A highly efficient and selective aerobic cross-dehydrogenative-coupling reaction photocatalyzed by a platinum(II) terpyridyl complex

Article abstract of DOI:10.1002/chem.201204572

Thanks to the superior redox potential of platinum(II) complex compared with that of Ru(bpy)₃²⁺ in the excited state, an efficient and selective visible-light-induced CDC reaction has been developed by using a catalytic amount (0.25

Full text of DOI:10.1002/chem.201204572

FULL PAPER
DOI: 10.1002/chem.201204572
A Highly Efficient and Selective Aerobic Cross-Dehydrogenative-Coupling
Reaction Photocatalyzed by a Platinum(II) Terpyridyl Complex
Jian-Ji Zhong,[a] Qing-Yuan Meng,[a] Ge-Xia Wang,[a] Qiang Liu,[a, b] Bin Chen,[a]
Ke Feng,[a] Chen-Ho Tung,[a] and Li-Zhu Wu*[a]
Abstract: Thanks to the superior redox
exclusively obtained under ambient air
conditions. A spectroscopic study and
product analysis revealed that the
CDC reaction is initiated by photoin-
duced electron-transfer from N-phenyl-
tetrahydroisoquinoline to the complex.
An EPR (electron paramagnetic reso-
nance) experiment provides direct evi-
dence on the generation of superoxide
potential of platinum(II) complex com-
2+
pared with that of RuACHTNUTRGNEUNG(bpy)3 in the
ꢀC
excited state, an efficient and selective
visible-light-induced CDC reaction has
been developed by using a catalytic
amount (0.25%) of 1. With the aid of
FeSO4 (2 equiv), the corresponding
amide could not be detected under visi-
ble-light irradiation (l=450 nm), but
the desired cross-coupling product was
radical anion (O2 ) rather than singlet
oxygen (1O2) under irradiation of the
reaction system, in contrast to that re-
ported in the literature. Combined, the
photoinduced electron-transfer and
subsequent formation of superoxide
Keywords: aerobic reaction · cross-
coupling · platinum · radicals · visi-
ble-light catalysis
ꢀC
radical anion (O2 ) results in a clean
and facile transformation.
Introduction
ACHTUNGTRENaNUNG lkyl malonates, dialkyl phophonates, and ketones, respec-
tively. Significantly, molecular oxygen was found capable of
facilitating the photoredox catalysis remarkably well, and
The cross-dehydrogenative-coupling (CDC) reaction[1] is
one of the most powerful tools to construct C C bonds di-
ꢀC
[2]
ꢀ
the superoxide radical anion (O2 ) has been demonstrated
ꢀ
rectly from two different C H bonds under oxidative condi-
to be responsible for the large rate of acceleration of the
aerobic photocatalytic reactions. Moreover, Rueping et al.[10]
reported a dual catalytic system combining photoredox cat-
alysis with Lewis base catalysis for the Mannich reaction.
Rovis et al.[11] realized a catalytic asymmetric a-acylation of
tertiary amines with aldehydes by combination of chiral N-
heterocyclic carbene catalysis and photoredox catalysis. The
group of Blechert and Wang[12] made use of mesoporous
tions. Such a coupling makes the reaction more atom-eco-
nomic and simpler because it avoids the prefunctionalization
and defunctionalization that have been part of the tradition-
al synthetic design. With the aid of a sacrificial oxidant, inor-
ganic metal salts and organic oxidants have been successful-
ly employed for the transformation in the past decade.[1–3]
Recently, the use of visible light[4–7] to initiate a CDC reac-
tion has appeared at the forefront. Stephenson et al.[8] took
the lead in realizing the oxidative coupling of nitroalkanes
and tetrahydroisoquinolines through visible-light catalysis.
Kçnig,[9a] Tan,[9b] and our group[9c] developed the metal-free
visible-light oxidative coupling of tetrahydroisoquinoline de-
rivatives with various nucleophiles such as nitroalkanes, di-
ꢀ
graphitic carbon nitride to construct C C bonds of tertiary
amines with nucleophiles under visible light. All of the stud-
ies indicate that the visible-light catalytic CDC reaction is
an interesting subject, whereas a photocatalyst that can har-
ness visible light to initiate a robust and efficient reaction
has yet to be developed.
