Gold-catalyzed furan/yne cyclizations for the regiodefined assembly of multisubstituted protected 1-naphthols

Article abstract of DOI:10.1021/jo202541p

The gold(I)-catalyzed intramolecular cycloisomerization of furan/ynes bearing a silyloxy or allyloxy group has been developed, which provides a highly efficient access to protected 1-naphthol derivatives with enal or enone moiety. The method offers several advantages such as high stereoselectivities, mild reaction conditions, and easily accessible starting materials. In addition, the naphthyl products could be further transformed into the important benzocoumarins in a one-pot procedure.

Full text of DOI:10.1021/jo202541p

Article
pubs.acs.org/joc
Gold-Catalyzed Furan/Yne Cyclizations for the Regiodefined
Assembly of Multisubstituted Protected 1-Naphthols
Chengyu Wang,‡ Yifeng Chen,† Xin Xie,† Jun Liu,† and Yuanhong Liu*,†
†State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345
Lingling Lu, Shanghai 200032, People’s Republic of China
‡Department of Chemistry, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, People’s Republic of
China
S
* Supporting Information
ABSTRACT: The gold(I)-catalyzed intramolecular cyclo-
isomerization of furan/ynes bearing a silyloxy or allyloxy
group has been developed, which provides a highly efficient
access to protected 1-naphthol derivatives with enal or enone
moiety. The method offers several advantages such as high
stereoselectivities, mild reaction conditions, and easily
accessible starting materials. In addition, the naphthyl products
could be further transformed into the important benzocou-
marins in a one-pot procedure.
furylcarbinol derivatives bearing an (o-alkynyl)phenyl moiety
would be effective for the general synthesis of functionalized
naphthols via gold-catalyzed reaction (Scheme 1). In this
INTRODUCTION
■
Naphthol and its protected derivatives represent an important
structural motif as they occur widely in numerous natural
products with biological activities and in pharmaceuticals.1 For
example, they can be found in furomollugin,1a mollugin,1a,b
naphthohydroquinones,1c dioncophylline E,1d anti-cancer
agents of (+)-gossypol,1e and bactericidal antibiotic drugs of
rifampicin, which are used to treat mycobacterium infections,
including tuberculosis and Hansen’s disease.1f Therefore, the
development of new and efficient methodologies for the
synthesis of naphthol derivatives are highly attractive. However,
only limited reports for the preparation of these compounds
have been known, such as metal2a,b or Lewis acid2c catalyzed
ring-opening of oxabicyclic alkenes,2 multicomponent reac-
tions,3 annulations of phthalides with acrylates,4 reactions of
allenoates with organozinc reagents,5 copper-catalyzed cascade
reactions of 3-(2-halophenyl)-3-oxopropanoates,6 Pd-catalyzed
annulation of alkynes with ortho-ester-containing phenyl-
boronic acids,7 and Pd-catalyzed hydroxylation of aryl halides.8
These methods usually require high temperature and/or a
prolonged reaction time. Thus, the development of synthetic
routes that allows the facile assembly of multisubstituted
naphthols in a regioselective manner under mild reaction
conditions still remains an important objective.
Scheme 1
design, the furan moiety could be easily introduced through
nucleophilic addition of 2-furanyllithium to an aldehyde.12
Herein, we report our success in gold-catalyzed cycloisomeriza-
tion of furan/ynes 1 to highly functionalized 1-naphthols 2
protected with a TBS group with high (Z)-stereoselectivity. It is
noted that although the cyclization of furan/ynes has been
proven to be a versatile method for phenol synthesis via exo-
cyclization of terminal alkynes as reported by Hashmi et al.13
(Scheme 2), there is still a lack of a general synthetic method
for naphthol derivatives in this system. It is also noted that
there is no report for the ring-opening cyclization of furan/ynes
with an o-arylalkynyl-related skeleton to generate benzo-fused
carbocycles.14 We also report the further transfomations of
naphthalenes 2 to benzocoumarins in a one-pot procedure.
RESULTS AND DISCUSSION
■
Recently, we have developed a series furan/yne cyclizations via
gold-catalyzed9,10 endo-type cyclizations of internal alkynes
leading to aromatic compounds bearing enal or enone
functionalities with excellent stereoselectivity.11 In these
reactions, the furan rings were introduced into the substrates
through metal or Lewis acid catalyzed Friedel−Crafts reactions.
On the basis of these results, we hypothesized that 2-
Received: December 10, 2011
Published: January 19, 2012
© 2012 American Chemical Society
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stirring at 80 °C for 12 h (entry 11). Nonprotected 2-
furylcarbinol such as furan-2-yl(2-(phenylethynyl)phenyl)-
methanol only resulted in a complicated mixture at room
temperature for 0.5 h using several gold catalysts under the
conditions as shown in Table 1, entries 3−5.
Scheme 2
Next, we investigated the scope of this intramolecular
cycloisomerization to naphthol derivatives. The results revealed
that this methodology provides rapid access to a wide range of
multisubstituted 1-naphthol derivatives with high stereo-
selectivities (Table 2). As shown in Table 2, the reactions are
compatible with arylalkynes bearing common functional groups
on the aromatic ring, including electron-withdrawing p-chloro
(2b) and o-bromo (2c) groups and electron-rich p-methyl
(2d), 3,5-dimethoxy (2e), and 1-naphthyl (2f) groups. The
corresponding products could be obtained in good to high
yields of 62−91%. Among these reactions, the sterically
demanding cases of 2c (o-bromo) and 2f (1-naphthyl) afforded
lower yields of 62−64%. A thienyl group was also suitable in
this cyclization reaction, furnishing 2g in 84% yield. 1-
Cyclohexenyl tethered alkynes underwent the reaction readily
to generate the naphthyl ether 2h in 74% yield. The reaction
with the alkyl-substituted alkyne such as cyclopropyl (2i) or n-
butyl (2j) required a longer reaction time at room temperature.
However, heating the reaction mixture to 50 °C could reduce
the reaction time to 2−3 h. Introducing the synthetically
valuable fluoro, bis(methoxy) or methylenedioxy groups on the
parent phenyl ring did not influence the efficiency of this
cyclization reaction, high yields were achieved in all cases (2k-
2m). When an R2 group on the furan ring is alkyl or phenyl
group, the enone products 2n and 2o were formed in 78% and
97% yields, respectively, with exclusively (Z)-configuration of
the double bond. The reaction has also been successfully
extended to furan/yne 1p without the fused aromatic ring to
give the Indane derivative 2p in 59% yield.
The requisite substrates of TBS-protected (o-alkynyl)phenyl
2-furylcarbinols 1 could be easily prepared in good to high
yields through addition of the corresponding furanyllithium
reagents to (o-alkynyl)benzaldehydes12 followed by ether
formation with TBSCl. Compound 1a was selected as a
model substrate to probe the feasibility of the intramolecular
furan/yne cyclization reaction. It was found that the frequently
used cationic gold(I) complexes such as PPh3AuNTf2,
PPh3AuBF4, PPh3AuSbF6, or PPh3AuOTf only led to a
complicated reaction mixture (Table 1, entries 1−4). To our
delight, when 2 mol % of Echavarren’s catalyst (A)15 with a
bulky biarylphosphine ligand (Johnphos) was used as the
catalyst, the desired 1-naphthyl TBS ether 2a with an enal
moiety could be isolated in a high yield of 89% in toluene for 2
h at room temperature (entry 5). X-ray crystallographic analysis
of compound 2a unambiguously confirmed the structure of
1,2,3-trisubstituted naphthalene 2.16 Apparently, the furan ring
was opened during the catalytic process. It is interesting to note
that 2a was formed with high stereoselectivity (Z/E = 50:1).
The reaction could also be well performed in THF to generate
2a in 90% yield; however, the product was often contaminated
with small amounts of colored impurities (entry 6). In DCM,
only 32% yield of 2a with lower stereoselectivity was obtained
(entry 7). A decrease of the catalyst loading to 0.2 mol %
afforded 75% of 2a (entry 8). The above results indicated that
the nature of the ligand on the gold(I) complex has an
important influence on the reaction process. Control experi-
ments with PPh3AuCl or AgSbF6 could not gave the desired
naphthalene product 2a (entries 9 and 10). When PtCl2 was
used as catalyst, 84% of the strating material was recovered after
Interestingly, deprotection of the naphthalene 2a by TBAF
led to the quantitive formation of unstable lactol 3, which can
be readily converted to benzocoumarin 4 by PDC oxidation in
a one-pot procedure (Scheme 3, eq 1). The reaction could be
Table 1. Optimization Studies for the Formation of 1-Naphthyl TBS Ether 2a
a
entry
catalyst (mol %)
solvent
time (h)
yield (%) of 2a
1
2
PPh3AuNTf2 (5)
PPh3AuBF4 (5)
PPh3AuSbF6 (5)
PPh3AuOTf (5)
A (2)
DCM
DCM
DCM
THF
1
1.5
1
3
4
1
5
toluene
THF
2
89 (50:1)
b
6
A (2)
1
90 (39:1)
7
A (2)
DCM
toluene
toluene
toluene
toluene
4
32 (5.3:1)
c
8
A (0.2)
15
2
75 (50:1)
9
PPh3AuCl (5)
AgSbF6 (5)
PtCl2 (10)
d
e
f
10
11
6
12
a
0.2 mmol scale. [Substrate] = 0.1 M. All yields are isolated yields. The ratios of Z/E isomers are shown in parentheses, which were determined by
b
c
d
e
1H NMR. Contaminated with small amounts of colored impurities. 5 mmol scale. [Substrate] = 1.0 M. 91% of 1a was recovered. 90% of 1a was
recovered. The reaction was carried out at 80 °C, and 84% of 1a was recovered.
f
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provides a facile route for functionalized benzocoumarins.
