Copper-catalyzed dimerization fragmentation cyclization reactions of (E)-1-en-4-yn-3-ols as a versatile approach for the synthesis of multisubstituted 1H-cyclopenta[b]naphthalenes

Article abstract of DOI:10.1039/c1ob06087b

An intermolecular condensation reaction of 1,3,5-triarylenynols catalyzed by copper is developed. This reaction is a straightforward method for the synthesis of highly conjugated 1H-cyclopenta[b]naphthalene. Fluorescent properties have been determined for

Full text of DOI:10.1039/c1ob06087b

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PAPER
Copper-catalyzed dimerization fragmentation cyclization reactions of
(E)-1-en-4-yn-3-ols as a versatile approach for the synthesis of
multisubstituted 1H-cyclopenta[b]naphthalenes†
Xiang-Chuan Wang,a Jie Hu,a Peng-Shuai Sun,a Mei-Jin Zhong,a Shaukat Alia and Yong-Min Liang*a,b
Received 5th July 2011, Accepted 5th August 2011
DOI: 10.1039/c1ob06087b
An intermolecular condensation reaction of 1,3,5-triarylenynols catalyzed by copper is
developed. This reaction is a straightforward method for the synthesis of highly conjugated
1H-cyclopenta[b]naphthalene. Fluorescent properties have been determined for some of the products.
a 92% yield of the desired product 1H-cyclopenta[b]naphthalene
Introduction
2a after 1 h (Table 1, entry 1). In an attempt to accelerate this
As multifunctional molecules, indene moieties are key substruc-
transformation, the amount of catalyst was increased to 10 mol%,
tures in both targets and building blocks for various biologically
but the yield of the desired product was reduced to 84%. We then
active molecules1 and functional materials, such as fluorescent
reduced CuOTf to 2 mol%, but this also reduced the yield. Using
materials.2 Consequently, much attention has been paid to the
synthesis of indene derivatives. In this context, it is relevant that
Cu(OAc)2, CuBr2, Cu(OTf)2 and CuSO4 as catalysts, slightly lower
yields of 2a were obtained (Table 1, entries 4–7). Cu(acac)2 or CuBr
Tian and co-workers reported the regioselective FeCl3-catalyzed
was completely ineffective (Table 1, entries 8 and 9). Other Lewis
synthesis of structurally diverse indene derivatives from readily
accessible N-benzylic sulfonamides and disubstituted alkynes.3 In
the same year, Chatterjee and Roy reported the Ir–Sn-catalyzed
acids and Brønsted acids did not give an improved result (Table
1, entries 10–15). Solvents, such as CH3CN, CH2Cl2, toluene and
THF, were also tested in the presence of CuOTf, however, no
propargylic alcohols to substituted indenes.4 The one-step syn-
superior result was obtained (Table 1, entries 16–19). Thus, enynol
1a (0.5 mmol), CuOTf (5 mol%) and CH3NO2 (5 mL) at 80 ◦C
under Ar atmosphere was chosen as the standard conditions.
Under the optimized reaction conditions, various enynols
bearing different aryl substituents were then subjected to this
condensation reaction. All reactions were complete within 3 h in
moderate to high yields (76–92%), as shown in Table 2. Substrates
bearing electron-donating aryl substituents (Table 2, entries 2–
4) reacted smoothly to give the expected products in high yields.
When electron-withdrawing groups (Table 2, entries 5–7) were
employed, slightly lower yields were obtained. When either R2
or R3 in 1 was an electron-donating group (Table 2, entries 8–9)
the reaction gave a slightly lower yield. But when R2 or R3 in
1 is an electron-withdrawing group (Table 2, entries 10–15) the
desired products were afforded in good yields. In order to expand
the substrate scope, enynols with 2-thienyl, 2-furyl and 2-naphthyl
substituents were also tested. As can be seen in Scheme 1, the
expected highly conjugated products were isolated in moderate to
high yields (52–95%)
Considering the highly conjugated structure obtained by our
method, we assumed that these products might be useful in fluores-
cent materials chemistry.8 We then tested the fluorescent properties
for product 2a, 2p, 1q, 2r, 2s and 3n (Table 3). As illustrated in
Fig. 1, the absorption band near the UV region shows strong
fluorescence. The compounds thus prepared emitted blue light
when excited at 365 nm (Fig. 2). It makes them extremely useful for
sensing and labeling purposes. The fluorescence quantum yields of
thesis of highly conjugated carbon-rich indenes, p-electron-rich
species which have special chemical and physical properties,5 has
been rarely reported.
In the context of our ongoing efforts to synthesise indene
derivatives,6 we found that the 1-en-4-yn-3-ol substrate might
be perfect in a domino process.7 We envisioned that (E)-
1,3,5-triphenylpent-1-en-4-yn-3-ol derivatives could realize an
isomerization/Friedel–Crafts type reaction and [4 + 2] cyclization
to afford highly conjugated carbon-rich indenes in the presence
of a Lewis acid. Herein, we report a Cu(I)-catalyzed tandem
isomerization/Friedel–Crafts reaction/[4 + 2] cyclization to give
cyclopenta[b]naphthalenes. In this reaction, several new carbon–
carbon bonds were achieved, along with one carbon–carbon bond
cleavage.
Results and discussion
We started by using 0.5 mmol of (E)-1,3,5-triphenylpent-1-en-4-
yn-3-ol 1a and 5 mol% of CuOTf in MeNO2 at 80 ◦C and achieved
aState Key Laboratory of Applied Organic Chemistry, Lanzhou University,
Lanzhou, 730000, P. R. China. E-mail: liangym@lzu.edu.cn; Fax: 0086-
931-8912582
bLaboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics,
Chinese Academy of Science, Lanzhou, 730000, P.R. China
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c1ob06087b
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Table 1 Optimization of the reaction conditionsa
Entry
Catalyst
Solvent
T/h
Yield (%)b
1
2
3
4
5
6
7
8
CuOTf
CuOTf (10%)
CuOTf (2%)
Cu(OAc)2
CuBr2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3NO2
CH3CN
CH2Cl2
1.5
1.5
1.5
2
2
2
2
2
2
3
2
0.5
1
5
5
3
4
2
3
92
92
92
85
78
72
81
CuSO4
Cu(OTf)2
Cu(acac)2
CuBr
ZnCl2
FeCl3
N.R.c
N.R.c
65
71
Trace
30
38
38
86
51
45
40
9
10
11
12
13
14
15
16
17
18
19
TiCl4
BF3·Et2O
Scheme 1 Cu(I)-Catalyzed condensation cyclization reaction of enynols.
Table 3 Selected photophysical parameters of compounds
TsOH
TsOH
CuOTf
CuOTf
CuOTf
CuOTf
a
b
c
d
Compound
lexc
lem
Dl
Uf
toluene
THF
2a
2p
2q
2r
2s
3n
360
333
339
372
366
348
400
393
395
401
416
399
40
60
57
29
50
51
0.43
0.08
0.11
0.25
0.66
0.22
a Reaction conditions: enynol 1a (0.5 mmol), catalyst (5 mol%) and solvent
(5 mL) at 80 ◦C under Ar atmosphere. b Isolated yield. c No Reaction.
