, 105.16, 105.88, 124.60, 127.30,
127.53, 127.87, 128.24, 128.26, 128.30, 128.91, 129.45, 129.50,
129.57, 130.13, 133.44, 133.73, 136.01, 137.17, 137.50, 140.82,
147.25, 147.48, 202.58; HR-MS (EI): m/z=416.1410, calcd.
for C29H20O3: 416.1412.
(10-Butyl-3-methylphenanthren-4-yl)
methanone (4j)
ACHTUNGTRENN(UNG phenyl)-
Method B and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) to afford the title prod-
uct as a sticky yellow oil; yield: 73%. It could be solidified
as a foamy solid by the treatment with hot hexane; mp 99–
1
1008C. H NMR (400 MHz, CDCl3, Me4Si): d=1.00 (t, J=
(8-Methyl-5-phenyl-2,3-dihydro-1H-cyclopenta[a]-
naphthalen-9-yl)ACTHNUTRGNE(NUG phenyl)methanone (4n)
7.2 Hz, 3H), 1.48–1.54 (m, 2H), 1.78–1.83 (m, 2H), 2.33 (s,
3H), 3.08–3.15 (m, 2H), 7.16–7.20 (m, 1H), 7.29 (t, J=
7.2 Hz, 2H), 7.35–7.39 (m, 1H), 7.42–7.46 (m, 1H), 7.51 (d,
J=8.4 Hz, 1H), 7.54 (s, 1H), 7.71 (dd, J=1.6, 8.0 Hz, 1H),
7.77 (d, J=6.8 Hz, 2H), 8.12 (d, J=8.4 Hz, 1H), 8.31 (d, J=
8.4 Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si): d=
14.02, 20.22, 22.89, 32.35, 33.40, 125.26, 126.37, 126.49,
126.89, 128.14, 128.34, 128.57, 128.75, 129.03, 129.41, 130.41,
133.11, 133.28, 133.51, 136.64, 136.97, 137.48, 202.40; HR-
MS (EI): m/z=352.1822, calcd. for C26H24O: 352.1827.
Method B and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a yellow oil; yield: 76%. 1H NMR (400 MHz, CDCl3,
Me4Si): d=1.85–1.92 (m, 1H), 1.98–2.05 (m, 1H), 2.21 (s,
3H), 2.50–2.58 (m, 1H), 2.93–3.01 (m, 2H), 3.11–3.19 (m,
1H), 7.18 (d, J=8.8 Hz, 1H), 7.32 (s, 1H), 7.37–7.50 (m,
7H), 7.54 (t, J=7.2 Hz, 1H), 7.87 (d, J=8.8 Hz, 3H);
13C NMR (75.5 MHz, CDCl3, Me4Si): d=19.64, 24.96, 33.45,
34.66, 124.35, 127.05, 127.22, 127.92, 128.14, 128.26, 128.82,
129.78, 130.13, 132.58, 133.45, 135.06, 136.93, 138.27, 139.53,
141.24, 142.82, 201.63; HR-MS (EI): m/z=362.1673, calcd.
for C27H22O: 362.1671.