When 2a was reduced to an alcohol by Luche reduction
followed by deprotection, naphthol 5 could be obtained in 78%
overall yield (Scheme 3, eq 2). When TBS-protecting group
was replaced by an allyl group, the desired cyclization also
proceeded smoothly to afford enal 7 in 70% yield (Z/E = 50:1)
(Scheme 4).
Table 2. Gold-Catalyzed Formation of Naphthol Derivatives
2
a
Scheme 4
We propose the following reaction mechanism for this
cyclization reaction (Scheme 5).11,13l Initial coordination of the
Scheme 5
gold catalyst to the triple bond affords intermediate 8. This is
followed by intramolecular nucleophilic attack of the C-3 on
the furan ring to the triple bond in a highly regioselective 7-
endo-dig manner to give a cation 9, which isomerizes to a
cyclopropyl gold carbenoid 11.19 Alternatively, the cyclization
may also proceed via attack of C-2 on the furan ring20 to yield a
spiro cycle 10, from which rearrangement would give the same
intermediate 11. Ring-opening of 11 followed by deprotonation
and deauration leads to naphthalene 2 with a Z-enone or enal
moiety. The preferred endo-selectivity for all reactions may be
attributed to the formation of stable aromatic products. It
should be noted that the endo-type cyclization in furan/yne
cycloisomerization is rare.11,20
a
Isolated yields. The ratios of Z/E isomers are shown in parentheses,
b
1
which were determined by H NMR. 50 °C.
Scheme 3
In summary, we have developed an efficient gold(I)-catalyzed
intramolecular cyclizations of furan/ynes bearing a silyloxy or
allyloxy group in the α-position of the furan ring, which
provides a rapid access to functionalized 1-naphthol derivatives
with an enal or enone moiety under mild reaction conditions.
The products could be further transformed to the important
benzocoumarin derivatives. Further investigation of this
cycloisomerization in related reaction systems and its
application toward polyaromatic compounds is in progress.
EXPERIMENTAL SECTION
conveniently carried out by addition of 3 Å molecular sieves,
PDC and TBAF successively to a THF solution of 2a followed
by stirring the mixture overnight. Compound 4 exhibits a blue
fluorescence in organic solvents. Benzocoumarins are an
important class of naturally occurring substances,17 and they
are also known as fluorescent-active materials.18 Our method
■
Typical Procedure for the Synthesis of TBS-Protected (o-
Alkynyl)phenyl-2-furylcarbinols (1). To a solution of furan (0.48
mL, 6.5 mmol) in THF (10 mL) at 0 °C was added n-BuLi (2.5 mL,
2.4 M in hexanes, 6.0 mmol). After the solution was stirred at the same
temperature for 2 h, a THF (5 mL) solution of 2-(phenylethynyl)-
benzaldehyde (1.0 g, 5 mmol) was added at −78 °C. The resulting
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solution was warmed to room temperature and stirred for 1 h. The
mixture was quenched with saturated ammonium chloride solution.
The reaction mixture was extracted with ethyl acetate, washed with
saturated NaCl solution, and dried over anhydrous Na2SO4. The
solvent was evaporated and the residue was purified by chromatog-
raphy on silica gel (petroleum ether/ethyl acetate/CH2Cl2 = 5:1:1) to
afford furan-2-yl(2-(phenylethynyl)phenyl)methanol.
92.5, 107.2, 110.1, 120.9, 121.0, 125.3, 126.3, 126.4, 126.77, 126.81,
127.4, 128.3, 128.7, 128.8, 130.4, 132.0, 133.1, 133.2, 142.0, 143.6,
156.4. HRMS (EI) calcd for C29H30O2Si: 438.2015, found 438.2012.
tert-Butyl(furan-2-yl(2-(thiophene-2-ylethynyl)phenyl)-
methoxy)dimethylsilane (1g): yield 66%; yellow oil; 1H NMR (400
MHz, CDCl3, Me4Si) δ 0.05 (s, 3H), 0.08 (s, 3H), 0.91 (s, 9H), 6.05
(d, J = 2.4 Hz, 1H), 6.25−6.26 (m, 1H), 6.29 (s, 1H), 6.99−7.01 (m,
1H), 7.22−7.46 (m, 6H), 7.77 (d, J = 7.6 Hz, 1H); 13C NMR (100.6
MHz, CDCl3, Me4Si) δ −5.1, −5.0, 18.3, 25.8, 68.4, 87.6, 90.7, 106.9,
110.0, 120.5, 123.2, 126.7, 127.1, 127.3, 127.4, 128.7, 131.4, 131.7,
142.0, 143.7, 156.2; HRMS (EI) calcd for C23H26O2SSi 394.1423,
found 394.1421.
tert-Butyl((2-(cyclohexenylethynyl)phenyl)(furan-2-yl)-
methoxy)dimethylsilane (1h): yield 80%; yellow oil; 1H NMR (400
MHz, CDCl3, Me4Si) δ 0.04 (s, 3H), 0.05 (s, 3H), 0.90 (s, 9H), 1.55−
1.68 (m, 4H), 2.13−2.18 (m, 4H), 5.96−5.97 (m, 1H), 6.15 (s, 1H),
6.25 (s, 2H), 7.18−7.38 (m, 4H), 7.71 (d, J = 7.6 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si) δ −5.1, −5.0, 18.3, 21.5, 22.3, 25.75,
25.81, 29.1, 68.3, 84.3, 96.4, 106.7, 110.0, 120.7, 121.4, 126.6, 127.1,
128.0, 131.4, 135.0, 141.8, 143.4, 156.5; HRMS (EI) calcd for
C25H32O2Si 392.2172, found 392.2175.
tert-Butyl((2-(cyclopropylethynyl)phenyl)(furan-2-yl)-
methoxy)dimethylsilane (1i): yield 73%; yellow oil; 1H NMR (400
MHz, CDCl3, Me4Si) δ 0.03 (s, 3H), 0.05 (s, 3H), 0.68−0.76 (m, 2H),
0.83−0.87 (m, 2H), 0.90 (s, 9H), 1.40−1.44 (m, 1H), 5.93 (d, J = 3.2
Hz, 1H), 6.18 (s, 1H), 6.24−6.25 (m, 1H), 7.16−7.33 (m, 4H), 7.68
(d, J = 8.0 Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si) δ −5.1,
−5.0, 0.2, 8.7, 8.8, 18.3, 25.8, 68.2, 73.1, 98.8, 106.7, 110.0, 121.5,
126.5, 127.1, 127.6, 131.5, 141.7, 143.6, 156.7; HRMS (EI) calcd for
C22H28O2Si 352.1859, found 352.1862.
To a solution of the above alcohol in DCM (20 mL) were added
imidazole (0.68 g, 10 mmol) and TBSCl (1.1 g, 7.5 mmol). The
mixture stirred at room temperature for 1 h before addition of a
saturated ammonium chloride solution. The reaction mixture was
extracted with ethyl acetate, washed with saturated NaCl solution,
dried over Na2SO4, and concentrated in vacuo. The residue was
purified by chromatography on silica gel (petroleum ether/ethyl
acetate =20:1) to afford tert-butyl(furan-2-yl(2-(phenylethynyl)-
phenyl)methoxy)dimethylsilane (1a) in 79% overall yield as a light
1
yellow oil: H NMR (300 MHz, CDCl3, Me4Si) δ 0.05 (s, 3H), 0.08
(s, 3H), 0.91 (s, 9H), 6.01 (d, J = 3.0 Hz, 1H), 6.24−6.26 (m, 1H),
6.36 (s, 1H), 7.27−7.50 (m, 9H), 7.78 (d, J = 7.5 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si) δ −5.1, −5.0, 18.3, 25.8, 68.4, 86.9, 94.4,
106.9, 110.1, 120.8, 123.2, 126.7, 127.3, 128.3, 128.4, 128.6, 131.4,
131.7, 141.9, 143.7, 156.5; HRMS (EI) calcd for C25H28O2Si 388.1859,
found 388.1856.
tert-Butyl((2-((4-chlorophenyl)ethynyl)phenyl)(furan-2-yl)-
methoxy)dimethylsilane (1b): yield 60%; brown oil; 1H NMR (400
MHz, CDCl3, Me4Si) δ 0.05 (s, 3H), 0.07 (s, 3H), 0.91 (s, 9H), 5.99
(d, J = 2.4 Hz, 1H), 6.25 (s, 1H), 6.31 (s, 1H), 7.25−7.41 (m, 7H),
7.47 (d, J = 7.6 Hz, 1H), 7.77 (d, J = 7.6 Hz, 1H); 13C NMR (100.6
MHz, CDCl3, Me4Si) δ −5.1, −5.0, 18.3, 25.8, 68.4, 87.9, 93.3, 106.9,
110.2, 120.5, 121.7, 126.7, 127.3, 128.7, 128.8, 131.7, 132.6, 134.3,
141.9, 143.8, 156.5; HRMS (EI) calcd for C25H2735ClO2Si 422.1469,
found 422.1468.