Table 2 Copper-Catalyzed condensation of various enynolsa
a Excitation wavelength. b Emission wavelength. c Stokes shift, computed
as Dl = lexc - lem
d Fluorescence quantum yield CH2Cl2 at 25 ◦C.
.
Entry
Products
T/h
Yield (%)b
1
2
3
4
5
6
7
8
2a R1 = R2 = R3 = H
1.5
2
1.5
1
1
2
2
2
1.5
2.5
1.5
2
92
88
84
86
88
76
80
77
76
82
88
86
90
92
91
2b R1 = p-CH3, R2 = R3 = H
2c R1 = p-OCH3, R2 = R3 = H
2d R1 = p-NHAc, R2 = R3 = H
2e R1 = p-F, R2 = R3 = H
2f R1 = p-Cl, R2 = R3 = H
2g R1 = p-Br, R2 = R3 = H
2h R1 = H, R2 = R3 = o-CH3
2i R1 = H, R2 = R3 = p-CH3
2j R1 = H, R2 = R3 = o-Cl
2k R1 = H, R2 = R3 = p-Cl
2l R1 = H, R2 = R3 = p-Br
2m R1 = R2 = H, R3 = p-CN
2n R1 = R2 = H, R3 = p-NO2
2o R1 = p-Cl, R2 = p-CH3, R3 = p-NO2
Fig. 1 Fluorescence excitation and emission spectrum for 2a, 2p, 1q, 2r,
2s and 3n in CH2Cl2 (1 ¥ 10-5 M) at 293 K.
9
10
11
12
13
14
15
2
2
2
a General conditions: enynol 1 (0.5 mmol), CuOTf (5 mol%), and CH3NO2
(5 mL) at 80 ◦C under Ar. b Isolated yield.
these products were found to be up to 0.66, which is much higher
than for many known fluorescent compounds. It indicates that
these compounds are good candidates for fluorescent materials.
For example, 2n can react with amino acids after a simple func-
tional transformation (Scheme 2). Specific recognition properties
by the target biomolecules are essential for the development of
sensitive fluorescence-based probes9
Fig. 2 Compound 2s emitted blue light when excited at 365 nm.
Based on the above experimental results, a plausible mechanism
for the Cu-catalyzed tandem reactions is proposed (Scheme 3).
Initially, 1o undergoes a rearrangement to furnish the intermediate
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Anal. Calcd for C23H18O: C, 89.00; H, 5.85. Found: C, 89.09; H,
5.81.
1b: silica gel column purification with hexane/ethyl acetate
(10/1, v/v);1H NMR (400 MHz, CDCl3): d 7.70 (d, J = 8.4 Hz,
2H), 7.25–7.60 (m, 12H), 7.06 (d, J = 16 Hz, 1H), 6.52 (d, J =
16 Hz, 1H), 2.85 (brs, 1H), 2.42 (s, 3H); 13C NMR (100 MHz,
CDCl3, ppm): d 140.5, 137.6, 136.1, 133.0, 131.7, 129.0, 128.80,
128.4, 128.2, 127.8, 126.8, 125.7, 122.4, 90.1, 87.2, 73.0, 21.0. IR
(neat, cm-1): 2862, 1548, 1401, 1236, 1031, 698. Anal. Calcd for
C24H20O: C, 88.85; H, 6.21. Found: C, 88.93; H, 6.16.
1c: silica gel column purification with hexane/ethyl acetate
Scheme 2 Reaction of compound 2n with amino acids.
1
(10/1, v/v); H NMR (400 MHz, CDCl3): d 7.77–7.76 (m, 2H),
7.75–7.60 (m, 2H), 7.50–7.48 (m, 2H), 7.41–7.30 (m, 6H),7.09–7.05
(d, J = 16 Hz, 1H), 7.00–6.98 (m, 2H), 6.57–6.53 (d, J = 16 Hz,
1H), 3.85 (s, 3H), 3.22 (brs, 1H); 13C NMR (100 MHz, CDCl3,
ppm): d 159.1, 136.1, 135.6, 133.0, 131.7, 128.7, 128.537, 128.4
128.3, 128.2, 127.1, 126.8, 122.3, 113.6, 90.1, 87.2, 72.7, 55.2. IR
(neat, cm-1): 2912, 1521, 1392, 1190, 1019, 765. Anal. Calcd for
C24H20O2: C, 84.68; H, 5.92. Found: C, 84.59; H, 5.88.
1d: silica gel column purification with hexane/ethyl acetate
(10/1, v/v); H NMR (400 MHz, acetone): d 9.25 (s, 1H), 7.83–
Scheme 3 Plausible mechanism.
1
5.10 Coordination of the other 1o to the copper catalyst gives
complex 6. Then, electrophilic addition of the allylic cation center
of 6 to enynol 5 gives the propargylic carbocation 7 and CuOTf
is released for the next catalytic cycle. Subsequently, 7 undergoes
a stereoselective Grob fragmentation to furnish the intermediate
8 along with elimination of R3PhCHO.11 Then [4 + 2] cyclization
and aromatization reaction gives the final product.12
7.70 (m, 1H), 7.56–7.07 (m, 3H), 7.56–7.54 (m, 2H), 7.50–7.45
(m, 2H), 7.40–7.39 m, 3H), 7.35–7.31 (m, 2H), 7.26–7.24 (m, 2H),
7.04–7.00 (d, J = 16 Hz, 1H), 6.57–6.53 (d, J = 16 Hz, 1H), 5.62
(brs, 1H), 2.10 (s, 3H); 13C NMR (100 MHz, acetone, ppm): d
168.1, 143.4, 139.4, 138.9, 136.7, 134.4, 131.5, 128.6, 127.7, 126.
7, 126.3, 122.9, 118.8, 91.4, 86.1, 72.1, 23.4. IR (neat, cm-1): 3059,
2989, 1498, 1384, 1179, 1002, 796. Anal. Calcd for C25H21NO2: C,
81.72; H, 5.76; N, 3.81. Found: C, 81.61; H, 5.78, N, 3.86.
1e: silica gel column purification with hexane/ethyl acetate
(10/1, v/v); 1H NMR (400 MHz, CDCl3, ppm): d 7.80–7.79 (m,
2H), 7.61–7.58 (m, 2H), 7.49–7.46 (m, 2H), 7.42–7.31 (m, 5H),
7.15–7.11 (t, J = 8 Hz, 2H), 7.03 (d, J = 16 Hz, 1H), 6.47 (d, J =
16 Hz, 1H), 3.28 (brs, 1H); 13C NMR (100 MHz, CDCl3, ppm): d
163.7, 161.3, 139.4, 139.4, 136.1, 132.9, 131.9, 129.4, 128.9, 128.7,
128.5, 128.2, 127.9, 127.9, 127.1, 122.3, 115.4, 115.2, 89.9, 87.8,
72.9. IR (neat, cm-1): 3021, 1708, 1472, 1079, 1019, 765. Anal.
Calcd for C23H17O F: C, 84.12; H, 5.22. Found: C, 84.21; H, 5.26.