(6-Fluoro-3-methyl-10-phenylphenanthren-4-yl)-
ACHTUNGTRENNUNG(phenyl)methanone (4k)
Method A and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a sticky yellow oil; yield: 58%. It could be solidified as a
foamy solid by the treatment with hot hexane; mp 172–
(2-Methyl-5,7-diphenylnaphthalen-1-yl)
methanone (4o)
ACHTUNGTRENN(UNG phenyl)-
1
1738C. H NMR (400 MHz, CDCl3, Me4Si): d=2.33 (s, 3H),
Method B and column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a yellow oil; yield: 48%. 1H NMR (400 MHz, CDCl3,
Me4Si): d=2.30 (s, 3H), 7.28–7.31 (m, 2H), 7.34–7.37 (m,
7.15–7.20 (m, 1H), 7.36–7.53 (m, 9H), 7.60 (s, 1H), 7.42 (dd,
J=6.0, 8.8 Hz, 1H), 7.84 (d, J=7.6 Hz, 2H), 7.92 (d, J=
8.8 Hz, 1H), 8.06 (dd, J=2.4, 12.8 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si): d=20.07, 112.17 (d, J=
24.6 Hz), 115.68 (d, J=23.9 Hz), 127.28, 127.49, 127.66 (d,
J=3.7 Hz), 127.93, 128.37, 128.97, 129.39 (d, J=1.5 Hz),
129.45, 129.60, 129.85 (d, J=9.1 Hz), 130.03, 130.58, 130.69
(d, J=9.1 Hz), 131.85, 133.92, 136.85, 137.23, 138.03 (d, J=
2.9 Hz), 140.50, 160.54 (d, J=245.4 Hz), 202.19; HR-MS
(EI): m/z=390.1421, calcd. for C28H19OF: 390.1420.
2H), 7.42–7.47 (m, 3H), 7.49–7.57ACTHNUTRGNEUNG(m, 7H), 7.65 (d, J=
2.0 Hz, 1H), 7.70 (bs, 1H), 7.88–7.92 (m, 3H); 13C NMR
(100.6 MHz, CDCl3, Me4Si): d=19.66, 122.28, 126.31, 126.93,
127.43, 127.45, 127.47, 128.34, 128.58, 128.72, 128.88, 129.14,
129.74, 130.03, 131.33, 132.53, 133.88, 136.45, 137.50, 138.81,
140.46, 140.64, 140.98, 200.39. HR-MS (EI): m/z=398.1670,
calcd. for C30H22O: 398.1671.
398
asc.wiley-vch.de
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 392 – 400

Gold-Catalyzed Cascade Friedel–Crafts/Furan-Yne Cyclization/Heteroenyne Metathesis
127.99, 128.46, 128.64, 128.91, 129.47, 129.49, 129.59, 129.68,
Typical Procedure for the Synthesis of 2-Methyl-5-{3-
phenyl-1-[2-(phenylethynyl)-phenyl]prop-2-ynyl}furan
(2a)
130.00, 130.04, 131.36, 133.22, 133.75, 134.72, 134.82, 136.23,
137.33, 145.23, 145.54, 201.86; HR-MS (EI): m/z=498.0485,
calcd. for C28H19OI: 498.0481.
To a solution of alcohol 1a (6.0 mmol, 1.85 g in 90 mL dry
CH2Cl2) were added 2-methylfuran (15.0 mmol, 1.23 g,
1.35 mL) and TsOH·H2O (1.8 mmol, 342 mg). The mixture
was kept at room temperature and the reaction was moni-
tored by TLC. After two hours, the reaction was completed.
The solvent was evaporated under vacuum at room temper-
ature. Purification of the crude product by flash column
chromatography on silica-gel (petroleum ether:diclorome-
thane=10:1) afforded the title compound as a light yellow
sticky liquid; yield: 1.91 g (85%). 1H NMR (400 MHz,
CDCl3, Me4Si): d=2.22 (s, 3H), 5.86–5.88 (m, 2H), 6.11 (d,
J=2.8 Hz, 1H), 7.23–7.28 (m, 4H), 7.31–7.37 (m, 4H), 7.44–
(10-Butyl-9-iodo-3-methylphenanthren-4-yl)
methanone (13b)
ACHTUNGTRENN(UNG phenyl)-
Five equiv. of I2 were used. The proudtc was isolated as a
1
brown oil; yield: 39%. H NMR (400 MHz, CDCl3, Me4Si):
d=1.07 (t, J=7.2 Hz, 3H), 1.58–1.67 (m, 2H), 1.74–1.79 (m,
2H), 2.34 (s, 3H), 3.52 (t, J=8.4 Hz, 2H), 7.20–7.24 (m,
1H), 7.29 (t, J=7.6 Hz, 2H), 7.42–7.47 (m, 2H), 7.53 (d, J=
8.4 Hz, 1H), 7.68 (dd, J=8.2, 1.2 Hz, 2H), 8.18 (d, J=
8.4 Hz, 1H), 8.27 (d, J=8.4 Hz, 1H), 8.38 (dd, J=8.4,
1.2 Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si): d=
14.02, 20.43, 23.15, 31.60, 40.41, 107.78, 126.08, 126.42,
127.23, 127.68, 128.75, 128.92, 129.16, 129.39, 129.70, 129.93,
133.57, 134.35, 134.61, 136.66, 137.29, 141.85, 201.81; HR-
MS (EI): m/z=478.0798, calcd. for C26H23IO: 478.0794.