((2-((2-Bromophenyl)ethynyl)phenyl)(furan-2-yl)methoxy)-
(tert-butyl)dimethylsilane (1c): yield 64%; yellow solid; mp 64−66
°C; 1H NMR (300 MHz, CDCl3, Me4Si) δ 0.07 (s, 3H), 0.08 (s, 3H),
0.91 (s, 9H), 6.02 (d, J = 3.0 Hz, 1H), 6.21−6.23 (m, 1H), 6.48 (s,
1H), 7.13−7.18 (m, 1H), 7.24−7.32 (m, 3H), 7.39−7.60 (m, 4H),
7.81 (d, J = 8.4 Hz, 1H); 13C NMR (75.5 MHz, CDCl3, Me4Si) δ
−4.98, −4.86, 18.3, 25.8, 68.3, 91.5, 92.6, 107.0, 110.0, 120.4, 125.2,
125.4, 126.8, 127.0, 127.3, 129.0, 129.4, 132.0, 132.4, 133.3, 142.0,
144.0, 156.3; HRMS (EI) calcd for C25H2779BrO2Si 466.0964, found
466.0967.
tert-Butyl(furan-2-yl(2-(hex-1-ynyl)phenyl)methoxy)-
1
dimethylsilane (1j): yield 55%; yellow oil; H NMR (300 MHz,
CDCl3, Me4Si) δ 0.04 (s, 3H), 0.05 (s, 3H), 0.90−0.96 (m, 12H),
1.40−1.56 (m, 4H), 2.40 (t, J = 6.9 Hz, 2H), 5.92 (d, J = 3.0 Hz, 1H),
6.23−6.26 (m, 2H), 7.16−7.35 (m, 4H), 7.70 (d, J = 7.8 Hz, 1H); 13C
NMR (100.6 MHz, CDCl3, Me4Si) δ −5.1, −5.0, 13.6, 18.3, 19.2, 21.9,
25.8, 30.8, 68.3, 78.1, 95.5, 106.7, 110.0, 121.7, 126.6, 127.1, 127.7,
131.6, 141.8, 143.5, 156.7; HRMS (EI) calcd for C23H32O2Si 368.2172,
found 368.2166.
tert-Butyl((5-fluoro-2-(phenylethynyl)phenyl)(furan-2-yl)-
methoxy)dimethylsilane (1k): yield 83%; yellow solid; mp 69−71
°C; 1H NMR (300 MHz, CDCl3, Me4Si) δ 0.05 (s, 3H), 0.09 (s, 3H),
0.91 (s, 9H), 6.04 (d, J = 3.3 Hz, 1H), 6.24−6.26 (m, 1H), 6.30 (s,
1H), 6.93−6.99 (m, 1H), 7.32−7.35 (m, 4H), 7.42−7.52 (m, 4H); 13C
NMR (75.5 MHz, CDCl3, Me4Si) δ −5.1, −5.0, 18.3, 25.8, 68.1 (d, J =
1.1 Hz), 85.9, 94.2 (d, J = 1.8 Hz), 107.1, 110.2, 113.9 (d, J = 23.9 Hz),
114.7 (d, J = 22.6 Hz), 116.8 (d, J = 3.3 Hz), 123.1, 128.4, 131.4, 133.5
(d, J = 8.1 Hz), 142.1, 146.7 (d, J = 8.1 Hz), 155.7, 162.8 (d, J = 248.9
Hz); HRMS (EI) calcd for C25H27FO2Si 406.1764, found 406.1761.
tert-Butyl((4,5-dimethoxy-2-(phenylethynyl)phenyl)(furan-
tert-Butyl(furan-2-yl(2-(p-tolylethynyl)phenyl)methoxy)-
1
dimethylsilane (1d): yield 87%; yellow solid; mp 65−68 °C; H
NMR (400 MHz, CDCl3, Me4Si) δ 0.05 (s, 3H), 0.07 (s, 3H), 0.91 (s,
9H), 2.36 (s, 3H), 6.01 (d, J = 2.8 Hz, 1H), 6.24 (s, 1H), 6.35 (s, 1H),
7.15 (d, J = 7.6 Hz, 2H), 7.25 (t, J = 7.6 Hz, 1H), 7.33−7.40 (m, 4H),
7.47 (d, J = 7.6 Hz, 1H), 7.77 (d, J = 7.6 Hz, 1H); 13C NMR (75.5
MHz, CDCl3, Me4Si) δ −5.08, −5.0, 18.4, 21.5, 25.8, 68.3, 86.3, 94.6,
106.8, 110.1, 120.1, 121.0, 126.6, 127.2, 128.4, 129.1, 131.3, 131.6,
138.5, 141.9, 143.6, 156.5; HRMS (EI) calcd for C26H30O2Si 402.2015,
found 402.2012.
1
2-yl)methoxy)dimethylsilane (1l): yield 74%; brown oil; H NMR
(300 MHz, CDCl3, Me4Si) δ 0.090 (s, 3H), 0.094 (s, 3H), 0.92 (s,
9H), 3.88 (s, 3H), 3.91 (s, 3H), 6.01 (d, J = 3.3 Hz, 1H), 6.24−6.26
(m, 1H), 6.31 (s, 1H), 6.97 (s, 1H), 7.28−7.34 (m, 5H), 7.43−7.46
(m, 2H); 13C NMR (75.5 MHz, CDCl3, Me4Si) δ −5.1, −5.0, 18.3,
25.7, 55.78, 55.83, 68.2, 86.9, 92.9, 106.6, 109.5, 110.0, 112.6, 113.6,
123.3, 128.0, 128.3, 131.2, 137.3, 141.9, 147.8, 149.5, 156.5; HRMS
(EI) calcd for C27H32O4Si 448.2070, found 448.2075.
tert-Butyl(furan-2-yl(6-(phenylethynyl)benzo[d][1,3]dioxol-
5-yl)methoxy)dimethylsilane (1m): yield 70%; brown solid; 1H
NMR (300 MHz, CDCl3, Me4Si) 0.06 (s, 3H), 0.08 (s, 3H), 0.91 (s,
9H), 5.97 (d, J = 1.2 Hz, 1H), 6.00 (d, J = 1.2 Hz, 1H), 6.06 (d, J = 3.3
Hz, 1H), 6.25−6.27 (m, 1H), 6.31 (s, 1H), 6.91 (s, 1H), 7.21 (s, 1H),
7.23−7.34 (m, 4H), 7.44−7.47 (m, 2H); 13C NMR (75.5 MHz,
CDCl3, Me4Si) δ −5.1, −5.0, 18.3, 25.8, 68.3, 87.0, 92.9, 101.4, 106.5,
107.3, 110.0, 110.8, 113.8, 123.3, 128.1, 128.4, 131.3, 139.4, 141.9,
146.6, 148.3, 156.4; HRMS (EI) calcd for C26H28O4Si 432.1757, found
432.1755.
tert-Butyl((2-((3,5-dimethoxyphenyl)ethynyl)phenyl)(furan-
2-yl)methoxy)dimethylsilane (1e): yield 81%; yellow oil; 1H NMR
(400 MHz, CDCl3, Me4Si) δ 0.05 (s, 3H), 0.08 (s, 3H), 0.91 (s, 9H),
3.80 (s, 6H), 6.01 (d, J = 2.4 Hz, 1H), 6.26 (d, J = 1.6 Hz, 1H), 6.34
(s, 1H), 6.47 (d, J = 1.6 Hz, 1H), 6.62 (d, J = 1.6 Hz, 2H), 7.27 (t, J =
7.6 Hz, 1H), 7.34 (d, J = 0.4 Hz, 1H), 7.40 (t, J = 7.2 Hz, 1H), 7.48 (d,
J = 7.2 Hz, 1H), 7.77 (d, J = 7.6 Hz, 1H); 13C NMR (75.5 MHz,
CDCl3, Me4Si) δ −5.1, −5.0, 18.4, 25.8, 55.3, 68.3, 86.5, 94.4, 101.7,
106.9, 109.2, 110.1, 120.6, 124.5, 126.6, 127.3, 128.7, 131.6, 141.9,
143.8, 156.4, 160.5; HRMS (EI) calcd for C27H32O4Si 448.2070, found
448.2074.