1f: silica gel column purification with hexane/ethyl acetate
Conclusions
In summary, we have developed a novel intermolecular conden-
sation reaction of 1,3,5-triarylenynols catalyzed by copper, which
involves dimerization fragmentation and 6-p cyclization and arom-
atization. This reaction is a straightforward method for the synthe-
sis of highly conjugated aromatic 1H-cyclopenta[b]naphthalenes.
These products are extremely useful in materials chemistry.
Experimental section
1
(10/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.08–8.07 (d,
General remarks
J = 1.6 Hz, 1H), 7.63–7.61 (m, 2H), 7.61–7.50 (m, 3H), 7.42–7.31
(m, 9H), 7.19–7.15(d, J = 16 Hz, 1H), 6.72–6.69 (d, J = 16 Hz,
1H), 3.61 (brs, 1H); 13C NMR (100 MHz, CDCl3, ppm): d139.7,
136.0, 132.2, 131.6, 131.2, 130.4, 129.5, 129.1, 128.5, 128.1, 127.4,
126.8, 126.8, 122.3, 88.9, 86.9, 72.0. IR (neat, cm-1): 3026, 1721,
1452, 1076, 1032, 785. Anal. Calcd for C23H17OCl: C, 80.11; H,
4.97. Found: C, 80.18; H, 4.96.
Column chromatography was carried out on silica gel. 1H NMR
spectra were recorded on 400 MHz in CDCl3 and 13C NMR spectra
were recorded on 100 MHz in CDCl3 using TMS as internal
standard. IR spectra were recorded on a FT-IR spectrometer
and only major peaks are reported in cm-1. Melting points were
determined on a microscopic apparatus and were uncorrected. All
new compounds were further characterized by element analysis;
copies of their 1H NMR and 13C NMR spectra are provided.
1g: silica gel column purification with hexane/ethyl acetate
1
(10/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 7.64–7.62 (d,
J = 8.4 Hz, 1H), 7.47–7.45 (m, 2H), 7.38–7.34(m, 7H), 7.22–7.16
(m, 3H), 6.97–6.93(d, J = 16 Hz, 1H), 6.39–6.35 (d, J = 16 Hz,
1H), 3.40 (brs, 1H); 13C NMR (100 MHz, CDCl3, ppm): d141.9,
135.8, 133.6, 132.4, 131.7, 129.5, 128.7, 128.6, 128.5, 128.4, 128.3,
128.3, 128.0, 127.3, 126.9, 122.0, 89.5, 87.7, 72.7. IR (neat, cm-1):
3054, 1703, 1439, 1055, 1022, 799. Anal. Calcd for C23H17OBr: C,
70.96; H, 4.40. Found: C, 71.01; H, 4.46.
General procedure 1: Synthesis of 1,3,5-triaryl-1-en-4-yn-3-ols10
1a: silica gel column purification with hexane/ethyl acetate (10/1,
v/v); 1H NMR (400 MHz, CDCl3): d 7.75–7.75 (m, 2H), 7.50–7.48
(m, 2H), 7.47–7.33 (m, 4H), 7.28–7.22 (m, 7H), 7.01–6.97 (d, J =
16 Hz, 2H), 6.99–6.93 (d, J = 16 Hz, 2H), 3.19 (brs, 1H); 13C NMR
(100 MHz, CDCl3 ppm): d 143.6, 136.3, 133.1, 132.2, 132.0, 129.2,
128.8, 128.7, 128.5, 128.5, 128.1, 128.1, 127.1, 126.1, 122.5, 90.2,
87.6, 73.39. IR (neat, cm-1): 2867, 1594, 1432, 1220, 1021, 732.
1h: silica gel column purification with hexane/ethyl acetate
1
(10/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 7.82–7.80 (d,
J = 8.4 Hz, 1H), 7.50–7.45 (m, 4H), 7.38–7.35 (m, 3H), 7.21–7.16
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(m, 4H), 7.06–7.02 (d, J = 16 Hz, 1H), 6.49–6.45 (d, J = 16 Hz,
1H), 2.81(brs, 1H), 2.42 (s, 3H), 2.38 (s, 3H); 13C NMR (100 MHz,
CDCl3, ppm): d 143.5, 138.7, 137.7, 133.3, 131.9, 131.6, 131.6,
129.2, 129.0, 129. 7, 128.9, 128.5, 128.3, 127.8, 126.8, 126.7, 125.8,
119.2, 89.3, 87.6, 73.3, 21.4, 21.2 IR (neat, cm-1): 2985, 1717, 1398,
1025, 985, 785. Anal. Calcd for C25H22O: C, 88.72; H, 6.55. Found:
C, 88.65; H, 6.59.
1i: silica gel column purification with hexane/ethyl acetate
(10/1, v/v); 1H NMR (400 MHz, CDCl3, ppm): d 7.85–7.83 (d, J =
15.6 Hz, 1H), 7.51–7.37 (m, 7H), 7.22–7.18 (m, 4H), 7.09–7.05(d,
J = 15.6 Hz, 1H), 6.51–6.48 (d, J = 15.6 Hz, 1H), 2.93(brs, 1H), 2.43
(s, 3H), 2.40 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm): d143.5,
138.8, 137.7, 133.3, 131.9, 131.6, 129.2, 129.0, 128.9, 128.4, 127.8,
126.8, 125.8, 119.2, 89.3, 87.6, 73.3, 21.5, 21.2. IR (neat, cm-1):
3015, 1720, 1418, 1025, 985, 735. Anal. Calcd for C25H22O: C,
88.72; H, 6.55. Found: C, 88.69; H, 6.51.
1j: silica gel column purification with hexane/ethyl acetate
(10/1, v/v);1H NMR (400 MHz, CDCl3, ppm): d 7.85–7.83 (d,
J = 7.6 Hz, 2H), 7.54–7.54 (d, J = 1.6 Hz, 1H), 7.53–7.37 (m, 4H),
7.36–7.35 (m, 2H), 7.30–7.23 (m, 4H), 6.96–6.92 (d, J = 15.6 Hz,
1H), 6.501–6.46 (d, J = 15.6 Hz, 1H), 3.20 (brs, 1H); 13C NMR
(100 MHz, CDCl3, ppm): d 142.9, 138.0, 134.6, 134.3, 134.1, 131.7,
130.0, 129.8, 129.7, 129.1, 128.6, 128.3, 128.0, 127.9, 126.8, 125.8,
125.2, 123.9, 91.0, 86.2, 73.1. IR (neat, cm-1): 3038, 1761, 1432,
1001, 962, 712. Anal. Calcd for C23H16OCl2: C, 72.83; H, 4.25.
Found: C, 72.79; H, 4.21.
128.6, 128.4, 128.3, 127.4, 126.6, 125.8, 123.8, 121.9, 89.1, 87.9,
73.0. IR (neat, cm-1): 3029, 1740, 1471, 1203, 1075, 672. Anal.
Calcd for C23H17NO3: C, 77.73; H, 4.82; N, 3.94. Found: C, 77.69;
H, 4.85; N, 3.89.