Thanks to visible-light absorption, long excited-state life-
time, high luminescent quantum yield, and good chemical
stability, platinum(II) polypyridyl complexes[13–17] have been
promising to initiate photochemical reactions.[18–19] With visi-
ble-light irradiation, for example, pyridine derivatives, 3,4-
diarylpyrroles, and 3,4-diarylthiophenes have been success-
fully obtained,[18] respectively, in the absence of any oxi-
dants. On the other hand, we have shown that platinum(II)
polypyridyl complexes are ideal sensitizers for photooxida-
tion by using molecular oxygen,[19] in which singlet oxygen
[a] J.-J. Zhong, Q.-Y. Meng, G.-X. Wang, Dr. Q. Liu, Dr. B. Chen,
Dr. K. Feng, Prof. Dr. C.-H. Tung, Prof. Dr. L.-Z. Wu
Key Laboratory of Photochemical Conversion
and Optoelectronic Materials
Technical Institute of Physics and Chemistry and
University of Chinese Academy of Sciences
Chinese Academy of Sciences
Beijing 100190 (P.R. China)
Fax : (+86)10-8254-3580
E-mail: lzwu@mail.ipc.ac.cn
(1O2) was generated upon irradiation of light in the visible
[b] Dr. Q. Liu
State Key Laboratory of Applied Organic Chemistry
College of Chemistry and Chemical Engineering
Lanzhou University, Lanzhou 730000 (P.R. China)
2+
region. Compared with the famous RuACTHNUTRGENUG(N bpy)3 that is em-
ployed in visible-light catalysis,[20–22] the platinum(II) com-
plex is still in its infancy.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201204572.
Chem. Eur. J. 2013, 19, 6443 – 6450
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
6443

and byproduct amide 5 were
obtained similar to that ob-
served in the literature.[3j,k,l]
Molecular oxygen[24–25] is cru-
cial for this CDC reaction.
When the reaction took place
in an atmosphere of nitrogen,
no photoproduct was observed
(Table 1, entry 6). As men-
tioned above, the platinum(II)
complex is an ideal photosensi-
tizer for producing singlet
oxygen (1O2).[19] However, the
ꢀC
superoxide radical anion (O2
)
was recently proposed as the
active species in the CDC reac-
tion.[9c] To make things clear,
we studied the active species of
Scheme 1. Visible-light catalysis of indolation with tetrahydroisoquinolines by a platinum(II) complex 1.
In the present work, we wish to report a highly efficient
and selective visible-light-induced CDC reaction by using a
catalytic amount (0.25 mol%) of a platinum(II) terpyridyl
complex 1 (Scheme 1). With this system, we are able to
obtain the desired coupling compounds of N-phenyltetrahy-
droisoquinolines and indoles within a short reaction time.
Under ambient air conditions, the addition of FeSO4
(2.0 equiv) improved the reaction selectivity remarkably,
and the desired cross-coupling product was obtained exclu-
sively. A spectroscopic study and product analysis reveal
that the CDC reaction is initiated by photoinduced electron-
transfer from N-phenyltetrahydroisoquinoline to the plati-
num(II) terpyridyl complex 1. In contrast to the previous
studies[19] on photosensitized oxidation by platinum(II) com-
plexes, the EPR measurement demonstrates for the first
oxygen in the reaction system of platinum(II) complex 1 by
EPR, in which 2,2,6,6-tetramethyl-1-piperidine (TEMP) was
used to capture 1O2, and 5,5-dimethyl-1-pyrroline-N-oxide
(DMPO) was used as a probe to trap O2 . As shown in
Figure 1, irradiation of the DMF solution of TEMP and the
ꢀC
platinum(II) complex 1 in air by blue LEDs resulted in the
1
formation of characteristic signal of O2, similar to our pre-
vious observation.[19] When N-phenyltetrahydroisoquinoline
1
was added into the solution, however, the O2 signal could
ꢀC
not be detected. Instead, the characteristic signal of O2
was clearly observed when DMPO was used as radical scav-
enger.
ꢀC
Table 1. Optimization of reaction conditions.[a]
time that superoxide radical anion (O2 ) rather than singlet
oxygen (1O2) was responsible for the facile transformation.
The higher efficiency and selectivity is attributed to the su-
perior redox potential of platinum(II) complex 1 compared
with that of RuACHTUNGTRENNUNG
(bpy)32+[23] in the excited state.