tert-Butyl(furan-2-yl(2-(naphthalen-1-ylethynyl)phenyl)-
methoxy)dimethylsilane (1f): yield 56%; yellow oil; 1H NMR (400
MHz, CDCl3, Me4Si) δ 0.08 (s, 3H), 0.11 (s, 3H), 0.92 (s, 9H), 6.01
(d, J = 3.6 Hz, 1H), 6.23−6.24 (m, 1H), 6.52 (s, 1H), 7.28−7.35 (m,
2H), 7.40−7.45 (m, 2H), 7.48−7.56 (m, 2H), 7.60−7.62 (m, 1H),
7.69−7.71 (m, 1H), 7.80−7.85 (m, 3H), 8.27−8.29 (m, 1H). 13C
NMR (100.6 MHz, CDCl3, Me4Si) δ −5.0, −4.9, 18.4, 25.8, 68.6, 91.8,
tert-Butyldimethyl((5-methylfuran-2-yl)(2-(phenylethynyl)-
phenyl)methoxy)silane (1n): (5-Methylfuran-2-yl)lithium was used
instead of 2-furanyllithium: yield 71%; yellow oil; 1H NMR (400 MHz,
1918
dx.doi.org/10.1021/jo202541p | J. Org. Chem. 2012, 77, 1915−1921

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Article
CDCl3, SiMe4) δ 0.18 (s, 3H), 0.21 (s, 3H), 1.04 (s, 9H), 2.34 (s, 3H),
5.94−5.96 (m, 2H), 6.43 (s, 1H), 7.36−7.38 (m, 1H), 7.44−7.50 (m,
4H), 7.58−7.60 (m, 3H), 7.90−7.92 (m, 1H); 13C NMR (100.6 MHz,
CDCl3, Me4Si) δ −4.96, −4.93, 13.6, 18.4, 25.9, 68.4, 87.1, 94.4, 106.1,
107.8, 120.8, 123.4, 126.7, 127.1, 128.2, 128.3, 128.5, 131.4, 131.6,
144.0, 151.5, 154.7; HRMS (EI) calcd for C26H30O2Si 402.2015, found
402.2014.
tert-Butyldimethyl((2-(phenylethynyl)phenyl)(5-phenylfur-
an-2-yl)methoxy)silane (1o): (5-Phenylfuran-2-yl)lithium was used
instead of 2-furanyllithium: yield 77%; yellow oil; 1H NMR (300 MHz,
CDCl3, Me4Si) δ 0.10 (s, 3H), 0.14 (s, 3H), 0.94 (s, 9H), 6.00 (d, J =
3.3 Hz, 1H), 6.41 (s, 1H), 6.53 (d, J = 3.3 Hz, 1H), 7.22−7.51 (m,
11H), 7.62 (d, J = 7.5 Hz, 2H), 7.83 (d, J = 7.8 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si) δ −4.9, 18.4, 25.8, 68.5, 87.0, 94.7, 105.8,
109.0, 120.9, 123.2, 123.6, 126.6, 127.0, 127.3, 128.25, 128.31, 128.6,
131.0, 131.5, 131.6, 143.7, 153.1, 156.4; HRMS (EI) calcd for
C31H32O2Si 464.2172, found 464.2178.
(Z)-3-(1-(tert-Butyldimethylsilyloxy)-3-p-tolylnaphthalen-2-
yl)acrylaldehyde (2d): yield 79% (Z/E = 25:1); yellow oil. Major
isomer: H NMR (400 MHz, CDCl3, Me4Si) δ 0.15 (s, 6H), 1.14 (s,
1
9H), 2.49 (s, 3H), 6.17 (dd, J = 10.8, 8.2 Hz, 1H), 7.29−7.41 (m, 5H),
7.57−7.61 (m, 3H), 7.87−7.90 (m, 1H), 8.22−8.24 (m, 1H), 9.82 (d, J
= 8.4 Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si) δ −3.0, 18.4,
21.1, 26.0, 120.4, 122.9, 123.7, 125.5, 126.9, 127.3, 127.7, 128.9, 129.8,
130.6, 134.4, 137.2, 137.4, 139.6, 145.6, 149.3, 194.0. Minor isomer:
1H NMR (400 MHz, CDCl3, Me4Si) 9.61 (d, J = 8.0 Hz, 1H); IR
(neat) 2955, 2930, 2858, 1679, 1490, 1374, 1258, 1090, 827, 751, 704
cm−1; HRMS (EI) calcd for C26H30O2Si 402.2015, found 402.2013.
( Z ) - 3 - ( 1 - ( t e r t - B u t y l d i m e t h y l s i l y l o x y ) - 3 - ( 3 , 5 -
dimethoxyphenyl)naphthalen-2-yl)acrylaldehyde (2e): yield
85% (Z/E = 25:1); yellow solid. Major isomer: 1H NMR (400
MHz, CDCl3, Me4Si) δ 0.06 (s, 6H), 1.05 (s, 9H), 3.80 (s, 6H), 6.11
(dd, J = 11.2, 8.0 Hz, 1H), 6.48 (t, J = 2.4 Hz, 1H), 6.52 (m, 2H), 7.32
(d, J = 11.6 Hz, 1H), 7.48−7.55 (m, 3H), 7.80−7.82 (m, 1H), 8.12−
8.15 (m, 1H), 9.75 (d, J = 8.0 Hz, 1H); 13C NMR (100.6 MHz,
CDCl3, Me4Si) δ −3.1, 18.4, 26.0, 55.3, 99.3, 108.2, 120.1, 122.6,
123.8, 125.6, 127.1, 127.4, 127.7, 130.5, 134.3, 139.5, 142.3, 145.5,
149.2, 160.4, 194.0. Minor isomer: 1H NMR (400 MHz, CDCl3,
Me4Si) 6.34 (dd, J = 16.2, 7.6 Hz, 1H), 9.54 (d, J = 7.6 Hz, 1H);
HRMS (EI) calcd for C27H32O4Si 448.2070, found 448.2069.
tert-Butyl(furan-2-yl(2-(phenylethynyl)cyclopent-1-enyl)-
methoxy)dimethylsilane (1p): yield 57%; brown oil; 1H NMR (300
MHz, CDCl3, Me4Si) δ 0.11 (s, 6H), 0.92 (s, 9H), 1.85−1.95 (m, 2H),
2.37−2.68 (m, 4H), 5.89 (s, 1H), 6.22 (m, 1H), 6.29−6.30 (m, 1H),
7.28−7.33 (m, 4H), 7.42−7.45 (m, 2H); 13C NMR (74.5 MHz,
CDCl3, Me4Si) δ −5.1, −4.9, 18.3, 22.4, 25.8, 31.2, 36.7, 66.7, 85.2,
94.5, 105.7, 110.0, 120.3, 123.5, 128.0, 128.3, 131.4, 141.6, 150.8,
155.6; HRMS (EI) calcd for C24H30O2Si 378.2015, found 378.2016.
Typical Procedure for Au(I)-Catalyzed Cyclization Reactions
of TBS-Protected (o-Alkynyl)phenyl 2-Furylcarbinols 1 to
Naphthol Derivatives 2. To a solution of tert-butyl(furan-2-yl(2-
(phenylethynyl)phenyl)methoxy)dimethylsilane (1a) (77.7 mg, 0.2
mmol) in toluene (2 mL) was added gold catalyst (acetonitrile)[(2-
biphenyl)di-tert-butylphosphine]gold(I) hexafluoroantimonate (3.08
mg, 0.004 mmol). The resulting solution was stirred at room
temperature for 2 h. Then the solvent was evaporated under reduced
pressure and the residue was purified by chromatography on silica gel
(petroleum/ethyl acetate = 20:1) to afford 69 mg of the product 3-(1-
(tert-Butyldimethylsilyloxy)-3-phenylnaphthalen-2-yl) acrylaldehyde
(Z)-3-(8′-(tert-Butyldimethylsilyloxy)-1,6′-binaphthyl-7′-yl)-
acrylaldehyde (2f): yield 62% (Z/E = 25:1); red oil. Major isomer:
1H NMR (400 MHz, CDCl3, Me4Si) δ 0.10 (s, 6H), 1.04 (s, 9H), 5.87
(dd, J = 11.2, 8.0 Hz, 1H), 7.03 (d, J = 11.2 Hz, 1H), 7.32−7.36 (m,
1H), 7.40−7.47 (m, 3H), 7.49−7.57 (m, 4H), 7.79−7.81 (m, 1H),
7.87−7.90 (m, 2H), 8.19−8.22 (m, 1H), 9.72 (d, J = 8.0 Hz, 1H); 13C
NMR (75.5 MHz, CDCl3, Me4Si) δ −3.2, −3.0, 18.4, 26.0, 121.5,
123.6, 123.8, 125.2, 125.66, 125.72, 125.9, 126.3, 127.3, 127.4, 127.4,
127.7, 128.2, 128.3, 130.5, 131.8, 133.4, 134.4, 137.9, 138.1, 144.6,
149.1, 193.7. Minor isomer: 1H NMR (400 MHz, CDCl3, Me4Si) 6.02
(dd, J = 16.4, 7.8 Hz, 1H), 9.36 (d, J = 7.8 Hz, 1H); IR (neat) 2955,
2930, 2858, 1679, 1377, 1260, 1107, 828, 779, 735 cm−1; HRMS
(MALDI/DHB) calcd for C29H31O2Si [M + H]+ 439.2088, found
439.2093.