7.47 (m, 2H), 7.52–7.55ACTHNUTRGNEU(GN m, 3H), 7.68 (dd, J=1.2, 8.0 Hz,
1H); 13C NMR (100.6 MHz, CDCl3, Me4Si): d=13.61, 36.03,
83.19, 87.22, 87.83, 94.45, 106.23, 107.49, 122.34, 123.16,
123.29, 127.18, 127.98, 128.09, 128.14, 128.32, 128.36, 128.79,
131.55, 131.74, 132.13, 140.91, 151.26, 151.72; HR-MS (EI):
m/z=372.1511, calcd. for C28H20O: 372.1514.
Supporting Information
Experimental details, spectroscopic characterization of all
new compounds and X-ray crystallography of compound 4m
are given in the Supporting Information.
2-{1-[2-(hex-1-ynyl)phenyl]-3-phenylprop-2-ynyl}-5-
methylfuran (2b)
This product was obtained according to the procedure de-
scribed for 2a. Column chromatography on silica gel (petro-
leum ether:dichloromethane=2:1) afforded the title product
as a yellow oil; yield: 72%. 1H NMR (400 MHz, CDCl3,
Me4Si): d=0.92 (d, J=7.2 Hz, 3H), 1.44–1.50 (m, 2H), 1.57–
1.60 (m, 2H), 2.23 (s, 3H), 2.44 (t, J=7.2 Hz, 2H), 5.78 (s,
1H), 5.86–5.87 (m, 1H), 6.04 (d, J=2.8 Hz, 1H), 7.18–7.21
(m, 1H), 7.25–7.29 (m, 4H), 7.41 (d, J=7.6 Hz, 1H), 7.44–
7.46 (m, 2H), 7.61 (d, J=7.6 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si): d=13.61, 13.62, 19.25, 21.95,
30.75, 35.77, 78.33, 82.82, 88.14, 95.54, 106.10, 107.30, 123.16,
123.39, 127.00, 127.91, 127.92, 127.96, 128.11, 131.72, 132.06,
140.64, 151.49, 151.61; HR-MS (EI): m/z=352.1831, calcd.
for C26H24O: 352.1827.
Acknowledgements
We thank the National Natural Science Foundation of China
(Grant Nos. 20872163, 20732008, 20821002), the Chinese
Academy of Science, Science and Technology Commission of
Shanghai Municipality (Grant No. 08QH14030) and the
Major State Basic Research Development Program (Grant
No. 2006CB806105) for financial support.
References
Typical Procedure for the Synthesis of (9-Iodo-3-
[1] a) K. C. Nicolaou, D. J. Edmonds, P. G. Bulger, Angew.