1o: silica gel column purification with hexane/ethyl acetate
(10/1, v/v);1H NMR (400 MHz, CDCl3, ppm): d 8.22(s, 1H),
8.09–8.06 (m, 1H), 7.70–7.68 (d, J = 8.8 Hz, 3H), 7.48–7.36 (m,
5H), 7.18–7.16 (d, J = 8 Hz, 4H), 7.04–7.00 (d, J = 15.6 Hz,
1H), 6.56–6.52 (d, J = 15.6 Hz, 1H), 3.26 (brs, 1H), 2.38(s, 3H);
13C NMR (100 MHz, CDCl3, ppm): d 148.3, 141.4, 139.2, 137.7,
135.6, 133.9, 132.7, 131.6, 129.4, 129.1, 128.9, 128.6, 127.3, 126.7,
122.5, 121.4, 118.6, 88.3, 88.1, 72.5, 21.5. IR (neat, cm-1): 3062,
1801, 1462, 1185, 1023, 705. Anal. Calcd for C24H18ClNO3: C,
71.38; H, 4.49; N, 3.47. Found: C, 71.26; H, 4.52; N, 3.41.
1p: silica gel column purification with hexane/ethyl acetate
(10/1, v/v);1H NMR (400 MHz, CDCl3, ppm): d 7.59–7.57 (m,
2H), 7.51–7.49 (d, J = 3.6 Hz, 3H), 7.39–7.30 (m, 6H), 7.13–
7.09 (d, J = 16 Hz, 1H), 6.68–6.64 (d, J = 16 Hz, 1H), 6.59–6.58
(d, J = 3.2 Hz, 1H), 6.42–6.40 (m, 1H), 3.55 (brs, 1H); 13C NMR
(100 MHz, CDCl3, ppm): d 154.5, 142.9, 135.9, 131.9, 131.8, 131.8,
130.8, 129.2, 128.7, 128.5, 128.5, 128.3, 128.0, 126.9, 125.8, 122.0,
110.3, 107.1, 87.7, 86.5, 68.5. IR (neat, cm-1): 3012, 1719, 1401,
1064, 962, 691. Anal. Calcd for C21H16O2: C, 83.98; H, 5.37. Found:
C, 83.95; H, 5.41.
1q: silica gel column purification with hexane/ethyl acetate
(10/1, v/v);1H NMR (400 MHz, CDCl3, ppm): d 7.64–7.63 (m,
2H), 7.62–7.53 (m, 2H), 7.51–7.34 (m, 8H), 7.19–7.13 (d, J =
15.6 Hz, 1H), 7.08–7.06 (m, 1H), 6.68–6.65 (d, J = 15.6 Hz, 1H),
3.31 (brs, 1H); 13C NMR (100 MHz, CDCl3, ppm): d 148.4, 135.8,
131.8, 131.7, 129.4, 128.7, 128.5, 128.3, 128.90, 126.9, 126.7, 125.8,
124.8, 121.9, 89.2, 86.7, 70.4. IR (neat, cm-1):3009, 1703, 1415,
1035, 978, 645. Anal. Calcd for C21H16OS: C, 79.71; H, 5.10.
Found: C, 79.65; H, 5.11.
1i: silica gel column purification with hexane/ethyl acetate
(10/1, v/v);1H NMR (400 MHz, CDCl3, ppm): d 8.31(s, 1H),
7.95–7.91 (m, 4H), 7.64–7.62(m, 2H), 7.61–7.54 (m, 2H), 7.49–
7.47 (m, 2H), 7.42–7.27 (m, 6H), 7.16–7.12 (d, J = 15.6 Hz, 1H),
6.63–6.59 (d, J = 15.6 Hz, 1H), 3.07 (brs, 1H); 13C NMR (100 MHz,
CDCl3, ppm): d 140.7, 136.2, 133.2, 133.1, 132.8, 131.9, 129.6,
128.8, 128.7, 128.5, 128.5, 128.4, 128.1, 127.7, 127.1, 126.4, 126.3,
124.4, 124.4, 122.4, 90.0, 87.8, 73.5. IR (neat, cm-1): 2975, 1707,
1385, 1015, 979, 765. Anal. Calcd for C27H20O: C, 89.97; H, 5.59.
Found: C, 90.03; H, 5.61.
1s: silica gel column purification with hexane/ethyl acetate
(10/1, v/v);1H NMR (400 MHz, CDCl3, ppm): d 8.71(s, 1H),
8.07–8.05(m, 1H), 7.89–7.87 (m, 1H), 7.78–7.76 (m, 2H), 7.70–
7.64 (m, 7H), 7.50–7.41 (m, 1H), 7.40–7.28 (m, 9H), 7.20–7.16
(d, J = 16 Hz, 1H), 6.78–6.74 (d, J = 16 Hz, 1H), 2.95 (brs, 1H);
13C NMR (100 MHz, CDCl3, ppm): d 138.0, 134.7, 133.6, 133.5,
133.2, 133.0, 132.9, 132.8, 131.7, 131.0 130.3, 129.6, 128.8, 128.3,
128.2, 128.0, 128.0, 127.8, 127.7, 127.6, 127.2, 126.8, 126.7, 126.5,
126.3, 126.0, 125.6, 125.5, 125.0, 124.1, 123.8, 119.7, 90.9, 88.4,
73.2. IR (neat, cm-1):2965, 1718, 1379, 1020, 962, 755. Anal. Calcd
for C35H24O: C, 91.27; H, 5.25. Found: C, 91.23; H, 5.29.
1k: silica gel column purification with hexane/ethyl acetate
1
(10/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 7.87–7.85 (d,
J = 4.8 Hz, 1H), 7.48–7.45 (m, 2H), 7.37–7.35 (m, 3H), 7.28–
7.24 (m, 4H), 7.21–7.19 (m, 1H), 7.02–6.98 (d, J = 16 Hz, 1H),
6.50–6.46 (d, J = 16 Hz, 1H), 3.40 (brs, 1H); 13C NMR (100 MHz,
CDCl3, ppm): d 138.5, 135.835, 134.215, 133.1, 131.6, 130.8, 129.9,
128.7, 128.5, 128.4, 128.2, 128.1, 126.9, 122.1, 88.5, 87.1, 71.6. IR
(neat, cm-1):3031, 1758, 1429, 1012, 965, 694. Anal. Calcd for
C23H16OCl2: C, 72.83; H, 4.25. Found: C, 72.76; H, 4.28.
1l: silica gel column purification with hexane/ethyl acetate
(10/1, v/v); 1H NMR (400 MHz, CDCl3, ppm): d 7.77–7.73 (m,
2H), 7.51–7.49 (m, 3H), 7.46–7.40 (m, 6H), 7.29–7.27 (d, J =
8.8 Hz, 2H), 6.94–6.90(d, J = 16 Hz, 1H), 6.47–6.43 (d, J =
16 Hz, 1H), 2.85 (brs, 1H); 13C NMR (100 MHz, CDCl3, ppm):
d 142.9, 135.0, 133.3, 133.3, 133.0, 131.7, 131.7, 128.6, 128.5,
128.3, 128.1, 125.9, 125.8, 123.2, 121.9, 121.2, 90.8, 86.6, 73.2.
IR (neat, cm-1):3029, 1765, 1398, 1003, 945, 672. Anal. Calcd for
C23H16OBr2: C, 59.00; H, 3.44. Found: C, 58.95; H, 3.38.