1
(2a) in 89% yield (Z/E = 50:1) as a yellow solid. Major isomer: H
(Z)-3-(1-(tert-Butyldimethylsilyloxy)-3-(thiophene-2-yl)-
naphthalen-2-yl)acrylaldehyde (2g): yield 84% (Z/E = 33:1);
yellow oil. Major isomer: 1H NMR (400 MHz, CDCl3, Me4Si) δ 0.32
(s, 6H), 1.31 (s, 9H), 6.47 (dd, J = 11.2, 8.0 Hz, 1H), 7.34−7.38 (m,
2H), 7.62−7.63 (m, 1H), 7.71−7.79 (m, 3H), 7.95 (s, 1H), 8.06−8.08
(m, 1H), 8.38 (d, J = 7.2 Hz, 1H), 9.99 (d, J = 8.0 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si) δ −3.0, 18.4, 26.0, 120.0, 123.4, 123.8,
125.9, 126.2, 127.2, 127.4, 127.5, 127.8, 128.1, 131.3, 131.8, 134.2,
141.7, 145.1, 149.4, 194.0. Minor isomer: 1H NMR (400 MHz, CDCl3,
Me4Si) 6.73 (dd, J = 16.4, 8.4 Hz, 1H), 9.87 (d, J = 8.4 Hz, 1H);
HRMS (EI) calcd for C23H26O2SSi 394.1423, found 394.1421.
(Z)-3-(1-(tert-Butyldimethylsilyloxy)-3-cyclohexenylnaph-
thalen-2-yl)acrylaldehyde (2h): yield 74% (Z/E = 25:1); yellow oil.
NMR (400 MHz, CDCl3, Me4Si) δ 0.09 (s, 6H), 1.07 (s, 9H), 6.10
(dd, J = 11.2, 8.4 Hz, 1H), 7.31 (d, J = 11.6 Hz, 1H), 7.38−7.43 (m,
5H), 7.52−7.55 (m, 3H), 7.82−7.84 (m, 1H), 8.15−8.17 (m, 1H),
9.75 (d, J = 8.0 Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si) δ
−3.0, 18.4, 26.0, 120.3, 123.0, 123.8, 125.6, 127.0, 127.37, 127.38,
127.7, 128.2, 129.9, 130.6, 134.4, 139.6, 140.3, 145.4, 149.3, 194.0.
Minor isomer: 1H NMR(400 MHz, CDCl3, Me4Si) 6.23 (dd, J = 16.6,
8.4 Hz, 1H), 9.53 (d, J = 8.0 Hz, 1H); HRMS (EI) calcd for
C25H28O2Si 388.1859, found 388.1862.
(Z)-3-(1-(tert-Butyldimethylsilyloxy)-3-(4-chlorophenyl)-
naphthalen-2-yl)acrylaldehyde (2b): yield 91% (Z/E = 33:1); red
oil. Major isomer: 1H NMR (400 MHz, CDCl3, Me4Si) δ 0.06 (s, 6H),
1.05 (s, 9H), 6.09 (dd, J = 11.6, 8.2 Hz, 1H), 7.26 (d, J = 11.2 Hz, 1H),
7.29−7.31 (m, 2H), 7.37−7.39 (m, 2H), 7.48−7.53 (m, 3H), 7.79−
7.82 (m, 1H), 8.12−8.15 (m, 1H), 9.71 (d, J = 8.0 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si) δ −3.0, 18.4, 26.0, 120.0, 122.9, 123.8,
125.8, 127.1, 127.5, 127.8, 128.4, 130.9, 131.2, 133.6, 134.3, 138.3,
138.8, 145.0, 149.5, 193.7. Minor isomer: 1H NMR(400 MHz, CDCl3,
Me4Si) 6.23 (dd, J = 16.4, 7.6 Hz, 1H), 9.52 (d, J = 8.0 Hz, 1H);
HRMS (EI) calcd for C25H2735ClO2Si: 422.1469, found 422.1465.
(Z)-3-(3-(2-Bromophenyl)-1-(tert-butyldimethylsilyloxy)-
naphthalen-2-yl)acrylaldehyde (2c): yield 64% (Z/E = 33:1);
1
Major isomer: H NMR (400 MHz, CDCl3, Me4Si) δ 0.15 (s, 6H),
1.11 (s, 9H), 1.72−1.75 (m, 4H), 2.21−2.22 (m, 4H), 5.84 (s, 1H),
6.21 (dd, J = 11.2, 8.2 Hz, 1H), 7.40 (s, 1H), 7.49−7.55 (m, 2H), 7.65
(d, J = 11.2 Hz, 1H), 7.81 (d, J = 8.0 Hz, 1H), 8.12 (d, J = 8.4 Hz,
1H), 9.66 (d, J = 8.0 Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si)
δ −2.9, 18.5, 21.9, 22.8, 25.5, 26.0, 30.3, 120.0, 120.9, 123.5, 125.1,
126.7, 127.0, 127.5, 129.1, 130.4, 134.7, 138.2, 142.9, 145.5, 149.2,
193.5. Minor isomer: 1H NMR (400 MHz, CDCl3, Me4Si) 6.99 (dd, J
= 16.4, 8.4 Hz, 1H), 9.74 (d, J = 7.6 Hz, 1H); IR (neat) 2931, 2858,
2360, 1676, 1373, 1264, 1104, 829, 734, 702 cm−1; HRMS (EI) calcd
for C25H32O2Si: 392.2172, found 392.2171.
1
yellow oil. Major isomer: H NMR (300 MHz, CDCl3, Me4Si) δ 0.09
(s, 3H), 0.11 (s, 3H), 1.05 (s, 9H), 5.95 (dd, J = 11.4, 8.3 Hz, 1H),
7.19−7.40 (m, 5H), 7.52−7.55 (m, 2H), 7.63 (d, J = 8.3 Hz, 1H),
7.79−7.82 (m, 1H), 8.14−8.17 (m, 1H), 9.64 (d, J = 8.1 Hz, 1H); 13C
NMR (75.5 MHz, CDCl3, Me4Si) δ −3.2, −3.0, 18.4, 26.0, 120.6,
122.5, 123.7, 123.8, 125.8, 127.3, 127.37, 127.42, 127.8, 129.4, 130.7,
131.2, 132.6, 134.2, 138.9, 141.1, 144.3, 149.2, 194.0. Minor isomer:
1H NMR (300 MHz, CDCl3, Me4Si) 9.48 (d, J = 7.8 Hz, 1H); IR
(neat) 3054, 2956, 2930, 1679, 1376, 1258, 1105, 826, 732 cm−1;
HRMS (EI) calcd for C25H2779BrO2Si 466.0964, found 466.0967.
(Z)-3-(1-(tert-Butyldimethylsilyloxy)-3-cyclopropylnaphtha-
len-2-yl)acrylaldehyde (2i). yield 80% (Z/E = 25:1); yellow solid.
1
Major isomer: H NMR (400 MHz, CDCl3, Me4Si) δ 0.20 (s, 6H),
0.90−0.91 (m, 2H), 1.11−1.17 (m, 11H), 2.00−2.07 (m, 1H), 6.39
(dd, J = 11.2, 8.0 Hz, 1H), 7.33 (s, 1H), 7.52−7.60 (m, 2H), 7.83−
7.87 (m, 2H), 8.17 (d, J = 8.0 Hz, 1H), 9.76 (d, J = 8.0 Hz, 1H); 13C
NMR (100.6 MHz, CDCl3, Me4Si) δ −3.1, 7.8, 14.5, 18.3, 25.9, 118.3,
122.3, 123.5, 124.8, 126.4, 126.9, 127.2, 130.9, 134.5, 139.6, 145.1,
148.6, 194.2. Minor isomer: 1H NMR (400 MHz, CDCl3, Me4Si) 7.18
1919
dx.doi.org/10.1021/jo202541p | J. Org. Chem. 2012, 77, 1915−1921

The Journal of Organic Chemistry
Article
(dd, J = 16.2, 8.0 Hz, 1H), 9.89 (d, J = 8.0 Hz, 1H); IR (neat) 2955,
2930, 2858, 1679, 1379, 1256, 1011, 827, 780, 736 cm−1; HRMS (EI)
calcd for C22H28O2Si 352.1859, found 352.1860.
