Approach to construct polysubstituted 1,2-dihydronaphtho[2,1-b]furans and their aerobic oxidative aromatization

Article abstract of DOI:10.1021/jo300827s

Triarylaminium salt was disclosed as an efficient initiator for the novel Friedel-Crafts alkylation/annulation cascade reaction between chalcone epoxides and 2-naphthols to construct polysubstituted 1,2-dihydronaphtho[2,1-b]furans. The DDQ/NaNO₂/O₂ catalytic system was first applied to the aerobic oxidative aromatization of heterocycles, and a simple and efficient one-pot tandem FC alkylation/annulation/aerobic oxidative aromatization procedure was also developed for the synthesis of complex naphtho[2,1-b]furans.

Full text of DOI:10.1021/jo300827s

Note
pubs.acs.org/joc
Approach to Construct Polysubstituted 1,2-
Dihydronaphtho[2,1‑b]furans and Their Aerobic Oxidative
Aromatization
Congde Huo,* Xiaolan Xu, Jinzhu An, Xiaodong Jia, Xicun Wang,* and Cheng Wang
Key Laboratory of Eco-Environment-Related Polymer Materials Ministry of Education; Key Laboratory of Polymer Materials of
Gansu Province; College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, Gansu 730070, China
S
* Supporting Information
ABSTRACT: Triarylaminium salt was disclosed as an efficient initiator for the novel Friedel−Crafts alkylation/annulation
cascade reaction between chalcone epoxides and 2-naphthols to construct polysubstituted 1,2-dihydronaphtho[2,1-b]furans. The
DDQ/NaNO2/O2 catalytic system was first applied to the aerobic oxidative aromatization of heterocycles, and a simple and
efficient one-pot tandem FC alkylation/annulation/aerobic oxidative aromatization procedure was also developed for the
synthesis of complex naphtho[2,1-b]furans.
riedel−Crafts (FC) alkylation is one of the oldest but also
is necessary to try to expand our method to electron-rich arenes.
Fmost powerful methods for carbon−carbon bond con- In this paper, we disclosed that naphthols were also good donors
in triarylaminium salt initiated FC alkylation. Also, very
interestingly, 2-naphthols gave 1,2-dihydronaphtho[2,1-b]furans
as products through a FC alkylation/annulation cascade reaction
with good yield (Scheme 1). The 1,2-dihydrofuran compounds
could then be easily and efficiently aromatized to the
corresponding naphtho[2,1-b]furans by employing a catalytic
amount of DDQ and molecular oxygen as terminal oxidant. It is
worth mentioning that the direct transformation of chalcone
epoxides with 2-naphthols into naphtho[2,1-b]furans could also
be carried out in one pot with a simple and efficient tandem
procedure (Scheme 1).
struction and has been widely used to generate important classes
of building blocks.1−5,6a With the recent increased environmental
and economic awareness, the development of greener and/or
sustainable methods for this fundamental transformation has
emerged in recent years. First of all, the development of FC
reactions using catalytic amounts of catalyst is highly desirable.2
At the same time, the developments of protocols that replace
toxic alkyl halides with more benign and environmentally
acceptable alkylating reagents were recently focused on π-
activated alcohols as pre-electrophiles.1c For example, benzyl
alcohols have become valuable pre-electrophiles in FC alkylation
through the formation of stabilized benzylic cation intermediates,
due to their availability, lower toxicity, and highly atom-
economical character3−5 (Scheme 1).
Naphthofuran derivatives have been isolated from various
natural sources, and are well-known for various types of
biological activity.7a−e,8 However, the reports on the synthesis
of naphthofurans, especially 1,2-dihydronaphthofurans, are
relatively limited.7f−l A few analogues of our one-pot prepared
polysubstituted naphtho[2,1-b]furans have been synthesized in
3−4 steps to evaluate their bioactive potential.8 Therefore, the
development of a versatile method to synthesize polysubstituted
1,2-dihydronaphtho[2,1-b]furans and naphtho[2,1-b]furans is
Our group has had a long-standing interest in the stable
triarylaminium salt initiated radical cation mediated trans-
formation and its synthetic potential.6 Recently, we demon-
strated that tris(4-bromophenyl)-aminium hexachloro-antimo-
nate (TBPA+.SbCl6 ) is a highly efficient (1−5 mol %) initiator
−
for the FC reaction between chalcone epoxides and heteroarenes
to construct complex β-heteroaryl α-ketols.6a The development
of the FC reaction of electron-rich arenes seems generally behind
that of relatively reactive electron-rich heteroarenes.2b Hence, it
Received: April 26, 2012
© XXXX American Chemical Society
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Scheme 1. To Make FC Alkylation Greener and/or Sustainable
highly desired. In this paper, 51 highly substituted 1,2-
dihydronaphtho[2,1-b]furan or naphtho[2,1-b]furan derivatives
were provided by our procedure in one step. Studies on the
bioactivity of these new naphthofuran derivatives are currently
underway.
Scheme 2). Compound 3a was easily and efficiently aromatized
to the corresponding naphtho[2,1-b]furans 5a by oxidation with
DDQ at room temperature in an hour. The aromatization of 4a
was also efficient but with a little higher temperature and a little
longer time. However, the use of a stoichiometric amount of
DDQ would detract from our effort to make a greener FC
reaction. Recently, the use of a catalytic amount of DDQ with
NaNO2 as co-catalyst under acidic conditions has been reported
for the aerobic oxidation of alcohol.10 We envisioned that this
system might also be utilized to promote aerobic oxidative
aromatization in our study. To our delight, after simple
screening, DDQ (5 mol %)/NaNO2 (10 mol %)/AcOH/O2
was identified as the optimal reaction condition, which
functioned as well as a stoichiometric amount of DDQ. This
should be the first application of the DDQ/NaNO2/O2 catalytic
system to the aerobic oxidative aromatization of heterocycles.
The structures of 3a, 4a, and 5a were fully characterized, and
stereochemistry of 3j, 4j, and 5j was determined by X-ray
crystallographic analysis.11
Naphthols were chosen as model compounds, because they
have been demonstrated to be good donors in some FC
alkylation examples.2a−c,9 We first investigated the reaction of
chalcone epoxide 1a with 1-naphthol under the previously
optimized reaction conditions (5 mol % TBPA+.SbCl6 in
−
Ch2Cl2 at room temperature).6a A similar FC reaction occurred,
and β-functionalized α-ketol diastereomers 3a′ and 4a′ were
given in high yield (90%, Scheme 2). However, when 2-naphthol
was employed as a nucleophile, to our surprise, a FC alkylation/
annulation cascade reaction occurred and 1,2-dihydronaphtho-
[2,1-b]furans 3a and 4a were achieved in good yield (71%,
Scheme 2. TBPA+.SbCl6− Induced Reaction between 1a and 1-
Naphthol or 2-Naphthol
Encouraged by the above-mentioned initial results, we started
to optimize the transformation. A range of solvents were
screened first. Optimization revealed that the reaction was quite
sensitive to the solvents. The highest yield and diastereoselec-
tivity was observed when CHCl3 was used as solvent (91%, 3:1).