Conditions[a]
t
Conv. 4a
5
Results and Discussion
[h] [%][b] [%][b] [%][b]
1
2
3
4
CH3CN
H2O
2
6
4
2
2
24
4
4
100
18
30
100
100
0
100
100
100
45
14.8
15
57
–
47.6
trace
4.8
18
100
–
Our initial study focused on the CDC coupling reaction of
N-phenyltetrahydroisoquinoline with indole at room tem-
perature. As N-phenyltetrahydroisoquinoline 2a and indole
3a were irradiated by blue LEDs (l=450 nm) at ambient
conditions for 2 h, the desired product 4a was obtained in a
moderate yield accompanying with the formation of byprod-
DMF/H2O
DMF
5[c] DMF
6
7
8
DMF, in N2
–
DMF, FeSO4 (2.0 equiv)
CH3CN, FeSO4 (2.0 equiv)
DMF, FeSO4 (1.1 equiv)
93
65
75
91
93
76
–
28
16
–
–
15
uct amide 5 (Table 1). Complete conversion of N-phenyl
ACHTUNGTNERtNUNG et-
9
4
ACHTUNGTRENNUNG
10
DMF, 3a (1.2 equiv), FeSO4 (2.0 equiv) 12 100
100
12[e] DMF, 3a (2.0 equiv), FeSO4 (2.0 equiv) 12 100
11[d] DMF, 3a (2.0 equiv), FeSO4 (2.0 equiv)
6
within 2 h irradiation. However, the conversion was rather
low in either H2O or a mixed solution of DMF and H2O,
even after a prolonged reaction time (Table 1, entries 1–4).
It was noted that in the absence of indole 3a, N-phenyltetra-
hydroisoquinoline was transformed into the corresponding
amide 5 in a quantitative yield within 2 h (Table 1, entry 5),
whereas in the presence of 3a both the desired product 4a
[a] Reaction conditions: N-phenyltetrahydroisoquinoline (0.1 mmol), 3a
(0.3 mmol), 1 (0.25 mol%), solvent (2 mL), ambient air, blue LEDs (l=
450 nm) irradiation. [b] Yields detected by NMR spectroscopy using an
internal standard, 4-nitroacetophenone. [c] 3a was not added. [d] 3a
(2.0 equiv) was used. [e] [Ru
replace 1 under the same conditions as entry 11.
ACHTUTGNRENNGU(bpy)3ACHTUGNTERN(NUGN PF6)2]·6H2O (1 mol%) was used to
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Cross-Dehydrogenative-Coupling Reaction
FULL PAPER
tion at room temperature, which was readily quenched by
N-phenyltetrahydroisoquinoline 2a following the Stern–
Volmer kinetics (Figure 2b). Evidently, N-phenyltetrahy-
droisoquinoline 2a interacted with platinum(II) complex 1
in the excited state. Since the energy of singlet excited state
of complex 1 is much lower than that of 2a, the singlet
energy-transfer from the excited complex 1 to 2a is thermo-
dynamically impossible. Therefore, the luminescence
quenching is probably due to the photoinduced electron-
transfer. Combining the electrochemical and spectroscopic
studies, we estimated the free-energy change (DG) of the
photoinduced electron-transfer process. According to the
determined oxidation potential Eox of 2a (0.82 V), reduction
potential Ered of complex 1 (ꢀ1.18 V), and the excited state
energy E00 of complex 1 that was read from the cross-point
of the absorption and luminescence spectra at 500 nm
(2.48 V, Figure 2), the negative free energy change (DG=
ꢀ0.48 V) calculated by using the Rehm–Weller Equation (1)
revealed that the photoinduced electron-transfer from com-
plex 1 to 2a is thermodynamically feasible. As compared
Figure 1. EPR measurement of a) a solution in DMF of platinum(II)
complex 1 without N-phenyltetrahydroisoquinoline in the presence of
DMPO (2.0ꢁ10ꢀ2 m); b) a solution in DMF of platinum(II) complex 1
without N-phenyltetrahydroisoquinoline in the presence of TEMP (2.0ꢁ
10ꢀ2 m); c and d) a solution in DMF of N-phenyltetrahydroisoquinoline
with the platinum(II) complex
1
(1.0ꢁ10ꢀ4 m) in the presence of
c) TEMP (2.0ꢁ10ꢀ2 m) and d) DMPO (2.0ꢁ10ꢀ2 m).
with Ru
positive redox potential (Ered =ꢀ1.18 V and ꢀ1.33 V, and
E00 =2.48 V and 2.12 V for complex 1 and Ru
(bpy)32+, the platinum(II) complex 1 has a more
ACHTUNGTRENNUNG
To understand the primary process of the reaction, we ex-
ACHTUNGTRENNUNG
amined the interaction between N-phenyltetrahydroiso
G
spectively).