= 11.2, 8.2 Hz, 1H), 6.93 (s, 1H), 7.20−7.36 (m, 6H), 9.63 (d, J = 8.4
Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si) δ −3.1, 18.4, 25.4,
25.9, 31.2, 33.4, 120.0, 122.6, 127.1, 128.1, 129.9, 130.4, 134.1, 140.8,
1
(Z)-3-(3-Butyl-1-(tert-butyldimethylsilyloxy)naphthalen-2-
yl)acrylaldehyde (2j): yield 68% (Z/E = 14:1); yellow solid. Major
isomer: 1H NMR (400 MHz, CDCl3, Me4Si) δ 0.06 (s, 6H), 0.93 (t, J
= 7.6 Hz, 3H), 1.03 (s, 9H), 1.12−1.42 (m, 2H), 1.58−1.64 (m, 2H),
2.71 (t, J = 7.6 Hz, 2H), 6.24 (dd, J = 11.2, 8.4 Hz, 1H), 7.37 (s, 1H),
7.40−7.49 (m, 2H), 7.57 (d, J = 10.8 Hz, 1H), 7.74 (d, J = 8.4 Hz,
1H), 8.04 (d, J = 8.4 Hz, 1H), 9.57 (d, J = 8.0 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si) δ −3.1, 13.9, 18.4, 22.6, 26.0, 32.5, 33.9,
121.0, 121.2, 123.6, 124.8, 126.3, 126.9, 127.1, 131.4, 134.6, 139.1,
144.8, 148.7, 194.1. Minor isomer: 1H NMR (400 MHz, CDCl3,
Me4Si) 6.80 (dd, J = 16.0, 8.0 Hz, 1H), 9.75 (d, J = 8.0 Hz); IR (neat)
2956, 2930, 2859, 1682, 1375, 1258, 1107, 1022, 830, 781, 748 cm−1;
HRMS (EI) calcd for C23H32O2Si 368.2172, found 368.2169.
(Z)-3-(1-(tert-Butyldimethylsilyloxy)-7-fluoro-3-phenylnaph-
thalen-2-yl)acrylaldehyde (2k): yield >99% (Z/E = 33:1); yellow
141.7, 145.9, 147.6, 149.3, 193.9. Minor isomer: H NMR (400 MHz,
CDCl3, Me4Si) 6.21 (dd, J = 16.4, 7.6 Hz,1H), 9.42 (d, J = 8.0 Hz,
1H); HRMS (EI) calcd for C24H30O2Si 378.2015, found 378.2020.
Synthesis of Benzocoumarin 4. To a solution of (Z)-3-(1-(tert-
butyldimethylsilyloxy)-3-phenylnaphthalen-2-yl)-acrylaldehyde (2a)
(117 mg, 0.3 mmol) in THF were added 3 Å MS (75 mg), PDC
(451.4 mg, 1.2 mmol), and TBAF (0.3 mL, 0.3 mmol, 1.0 M in THF)
successively, and the mixture was stirred overnight. After the reaction
was complete as monitored by thin-layer chromatography, the mixture
was filtered and the filter cake was washed with acetone. The solvent
was evaporated and the residue was purified by chromatography on
silica gel (petroleum ether/ethyl acetate = 5:1) to afford 5-phenyl-2H-
benzo[h]chromen-2-one 4 (55.0 mg, 67%) as a yellow solid: 1H NMR
(400 MHz, CDCl3, Me4Si) δ 6.42 (dd, J = 10.0, 1.6 Hz, 1H), 7.41−
7.53 (m, 5H), 7.61−7.64 (m, 3H), 7.83−7.88 (m, 2H), 8.54 (d, J = 7.2
Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si) δ 113.2, 115.3, 122.3,
122.4, 124.6, 127.0, 127.8, 128.0, 128.6, 129.1, 129.8, 134.3, 136.9,
138.2, 142.6, 151.9, 160.7; HRMS (EI) calcd for C19H12O2 272.0837,
found 272.0836.
1
solid. Major isomer: H NMR (300 MHz, CDCl3, Me4Si) δ 0.08 (s,
6H), 1.05 (s, 9H), 6.08 (dd, J = 11.1, 8.4 Hz, 1H), 7.26−7.41 (m, 7H),
7.51 (s, 1H), 7.72−7.83 (m, 2H), 9.71 (d, J = 8.4 Hz, 1H); 13C NMR
(75.5 MHz, CDCl3, Me4Si) δ −3.0, 18.4, 25.9, 107.5 (d, J = 22.6 Hz),
117.7 (d, J = 25.4 Hz), 121.2, 122.8 (d, J = 0.8 Hz), 127.5, 127.9 (d, J
= 8.5 Hz), 128.2, 129.9, 130.3 (d, J = 8.5 Hz), 130.9, 131.3 (d, J = 2.7
Hz), 138.9 (d, J = 2.7 Hz), 140.0, 145.0, 148.7 (d, J = 5.4 Hz), 160.6
(d, J = 246.9 Hz), 193.6. Minor isomer: 1H NMR (300 MHz, CDCl3,
Me4Si) 6.23 (dd, J = 16.2, 7.8 Hz, 1H), 9.51 (d, J = 7.8 Hz, 1H);
HRMS (EI) calcd for C25H27FO2Si 406.1764, found 406.1767.
(Z)-3-(1-(tert-Butyldimethylsilyloxy)-6,7-dimethoxy-3-phe-
nylnaphthalen-2-yl)acrylaldehyde (2l): yield 80% (Z/E = 11:1);
Synthesis of 1-Naphthol Derivative 5. To a solution of (Z)-3-
(1-(tert-butyldimethylsilyloxy)-3-phenylnaphthalen-2-yl)-acrylaldehyde
(2a) (117 mg, 0.3 mmol) in DCM (2 mL) and MeOH (2 mL) were
added CeCl3·7H2O (335 mg, 0.9 mmol) and NaBH4 (34 mg, 0.9
mmol) successively at 0 °C. The resulting solution was warmed to
room temperature and stirred for 3 h. The mixture was quenched with
water and extracted with ether. The combined organic phase was
washed with brine solution and dried over anhydrous Na2SO4. The
solvent was evaporated, and the residue was purified by chromatog-
raphy on silica gel (petroleum ether/ethyl acetate = 5:1) to afford (Z)-
3-(1-(tert-butyldimethylsilyloxy)-3-phenylnaphthalen-2-yl)-prop-2-en-
1
yellow solid. Major isomer: H NMR (300 MHz, CDCl3, Me4Si) δ
0.08 (s, 6H), 1.05 (s, 9H), 4.01 (s, 3H), 4.03 (s, 3H), 6.06 (dd, J =
11.1, 8.4 Hz, 1H), 7.11 (s, 1H), 7.27−7.43 (m, 8H), 9.73 (d, J = 8.4
Hz, 1H); 13C NMR (75.5 MHz, CDCl3, Me4Si) δ −2.94, −2.89, 18.4,
25.9, 55.9, 70.5, 102.8, 106.2, 118.8, 121.6, 122.2, 127.1, 128.0, 129.9,
130.3, 130.5, 138.0, 140.5, 145.8, 148.2, 149.2, 150.6, 194.1. Minor
1
1-ol (107.9 mg, 92%) as a yellow oil: H NMR (400 MHz, CDCl3,
Me4Si) δ 0.19 (s, 6H), 1.16 (s, 9H), 1.33 (bs, 1H), 3.91 (d, J = 6.4 Hz,
2H), 5.85 (dt, J = 11.2, 2.8 Hz, 1H), 6.54 (d, J = 11.2 Hz, 1H), 7.36−
7.54 (m, 8H), 7.83−7.85 (m, 1H), 8.19−8.21 (m, 1H); 13C NMR
(100.6 MHz, CDCl3, Me4Si) δ −3.1, 18.6, 26.1, 60.4, 122.4, 122.6,
123.2, 125.1, 126.3, 126.9, 127.1, 127.5, 127.6, 127.8, 129.8, 132.2,
133.7, 139.9, 141.4, 148.8; HRMS (EI) calcd for C25H30O2Si 390.2015,
found 390.2018.
1
isomer: H NMR (300 MHz, CDCl3, Me4Si) 6.21 (dd, J = 16.4, 8.1
Hz, 1H), 9.48 (d, J = 7.5 Hz, 1H); HRMS (EI) calcd for C27H32O4Si
448.2070, found 448.2067.
(Z)-3-(5-(tert-Butyldimethylsilyloxy)-7-phenylnaphtho[2,3-
d][1,3]dioxol-6-yl)acrylaldehyde (2m): yield 77% (Z/E = 20:1);
white solid. Major isomer: 1H NMR (300 MHz, CDCl3, Me4Si) δ 0.20
(s, 6H), 1.17 (s, 9H), 6.14−6.21 (m, 3H), 7.21 (s, 1H), 7.39−7.54 (m,
8H), 9.83 (d, J = 8.1 Hz, 1H); 13C NMR (75.5 MHz, CDCl3, Me4Si) δ
−3.0, 18.4, 26.0, 100.3, 101.3, 103.8, 119.2, 122.3, 123.7, 127.2, 128.1,
129.9, 130.4, 131.9, 138.3, 140.4, 145.6, 147.7, 148.68, 148.72, 194.0.