We next explored the synthesis of naphtho[2,1-b]furans in one
pot. At first, the model reaction of 1a (1 mmol) with 2-naphthol
(1.2 mmol) was carried out under the above optimized condition
(5 mol % TBPA+.SbCl6− in 5 mL CHCl3 at room temperature)
for 0.5 h, after washing with 5% NaOH (2.5 mL) to remove
excess 2-naphthol, then AcOH (1 mL), DDQ (5 mol %), and
NaNO2 (10 mol %) were added, and the reaction was performed
at reflux for 6 h under O2 atmosphere. To our delight, the desired
product 5a was obtained with a complete conversion and an
excellent isolated yield (81%, Table 1, entry 1). This tandem
reaction in one pot could simplify the synthetic procedure and
enhance the efficiency of preparing the naphtho[2,1-b]furans,
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Table 1. TBPA+.SbCl6− Induced Reaction of Chalcone Epoxides 1 with Naphthols 2
a
b
In each case, 1.2 equiv of 2-naphthols was employed. The reactions in entries 1 and 10 were scaled up to 0.1 mol (>10 g); no yield loss was
observed with even lower initiator loading (0.5%).
−
avoiding the separation and purification of intermediates, and
The generality and scope of this TBPA+.SbCl6 initiated FC
saving time and the use of solvents.
alkylation/annulation cascade reaction were similar to our
C
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Note
previously reported TBPA+.SbCl6 initiated FC reaction of
−
was heated under reflux for 6 h under O2 atmosphere. Then, the solvent
was evaporated and the residue was purified by column chromatography
over silica gel to afford the naphtho[2,1-b]furans 5.
chalcone epoxides with heteroarenes.6a Chalcone epoxides with
electron-rich aryl groups (such as 4-methoxyphenyl, piperonyl,
3,4,5-trimethoxyphenyl, and 4-(benzyloxy)phenyl groups) as R1
substituents gave the corresponding products in good to
excellent yields (entries 1−11, Table 1). It should be noted
that, with all changes in the R2 substituents, electron-rich aryls (4-
Me-C6H4, 4-MeO-C6H4), electron-deficient aryls (4-Cl-C6H4, 4-
Br-C6H4, 4-CN-C6H4), and heteroaryls such as 2-furanyl and 1-
methyl-1H-indol-3-yl groups were all tolerant of the reaction
conditions. Without a strong electron donating group on R1
substituents, the yields decreased significantly (entries 12−14,
Table 1).
(1-(4-Methoxyphenyl)-1,2-dihydronaphtho[2,1-b]furan-2-
yl)(phenyl)methanone (cis isomer 3a). White filamentous crystals,
mp 165−167 °C. 1H NMR (CDCl3, 400 MHz) δ 7.81 (d, J = 9.1 Hz,
2H), 7.68 (d, J = 7.0 Hz, 2H), 7.54 (t, J = 7.4 Hz, 1H), 7.48−7.32 (m,
3H), 7.34−7.18 (m, 3H), 6.66 (d, J = 8.8 Hz, 2H), 6.53−6.43 (m, 3H),
5.30 (d, J = 9.6 Hz, 1H), 3.62 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ
194.9, 158.4, 156.7, 136.0, 133.2, 130.3, 130.0, 129.9, 129.6, 129.6, 129.5,
128.7, 128.4, 127.8, 126.9, 123.2, 122.5, 121.1, 113.4, 112.4, 89.0, 54.9,
51.4. LRMS (EI) m/z 380 (M+, 17.6). HRMS (ESI) exact mass calcd for
C26H24NO3 [M+NH4]+ 398.1751, found 398.1758.
(1-(4-Methoxyphenyl)-1,2-dihydronaphtho[2,1-b]furan-2-
yl)(phenyl)methanone (trans isomer 4a). Colorless block crystals,
mp 132−133 °C. 1H NMR (CDCl3, 400 MHz) δ 8.03 (d, J = 7.0 Hz,
2H), 7.82 (d, J = 8.8 Hz, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.51 (dd, J = 8.4,
7.1 Hz, 2H), 7.35 (d, J = 8.6 Hz, 2H), 7.32−7.25 (m, 2H), 7.22 (d, J = 8.7
Hz, 2H), 6.89 (d, J = 8.6 Hz, 2H), 5.95 (d, J = 5.4 Hz, 1H), 5.30 (d, J =
5.4 Hz, 1H), 3.80 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ 194.8, 158.8,
157.0, 134.4, 134.2, 133.8, 130.4, 130.3, 130.1, 129.3, 129.0, 128.8, 128.8,
128.7, 126.8, 123.2, 122.8, 120.0, 114.4, 112.1, 91.7, 55.2, 50.1. LRMS
(EI) m/z 380 (M+, 13.6). HRMS (ESI) exact mass calcd for C26H24NO3
[M+NH4]+ 398.1751, found 398.1745.
The derivatives of 2-naphthol with electron donating groups
(such as 7-MeO-2-naphthol, 7-BnO-2-naphthol, 3-BnO-2-
naphthol) and with electron withdrawing groups (such as 6-Br-
2-naphthol, 6-CHO-2-naphthol, 6-CN-2-naphthol) were all
transformed into the corresponding naphthofurans smoothly
(entries 15−20, Table 1).
To evaluate the practicability of our method,12 the reaction
between chalcone epoxides (1a) and 2-naphthol (2a) has been
performed on a 0.1 mol scale [25.4 g 1a + 17.3 g 2a (1.2 equiv)]
in a single batch, and to our delight, no yield loss was observed
(1-(4-Methoxyphenyl)naphtho[2,1-b]furan-2-yl)(phenyl)-
1
methanone (5a). Yellow block crystals, mp 145−147 °C. H NMR
with even lower initiator loading (0.5 mol % TBPA+.SbCl6 in
−
(CDCl3, 400 MHz) δ 7.98−7.89 (m, 4H), 7.80 (d, J = 8.3 Hz, 1H), 7.74
(d, J = 9.0 Hz, 1H), 7.56−7.33 (m, 7H), 6.99 (d, J = 8.6 Hz, 2H), 3.89 (s,
3H). 13C NMR (CDCl3, 100 MHz) δ 184.8, 159.6, 152.9, 147.8, 137.5,
132.3, 131.3, 131.1, 131.0, 130.2, 129.7, 129.2, 128.8, 128.0, 126.9, 125.1,
124.6, 123.2, 122.1, 114.0, 112.7, 55.3. LRMS (EI) m/z 378 (M+, 100).
HRMS (ESI) exact mass calcd for C26H22NO3 [M+NH4]+ 396.1594,
found 396.1586.
250 mL CHCl3 at room temperature, finished in 18 min, 80%
isolated yield based on 1a) (Table 1, footnote b). That is to say,
here we present a practical and scalable synthetic entry to the
polysubstituted 1,2-dihydronaphtho[2,1-b]furan derivatives.