ACHTUNGTRENNUNG
DG0 ¼ EoxꢀEredꢀE00
ð1Þ
broad visible-light absorption, assigned to a mixture of
metal-to-ligand and ligand-to-ligand charge-transfer transi-
tions,[26–27] ranging from 400 to 500 nm (Figure 2a). Excita-
tion of the absorption resulted in moderately intense lumi-
nescence at lmax 608 nm (t=309 ns) in degassed DMF solu-
On the basis of above results, we proposed a plausible re-
action pathway shown in Scheme 2. Upon excitation of the
Scheme 2. A plausible reaction pathway.
platinum(II) complex 1 at l=450 nm, a single electron-
transfer reduction[28] of the excited platinum(II) complex 1*
by 2a takes place to generate radical cation 6 and one-elec-
ꢀC
tron-reduced radical 1 , which was subsequently quenched
ꢀC
by oxygen to generate the superoxide radical anion (O2
)
and the platinum(II) complex is recovered. Subsequently,
ꢀC
hydrogen abstraction of 6 by O2 , generates a hydroperox-
Figure 2. a) UV/Vis absorption and luminescence spectra of platinum(II)
complex 1 (1.0ꢁ10ꢀ5 m) in DMF. b) Luminescence spectra of platinum(II)
complex 1 (1.0ꢁ10ꢀ5 m) as a function of concentration of 2a in degassed
DMF with excitation at 450 nm. Inset is the Stern–Volmer plot of com-
plex 1 by 2a.
ide free radical and intermediate 7. There are two competi-
tive reaction pathways: one is that 7 would lose one electron
to give rise to a reactive intermediate iminium 8, followed
by nucleophile addition to give desired product 9; whereas,
Chem. Eur. J. 2013, 19, 6443 – 6450
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6445

L.-Z. Wu et al.
Table 2. Scope of indoles for the indolation of 2a.[a]
Product 4
3
t
Yield
in the other pathway, the generated hydroperoxide free radi-
cal reacts directly with 7 to yield the byproduct amide 5.
To further confirm the reaction mechanism, we intro-
duced FeSO4 to react with the hydroperoxide free radical
generated from the reaction. It was encouraging to see that
no amide was observed in the presence of the additive
FeSO4 (2 equiv). The selectivity of reaction was improved
greatly and the yield of the desired product was excellent
(Table 1, entry 7). An excess of FeSO4 and indole were
found to be necessary to obtain a good yield of the product
(Table 1, entry 9). The absence of any components of reac-
tion led to no or little formation of the desired product.
Taking all these results together, we performed the CDC re-
action under the optimized conditions: a DMF solution of
N-phenyltetrahydroisoquinoline and indole (2 equiv) with
the platinum(II) complex 1 (0.25%) in the presence of
FeSO4 (2 equiv) under an air atmosphere were irradiated by
blue LEDs (l=450 nm) at room temperature. Strikingly, the
[h] [%][b]
1
2
3a
3b
4a
4b
6
6
93 (81)
95 (76)
3
3c
4c 12 94 (80)
4
5
3d
3e
4d 24 92 (74)
performance of 0.25 mol% of platinum(II) complex 1 is
2+
much better than that of 1 mol% Ru
G
under the
same conditions. In addition, the byproduct amide 5 could
not be completely eliminated in the presence of FeSO4
4e 12 91 (78)
2+
(2 equiv) when RuACHTUNGTRENNUNG(bpy)3 was used (Table 1, entry 12).
To extend the scope of reaction, we utilized different sub-
stituted indoles, and the representative results are listed in
Table 2. Evidently, indoles with electron-donating groups
worked well with 2a giving the products in excellent yields
(Table 2, entries 2–7). When electron-withdrawing groups
were linked to indole, the reaction proceeded with slightly
poor yields (Table 2, entry 11). This may be due to the elec-
tron-withdrawing groups having a great influence on the
electron density of indole to reduce its nucleophilicity. With
a prolonged reaction time, the steric hindrance does not
seem to affect the yield of the reaction significantly
(Table 2, entry 4).