1m: silica gel column purification with hexane/ethyl acetate
(10/1, v/v);1H NMR (400 MHz, CDCl3, ppm): d 7.80–7.79 (d,
J = 4.4, 2H), 7.56–7.54 (d, J = 7.6 Hz, 4H), 7.46–7.38 (m, 8H),
7.05–7.01 (d, J = 15.6 Hz, 1H), 6.62–6.58 (d, J = 15.6 Hz, 1H),
3.45 (brs, 1H); 13C NMR (100 MHz, CDCl3, ppm): d 142.7, 140.6,
136.5, 132.1, 131.6, 128.7, 128.4, 128.3, 128.1, 127.2, 126.9, 125.7,
121.9, 118.7, 110.7, 89.2, 87.7, 72.8. IR (neat, cm-1): 3023, 1708,
1426, 1003, 672. Anal. Calcd for C24H17NO: C, 85.94; H, 5.11; N,
4.18. Found: C, 85.89; H, 5.17; N, 4.23.
1n: silica gel column purification with hexane/ethyl acetate
(10/1, v/v);1H NMR (400 MHz, CDCl3, ppm): d 8.17–8.15 (d,
J = 8.4, 2H), 7.80–7.76 (m, 2H), 7.57–7.52 (m, 4H), 7.46–7.42 (m,
2H), 7.38–7.35 (m, 4H), 7.09–7.05 (d, J = 15.6 Hz, 1H), 6.54–
6.61 (d, J = 15.6 Hz, 1H), 3.20 (brs, 1H); 13C NMR (100 MHz,
CDCl3, ppm): d 147.0, 142.7, 142.8, 137.4, 131.7, 128.9, 128.7,
General procedure for the preparation of 2
To
a solution of 1,3,5-triaryl-1-en-4-yn-3-ol derivatives 1
(0.50 mmol) in CH3NO2 (5.0 mL) was added 5 mmol% CuOTf
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at 80 ◦C under Ar. When the reaction was considered complete, as
determined by TLC analysis, the reaction mixture was quenched
by addition of saturated aqueous NH4Cl and diluted with ethyl
ether (40 mL), washed with water, saturated brine, dried over
Na2SO4 and evaporated under reduced pressure. The residue
was purified by chromatography on silica gel to afford the
corresponding 1H-cyclopenta[b]naphthalenes 2a–2s
128.6, 128.5, 128.4, 128.3, 128.3, 127.9, 127.7, 127.6, 127.5, 127.2,
126.9, 126.8, 123.2, 116.5, 115.9, 115.6, 114.1, 114.0, 113.9, 113.8,
110.6, 110.4, 99.4, 85.3, 55.0. IR (neat, cm-1):2926, 1614, 1508,
1248, 71034, 697. Anal. Calcd for C39H24F2: C, 88.28; H, 4.56.
Found: C, 88.31; H, 4.61.
2f: silica gel column purification with hexane/ethyl acetate
(100/1, v/v); 1H NMR (400 MHz, CDCl3, ppm): 1H NMR
(400 MHz, CDCl3, ppm): d 8.29–8.26 (d, J = 8.8 Hz, 1H), 7.545–
7.540 (d, J = 2 Hz, 1H), 7.34–7.31 (m, 1H), 7.31–7.16 (m, 5H),
7.13–7.07 (m, 7H), 6.97–6.95 (m, 3H), 6.94–6.93 (m, 1H), 6.76–
6.74 (d, J = 8 Hz, 2H), 6.64–6.62 (d, J = 8 Hz, 2H), 6.383–6.378 (d,
J = 2 Hz, 2H), 4.915–4.91 (d, J = 2 Hz, 1H); 13C NMR (100 MHz,
CDCl3, ppm): d 149.2, 143.9, 142.4, 140.3, 138.1, 135.9, 135.0,
133.7, 132.3, 132.2, 132.1, 131.5, 131.1, 131.1, 130.3, 129.3, 128.5,
128.5, 128.5, 128.2, 127.6, 127.6, 127.6, 127.2, 126.8, 126.8, 126.7,
125.6, 123.1, 116.5, 99.6, 85.1, 55.1. IR (neat, cm-1): 3056, 1458,
1377, 1248, 756, 697. Anal. Calcd for C39H24Cl2: C, 83.12; H, 4.29.
Found: C, 83.15; H, 4.21.
2a: silica gel column purification with hexane/ethyl acetate
1
(100/1, v/v);, H NMR (400 MHz, CDCl3, ppm): d 8.39–8.37
(d, J = 12.8 Hz, 1H), 7.65–7.64 (m, 1H), 7.45–7.44 (m, 1H), 7.43–
7.16 (m, 9H), 7.10–7.06 (m, 4H), 7.05–7.04 (m, 2H), 6.98–6.85 (m,
2H), 6.84–6.74 (m, 2H), 6.51–6.50 (d, J = 2.4 Hz, 1H), 5.04–5.03
(d, J = 2.4 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm): d 149.2,
143.9, 142.4, 140.3, 138.1, 135.9, 135.0, 133.7, 132.3, 132.2, 132.0,
131.7, 131.5, 131.2, 131.1, 130.3, 129.4, 129.3, 128.8, 128.5, 128.5,
128.3, 127.7, 127.6, 127.6, 127.2, 127.1, 126.8, 126.7, 125.6, 123.0,
116.5, 99.5, 85.0, 55.0. IR (neat, cm-1): 3062, 1708, 1592, 1076,
755. Anal. Calcd for C39H26: C, 94.70; H, 5.30. Found: C, 94.76;
H, 5.25.
2b: silica gel column purification with hexane/ethyl acetate
(100/1, v/v); 1H NMR (400 MHz, CDCl3, ppm): d 8.48–8.46(m,
1H), 7.67 (s, 1H), 7.56–7.32(m, 11H), 7.27–7.12(m, 4H), 6.85–6.79
(m, 4H), 6.56–6.55 (d, J = 2.4 Hz, 1H), 5.04–5.03(d, J = 2.4 Hz,
1H), 2.35 (s, 3H), 2.20 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm):
d 148.5, 145.3, 141.0, 139.7, 139.0, 136.9, 135.5, 135.3, 134.0, 132.9,
132.6, 131.5, 131.3, 131.2, 130.2, 128.6, 128.4, 128.3, 128.2, 128.1,
128.0, 127.6, 127.2, 126.5, 126.4, 125.8, 125.7, 123.5, 116.1, 98.7,
85.9, 54.9, 21.8, 21.1. IR (neat, cm-1):2923, 1693, 1445, 820, 735.
Anal. Calcd for C41H30: C, 94.21; H, 5.79. Found: C, 94.28; H,
5.71.