In summary, we have demonstrated a concise and scalable
method to construct polysubstituted 1,2-dihydronaphtho[2,1-
b]furans. Chalcone epoxides acted as valuable halogen-free pre-
electrophiles. Triarylaminium salt was disclosed as a highly
efficient initiator for this FC alkylation/annulation cascade
reaction. DDQ/NaNO2/AcOH/O2 was proven to be efficient in
the aerobic oxidative aromatization of 1,2-dihydronaphtho[2,1-
b]furans, and the direct transformation of chalcone epoxides with
2-naphthols into complex naphtho[2,1-b]furans was also
developed in one pot with a simple and efficient tandem
procedure.
( 4 - Me t h o x yp h e n yl ) ( 1 - ( 4 - m e t h o xy ph e n y l ) - 1 , 2 -
dihydronaphtho[2,1-b]furan-2-yl)methanone (cis isomer 3b).
1
Colorless needle crystals, mp 185−187 °C. H NMR (CDCl3, 400
MHz) δ 7.80 (d, J = 8.8 Hz, 2H), 7.72 (d, J = 8.9 Hz, 2H), 7.39 (d, J = 8.8
Hz, 1H), 7.33−7.13 (m, 3H), 6.87 (d, J = 8.9 Hz, 2H), 6.69 (d, J = 8.7
Hz, 2H), 6.49 (d, J = 8.7 Hz, 2H), 6.43 (d, J = 9.6 Hz, 1H), 5.28 (d, J =
9.6 Hz, 1H), 3.87 (s, 3H), 3.62 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ
193.1, 163.6, 158.4, 156.8, 130.2, 130.0 (2C), 129.7, 129.6, 129.0, 128.8,
126.9, 123.2, 122.6, 121.2, 113.7, 113.4, 112.5, 88.9, 55.5, 55.0, 51.6.
LRMS (EI) m/z 410 (M+, 12.5). HRMS (ESI) exact mass calcd for
C27H26NO4 [M+NH4]+ 428.1856, found 428.1859.
(4-Methoxyphenyl)(1-(4-methoxyphenyl)naphtho[2,1-b]-
furan-2-yl)methanone (5b). Yellow block crystals, mp 165−167 °C.
1H NMR (CDCl3, 400 MHz) δ 8.01 (d, J = 8.6 Hz, 2H), 7.92 (dd, J =
12.2, 8.6 Hz, 2H), 7.80 (d, J = 8.5 Hz, 1H), 7.73 (d, J = 9.0 Hz, 1H), 7.45
(m, 3H), 7.36 (t, J = 7.7 Hz, 1H), 7.02 (d, J = 8.7 Hz, 2H), 6.90 (d, J = 8.5
Hz, 2H), 3.89 (s, 3H), 3.86 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ
183.2, 163.1, 159.5, 152.6, 148.1, 132.2, 131.1, 131.0, 130.6, 130.2, 129.8,
129.1, 128.8, 126.8, 125.1, 124.9, 123.3, 122.1, 114.0, 113.4, 112.7, 55.4,
55.2. LRMS (EI) m/z 408 (M+, 100). HRMS (ESI) exact mass calcd for
C27H24NO4 [M+NH4]+ 426.1700, found 426.1691.
(1-(4-Methoxyphenyl)-1,2-dihydronaphtho[2,1-b]furan-2-
yl)(p-tolyl)methanone (cis isomer 3c). White filamentous crystals,
mp 176−178 °C. 1H NMR (CDCl3, 400 MHz) δ 7.80 (d, J = 8.5 Hz,
2H), 7.61 (d, J = 8.1 Hz, 2H), 7.39 (d, J = 8.8 Hz, 2H), 7.32−7.23 (m,
2H), 7.19 (d, J = 7.9 Hz, 2H), 6.68 (d, J = 8.7 Hz, 2H), 6.55−6.38 (m,
3H), 5.28 (d, J = 9.5 Hz, 1H), 3.61 (s, 3H), 2.41 (s, 3H). 13C NMR
(CDCl3, 100 MHz) δ 194.3, 158.5, 156.8, 144.2, 133.5, 130.3, 130.0
(2C), 129.7, 129.6, 129.2, 128.8, 128.0, 126.9, 123.2, 122.6, 121.2, 113.4,
112.5, 89.0, 55.0, 51.5, 21.7. LRMS (EI) m/z 394 (M+, 9.9). HRMS
(ESI) exact mass calcd for C27H26NO3 [M+NH4]+ 412.1907, found
412.1918.
(1-(4-Methoxyphenyl)-1,2-dihydronaphtho[2,1-b]furan-2-
yl)(p-tolyl)methanone (trans isomer 4c). Colorless block crystals,
mp 123−124 °C. 1H NMR (CDCl3, 400 MHz) δ 7.87 (d, J = 8.2 Hz,
2H), 7.77 (d, J = 8.7 Hz, 2H), 7.40−7.21 (m, 6H), 7.17 (d, J = 8.7 Hz,
2H), 6.84 (d, J = 8.7 Hz, 2H), 5.89 (d, J = 5.3 Hz, 1H), 5.21 (d, J = 5.4
EXPERIMENTAL SECTION
■
General Information. The starting materials and reagents,
purchased from commercial suppliers, were used without further
purification. Literature procedures were used for the preparation of
chalcone epoxides. Solvents were purified by standard methods. Flash
chromatography was carried out using silica gel 200−300. 1HNMR (400
MHz) and 13CNMR (100 MHz) spectra were measured with TMS as
internal standard when CDCl3 was used as solvent. High-resolution
electrospray ionization (HRESI) mass spectra were recorded by a
QTOF-2 Micromass spectrometer.
−
Typical Procedure for TBPA+.SbCl6 Induced Reaction of
Chalcone Epoxides and 2-Naphthols. Chalcone epoxides (1, 1
mmol) and 2-naphthols (2, 1.2 mmol) were dissolved in CH3Cl (10
−
mL) at ambient temperature; TBPA+.SbCl6 (0.05 mmol) was then
added in portion under stirring. The reaction completed within half an
hour as monitored by TLC. The diastereomer products were isolated by
column chromatographic separation with the rapidly eluting the trans
isomer 4 and the slowly eluting the cis isomer 3.
Typical Procedure for the Synthesis of Naphtho[2,1-b]furans
in One Pot. Chalcone epoxides (1, 1 mmol) and 2-naphthols (2, 1.2
mmol) were dissolved in CH3Cl (10 mL) at ambient temperature,
−
TBPA+.SbCl6 (0.05 mmol) was then added in one portion under
stirring. After 0.5 h, the reaction mixture was washed with 5% NaOH
(2.5 mL) to remove excess 2-naphthol, then AcOH (1 mL), DDQ (5
mol %) and NaNO2 (10 mol %) were added, and the reaction mixture
D
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Note
Hz, 1H), 3.77 (s, 3H), 2.43 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ
194.3, 158.8, 157.0, 144.8, 134.5, 131.6, 130.4, 130.3, 130.0, 129.4 (2C),
129.0, 128.7, 126.7, 123.1, 122.7, 120.0, 114.4, 112.1, 91.6, 55.2, 50.2,
21.7. LRMS (EI) m/z 394 (M+, 3.0). HRMS (ESI) exact mass calcd for
C27H26NO3 [M+NH4]+ 412.1907, found 412.1899.