Chem. 2006, 118, 7292; Angew. Chem. Int. Ed. 2006, 45,
7134; b) L. F. Tietze, Chem. Rev. 1996, 96, 115.
methyl-10-phenylphenanthren-4-yl)
methanone (13a)
ACHTUNGTRENN(UNG phenyl)-
To a solution of 2-methyl-5-{3-phenyl-1-[2-(phenylethynyl)-
phenyl]prop-2-ynyl}furan (2a) (74.5 mg, 0.2 mmol) in DCE
(2 mL) were added I2 (152.3 mg, 0.6 mmol), AuCl3 (0.2 mL,
0.01 mmol, used as a 0.05M solution in MeCN) and AgSbF6
(0.6 mL, 0.03 mmol, used as a 0.05M solution in MeCN)
subsequently. The flask was sealed and immersed into an oil
bath at 808C. After stirring for 6 h, the reaction mixture was
quenched at room temperature by saturated aqueous
Na2S2O3, and extracted with Et2O. The combined organic
layers were dried over Na2SO4, filtered and concentrated.
The residue was purified by chromatography on silica gel
(petroleum ether:dichloromethane=1:1) to afford (9-iodo-
[2] For recent reviews on gold-catalyzed reactions, see:
a) A. S. K. Hashmi, G. J. Hutchings, Angew. Chem.
2006, 118, 8064; Angew. Chem. Int. Ed. 2006, 45, 7896;
b) D. J. Gorin, F. D. Toste, Nature 2007, 446, 395;
c) A. S. K. Hashmi, Chem. Rev. 2007, 107, 3180; d) A.
Fꢂrstner, P. W. Davies, Angew. Chem. 2007, 119, 3478;
Angew. Chem. Int. Ed. 2007, 46, 3410; e) E. Jimꢃnez-
NfflÇez, A. M. Echavarren, Chem. Commun. 2007, 333;
f) B. H. Lipshutz, Y. Yamamoto, Chem. Rev. 2008, 108,
2793; g) E. Jimꢃnez-NfflÇez, A. M. Echavarren, Chem.
Rev. 2008, 108, 3326; h) D. J. Gorin, B. D. Sherry, F. D.
Toste, Chem. Rev. 2008, 108, 3351; i) A. Arcadi, Chem.
Rev. 2008, 108, 3266; j) N. T. Patil, Y. Yamamoto,
Chem. Rev. 2008, 108, 3395; k) Z. Li, C. Brouwer, C.
He, Chem. Rev. 2008, 108, 3239; l) A. S. K. Hashmi, M.
Rudolph, Chem. Soc. Rev. 2008, 37, 1766; m) J. Muzart,
Tetrahedron 2008, 64, 5815; n) H. C. Shen, Tetrahedron
2008, 64, 3885; o) P. Belmont, E. Parker, Eur. J. Org.
3-methyl-10-phenylphenanthren-4-yl)ACTHNUTRGNE(NUG phenyl)methanone
(13a) as a yellow oil; yield: 62.3 mg (63%). 1H NMR
(300 MHz, CDCl3, Me4Si): d=2.31 (s, 3H), 7.25–7.39 (m,
6H), 7.44–7.59 (m, 6H), 7.79 (d, J=7.2 Hz, 2H), 8.35 (d, J=
8.4 Hz, 1H), 8.43 (d, J=8.7 Hz, 1H); 13C NMR (75.5 MHz,
CDCl3, Me4Si): d=20.47, 106.85, 126.90, 127.28, 127.91,
Adv. Synth. Catal. 2011, 353, 392 – 400
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
399

Yifeng Chen et al.
FULL PAPERS
Chem. 2009, 6075; p) N. Shapiro, F. D. Toste, Synlett
2010, 675; q) A. S. K. Hashmi, Angew. Chem. Int. Ed.
2010, 49, 5232.
[9] For alkyne-aldehyde metathesis, see: a) J. U. Rhee, M.
Krische, Org. Lett. 2005, 7, 2493; b) A. Saito, M. Uma-
koshi, N. Yagyu, Y. Hanazawa, Org. Lett. 2008, 10,
1783; c) G. S. Viswanathan and C.-J. Lee, Tetrahedron
Lett. 2002, 43, 1613; d) C. Gonzµlez-Rodríguez, L. Es-
calante, J. A. Varela, L. Castedo, C. Saµ, Org. Lett.