Furthermore, we explored the variety of N-phenyltetrahy-
droisoquinolines. For both electron-withdrawing and elec-
tron-donating groups, the desired products could be ob-
tained in excellent yields (Table 3). In spite of this, the reac-
tion time is dependent on the linking groups; electron-do-
nating groups need more time to achieve higher yields
(Table 3, entries 1–3). Good to excellent yields were also ob-
tained by using more nucleophilic substrates, such as nitroal-
kanes and malonate esters, to replace indoles (Table 4). Sig-
nificantly, when the aerobic oxidative coupling was carried
out under ambient sunlight, the combination of 2a with 3a
could give rise to the desired product in 76% yield
(Scheme 3). Clearly, the platinum(II) complex 1 is an ideal
6
7
8
3 f
3g
3h
4 f 12 89 (75)
4g 12 90 (76)
4h
6
6
85 (68)
82 (63)
9
3i
4i
10
11
3j
4j
6
6
85 (67)
78 (56)
3k
4k
[a] Reaction conditions: N-phenyltetrahydroisoquinoline 2a (0.1 mmol),
indoles (0.2 mmol), FeSO4 (0.2 mmol), platinum(II) complex
1
(0.25 mol%), DMF (2 mL), ambient air, blue LEDs irradiation.
[b] Yields detected by NMR spectroscopy using an internal standard, 4-
nitroacetophenone; the isolated product yields are given in parentheses.
Scheme 3. Visible-light-driven aerobic CDC reaction under ambient sun-
shine irradiation.
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Cross-Dehydrogenative-Coupling Reaction
FULL PAPER
Table 3. Varieties of tetrahydroisoquinoline derivatives.[a]
photocatalyst capable of using sunlight and air for the envi-
ronmental benign CDC transformation.
2
Product 4
t
Yield
[h] [%][b]
Conclusion
95
(75)
1
2
3
4
5
6
2b
2c
2d
2e
2 f
2g
4l 18
We have developed a visible-light-induced CDC reaction[29]
by using a catalytic amount of platinum(II) complex 1
(0.25%). On account of its excellent photophysical and elec-
trochemical characteristics, a small quantity of platinum(II)
complex 1 can be employed as an efficient photocatalyst
even under ambient sunshine irradiation. With the aid of ad-
ditive FeSO4 (2 equiv), the byproduct amide 5 that is gener-
ally observed in the CDC transformation has been com-
pletely eliminated, resulting in the formation of the cross-
coupling product exclusively. Thanks to superior redox po-
94
(78)
4m 32
92
(72)
4n 32
tential of platinum(II) complex 1 compared with that of Ru-
AHCTUNGRTEG(NNUN bpy)3 in the excited state, the CDC transformation driven
2+
93
(78)
by complex 1 is more efficient and selective than the other
reported photocatalytic systems. An EPR experiment pro-
vides direct evidence for the generation of superoxide radi-
cal anion under light irradiation. This is, to the best of our
knowledge, the first example of the formation of a superox-
4o
4p
6
6
91
(77)
ꢀC
ide radical anion (O2 ) by a platinum(II) complex. Further
extension of visible-light catalytic systems by using powerful
platinum(II) complexes is actively undergoing in our labora-
tory.
93
(71)
4q 12
Experimental Section
[a] Reaction conditions: Tetrahydroisoquinolines (0.1 mmol), 3a
(0.2 mmol), FeSO4 (0.2 mmol), 1 (0.25 mol%), DMF (2 mL), ambient air,
blue LEDs irradiation. [b] Yield detected by NMR spectroscopy using an
internal standard, 4-nitroacetophenone; the isolated product yields are
given in parentheses, the isolated product yield was lower because of
some decomposition during the chromatography.
General: 1H NMR spectra were recorded by using a Bruker Avance
DPX 400 MHz instrument with tetramethylsilane (TMS) as an internal
standard. Multiplicities are indicated, s (singlet), d (doublet), t (triplet), q
(quartet), quint (quintet), sept (septet), m (multiplet); coupling constants
(J) are in Hertz (Hz). 13C NMR spectra were obtained at 100 MHz and
referenced to the internal solvent signals. Mass spectra were recorded
using a Trio-2000 GC-MS spectrometer. Commercially available reagents
and solvents were used without further purification unless indicated oth-
erwise. All of the N-aryl tetrahydroiso-
quinolines needed for CDC reactions
were prepared by using the reported
Table 4. The visible-light-induced CDC reaction[a] of tetrahydroisoquinolines with other nucleophiles catalyzed
by the platinum(II) complex 1.
procedure and purified through
column chromatography (300–400
mesh). Irradiation was performed by
using blue LEDs (1 W, l=(450ꢁ
10) nm, 145 Lm @700 mA).