MHz) δ 183.0, 159.9, 153.5, 147.0, 141.2, 132.8, 131.7, 131.3, 131.1,
129.9, 129.3, 128.8, 127.3, 125.5, 124.0, 123.2, 122.0, 118.1, 115.1, 114.1,
112.6, 55.3. LRMS (EI) m/z 403 (M+, 100). HRMS (ESI) exact mass
calcd for C27H21N2O3 [M+NH4]+ 421.1547, found 421.1552.
Furan-2-yl(1-(4-methoxyphenyl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)methanone (cis isomer 3g). Purple needle crystals, mp
175−177 °C. 1H NMR (CDCl3, 400 MHz) δ 7.81 (d, J = 8.9 Hz, 2H),
7.60 (d, J = 1.6 Hz, 1H), 7.38 (d, J = 8.9 Hz, 1H), 7.32 − 7.21 (m, 3H),
7.11 (dd, J = 3.6, 0.7 Hz, 1H), 6.78 (d, J = 8.7 Hz, 2H), 6.54 (d, J = 8.8
Hz, 2H), 6.48 (dd, J = 3.6, 1.7 Hz, 1H), 6.23 (d, J = 9.7 Hz, 1H), 5.43 (d,
J = 9.7 Hz, 1H), 3.63 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ 184.0,
158.6, 156.7, 151.3, 146.0, 130.3, 130.1, 130.0, 129.7, 129.3, 128.8, 126.9,
123.3, 122.7, 121.1, 118.1, 113.6, 112.6, 112.4, 89.0, 55.0, 51.2. LRMS
(EI) m/z 370 (M+, 34.8). HRMS (ESI) exact mass calcd for C24H22NO4
[M+NH4]+ 388.1543, found 388.1546.
Furan-2-yl(1-(4-methoxyphenyl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)methanone (trans isomer 4g). White powder solid,
mp 102−104 °C. 1H NMR (CDCl3, 400 MHz) δ 7.79 (d, J = 9.0 Hz,
2H), 7.66 (d, J = 1.0 Hz, 1H), 7.35 (d, J = 3.6 Hz, 1H), 7.33−7.21 (m,
4H), 7.17 (d, J = 8.7 Hz, 2H), 6.84 (d, J = 8.7 Hz, 2H), 6.56 (dd, J = 2.8,
1.4 Hz, 1H), 5.61 (d, J = 5.4 Hz, 1H), 5.25 (d, J = 5.4 Hz, 1H), 3.77 (s,
3H). 13C NMR (CDCl3, 100 MHz) δ 184.5, 158.8, 157.0, 150.3, 147.5,
134.3, 130.5, 130.3, 130.1, 128.9, 128.8, 126.8, 123.3, 122.9, 120.4, 119.8,
114.3, 112.5, 111.9, 91.9, 55.2, 50.7. LRMS (EI) m/z 370 (M+, 22.3).
HRMS (ESI) exact mass calcd for C24H22NO4 [M+NH4]+ 388.1543,
found 388.1547.
(1-(4-Methoxyphenyl)naphtho[2,1-b]furan-2-yl)(p-tolyl)-
1
methanone (5c). Yellow block crystals, mp 176−178 °C. H NMR
(CDCl3, 400 MHz) δ 8.02−7.87 (m, 4H), 7.82 (d, J = 8.5 Hz, 1H), 7.74
(d, J = 9.0 Hz, 1H), 7.56−7.43 (m, 3H), 7.38 (t, J = 7.0, 1H), 7.22 (d, J =
8.1 Hz, 2H), 7.02 (d, J = 8.7 Hz, 2H), 3.91 (s, 3H), 2.42 (s, 3H). 13C
NMR (CDCl3, 100 MHz) δ 184.4, 159.6, 152.7, 148.0, 143.1, 134.9,
131.1, 131.0, 130.9, 130.0, 129.9, 129.2, 128.8 (2C), 126.9, 125.1, 124.8,
123.3, 122.1, 114.0, 112.7, 55.3, 21.6. LRMS (EI) m/z 392 (M+, 100).
HRMS (ESI) exact mass calcd for C27H24NO3 [M+NH4]+ 410.1751,
found 410.1755.
( 4 - C h l o r o p h e n y l ) ( 1 - ( 4 - m e t h o x y p h e n y l ) - 1 , 2 -
dihydronaphtho[2,1-b]furan-2-yl)methanone (cis isomer 3d).
1
White filamentous crystals, mp 175−178 °C. H NMR (CDCl3, 400
MHz) δ 7.81 (d, J = 8.6 Hz, 2H), 7.62 (d, J = 8.1 Hz, 2H), 7.36 (t, J = 8.1
Hz, 3H), 7.27 (s, 3H), 6.68 (d, J = 8.2 Hz, 2H), 6.50 (d, J = 8.1 Hz, 2H),
6.39 (d, J = 9.6 Hz, 1H), 5.28 (d, J = 9.6 Hz, 1H), 3.63 (s, 3H). 13C NMR
(CDCl3, 100 MHz) δ 194.0, 158.6, 156.6, 139.6, 134.4, 130.4, 130.1,
130.0, 129.7, 129.4, 129.3, 128.8, 127.0, 123.3, 122.5, 120.9, 113.5, 112.4,
89.0, 55.0, 51.5. LRMS (EI) m/z 414 (M+, 55.0). HRMS (ESI) exact
mass calcd for C26H23ClNO3 [M+NH4]+ 432.1361, found 432.1364.
( 4 - C h l o r o p h e n y l ) ( 1 - ( 4 - m e t h o x y p h e n y l ) - 1 , 2 -
dihydronaphtho[2,1-b]furan-2-yl)methanone (trans isomer
4d). Colorless block crystals, mp 163−165 °C. 1H NMR (CDCl3, 400
MHz) δ 7.95 (d, J = 8.6 Hz, 2H), 7.74−7.82 (m, 2H), 7.48 (d, J = 8.6 Hz,
2H), 7.38−7.24 (m, 4H), 7.20 (d, J = 8.6 Hz, 2H), 6.87 (d, J = 8.6 Hz,
2H), 5.84 (d, J = 5.5 Hz, 1H), 5.29 (d, J = 5.5 Hz, 1H), 3.80 (s, 3H). 13C
NMR (CDCl3, 100 MHz) δ 193.8, 158.9, 156.8, 140.3, 134.2, 132.6,
130.8, 130.5, 130.3, 130.1, 129.1, 129.0, 128.8, 126.8, 123.3, 122.8, 119.9,
114.5, 112.0, 91.7, 55.2, 49.9. LRMS (EI) m/z 414 (M+, 52.0). HRMS
(ESI) exact mass calcd for C26H23ClNO3 [M+NH4]+ 432.1361, found
432.1359.