Minor isomer: 1H NMR (300 MHz, CDCl3, Me4Si) 6.29 (dd, J = 16.4,
8.4 Hz, 1H), 9.61 (d, J = 8.1 Hz, 1H); HRMS (EI) calcd for
C26H28O4Si 432.1757, found 432.1760.
(Z)-4-(1-(tert-Butyldimethylsilyloxy)-3-phenylnaphthalen-2-
yl)but-3-en-2-one (2n): yield 78%; yellow oil; 1H NMR (300 MHz,
CDCl3, Me4Si) δ 0.10 (s, 6H), 1.07 (s, 9H), 1.86 (s, 3H), 6.13 (d, J =
12.3 Hz, 1H), 6.92 (d, J = 12.3 Hz, 1H), 7.35−7.39 (m, 5H), 7.46−
7.50 (m, 3H), 7.78−7.81 (m, 1H), 8.10−8.14 (m, 1H); 13C NMR
(75.5 MHz, CDCl3, Me4Si) δ −3.0, 18.4, 26.0, 28.6, 122.4, 122.9,
123.4, 125.3, 126.9, 127.09, 127.12, 127.8, 128.0, 129.8, 132.7, 134.2,
138.2, 139.1, 140.8, 148.8, 199.9; HRMS (MALDI/DHB) calcd for
C26H31O2Si [M + H]+ 403.2088, found 403.2098.
To a solution of above alcohol (105 mg, 0.27 mmol) in THF (2.7
mL) was added TBAF (0.27 mmol, 0.27 mL, 1.0 M solution in THF)
at 0 °C. The resulting solution was warmed to room temperature and
stirred for 1 h. The mixture was quenched with water and extracted
with ether. The combined organic phase was washed with brine
solution and dried over anhydrous Na2SO4. The solvent was
evaporated and the residue was purified by chromatography on silica
gel (petroleum ether/ethyl acetate/dichloromethane = 3:1:1) to afford
(Z)-2-(3-hydroxyprop-1-enyl)-3-phenylnaphthalen-1-ol 5 (63 mg,
1
85%) as a yellow oil: H NMR (400 MHz, CDCl3, Me4Si) δ 2.43
(bs, 1H), 4.03 (d, J = 6.4 Hz, 2H), 6.00 (dt, J = 11.2, 7.6 Hz, 1H), 6.31
(d, J = 11.2 Hz, 1H), 6.73 (s, 1H), 7.30−7.46 (m, 8H), 7.73−7.75 (m,
1H), 8.23−8.25 (m, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si) δ
59.7, 115.4, 120.7, 122.6, 123.6, 125.4, 126.8, 127.1, 127.4, 127.5,
127.9, 129.6, 133.1, 133.6, 139.5, 141.0, 148.3; HRMS (ESI) calcd for
C19H15O2 [M − H]− 275.1078, found 275.10717.
2-(Allyloxy(2-(phenylethynyl)phenyl)methyl)furan (6). Com-
pound 6 was prepared by the reaction of the corresponding alcohol
(Z)-3-(1-(tert-Butyldimethylsilyloxy)-3-phenylnaphthalen-2-
yl)-1-phenylprop-2-en-1-one (2o): yield 97%; yellow solid; mp
1
1
with allyl bromide using NaH as base: H NMR (CDCl3, Me4Si, 300
88−89 °C; H NMR (400 MHz, CDCl3, Me4Si) δ 0.40 (s, 6H), 1.34
MHz) δ 4.08 (d, J = 5.7 Hz, 2H), 5.20 (d, J = 10.5 Hz, 1H), 5.32 (dd, J
= 17.6, 1.5 Hz, 1H), 5.93−6.02 (m, 1H), 6.07 (s, 1H), 6.13 (d, J = 3.0
Hz, 1H), 6.27−6.29 (m, 1H), 7.26−7.40 (m, 6H), 7.42−7.53 (m, 3H),
7.75 (d, J = 7.8 Hz, 1H); 13C NMR (75.5 MHz, CDCl3, Me4Si) δ
70.00, 73.75, 86.74, 94.49, 108.60, 110.10, 117.45, 122.06, 123.06,
126.74, 127.64, 128.34, 128.37, 128.65, 131.42, 131.93, 134.37, 140.86,
142.56, 153.85; HRMS (ESI) calcd for C22H18O2Na [M + Na]+
337.1204, found 337.1199.
(s, 9H), 6.98 (dd, J = 12.0, 1.2 Hz, 1H), 7.26−7.30 (m, 1H), 7.38−
7.67 (m, 11H), 7.77 (d, J = 8.0 Hz, 2H), 7.94 (d, J = 8.0 Hz, 1H), 8.30
(d, J = 7.6 Hz, 1H); 13C NMR (100.6 MHz, CDCl3, Me4Si) δ −3.1,
18.6, 26.1, 122.8, 123.0, 123.2, 124.8, 126.4, 126.5, 127.0, 127.59,
127.61, 128.1, 130.1, 131.9, 134.1, 137.5, 139.4, 141.2, 149.1, 191.2;
HRMS (EI) calcd for C31H32O2Si 464.2172, found 464.2170.
(Z)-3-(4-(tert-Butyldimethylsilyloxy)-6-phenyl-2,3-dihydro-
1H-inden-5-yl)acrylaldehyde (2p): yield 59% (Z/E = 33:1); yellow
1
solid. Major somer: H NMR (400 MHz, CDCl3, Me4Si) δ 0.09 (s,
(Z)-3-(1-(Allyloxy)-3-phenylnaphthalen-2-yl)acrylaldehyde
6H), 0.95 (s, 9H), 2.06−2.13 (m, 2H), 2.90−2.97 (m, 4H), 5.94 (dd, J
(7): yield 70% (Z/E = 50:1); white soild. Major isomer: 1H NMR (400
1920
dx.doi.org/10.1021/jo202541p | J. Org. Chem. 2012, 77, 1915−1921

The Journal of Organic Chemistry
Article
MHz, CDCl3, Me4Si) δ 4.38 (dd, J = 5.6, 0.8 Hz, 2H), 5.24 (dd, J =
10.8, 0.8 Hz, 1H), 5.39 (dd, J = 17.2, 0.8 Hz, 1H), 5.98−6.08 (m, 1H),
6.13 (dd, J = 11.4, 8.0 Hz, 1H), 7.24 (d, J = 11.2 Hz, 1H), 7.25−7.43
(m, 5H), 7.54−7.57 (m, 2H), 7.66 (s, 1H), 7.84−7.87 (m, 1H), 8.17−
8.19 (m, 1H), 9.81 (d, J = 8.0 Hz, 1H); 13C NMR (100.6 MHz,
CDCl3, Me4Si) δ 74.58, 117.79, 122.92, 122.94, 125.06, 126.67,
127.05, 127.59, 127.65, 128.03, 128.26, 129.88, 130.36, 133.09, 134.60,
(k) Li, Z.; Brouwer, C.; He, C. Chem. Rev. 2008, 108, 3239. (l) Muzart,
J. Tetrahedron 2008, 64, 5815. (m) Shen, H. C. Tetrahedron 2008, 64,
3885. (n) Shapiro, N.; Toste, D. Synlett 2010, 675. (o) Rudolph, M.;
Hashmi, A. S. K. Chem. Commun. 2011, 47, 6536. (p) Alcaide, B.;
Almendros, P.; Alonso, J. M. Org. Biomol. Chem. 2011, 9, 4405.
(q) Corma, A.; Leyva-Per
1657.
́
ez, A.; Sabater, M. J. Chem. Rev. 2011, 111,
1
139.71, 139.99, 142.70, 153.11, 193.49. Minor isomer: H NMR (400
(10) For examples of gold-catalyzed intramolecular reactions of
alkynes tethered to five-membered ring heterocycles, see: (a) England,
D. B.; Padwa, A. Org. Lett. 2008, 10, 3631. (b) Verniest, G.; England,
D.; De Kimpe, N.; Padwa, A. Tetrahedron 2010, 66, 1496. (c) Gruit,
MHz, CDCl3, Me4Si) δ 6.79 (dd, J = 16.0, 8.0 Hz, 1H), 9.50 (d, J = 7.6
Hz, 1H); HRMS (ESI) calcd for C22H18O2Na [M + Na]+ 337.1204,
found 337.1203.
M.; Michalik, D.; Kruger, K.; Spannenberg, A.; Tillack, A.; Pews-
̈
Davtyan, A.; Beller, M. Tetrahedron 2010, 66, 3341. (d) Borsini1, E.;
Broggini, G.; Fasana1, A.; Baldassarri, C.; Manzo, A. M.; Perboni, A. D.
Beilstein J. Org. Chem. 2011, 7, 1468.
ASSOCIATED CONTENT
* Supporting Information
X-ray crystallography of compound 2a and spectroscopic
characterization of all new compounds. This material is
available free of charge via the Internet at http://pubs.acs.org.
■
S
(11) (a) Chen, Y.; Lu, Y.; Li, G.; Liu, Y. Org. Lett. 2009, 11, 3838.