2g: silica gel column purification with hexane/ethyl acetate
1
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.40–8.38
(d, J = 8.8 Hz, 1H), 7.90 (s, 1H), 7.66–7.63 (m, 1H), 7.63–7.25 (m,
11H), 7.17–7.02(m, 5H), 6.64–6.62 (d, J = 8.4 Hz, 2H), 6.57–6.56
(d, J = 2 Hz, 2H), 5.09–5.08 (d, J = 2 Hz, 1H); 13C NMR (100 MHz,
CDCl3, ppm): d 149.4, 143.9, 142.3, 140.2, 138.0, 135.8, 135.5,
134.1, 132.2, 131.5, 131.1, 131.1, 130.5, 130.2, 129.6, 129.3, 128.8,
128.6, 128.5, 128.5, 128.4, 128.3, 127.7, 127.6, 127.6, 127.2, 126.8,
123.1, 120.6, 120.2, 116.6, 99.7, 85.0, 55.1. IR (neat, cm-1):3023,
1599, 1490, 1027, 732, 696. Anal. Calcd for C39H24Br2: C, 71.80;
H, 3.71. Found: C, 71.86; H, 3.68.
2h: silica gel column purification with hexane/ethyl acetate
1
2c: silica gel column purification with hexane/ethyl acetate
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.51–8.49
1
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 7.37–7.22
(d, J = 8 Hz, 1H), 7.80–7.78 (d, J = 8.4 Hz, 1H), 7.57–7.53 (m,
1H), 7.41–7.30(m, 2H), 7.23–7.19 (m, 4H), 7.14–7.12 (m, 2H),
7.04–6.84 (m, 9H), 6.52–6.51 (d, J = 2.4 Hz, 2H), 5.09–5.08 (d,
J = 2.4 Hz, 1H), 2.42 (s, 3H), 2.36 (s, 3H), 2.29 (s, 3H); 13C NMR
(100 MHz, CDCl3, ppm): d 149.6, 145.1, 141.4, 139.8, 138.3, 137.0,
136.3, 136.1, 135.6, 133.7, 133.0, 132.7, 131.9, 131.6, 131.4, 131.1,
131.0, 129.1, 129.0, 128.8, 128.5, 128.3, 128.2, 128.0, 127.8, 127.8,
126.9, 126.8, 125.8, 125.7, 125.7, 125.4, 120.5, 116.2, 99.1, 85.2,
54.6, 21.6, 21.1, 21.09. IR (neat, cm-1): 2924, 1600, 1488, 1092,
755, 700. Anal. Calcd for C42H32: C, 93.99; H, 6.01. Found: C,
94.05; H, 6.07.
(m, 12H), 7.16–7.02(m, 6H), 6.84–6.82 (d, J = 8.8 Hz,, 9H), 6.05
(s, 1H), 5.08–5.07 (d, J = 2.4 Hz, 1H), 3.76 (s, 3H), 3.71 (s, 3H); 13
C
NMR (100 MHz, CDCl3, ppm): d 157.7, 147.3, 144.8, 141.3, 140.1,
139.1, 136.9, 134.1, 132.1, 131.4, 131.2, 131.1, 129.4, 129.1, 128.5,
128.4, 128.4, 128.2, 127.4, 127.3, 127.3, 126.7, 126.5, 123.5, 117.5,
112.7, 106.1, 98.7, 85.9, 55.2, 55.1, 54.8. IR (neat, cm-1):2926, 1598,
1498, 1071, 755, 696. Anal. Calcd for C41H30O2: C, 88.78; H, 5.45.
Found: C, 88.71; H, 5.39.
2d: silica gel column purification with hexane/ethyl acetate
1
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.45–8.43(d,
J = 8.8 Hz, 1H), 7.94–7.91(m, 1H), 7.60(s, 2H), 7.37–7.26 (m, 9H),
7.12–7.00 (m, 6H), 7.00–6.88 (m, 5H),6.53–6.52 (d, J = 2 Hz, 1H),
5.08 (d, J = 2.4 Hz, 1H), 2.07 (s, 6H); 13C NMR (100 MHz, CDCl3,
ppm): d 168.5, 148.5, 145.2, 141.9, 140.0, 138.8, 136.8, 136.6,
136.02 133.2, 132.5, 131.5, 131.2, 131.2, 129.1, 128.6, 128.5, 128.3,
128.3, 128.1, 127.4, 127.4, 127.1, 127.0, 126.9, 126.7, 126.0, 123.4,
120.0, 116.2, 115.6, 99.1, 85.6, 55.0, 29.7. IR (neat, cm-1):2924,
1654, 1486, 1073, 755, 697. Anal. Calcd for C43H32ON2: C, 84.84;
H, 5.30; N, 4.60. Found: C, 84.81; H, 5.30; N, 4.52.
2i: silica gel column purification with hexane/ethyl acetate
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.47–8.45
1
(d, J = 8.4 Hz, 1H), 7.59–7.75 (m, 1H), 7.47–7.44 (m, 1H), 7.38–
7.36 (m, 2H), 7.26–7.23 (m, 4H), 7.19–7.17 (m, 1H), 7.10–6.87 (m,
9H), 6.57 (s, 1H), 5.12 (s, 1H), 2.46 (s, 3H), 2.41 (s, 3H), 2.34 (s,
3H); 13C NMR (100 MHz, CDCl3, ppm): d 149.4, 145.2, 141.4,
139.6, 138.2, 137.0, 136.3, 136.0, 135.7, 133.7, 133.7, 133.0, 132.8,
131.9, 131.5, 131.4, 131.1, 131.0, 129.0, 129.0, 128.5, 128.2, 127.8,
127.8, 126.9, 126.8, 125.8, 125.7, 125.4, 120.5, 116.2, 99.2, 54.6,
21.5, 21.1, 21.1. IR (neat, cm-1):3026, 1617, 1446, 1027, 819, 732.
Anal. Calcd for C42H32: C, 93.99; H, 6.01. Found: C, 93.94; H,
5.95.
2e: silica gel column purification with hexane/ethyl acetate
1
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.54–8.50
(m, 1H), 7.47–7.32 (m, 12H), 7.23–7.21 (m, 1H), 7.16–7.13 (m,
3H), 7.07–7.05 (m, 1H), 6.90–6.88 (m, 2H), 6.86–6.64 (m, 2H),
6.57–6.56 (d, J = 2 Hz, 1H), 5.11–5.10 (d, J = 1.6 Hz, 1H); 13C
NMR (100 MHz, CDCl3, ppm): d 162.6, 162.3, 160.1, 159.9, 148.4,
144.1, 142.3, 140.3, 138.4, 136.2, 134.2, 134.1, 132.6, 132.6, 132.5,
132.4, 131.7, 131.5, 131.1, 131.0, 130.7, 129.7, 129.7, 128.9, 128.8,
2j: silica gel column purification with hexane/ethyl acetate
1
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.47–8.45
(d, J = 8 Hz, 1H), 7.70–7.67 (m, 1H), 7.67–7.59 (m, 1H), 7.57–
7.46 (m, 1H), 7.44–7.30 (m, 6H), 7.13–7.00 (m, 9H), 6.97–6.93
(m, 2H), 6.51–6.50 (d, J = 1.6 Hz, 2H), 5.04–5.03 (d, J = 2 Hz,
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1H); 13C NMR (100 MHz, CDCl3, ppm): d 148.7, 145.5,140.7,
139.4, 138.2, 136.2, 134.2, 133.4, 132.5, 132..0, 131.8, 131.4, 131.4,
131.3, 129.8,129.5, 129.3, 129.2, 128.7, 128.6, 127.9, 127.3, 127.2,
127.1, 126.4, 126.3, 125.8, 124.7, 116.4, 98.0, 86.4, 54.5. IR (neat,
cm-1):2924, 1600, 1488, 1092, 825, 700. Anal. Calcd for C39H23Cl3:
C, 78.34; H, 3.88. Found: C, 78.39; H, 3.92.