Furan-2-yl(1-(4-methoxyphenyl)naphtho[2,1-b]furan-2-yl)-
methanone (5g). Yellow needle crystals, mp 240−241 °C. 1H NMR
(CDCl3, 400 MHz) δ 7.95 (d, J = 8.5 Hz, 2H), 7.71−7.60 (m, 4H),
7.44−7.54 (m, 3H), 7.37 (t, J = 7.7 Hz, 1H), 7.08 (d, J = 8.4 Hz, 2H),
6.61 (dd, J = 3.2, 1.4 Hz, 1H), 3.93 (s, 3H). 13C NMR (CDCl3, 100
MHz) δ 170.2, 159.6, 152.7, 151.4, 147.1, 146.7, 131.4, 131.0, 130.9,
130.3, 129.2, 128.8, 127.0, 125.2, 124.4, 123.3, 122.3, 120.6, 114.0, 112.5,
112.2, 55.3. LRMS (EI) m/z 368 (M+, 100). HRMS (ESI) exact mass
calcd for C24H20NO4 [M+NH4]+ 386.1387, found 386.1386.
(1-(Benzo[d][1,3]dioxol-5-yl)-1,2-dihydronaphtho[2,1-b]-
furan-2-yl)(phenyl)methanone (cis isomer 3i). Colorless block
crystals, mp 193−195 °C. 1H NMR (CDCl3, 400 MHz) δ 7.81 (d, J = 8.6
Hz, 2H), 7.72 (d, J = 8.0 Hz, 2H), 7.54 (td, J = 7.4, 1.4 Hz, 1H), 7.39 (dd,
J = 16.3, 9.0 Hz, 3H), 7.34−7.19 (m, 3H), 6.46 (dd, J = 9.6, 2.4 Hz, 1H),
6.37 (d, J = 7.9 Hz, 1H), 6.24 (d, J = 8.0 Hz, 1H), 6.20 (t, J = 1.2 Hz, 1H),
5.75 (d, J = 23.9 Hz, 2H), 5.25 (dd, J = 9.6, 1.9 Hz, 1H). 13C NMR
(CDCl3, 100 MHz) δ 194.7, 156.8, 147.4, 146.6, 136.1, 133.3, 131.3,
130.5, 130.1, 130.0, 128.8, 128.5, 127.9, 127.0, 123.3, 122.5, 122.1, 120.8,
112.5, 109.0, 107.6, 100.8, 89.0, 51.9. LRMS (EI) m/z 394 (M+, 92.0).
HRMS (ESI) exact mass calcd for C26H22NO4 [M+NH4]+ 412.1543,
found 412.1540.
(1-(Benzo[d][1,3]dioxol-5-yl)-1,2-dihydronaphtho[2,1-b]-
furan-2-yl)(phenyl)methanone (trans isomer 4i). Colorless needle
crystals, mp 186−188 °C. 1H NMR (CDCl3, 400 MHz) δ 7.99 (d, J = 7.1
Hz, 2H), 7.79 (t, J = 8.8 Hz, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.49 (t, J = 7.7
Hz, 2H), 7.22−7.36 (m, 4H), 6.76 (s, 2H), 6.69 (s, 1H), 5.94 (d, J = 1.3
Hz, 1H), 5.89 (d, J = 5.2 Hz, 2H), 5.21 (d, J = 5.3 Hz, 1H). 13C NMR
(CDCl3, 100 MHz) δ 194.7, 157.0, 148.3, 146.9, 136.2, 134.2, 133.8,
130.5, 130.3, 130.1,129.3, 128.8, 128.7, 126.8, 123.2, 122.7, 121.2, 119.8,
112.1, 108.5, 108.1, 101.1, 91.5, 50.5. LRMS (EI) m/z 394 (M+, 91.8).
HRMS (ESI) exact mass calcd for C26H22NO4 [M+NH4]+ 412.1543,
found 412.1545.
(4-Chlorophenyl)(1-(4-methoxyphenyl)naphtho[2,1-b]furan-
1
2-yl)methanone (5d). Yellow block crystals, mp 156−157 °C. H
NMR (CDCl3, 400 MHz) δ 7.95 (d, J = 8.8 Hz, 2H), 7.87 (d, J = 8.5 Hz,
2H), 7.80 (d, J = 8.4 Hz, 1H), 7.73 (d, J = 9.0 Hz, 1H), 7.48 (t, J = 7.5 Hz,
1H), 7.38 (dd, J = 16.9, 6.6 Hz, 5H), 7.00 (d, J = 8.7 Hz, 2H), 3.90 (s,
3H). 13C NMR (CDCl3, 100 MHz) δ 183.3, 159.7, 153.0, 147.5, 138.6,
135.8, 131.8, 131.1, 131.0, 130.6, 129.2, 128.8, 128.3, 127.1, 125.3, 124.4,
123.2, 122.0, 114.1, 112.6, 55.5. LRMS (EI) m/z 412 (M+, 100). HRMS
(ESI) exact mass calcd for C26H21ClNO3 [M+NH4]+ 430.1204, found
430.1210.
4-(1-(4-Methoxyphenyl)-1,2-dihydronaphtho[2,1-b]furan-2-
carbonyl)benzonitrile (cis isomer 3f). White needle crystals, mp
187−189 °C. 1H NMR (CDCl3, 400 MHz) δ 7.82 (d, J = 7.5 Hz, 2H),
7.67 (m, 4H), 7.37 (d, J = 8.8 Hz, 1H), 7.21−7.30 (m, 3H), 6.66 (d, J =
6.8 Hz, 2H), 6.49 (d, J = 6.9 Hz, 2H), 6.39 (d, J = 9.8 Hz, 1H), 5.31 (d, J
= 9.8 Hz, 1H), 3.63 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ 194.7,
158.7, 156.5, 139.1, 132.2, 130.6, 130.1, 129.8, 129.7, 129.2, 128.8, 128.3,
127.1, 123.5, 122.5, 120.6, 117.8, 116.2, 113.6, 112.2, 89.3, 55.0, 51.4.
LRMS (EI) m/z 405 (M+, 35.5). HRMS (ESI) exact mass calcd for
C27H23N2O3 [M+NH4]+ 423.1703, found 423.1697.
4-(1-(4-Methoxyphenyl)-1,2-dihydronaphtho[2,1-b]furan-2-
carbonyl)benzonitrile (trans isomer 4f). Pale yellow flake crystals,
mp 189−191 °C. 1H NMR (CDCl3, 400 MHz) δ 8.09 (d, J = 8.3 Hz,
2H), 7.76−7.82 (m, 4H), 7.38−7.22 (m, 4H), 7.17 (d, J = 8.7 Hz, 2H),
6.86 (d, J = 8.6 Hz, 2H), 5.81 (d, J = 5.6 Hz, 1H), 5.32 (d, J = 5.7 Hz,
1H), 3.78 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ 194.0, 159.0, 156.5,
137.5, 133.9, 132.4, 130.6, 130.2 (2C), 129.8, 129.0, 128.8, 127.0, 123.4,
122.8, 119.7, 117.8, 116.9, 114.5, 111.9, 91.9, 55.3, 49.6. LRMS (EI) m/z
405 (M+, 20.8). HRMS (ESI) exact mass calcd for C27H23N2O3 [M
+NH4]+ 423.1703, found 423.1704.