General procedure for the synthesis of
the photocatalyst: Complex 1 was pre-
Product, Yield [%][b]
pared by the reaction of [PtACHTUNGTRENNUNG(trpy)Cl]Cl
(trpy=4’-(4-methoxyphenyl)-2,2’:6’,2’’-
terpyridine) with HCCC6H4CCC6H5-4
(2 equiv), which was synthesized by
the literature method in the presence
of catalyst CuI and trimethylamine
under nitrogen in DMF at room tem-
perature. Recrystallization of the
crude product by diffusion of diethyl
ether vapor into an acetonitrile solu-
tion gave complex 1 as orange crystals.
1H NMR (400 MHz, DMSO): d=8.77–
8.48 (m, 6H), 8.28 (s, 2H), 7.95 (d, J=
4r 90 (81)
4u 81 (70)
4s 96 (83)
4v 95 (80)
4t 92 (78)
[a] Reaction conditions: Tetrahydroisoquinolines (0.1 mmol), nucleophile (0.3 mmol) was added, FeSO4
(0.2 mmol), 1 (0.25 mol%), DMF (2 mL), ambient air, blue LEDs irradiation. [b] Yields detected by NMR
spectroscopy using an internal standard, 4-nitroacetophenone; the isolated product yields are given in paren-
theses.
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6447

L.-Z. Wu et al.
7.8, 2H), 7.59 (d, J=19.4, 4H), 7.46 (s, 3H), 7.37 (d, J=7.6, 2H), 7.26 (d,
(m, 1H), 2.88 ppm (dt, J=16.3, 4.7, 1H); 13C NMR (100 MHz, acetone):
d=150.9, 138.7, 138.5, 136.4, 130.0, 129.7, 129.0, 127.8, 127.6, 126.6, 126.5,
126.3, 121.9, 120.2, 119.7, 119.0, 116.7, 112.1, 57.2, 43.1, 27.5 ppm; MS
(EI, 70 eV): m/z (%): 358 [M+], 264 (100), 253, 93.
J=7.5, 2H), 7.10 (d, J=7.7, 2H), 3.87 ppm (s, 3H); IR: n˜ =2118 cmꢀ1
;
fluorescence (DMF): lab =450; lem =608 nm; MS (FAB): m/z: 735 [M+];
elemental analysis calcd for C38H26ClN3O5Pt·0.5H2O: C 54.07; H 3.22; N
4.98; O 10.42; found: C 53.84; H 2.94; N 4.81; P 10.38.
1-(5-Methyl-1H-indol-3-yl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline (4b):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=20:1, Rf =0.7). 1H NMR (400 MHz, acetone): d=9.90 (s,
1H), 7.35 (dd, J=7.6, 2.7, 2H), 7.27–7.12 (m, 6H), 7.07 (d, J=7.9, 2H),
6.91 (dd, J=8.3, 1.5, 1H), 6.73–6.66 (m, 2H), 6.23 (s, 1H), 3.66 (dt, J=
10.2, 4.5, 2H), 3.07 (ddd, J=15.4, 8.9, 6.2, 1H), 2.88 (dt, J=16.3, 4.7,
1H), 2.31 ppm (s, 3H); 13C NMR (100 MHz, acetone): d=151.4, 139.6,
137.0, 136.9, 130.4, 130.0, 129.5, 128.9, 128.3, 127.9, 126.9, 126.1, 124.4,
120.8, 119.5, 119.1, 117.0, 112.5, 57.8, 43.4, 28.0, 22.3 ppm; MS (EI,
70 eV): m/z (%): 338 (100) [M+], 245, 232, 217, 121, 93; HRMS (ESI):
m/z calcd for C24H23N2: 339.18558 [M+H]; found: 339.18518.
General procedure for the preparation of N-phenyltetrahydroisoquino-
lines: Copper(I) iodide (200 mg, 1.0 mmol) and potassium phosphate
(4.25 g, 20.0 mmol) were put into a Schlenk-tube. The Schlenk-tube was
evacuated and back filled with nitrogen. Next, 2-propanol (10.0 mL), eth-
ylene glycol (1.11 mL, 20.0 mmol), Next, 1,2,3,4-tetrahydroisoquinoline
(2.0 mL, 15.0 mmol), and iodobenzene (1.12 mL, 10.0 mmol) were added
successively at room temperature. The reaction mixture was heated at
908C for 24 h and then allowed to cool to room temperature. Diethyl
ether (25 mL) and water (25 mL) were then added to the reaction mix-
ture. The organic layer was extracted with diethyl ether (2ꢁ25 mL). The
combined organic phases were washed with brine and dried over sodium
sulfate. The solvent was removed by rotary evaporation and purified by
column chromatography on silica gel using hexane/ethyl acetate (30:1) as
eluent.