(b) Chen, Y.; Li, G.; Liu, Y. Adv. Synth. Catal. 2011, 353, 392.
(c) Chen, Y.; Liu, Y. J. Org. Chem. 2011, 76, 5274.
(12) For our recent report on the cascade reaction of o-(alkynyl)
phenyl furanyl ketones with Grignard reagents leading to 7-
oxabicyclo[2.2.1]hepta-2,5-diene derivatives, see: Chen, Y.; Wang, L.;
Liu, Y.; Li, Y. Chem.Eur. J. 2011, 17, 12582.
AUTHOR INFORMATION
Corresponding Author
*Fax: (+86) 021-64166128. E-mail: yhliu@mail.sioc.ac.cn.
Notes
■
(13) For selected papers, see: (a) Hashmi, A. S. K.; Frost, T. M.; Bats,
J. W. J. Am. Chem. Soc. 2000, 122, 11553. (b) Hashmi, A. S. K.; Frost,
T. M.; Bats, J. W. Org. Lett. 2001, 3, 3769. (c) Hashmi, A. S. K.; Ding,
L.; Fischer, P.; Bats, J. W.; Frey, W. Chem.Eur. J. 2003, 9, 4339.
́
(d) Hashmi, A. S. K.; Weyrauch, J. P.; Rudolph, M.; Kurpejovic, E.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Angew. Chem., Int. Ed. 2004, 43, 6545. (e) Hashmi, A. S. K.; Rudolph,
We thank the National Natural Science Foundation of China
(Grant Nos. 20872163, 20732008, 20821002, and 21125210),
the Chinese Academy of Science, and the Major State Basic
Research Development Program (Grant No. 2011CB808700)
for financial support.
M.; Weyrauch, J. P.; Wolfle, M.; Frey, W.; Bats, J. W. Angew. Chem.,
̈
Int. Ed. 2005, 44, 2798. (f) Hashmi, A. S. K.; Weyrauch, J. P.;
Kurpejovic, E.; Frost, T. M.; Miehlich, B.; Frey, W.; Bats, J. W.
Chem.Eur. J. 2006, 12, 5806. (g) Hashmi, A. S. K.; Blanco, M. C.;
Kurpejovic, E.; Frey, W.; Bats, J. W. Adv. Synth. Catal. 2006, 348, 709.
(h) Hashmi, A. S. K.; Haufe, P.; Schmid, C.; Nass, A. R.; Frey, W.
Chem.Eur. J. 2006, 12, 5376. (i) Hashmi, A. S. K.; Salathe,
́
R.; Frey,
REFERENCES
■
W. Chem.Eur. J. 2006, 12, 6991. (j) Carretin, S.; Blanco, M. C.;
Corma, A.; Hashmi, A. S. K. Adv. Synth. Catal. 2006, 348, 1283.
(k) Hashmi, A. S. K.; Rudolph, M.; Bats, J. W.; Frey, W.; Rominger, F.;
Oeser, T. Chem.Eur. J. 2008, 14, 6672. (l) Hashmi, A. S. K.;
Rudolph, M.; Siehl, H.; Tanaka, M.; Bats, J. W.; Frey, W. Chem.Eur.
J. 2008, 14, 3703.
(1) (a) Son, J. K.; Jung, S. J.; Jung, J. H.; Fang, Z.; Lee, C. S.; Seo, C.
S.; Moon, D. C.; Min, B. S.; Kim, M. R.; Woo, M. H. Chem. Pharm.
Bull. 2008, 56, 213. (b) Itokawa, H.; Mihara, K.; Takeya, K. Chem.
Pharm. Bull. 1983, 31, 2353. (c) Itokawa, H.; Ibraheim, Z. Z.; Qiao, Y.-
F.; Takeya, K. Chem. Pharm. Bull. 1993, 41, 1869. (d) Bringmann, G.;
Messer, K.; Wolf, K.; Muhlbacher, J.; Grune, M.; Brun, R.; Louis, A. M.
̈
̈
(14) For PtCl2-catalyzed cyclization of 2-(2-alkynylphenyl)furan
without opening the furan rings, see: Martín, B.; Nevado, C.;
Cardenas, D. J.; Echavarren, A. M. J. Am. Chem. Soc. 2003, 125, 5757.
́
(15) Ferrer, C.; Echavarren, A. M. Angew. Chem., Int. Ed. 2006, 45,
1105.
Phytochemistry 2002, 60, 389. (e) Boonsri, S.; Karalai, C.;
Ponglimanont, C.; Chantrapromma, S.; Kanjana-opas, A. J. Nat.
Prod. 2008, 71, 1173. (f) Rinehart, K. L. Jr. Acc. Chem. Res. 1972, 5,
57.
(2) (a) Ballantine, M.; Menard, M. L.; Tam, W. J. Org. Chem. 2009,
74, 7570. (b) Chen, C.; Martin, S. F. J. Org. Chem. 2006, 71, 4810.
(c) Akai, S.; Ikawa, T.; Takayanagi, S.; Morikawa, Y.; Mohri, S.;
Tsubakiyama, M.; Egi, M.; Wada, Y.; Kita, Y. Angew. Chem., Int. Ed.
2008, 47, 7673.
(3) Huang, X.; Xue, J. J. Org. Chem. 2007, 72, 3965.
(4) Mal, D.; Jana, A. K.; Mitra, P.; Ghosh, K. J. Org. Chem. 2011, 76,
3392.
(5) Chai, G.; Lu, Z.; Fu, C.; Ma, S. Chem.Eur. J. 2009, 15, 11083.
(6) Xu, H.; Li, S.; Liu, H.; Fu, H.; Jiang, Y. Chem. Commun. 2010, 46,
7617.
(16) See the Supporting Information.
(17) For naturally occurring substances bearing a benzocoumarin
skeleton, see: (a) Cordero-Vargas, A.; Quiclet-Sire, B.; Zard, S. Z. Org.
Biomol. Chem. 2005, 3, 4432. (b) Konno, F.; Ishikawa, T.; Kawaata,
M.; Yamaguchi, K. J. Org. Chem. 2006, 71, 9818. (c) Wang, X.; Bastow,
K. F.; Sun, C.-M.; Lin, Y.-L.; Yu, H.-J.; Don, M.-J.; Wu, T.-S.;
Nakamura, S.; Lee, K.-H. J. Med. Chem. 2004, 47, 5816. (d) Dong, Y.;
Shi, Q.; Liu, Y.-N.; Wang, X.; Bastow, K. F.; Lee, K.-H. J. Med. Chem.
2009, 52, 3586.
(18) (a) Tang, C. W.; Van slyke, S. A.; Chen, C. H. J. Appl. Phys.
1989, 65, 3610. (b) Chiyomi, M.; Toshinobu, M.; Yasuko, K.;
Kenichiro, T.; Hideyuki, Y.; Hitoshi, N.; Masatoshi, Y.; Akira, T. Chem.
Pharm. Bull. 2005, 53, 750. (c) Naik, R. H. S. B.; Kumar, H. N. H.;
Hosamani, K. M.; Mahadevan, K. M. ARKIVOC 2009, No. ii, 11.
(19) For the electrophilic attack in C3-position of the furan ring, see
ref 13g,h.
(7) Tsukamoto, H.; Kondo, Y. Org. Lett. 2007, 9, 4227.
(8) Sergeev, A. G.; Schulz, T.; Torborg, C.; Spannenberg, A.;
Neumann, H.; Beller, M. Angew. Chem., Int. Ed. 2009, 48, 7595.
(9) For recent reviews on gold-catalyzed reactions, see: (a) Hashmi,
A. S. K.; Hutchings, G. J. Angew. Chem., Int. Ed. 2006, 45, 7896.
(b) Gorin, D. J.; Toste, F. D. Nature 2007, 446, 395. (c) Hashmi, A. S.
(20) (a) Hashmi, A. S. K.; Rudolph, M.; Huck, J.; Frey, W.; Bats, J.
W.; Hamzic, M. Angew. Chem., Int. Ed. 2009, 48, 5848. (b) Hashmi, A.
́
S. K.; Yang, W.; Rominger, F. Angew. Chem., Int. Ed. 2011, 50, 5762.
K. Chem. Rev. 2007, 107, 3180. (d) Furstner, A.; Davies, P. W. Angew.
̈
Chem., Int. Ed. 2007, 46, 3410. (e) Jimen
M. Chem. Commun. 2007, 333. (f) Lipshutz, B. H.; Yamamoto, Y.
Chem. Rev. 2008, 108, 2793. (g) Jimenez-Nunez, E.; Echavarren, A. M.
Chem. Rev. 2008, 108, 3326. (h) Gorin, D. J.; Sherry, B. D.; Toste, F.
D. Chem. Rev. 2008, 108, 3351. (i) Arcadi, A. Chem. Rev. 2008, 108,
3266. (j) Patil, N. T.; Yamamoto, Y. Chem. Rev. 2008, 108, 3395.
́
ez-Nunez, E.; Echavarren, A.
́
̃
́
́
̃
1921
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