2009, 11, 1531.
[3] Y. Chen, Y. Lu, G. Li, Y. Liu, Org. Lett. 2009, 11, 3838.
[4] For related papers, see: a) Y. Lu, X. Du, X. Jia, Y. Liu,
Adv. Synth. Catal. 2009, 351, 1517; b) Y. Lu, X. Fu, H.
Chen, X. Du, X. Jia, Y. Liu, Adv. Synth. Catal. 2009,
351, 129.
[10] For alkyne-ketone metathesis, see: a) C. E. Harding, M.
Hanack, Tetrahedron Lett. 1971, 12, 1253; b) R. J. Balf,
B. Rao, L. Weiler, Can. J. Chem. 1971, 49, 3135; c) M.
Hanack, C. E. Harding, J. Derocque, Chem. Ber. 1972,
105, 421; d) G. L. Lang, T.-W. Hall, J. Org. Chem. 1974,
39, 3819; e) C. E. Harding, G. R. Stanford, J. Org.
Chem. 1989, 54, 3054; f) C. E. Harding, S. L. King, J.
Org. Chem. 1992, 57, 883; g) J. Siso, A. Balog, D. P.
Curran, J. Org. Chem. 1992, 57, 4341; h) J. R. Grunwell,
M. F. Wempe, J. Mitchell, Tetrahedron Lett. 1993, 34,
7163; i) A. Balog, D. P. Curran, J. Org. Chem. 1995, 60,
337; j) A. Balog, S. J. Geib, D. P. Curran, J. Org. Chem.
1995, 60, 345; k) M. F. Wempe, J. R. Grunwell, J. Org.
Chem. 1995, 60, 2714; l) M. F. Wempe, J. R. Grunwell,
Tetrahedron Lett. 2000, 41, 6709; m) K. C. M. Kurtz,
R. P. Hsung, Y. Zhang, Org. Lett. 2006, 8, 231; n) T. Jin,
Y. Yamamoto, Org. Lett. 2007, 9, 5259; o) T. Jin, Y. Ya-
mamoto, Org. Lett. 2008, 10, 3137; for related papers,
see: p) P. García-García, M. A. Fernµndez-Rodríguez,
E. Aguilar, Angew. Chem. 2009, 121, 5642; Angew.
Chem. Int. Ed. 2009, 48, 5534; q) L. Liu, J. Zhang,
Angew. Chem. 2009, 121, 6209; Angew. Chem. Int. Ed.
2009, 48, 6093.
[11] a) J.-J. Lian, R.-S. Liu, Chem. Commun. 2007, 1337; for
gold-catalyzed cycloisomerization of Ac- or Piv-pro-
tected 1,6-diyn-4-en-3-ols to 2-naphthyl ketone via the
generation of allene intermediates, see: b) J. Zhao,
C. O. Hughes, F. D. Toste, J. Am. Chem. Soc. 2006, 128,
7436.
[12] The activation of benzylic alcohols by gold catalyst for
the substitution with furans has been described, see:
A. S. K. Hashmi, L. Schwarz, P. Rubenbauer, M. C.
Blanco, Adv. Synth. Catal. 2006, 348, 705.
[5] For gold-catalyzed furan/alkyne cyclization, see:
a) A. S. K. Hashmi, T. M. Frost, J. W. Bats, J. Am.
Chem. Soc. 2000, 122, 11553; b) A. S. K. Hashmi, T. M.
Frost, J. W. Bats, Org. Lett. 2001, 3, 3769; c) A. S. K.
Hashmi, T. M. Frost, J. W. Bats, Catal. Today 2002, 72,
19; d) A. S. K. Hashmi, L. Ding, P. Fischer, J. W. Bats,
W. Frey, Chem. Eur. J. 2003, 9, 4339; e) A. S. K.
Hashmi, L. Grundl, Tetrahedron 2005, 61, 6231;
f) A. S. K. Hashmi, J. P. Weyrauch, M. Rudolph, E.