1-(6-Methoxyl-1H-indol-3-yl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline
(4 f): Purified by column chromatography on silica gel (eluting with
hexane/ethyl acetate=20:1, Rf =0.5). 1H NMR (400 MHz, acetone): d=
9.83 (s, 1H), 7.43–7.31 (m, 2H), 7.22–7.12 (m, 5H), 7.06 (d, J=7.9, 2H),
6.89 (d, J=2.2, 1H), 6.69 (t, J=7.2, 1H), 6.62 (ddd, J=11.0, 5.5, 1.6,
2H), 6.22 (s, 1H), 3.76 (s, 3H), 3.68–3.60 (m, 2H), 3.13–3.00 (m, 1H),
2.88 ppm (dt, J=16.2, 4.8, 1H); 13C NMR (100 MHz, acetone): d=157.8,
151.4, 139.5, 139.4, 136.9, 130.4, 130.0, 129.5, 127.9, 126.9, 124.7, 122.5,
121.7, 119.8, 119.1, 116.8, 110.5, 95.9, 57.9, 56.2, 43.4, 28.0 ppm; MS (EI):
m/z (%): 354 [M+], 261 (100), 246, 217, 206, 93; HRMS (ESI): m/z calcd
for C24H21N2O [MꢀH]: 353.16484; found: 353.16548.
3-(2-Phenyl-1,2,3,4-tetrahydroisoquinolin-1-yl)-1H-indole-5-carboxylic
acid methyl ester (4i): Purified by column chromatography on silica gel
(eluting with hexane/ethyl acetate=15:1, Rf =0.2). 1H NMR (400 MHz,
acetone): d=10.40 (s, 1H), 8.41–8.31 (m, 1H), 7.77 (dd, J=8.6, 1.6, 1H),
7.43 (dd, J=8.6, 0.4, 1H), 7.38 (dd, J=4.7, 2.9, 1H), 7.24–7.14 (m, 5H),
7.14–7.06 (m, 2H), 6.89 (d, J=1.4, 1H), 6.77–6.67 (m, 1H), 6.32 (s, 1H),
3.81 (s, 3H), 3.65 (dd, J=7.5, 4.8, 2H), 3.08 (dt, J=15.3, 7.5, 1H),
2.90 ppm (dt, J=16.3, 4.7, 1H); 13C NMR (100 MHz, acetone): d=168.3,
150.9, 140.6, 138.7, 136.4, 130.0, 129.7, 129.0, 127.6, 127.3, 127.1, 126.6,
123.7, 123.6, 122.1, 120.9, 119.1, 117.0, 112.1, 57.2, 51.9, 43.23, 27.5 ppm;
MS (EI): m/z (%)=382.17 [M+], 288 (100), 277, 229, 218, 93.
General procedure for the visible-light-induced CDC reaction: The tetra-
hydroquinoline derivatives (0.1 mmol, 1 equiv), indole derivatives
(0.2 mmol, 2 equiv), FeSO4 (0.2 mmol, 2 equiv), and platinum(II) com-
plex 1 (0.00025 mmol, 0.0025 equiv) were dissolved in DMF (2 mL) in a
10 mL reaction tube equipped with magnetic stirring bar, and the result-
ing mixture was irradiated using blue LEDs under the ambient air condi-
tion. After the substrate was completely converted (monitored by TLC),
the reaction mixture was evaporated under reduced pressure until DMF
was gone. Then diethyl ether (25 mL) and water (25 mL) were added to
the residue. The organic layer was extracted with diethyl ether (3ꢁ
25 mL). The combined organic phases were washed with brine and dried
over sodium sulphate. The solvent was removed by rotary evaporation
and purified by column chromatography on silica gel by using hexane/
ethyl acetate (20:1) as eluent.
1-(1H-Indol-3-yl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline (4a): Purified
by column chromatography on silica gel (eluting with hexane/ethyl ace-
1
tate=20:1, Rf =0.6). H NMR (400 MHz, acetone): d=10.05 (s, 1H), 7.56
(d, J=8.0, 1H), 7.37 (d, J=7.6, 2H), 7.28–7.12 (m, 5H), 7.07 (dd, J=7.6,
5.1, 3H), 6.94 (t, J=7.5, 1H), 6.79 (s, 1H), 6.69 (t, J=7.0, 1H), 6.28 (s,
1H), 3.65 (dd, J=8.9, 4.7, 2H), 3.16–2.99 (m, 1H), 2.93–2.84 ppm (m,
1H); 13C NMR (100 MHz, acetone): d=150.8, 139.0, 138.1, 136.4, 130.0,
129.6, 129.0, 127.6, 127.4, 126.5, 125.5, 122.3, 120.6, 119.8, 119.4, 118.6,
116.3, 112.3, 57.3, 42.9, 27.5 ppm; MS (EI, 70 eV): m/z (%): 324 (100)
[M+], 229, 218, 202, 93, 68.