4-(1-(4-Methoxyphenyl)naphtho[2,1-b]furan-2-carbonyl)-
benzonitrile (5f). Yellow needle crystals, mp 186−188 °C. 1H NMR
(CDCl3, 400 MHz) δ 7.98−7.93 (m, 4H), 7.79 (d, J = 8.4 Hz, 1H), 7.73
(d, J = 9.0 Hz, 1H), 7.66 (d, J = 8.5 Hz, 2H), 7.49 (t, J = 7.5 Hz, 1H), 7.38
(m, 3H), 6.98 (d, J = 8.8 Hz, 2H), 3.90 (s, 3H). 13C NMR (CDCl3, 100
(1-(Benzo[d][1,3]dioxol-5-yl)naphtho[2,1-b]furan-2-yl)-
(phenyl)methanone (5i). Yellow block crystals, mp 144−146 °C. 1H
NMR (CDCl3, 400 MHz) δ 8.03−7.89 (m, 4H), 7.84 (d, J = 8.2 Hz,
1H), 7.72 (d, J = 9.0 Hz, 1H), 7.60−7.32 (m, 5H), 7.12−6.80 (m, 3H),
6.04 (d, J = 34.3 Hz, 2H). 13C NMR (CDCl3, 100 MHz) δ 184.7, 152.9,
147.8, 147.7, 137.5, 132.3, 131.1, 131.0, 130.3, 129.6, 129.2, 128.7, 128.0,
127.0, 126.0, 125.2, 123.4, 123.3, 122.0, 112.7, 110.3, 108.6,101.2.
LRMS (EI) m/z 392 (M+, 100). HRMS (ESI) exact mass calcd for
C26H20NO4 [M+NH4]+ 410.1387, found 410.1381.
Phenyl(1-(3,4,5-trimethoxyphenyl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)methanone (cis isomer 3j). Colorless block crystals,
mp 207−209 °C. 1H NMR (CDCl3, 400 MHz) δ 7.82 (d, J = 8.7 Hz,
E
dx.doi.org/10.1021/jo300827s | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
2H), 7.64 (d, J = 8.1 Hz, 2H), 7.52 (t, J = 7.5 Hz, 1H), 7.38 (m, 3H),
7.27−7.33 (m, 3H), 6.50 (d, J = 10.0 Hz, 1H), 5.92 (s, 2H), 5.23 (d, J =
10.0 Hz, 1H), 3.66 (s, 3H), 3.46 (s, 6H). 13C NMR (CDCl3, 100 MHz) δ
194.9, 156.9, 152.6, 136.9, 136.5, 133.2, 133.1, 130.5, 130.0 (2C), 128.8,
128.4, 127.7, 127.0, 123.3, 122.6, 120.2, 112.5, 106.0, 89.0, 60.6, 55.8,
55.7, 52.5. LRMS (EI) m/z 440 (M+, 31.6). HRMS (ESI) exact mass
calcd for C28H28NO5 [M+NH4]+ 458.1962, found 458.1960. Crystal
data for p21c: C28H24O5, M = 440.47, monoclinic, a = 15.598(8) Å, b =
5.885(7) Å, c = 24.320(3) Å, α = 90.00°, β = 99.165(10)°, γ = 90.00°, V
= 2204(4) Å3, T = 296(2) K, space group P2(1)/c, Z = 4, 15036
reflections measured, 4079 independent reflections (Rint = 0.0539). The
final R1 values were 0.0502 (I > 2σ(I)). The final wR(F2) values were
0.1078 (I > 2σ(I)). The final R1 values were 0.0874 (all data). The final
wR(F2) values were 0.1297 (all data).
(d, J = 9.0 Hz, 1H), 7.58−7.34 (m, 12H), 7.05 (d, J = 8.4 Hz, 2H), 5.13
(s, 2H). 13C NMR (CDCl3, 100 MHz) δ 184.9, 158.8, 153.0, 147.8,
137.5, 136.8, 132.3, 131.3, 131.2, 131.0, 130.3, 129.7, 129.2, 128.8, 128.6,
128.1, 128.0, 127.6, 127.0, 125.2, 124.9, 123.3, 122.1, 114.9, 112.7, 70.0.
LRMS (EI) m/z 454 (M+, 37.0). HRMS (ESI) exact mass calcd for
C32H26NO3 [M+NH4]+ 472.1907, found 472.1901.
7-Bromo-1-(4-methoxyphenyl)-1,2-dihydronaphtho[2,1-b]-
furan-2-yl)(phenyl)methanone (cis isomer 3o). White needle
crystals, mp 179−180 °C. 1H NMR (CDCl3, 400 MHz) δ 7.98 (s, 1H),
7.68 (m, 3H), 7.53 (t, J = 7.5 Hz, 1H), 7.45−7.22 (m, 4H), 7.15 (dd, J =
8.8, 4.9 Hz, 1H), 6.63 (d, J = 8.7 Hz, 2H), 6.47 (m, 3H), 5.28 (d, J = 9.7
Hz, 1H), 3.62 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ 194.6, 158.6,
157.1, 135.9, 133.4, 131.2, 130.7, 130.2, 129.6, 129.5, 129.2, 128.5, 128.4,
127.8, 124.2, 121.4, 116.9, 113.6, 113.5, 88.9, 55.0. LRMS (EI) m/z 458
(M+, 46.7). HRMS (ESI) exact mass calcd for C26H23BrNO3 [M+NH4]+
476.0856, found 476.0853.
7-Bromo-1-(4-methoxyphenyl)-1,2-dihydronaphtho[2,1-b]-
furan-2-yl)(phenyl)methanone (trans isomer 4o). Colorless block
crystals, mp 218−220 °C. 1H NMR (400 MHz, Chloroform-d) δ 8.06−
7.82 (m, 3H), 7.79−7.57 (m, 2H), 7.49 (t, J = 7.7 Hz, 2H), 7.31 (d, J =
8.7 Hz, 2H), 7.15 (m, 3H), 6.85 (d, J = 8.7 Hz, 2H), 5.91 (d, J = 5.5 Hz,
1H), 5.23 (d, J = 5.5 Hz, 1H), 3.79 (s, 3H). 13C NMR (CDCl3, 100
MHz) δ 194.5, 159.0, 157.3, 134.1, 134.0, 133.9, 131.2, 130.7, 130.1,
129.6, 129.3, 129.0, 128.8, 124.5, 120.4, 116.8, 114.5, 113.2, 91.7, 55.3.
LRMS (EI) m/z 458 (M+, 42.3). HRMS (ESI) exact mass calcd for
C26H23BrNO3 [M+NH4]+ 476.0856, found 476.0849.