´
Kurpejovic, Angew. Chem. 2004, 116, 6707; Angew.
Chem. Int. Ed. 2004, 43, 6545; g) A. S. K. Hashmi, M.
Rudolph, J. P. Weyrauch, M. Wçlfle, W. Frey, J. W.
Bats, Angew. Chem. 2005, 117, 2858; Angew. Chem. Int.
Ed. 2005, 44, 2798; h) A. S. K. Hashmi, J. P. Weyrauch,
E. Kurpejovic, T. M. Frost, B. Miehlich, W. Frey, J. W.
Bats, Chem. Eur. J. 2006, 12, 5806; i) A. S. K. Hashmi,
M. C. Blanco, E. Kurpejovic, W. Frey, J. W. Bats, Adv.
Synth. Catal. 2006, 348, 709; j) A. S. K. Hashmi, P.
Haufe, C. Schmid, A. R. Nass, W. Frey, Chem. Eur. J.
2006, 12, 5376; k) A. S. K. Hashmi, R. Salathꢃ, W. Frey,
Chem. Eur. J. 2006, 12, 6991; l) S. Carretin, M. C.
Blanco, A. Corma, A. S. K. Hashmi, Adv. Synth. Catal.
2006, 348, 1283; m) A. S. K. Hashmi, M. Wçlfle, F. Ata,
M. Hamzic, R. Salathꢃ, W. Frey, Adv. Synth. Catal.
2006, 348, 2501; n) A. S. K. Hashmi, F. Ata, E. Kurpe-
jovic, J. Huck, M. Rudolph, Top. Catal. 2007, 44, 245;
o) A. S. K. Hashmi, M. Rudolph, J. W. Bats, W. Frey, F.
Rominger, T. Oeser, Chem. Eur. J. 2008, 14, 6672;
p) A. S. K. Hashmi, M. Rudolph, H. Siehl, M. Tanaka,
J. W. Bats, W. Frey, Chem. Eur. J. 2008, 14, 3703;
q) A. S. K. Hashmi, M. Rudolph, J. Huck, W. Frey,
´
J. W. Bats, M. Hamzic, Angew. Chem. 2009, 121, 5962;
Angew. Chem. Int. Ed. 2009, 48, 5848.
[13] CCDC 782685 (4m) contains the supplementary crys-
tallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif or from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax (+44) 1223-336-033; or deposit@ccdc.cam.ac.uk.
[14] a) Y. Liu, S. Zhou, G. Li, B. Yan, S. Guo, Y. Zhou, H.
Zhang, P. G. Wang, Adv. Synth. Catal. 2008, 350, 797;
b) G. Li, S. Zhou, G. Su, Y. Liu, P. G. Wang, J. Org.
Chem. 2007, 72, 9830.
[6] For other metal-catalyzed furan/alkyne cyclizations,
see: a) B. Martín-Matute, D. J. Cµrdenas, A. M. Echa-
varren, Angew. Chem. 2001, 113, 4890; Angew. Chem.
Int. Ed. 2001, 40, 4754; b) B. Martín-Matute, C.
Nevado, D. J. Cµrdenas, A. M. Echavarren, J. Am.
Chem. Soc. 2003, 125, 5757.
[7] A. M. Machado, M. Munaro, T. D. Martins, L. Y. A.
Davila, R. Giro, M. J. Caldas, T. D. Z. Atvars, L. C. Ak-
celrud, Macromolecules 2006, 39, 3398.
[8] a) A. J. Floyd, S. F. Dyke, S. E. Ward, Chem. Rev. 1976,
76, 509; b) A. Kovµcs, A. Vasas, J. Hohmann, Phyto-
chemistry 2008, 69, 1084.
[15] For electrophilic attack in the C-3 position of the furan
ring, see Refs.[5i,5j]
400
asc.wiley-vch.de
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 392 – 400