134.2, 134.0, 133.0, 132.6, 132.4, 132.3, 131.2, 131.0, 130.9, 130.4,
129.4, 129.2, 129.1, 128.60, 128.3, 127.6, 127.0, 125.8, 123.8, 122.0,
119.5, 116.7, 100.3, 84.1, 54.4, 21.5, 21.1. IR (neat, cm-1): 2924,
1710, 1261, 1030, 802, 697. Anal. Calcd for C41H27Cl2NO2: C,
77.36; H, 4.28; N, 2.20. Found: C, 77.32; H, 4.21; N, 2.23.
2p: silica gel column purification with hexane/ethyl acetate
1
2k: silica gel column purification with hexane/ethyl acetate
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 7.34–7.28
1
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.45–8.43
(m, 14H), 7.23–7.18 (m, 4H), 7.00–6.98 (m, 1H), 6.67–6.66 (d, J =
2.4 Hz, 2H), 6.59–6.57 (m, 1H), 6.30–6.28 (m, 1H), 5.03–5.028
(d, J = 2.4 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm): d 147.7,
142.2, 139.3, 138.1, 137.8, 137.4, 131.7, 131.6, 130.0, 130.0, 128.7,
128.5, 128.2, 127.4, 127.0, 126.8, 126.6, 125.9, 124.5, 123.8, 123.1,
113.4, 98.3, 85.1, 54.7. IR (neat, cm-1): 2922, 1489, 1260, 1094,
800, 694. Anal. Calcd for C35H22O2: C, 88.58; H, 4.67. Found: C,
88.71; H, 4.69.
2q: silica gel column purification with hexane/ethyl acetate
(100/1, v/v); 1H NMR (400 MHz, CDCl3, ppm): d 7.365–7.25 (m,
14H), 7.22–7.18 (m, 4H), 6.99–6.98 (d, J = 4.4 Hz, 2H), 6.66–6.65
(d, J = 2 Hz, 2H), 6.58–6.56 (m, 1H), 6.29–6.28 (d, J = 3.2 Hz, 1H),
5.02–5.01 (d, J = 2 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm): d
147.6, 142.2, 140.7, 139.3, 138.1, 137.9, 137.8, 137.4, 131.7, 131.6,
131.6, 130.0, 128.7, 128.4, 128.2, 127.4, 126.9, 126.9, 126.8, 126.6,
125.9, 124.5, 123.8, 123.0, 113.4, 98.3, 85.1 54.7. IR (neat, cm-1):
2960, 1447, 1226, 1029, 862, 731. Anal. Calcd for C35H22S2: C,
82.97; H, 4.38. Found: C, 82.89; H, 4.41.
2r: silica gel column purification with hexane/ethyl acetate
(100/1, v/v); 1H NMR (400 MHz, CDCl3, ppm): d 8.60–8.58 (m,
1H), 7.88–7.86 (d, J = 8.4 Hz, 2H), 7.78–7.76 (d, J = 8.4 Hz, 2H),
7.67–7.66 (m, 1H), 7.48–7.33 (m, 16H), 7.27–7.26 (m, 1H), 7.17–
7.16 (m, 1H), 7.07–7.06 (d, J = 7.2 Hz, 1H), 7.00–6.96(m, 1H),
6.89 (s, 1H), 6.83–6.81 (m, 1H), 6.72 (s, 1H), 6.64 (s, 1H), 5.17–
5.16 (d, J = 1.6 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm): d
149.2, 145.7, 142.4, 141.4, 140.0, 138.3, 135.7, 134.5, 133.7, 132.6,
132.1, 131.5, 128.6, 128.5, 128.3, 128.2, 127.7, 127.3, 126.9, 126.7,
126.7, 126.4, 125.6, 125.4, 125.3, 124.7, 124.4, 123.4, 117.2, 99.1,
86.2, 54.8. IR (neat, cm-1): 3079, 1598, 1491, 1073, 760, 696. Anal.
Calcd for C47H30: C, 94.92; H, 5.08. Found: C, 94.96; H, 5.05.
2s: silica gel column purification with hexane/ethyl acetate
(100/1, v/v); 1H NMR (400 MHz, CDCl3, ppm): d 8.58–8.56 (d,
J = 8 Hz, 1H), 8.05 (s, 1H), 7.87–7.77 (m, 7H), 7.69–7.62 (m, 1H),
7.60–7.40 (m, 16H), 7.40–7.25 (m, 2H), 6.90–6.87 (m, 2H), 6.62–
6.57 (m, 4H), 5.34–5.33 (d, J = 2 Hz, 1H); 13C NMR (100 MHz,
CDCl3, ppm): d 149.2, 145.6, 141.2, 136.4, 133.8, 132.9, 132.8,
132.7, 132.6, 132.3, 132.0, 131.4, 129.1, 128.3, 128.2, 127.9, 127.8,
127.8, 127.8, 127.7, 127.6, 127.7, 127.4, 126.9, 126.8, 126.8, 126.7,
126.6, 126.4, 126.1, 126.0, 126.0, 125.7, 125.65, 125.6, 125.5, 120.5,
116.7, 99.7, 85.9, 55.3. IR (neat, cm-1): 3058, 1642, 1449, 1028, 911,
760. Anal. Calcd for C47H30: C, 95.13; H, 4.87. Found: C, 95.02;
H, 4.93.
(d, J = 8.4 Hz, 1H), 7.70–7.68 (d, J = 8.4 Hz, 1H), 7.60–7.57 (m,
1H), 7.46–7.42 (m, 2H), 7.30–7.26 (m, 5H), 7.20–7.13 (m, 2H),
7.02–6.95 (m, 5H), 6.87–6.85 (m, 2H), 6.50–6.49 (d, J = 2 Hz, 2H),
5.05–5.04 (d, J = 2 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm): d
148.8, 145.3, 140.9, 139.6, 137.2, 136.3, 134.9, 134.5, 133.1, 132.6,
132.6, 132.5, 132.4, 132.1, 131.8, 130.8, 129.8, 128.9, 128.7, 128.6,
128.6, 128.3, 128.2, 127.4, 127.34, 127.3, 126.5, 126.3, 126.3, 126.2,
125.8, 121.6, 116.3, 98.3, 86.3, 54.2. IR (neat, cm-1): 2854, 1644,
1446, 1074, 756, 698. Anal. Calcd for C39H23Cl3: C, 78.34; H, 3.88.
Found: C, 78.29; H, 3.91.