(7-Bromo-1-(4-methoxyphenyl)naphtho[2,1-b]furan-2-yl)-
(phenyl)methanone (5o). Yellow block crystals, mp 156−157 °C. 1H
NMR (CDCl3, 400 MHz) δ 8.06 (s, 1H), 7.95−7.84 (m, 2H), 7.84−
7.56 (m, 3H), 7.55−7.23 (m, 6H), 7.07−6.87 (m, 2H), 4.01−3.70 (m,
3H). 13C NMR (CDCl3, 100 MHz) δ 184.7, 159.7, 152.7, 148.0, 137.3,
132.4, 132.3, 131.1, 131.0, 130.8, 130.1, 129.6, 129.0, 128.0, 127.3, 124.8,
124.1, 122.1, 118.9, 114.1, 113.8, 55.3. LRMS (EI) m/z 456 (M+, 100).
HRMS (ESI) exact mass calcd for C26H21BrNO3 [M+NH4]+ 474.0699,
found 474.0702.
Phenyl(1-(3,4,5-trimethoxyphenyl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)methanone (trans isomer 4j). Colorless block crystals,
1
mp 188−190 °C. H NMR (CDCl3, 400 MHz) δ 8.00 (d, J =8.3 Hz,
2H), 7.79 (d, J = 8.6 Hz, 2H), 7.63 (t, J = 7.3 Hz, 1H), 7.49 (t, J = 7.6 Hz,
2H), 7.20−7.36 (m, 4H), 6.45 (s, 2H), 5.94 (d, J = 5.6 Hz, 2H), 5.23 (d, J
= 5.3 Hz, 1H), 3.83 (s, 3H), 3.72 (s, 6H). 13C NMR (CDCl3, 100 MHz)
δ 194.7, 157.0, 153.6, 137.9, 137.1, 134.2, 133.9, 130.6, 130.4, 130.0,
129.4, 128.7, 128.6, 126.8, 123.3, 122.8, 119.3, 112.1, 104.8, 91.4, 60.8,
56.1, 51.0. LRMS (EI) m/z 440 (M+, 18.4). HRMS (ESI) exact mass
calcd for C28H28NO5 [M+NH4]+ 458.1962, found 458.1960. Crystal
data for p-1: C28H24O5, M = 440.47, triclinic, a = 8.064(2) Å, b =
9.030(2) Å, c = 16.884(5) Å, α = 97.742(3)°, β = 98.905(3)°, γ =
111.668(2)°, V = 1104.0(5) Å3, T = 296(2) K, space group P1, Z = 2,
̅
6748 reflections measured, 4002 independent reflections (Rint
=
0.0178). The final R1 values were 0.0429 (I > 2σ(I)). The final
wR(F2) values were 0.1031 (I > 2σ(I)). The final R1 values were 0.0590
(all data). The final wR(F2) values were 0.1154 (all data).
Phenyl(1-(3,4,5-trimethoxyphenyl)naphtho[2,1-b]furan-2-
yl)methanone (5j). Yellow block crystals, mp 154−156 °C. 1H NMR
(CDCl3, 400 MHz) δ 7.96 (m, 2H), 7.85 (t, J = 7.4 Hz, 3H), 7.76 (d, J =
9.1 Hz, 1H), 7.57−7.30 (m, 5H), 6.68 (s, 2H), 3.92 (s, 3H), 3.78 (s, 6H).
13C NMR (CDCl3, 100 MHz) δ 185.1, 153.3, 153.1, 147.6, 137.6, 132.3,
(8-Methoxy-1-(4-methoxyphenyl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)(phenyl)methanone (cis isomer 3p). White needle
crystals, mp 153−155 °C. 1H NMR (CDCl3, 400 MHz) δ 7.85−7.62 (m,
4H), 7.53 (t, J = 7.4 Hz, 1H), 7.38 (t, J = 7.9 Hz, 2H), 7.23 (d, J =8.7 Hz,
1H), 6.90 (dd, J = 9.0, 2.5 Hz, 1H), 6.69 (d, J = 8.7 Hz, 2H), 6.52 (d, J =
2.5 Hz, 1H), 6.48 (dd, J =9.7, 2.9 Hz, 3H), 5.23 (d, J = 9.7 Hz, 1H), 3.62
(s, 6H). 13C NMR (CDCl3, 100 MHz) δ 195.0, 158.5, 158.3, 157.3,
136.1, 133.2, 131.2, 130.3, 130.0, 129.7, 129.5, 128.5, 127.8, 125.4, 120.3,
115.6, 113.4, 109.8, 101.2, 88.9, 55.0, 54.9, 51.5. LRMS (EI) m/z 410
(M+, 42.5). HRMS (ESI) exact mass calcd for C27H26NO4 [M+NH4]+
428.1856, found 428.1857.
(8-Methoxy-1-(4-methoxyphenyl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)(phenyl)methanone (trans isomer 4p). Yellow oil. 1H
NMR (CDCl3, 400 MHz) δ 7.98 (d, J = 7.4 Hz, 2H), 7.68 (t, J = 8.8 Hz,
2H), 7.62 (t, J = 7.4 Hz, 1H), 7.48 (t, J = 7.7 Hz, 2H), 7.20 (d, J = 8.6 Hz,
2H), 7.14 (d, J = 8.8 Hz, 1H), 6.83−6.91 (m, 3H), 6.54 (d, J = 2.4 Hz,
1H), 5.91 (d, J = 5.6 Hz, 1H), 5.18 (d, J = 5.6 Hz, 1H), 3.79 (s, 3H), 3.61
(s, 3H). 13C NMR (CDCl3, 100 MHz) δ 194.8, 158.8, 158.2, 157.5,
134.2, 133.8, 131.6, 130.3, 130.1, 129.3, 129.1, 128.7, 125.4, 119.3, 115.6,
114.4, 109.4, 101.4, 91.7, 55.3, 54.9, 50.2. LRMS (EI) m/z 410 (M+,
34.5). HRMS (ESI) exact mass calcd for C27H26NO4 [M+NH4]+
428.1856, found 428.1851.
(8-Methoxy-1-(4-methoxyphenyl)naphtho[2,1-b]furan-2-yl)-
(phenyl)methanone (5p). Yellow block crystals, mp 174−176 °C. 1H
NMR (CDCl3, 400 MHz) δ 7.94 (d, J = 8.3 Hz, 2H), 7.84 (dd, J = 10.9,
9.1 Hz, 2H), 7.58 (d, J = 9.0 Hz, 1H), 7.50 (t, J = 7.5 Hz, 1H), 7.45 (d, J =
8.8 Hz, 2H), 7.40 (t, J =7.4 Hz, 2H), 7.14 (d, J = 2.5 Hz, 1H), 7.09 (dd, J
= 8.9, 2.6 Hz, 1H), 7.00 (d, J =8.8 Hz, 2H), 3.86 (s, 3H), 3.51 (s, 3H).