2l: silica gel column purification with hexane/ethyl acetate
1
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.44–8.42
(d, J = 8.4 Hz, 1H), 7.70–7.68 (m, J = 8.8 Hz, 1H), 7.59–7.51 (m,
3H), 7.42–7.40 (m, 3H), 7.20–7.13 (m, 7H), 7.00–6.97 (m, 3H),
6.90–6.84 (m, 3H), 6.49–6.48 (d, J = 2.4 Hz, 2H), 5.03–5.02 (d,
J = 2 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm): d 148.7, 145.4,
140.8, 139.6, 137.8, 136.3, 135.4, 132.9, 132.8, 132.7, 132.5, 132.1,
131.8, 131.7, 131.6, 131.5, 130.4, 130.3, 130.2, 128.2, 127.4, 126.5,
126.3, 126.3, 126.2, 125.8, 122.8, 122.0, 121.4, 120.4, 116.4, 98.4,
86.5, 54.4. IR (neat, cm-1): 3026, 1598, 1491, 1028, 760, 696. Anal.
Calcd for C39H23Br3: C, 64.05; H, 3.17. Found: C, 64.01; H, 3.23.
2m: silica gel column purification with hexane/ethyl acetate
(100/1, v/v); 1H NMR (400 MHz, CDCl3, ppm): d 8.50–8.48(d,
J = 8.4 Hz, 1H), 7.75–7.73 (d, J = 8.4 Hz, 1H), 7.60–7.56 (m, 3H),
7.46–7.36 (m, 8H), 7.15–7.00 (m, 5H), 7.00–6.89 (m, 4H), 6.47–
6.46 (d, J = 2.4 Hz, 2H), 5.14–5.13 (d, J = 2.4 Hz, 1H); 13C NMR
(100 MHz, CDCl3, ppm): d 148.0, 146.7, 145.1, 139.7, 139.0, 136.4,
133.9, 133.0, 132.3, 132.0, 131.3, 131.2, 129.4, 128.7, 128.5, 128.1,
127.4, 127.3, 127.2, 127.1, 127.0, 125.9, 123.0, 119.0, 116.6, 110.4,
99.5, 85.4, 54.8. IR (neat, cm-1): 2854, 1460, 1376, 1073, 757, 696.
Anal. Calcd for C40H25N: C, 92.46; H, 4.85; N, 2.70. Found: C,
92.41; H, 4.81; N, 2.63.
2n: silica gel column purification with hexane/ethyl acetate
1
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.52–8.50
(d, J = 8.4 Hz, 1H), 8.18–8.16 (d, J = 8.4 Hz, 2H), 7.77–7.75 (m,
1H), 7.59–7.57 (m, 1H), 7.47–7.38 (m, 8H), 7.17–7.00 (m, 6H),
6.99–6.90 (m, 4H), 6.48–6.47 (d, J = 2 Hz, 2H), 5.19–5.18 (d, J =
2 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm): d 148.0, 147.3,
146.9, 146.9, 139.5, 138.9, 136.3, 134.0, 133.1, 132.0, 131.3, 131.2,
131.2, 129.4, 128.7, 128.5, 128.1, 127.4, 127.4, 127.3, 127.1, 127.0,
126.4, 125.9, 123.7, 123.0, 116.7, 99.5, 85.5, 54.5. IR (neat, cm-1):
2924, 1489, 1312, 1028, 803, 724. Anal. Calcd for C39H25NO2: C,
86.80; H, 4.67; N, 2.60. Found: C, 86.72; H, 4.76; N, 2.52.
Typical procedure for synthesis of 3n and characterization data of
3n
2o: silica gel column purification with hexane/ethyl acetate
1
(100/1, v/v); H NMR (400 MHz, CDCl3, ppm): d 8.42–8.41(d,
J = 8.4 Hz, 1H), 8.21–8.22 (m, 1H), 8.11–8.10 (d, J = 1.2 Hz, 1H),
7.76–7.61 (m, 1H), 7.61–7.40 (m, 1H), 7.35–7.34 (m, 4H), 7.24–
7.22 (m, 1H), 7.18–7.16 (m, 4H), 6.99–6.92 (m, 5H), 6.89–6.77 (m,
3H), 6.50–6.49 (d, J = 2.4 Hz, 1H), 5.15–5.18 (d, J = 2.4 Hz, 1H),
2.40 (s, 3H), 2.38 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm): d
148.4, 147.7, 145.7, 141.0, 140.1, 139.9, 139.2, 137.6, 134.7, 134.5,
To a solution of 2n (1.07 g 2 mmol) in EtOH (20 mL) was
added 2 eq SnCl2 at 50 ◦C. When the reaction was considered
complete, as determined by TLC analysis, the reaction mixture
was quenched by addition 20% NaOH and diluted with ethyl ether
(40 mL), washed with water, saturated brine, dried over Na2SO4
and evaporated under reduced pressure. The residue was purified
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by chromatography on silica gel to afford the corresponding
reaction intermediate (773 mg, yield 76%).
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1-Benylpyrrolidione-2-carboxylic acid (307 mg, 1.5 mmol) was
dissolved in CH2Cl2 (10 ml) and cooled to -15 ◦C. Et3N was
added (151 mg, 1.5 mmol), followed by ethyl chloroformate
(162 mg, 1.5 mmol). The suspension was stirred for 30 min, then
the reaction intermediate from the first step (509 mg, 1 mmol)
was added and stirring was continued for 6 h. the reaction
mixture was quenched by addition of water and diluted with
CH2Cl2 (100 mL), washed with water, saturated brine, dried over
Na2SO4 and evaporated under reduced pressure. The residue was
purified by chromatography on silica gel to afford corresponding
compounds 3n (591 mg, yield 85%).
1
3n: H NMR (400 MHz, CDCl3, ppm): d 9.40–9.38 (d, J =
8.8 Hz, 1H), 8.48–8.46 (d, J = 8 Hz, 1H), 7.69–7.67 (d, J = 8.4 Hz,
1H), 7.53–7.41 (m, 5H), 7.37–7.21 (m, 12H), 7.10–6.85 (m, 10H),
6.46–6.45 (d, J = 2 Hz, 1H), 5.06–5.05 (d, J = 2 Hz, 1H), 3.92–
3.89 (m, 1H), 3.57–3.53 (m, 1H), 3.33–3.29 (m, 1H), 3.10–3.08
(m, 1H), 2.45–2.40 (m, 1H), 2.30–3.24 (m, 1H), 2.02–1.98 (m,
1H), 1.78–1.72 (m, 3H); 13C NMR (100 MHz, CDCl3, ppm): d
172.6, 149.4, 145.4, 141.5, 139.4, 138.5, 138.4, 136.9, 136.7, 136.4,
134.4, 133.3, 132.9, 132.0, 131.6, 131.58, 131.3, 131.2, 129.2, 128.7,
128.67, 128.3, 128.2, 127.5, 127.3, 126.8, 126.9, 126.0, 125.9, 119. 5,
116.4, 99.3, 85.8, 68.0, 60.1, 54.5, 54.1, 30.8, 24.3. IR (neat, cm-1):
3062, 1708, 1592, 1076, 761, 732. Anal. Calcd for C51H40N2O: C,
87.90; H, 5.79; N, 4.02. Found: C, 87.82; H, 5.76; N, 4.07.
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Acknowledgements
We thank the NSF (NSF-21072080, NSF-20732002) for financial
support. We acknowledge the National Basic Research Program
of China (973 program), 2010CB833203.
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