13C NMR (CDCl3, 100 MHz) δ 184.7, 159.6, 158.4, 153.5, 147.5, 137.6,
132.3, 131.4, 131.3, 130.5, 130.2, 130.0, 129.7, 128.0, 125.8, 124.8, 121.5,
116.9, 113.9, 110.1, 103.0,55.4, 54.9. LRMS (EI) m/z 408 (M+, 100).
HRMS (ESI) exact mass calcd for C27H24NO4 [M+NH4]+ 426.1700,
found 426.1709.
131.3, 131.0, 130.5, 129.4, 129.3, 128.6, 127.9, 127.1, 125.3, 123.4, 121.7,
112.7, 107.1, 60.9, 56.1. LRMS (EI) m/z 438 (M+, 100). HRMS (ESI)
exact mass calcd for C28H26NO5 [M+NH4]+ 456.1805, found 456.1800.
Crystal data for p21n: C56H44O10, M = 876.91, monoclinic, a = 9.627(6)
Å, b = 22.777(15) Å, c = 20.968(14) Å, α = 90.00°, β = 90.706(7)°, γ =
90.00°, V = 4597(5) Å3, T = 296(2) K, space group P2(1)/n, Z = 4,
21885 reflections measured, 8308 independent reflections (Rint
=
0.0430). The final R1 values were 0.0588 (I > 2σ(I)). The final wR(F2)
values were 0.1052 (I > 2σ(I)). The final R1 values were 0.1454 (all
data). The final wR(F2) values were 0.1468 (all data).
(1-(4-(Benzyloxy)phenyl)-1,2-dihydronaphtho[2,1-b]furan-2-
yl)(phenyl)methanone (cis isomer 3k). White filamentous crystals,
mp 96−99 °C. 1H NMR (CDCl3, 400 MHz) δ 7.81 (d, J = 8.8 Hz, 2H),
7.65 (d, J = 7.1 Hz, 2H), 7.52 (t, J = 7.4 Hz, 1H), 7.22−7.41 (m, 11H),
6.66 (d, J = 8.7 Hz, 2H), 6.55 (d, J = 8.7 Hz, 2H), 6.48 (d, J = 9.6 Hz,
1H), 5.29 (d, J = 9.6 Hz, 1H), 4.85 (dd, J = 18.8, 11.6 Hz, 2H). 13C NMR
(CDCl3, 100 MHz) δ 194.9, 157.7, 156.7, 136.8, 136.1, 133.2, 130.3,
130.0, 129.9, 129.8, 129.7, 128.8, 128.5, 128.4, 127.9, 127.8, 127.4, 126.9,
123.2, 122.6, 121.0, 114.4, 112.5, 89.0, 69.7, 51.4. LRMS (EI) m/z 456
(M+, 8.5). HRMS (ESI) exact mass calcd for C32H28NO3 [M+NH4]+
474.2064, found 474.2060.
(1-(4-(Benzyloxy)phenyl)-1,2-dihydronaphtho[2,1-b]furan-2-
yl)(phenyl)methanone (trans isomer 4k). Pale yellow oil. 1H NMR
(CDCl3, 400 MHz) δ 7.97 (d, J = 7.4 Hz, 2H), 7.77 (dd, J = 8.9, 5.1 Hz,
2H), 7.60 (t, J = 7.4 Hz, 1H), 7.58−7.25 (m, 11H), 7.17 (d, J = 8.6 Hz,
2H), 6.92 (d, J = 8.6 Hz, 2H),5.89 (d, J = 5.4 Hz, 1H), 5.24 (d, J = 5.4 Hz,
1H), 5.01 (s, 2H). 13C NMR (CDCl3, 100 MHz) δ 194.6, 158.1, 157.0,
136.8, 134.7, 134.2, 133.8, 132.0, 130.4, 130.1, 129.3, 129.0, 128.8, 128.7,
128.6, 128.0, 127.5, 126.8, 123.2, 122.8, 120.0, 115.3, 115.1, 112.1, 91.7,
70.0, 50.1. LRMS (EI) m/z 456 (M+, 7.0). HRMS (ESI) exact mass calcd
for C32H28NO3 [M+NH4]+ 474.2064, found 474.2067.
(1-(4-(Benzyloxy)phenyl)naphtho[2,1-b]furan-2-yl)(phenyl)-
1
methanone (5k). Yellow block crystals, mp 145−147 °C. H NMR
(CDCl3, 400 MHz) δ 8.02−7.90 (m, 4H), 7.80 (d, J = 8.4 Hz, 1H), 7.72
F
dx.doi.org/10.1021/jo300827s | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
D. J. Med. Chem. 1989, 32, 1700. (c) Srivastava, V.; Negi, A. S.; Kumar, J.
K.; Faridi, U.; Sisodia, B. S.; Darokar, M. P.; Luqman, S.; Khanuja, S. P. S.
Bioorg. Med. Chem. Lett. 2006, 16, 911.
(9) (a) Brandes, S.; Bella, M.; Kjrsgaard, A.; Jorgensen, K. A. Angew.
Chem., Int. Ed. 2006, 45, 1147. (b) Chauhan, P.; Chimni, S. S. Eur. J. Org.
Chem. 2011, 9, 1636. (c) Wang, X.; Zheng, C.; Zhao, S.; Chai, Z.; Zhao,
G.; Yang, G. Tetrahedron: Asymmetry 2008, 19, 2699. (d) Kidwai, M.;
Saxena, S.; Khan, M. K. R.; Thukral, S. S. Bioorg. Med. Chem. Lett. 2005,
15, 4295. (e) Aoki, S.; Amamoto, C.; Oyamada, J.; Kitamura, T.
Tetrahedron 2005, 61, 9291.
ASSOCIATED CONTENT
* Supporting Information
Characterization of products 3, 4, and 5, and X-ray
crystallography data for 3j, 4j, and 5j. This material is available
free of charge via the Internet at http://pubs.acs.org.
■
S
AUTHOR INFORMATION
Corresponding Author
*E-mail: huocongde1978@hotmail.com
■
(10) Wang, L.; Li, J.; Yang, H.; Lv, Y.; Gao, S. J. Org. Chem. 2012, 77,
Notes
790.
(11) The X-ray crystal data (excluding structure factors) of compounds
3h, 4h, and 5h have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publication no CCDC 849649,
849650, and 849651. Copy of the data can be obtained, free of charge, on
application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax:
t44 (0) 1223 336033 or e-mail: deposit@ccdc.cam.ac.uk).
(12) (a) Mendoza, A.; Ishihara, Y.; Baran, P. S. Nat. Chem. 2012, 4, 21.
(b) Wernerova, M.; Hudlicky, T. Synlett 2010, 2701. (c) Ley, S. V. In
Practical Synthetic Organic Chemistry, Caron, S., Ed.; John Wiley & Sons:
New York, 2011; foreword.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank the National Natural Science Foundation of China
(21262029, 21002080) and the Natural Science Foundation of
Gansu Province (1107RJYA026) for financially supporting this
work.
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