3-(2-Phenyl-1,2,3,4-tetrahydroisoquinolin-1-yl)-1H-indole-6-carboxylic
acid methyl ester (4j): Purified by column chromatography on silica gel
(eluting with hexane/ethyl acetate=15:1, Rf =0.3). 1H NMR (400 MHz,
acetone): d=10.45 (s, 1H), 8.11 (s, 1H), 7.61 (dt, J=18.4, 4.9, 2H), 7.39–
7.33 (m, 1H), 7.23–7.14 (m, 5H), 7.07 (d, J=8.0, 2H), 7.02 (d, J=1.9,
1H), 6.71 (t, J=7.2, 1H), 6.30 (s, 1H), 3.85 (s, 3H), 3.63 (dd, J=7.5, 4.9,
2H), 3.07 (dt, J=15.3, 7.5, 1H), 2.92 ppm (t, J=4.7, 1H); 13C NMR
(100 MHz, acetone): d=167.3, 150.0, 137.8, 136.4, 135.4, 130.0, 129.0,
128.7, 128.2, 128.0, 126.7, 125.7, 123.3, 119.7, 119.4, 119.0, 118.1, 115.8,
113.6, 56.3, 51.2, 42.2, 26.7 ppm; MS (EI): m/z (%): 382 [M+], 289 (100),
277, 230, 218, 206, 93; HRMS (ESI): m/z calcd for C25H23N2O2 [M+H]:
383.17540; found: 383.17577.
1-(2-Methyl-1H-indol-3-yl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline (4d):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=20:1, Rf =0.4). 1H NMR (400 MHz, acetone): d=9.85 (s,
1H), 7.20 (d, J=8.2, 2H), 7.18–7.01 (m, 8H), 6.92 (t, J=7.5, 1H), 6.82–
6.71 (m, 2H), 6.07 (s, 1H), 3.69 (dt, J=13.0, 6.6, 1H), 3.66–3.54 (m, 1H),
3.06 (t, J=5.9, 2H), 2.14 ppm (s, 3H); 13C NMR (100 MHz, acetone): d=
152.1, 139.6, 136.5, 136.3, 134.6, 129.6, 129.4, 129.2, 127.0, 126.7, 121.1,
120.7, 120.0, 119.9, 119.6, 113.9, 111.2, 110.1, 57.7, 46.8, 28.9, 12.4 ppm;
MS (EI, 70 eV): m/z (%): 338 (100) [M+], 245, 218, 217, 209.
1-(5-Nitro-1H-indol-3-yl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline
(4k):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=15:1, Rf =0.2). 1H NMR (400 MHz, acetone) d=10.76 (s,
1H), 8.49 (d, J=2.2, 1H), 7.99 (dd, J=9.0, 2.3, 1H), 7.54 (d, J=9.0, 1H),
7.43–7.35 (m, 1H), 7.24–7.18 (m, 5H), 7.12 (d, J=7.9, 2H), 7.04 (s, 1H),
6.75 (t, J=7.2, 1H), 6.37 (s, 1H), 3.70–3.54 (m, 2H), 3.15–3.02 (m, 1H),
2.92 ppm (dd, J=12.9, 8.2, 1H); 13C NMR (100 MHz, acetone): d=150.0,
141.3, 140.1, 137.3, 135.4, 129.1, 128.9, 128.3, 128.1, 126.8, 125.9, 125.8,
121.0, 118.7, 117.0, 116.8, 116.5, 111.7, 56.3, 42.5, 26.7 ppm; MS (EI): m/z
(%): 369.14 (100) [M+], 264, 217, 206, 104, 77.
1-[4-(2-Methoxypropenyl)-1H-pyrrol-3-yl]-2-phenyl-1,2,3,4-tetrahydroiso-
quinoline (4g): Purified by column chromatography on silica gel (eluting
with hexane/ethyl acetate=20:1, Rf =0.5). 1H NMR (400 MHz, acetone):
d=9.90 (s, 1H), 7.41–7.33 (m, 1H), 7.28–7.13 (m, 6H), 7.08 (d, J=8.1,
2H), 6.96 (d, J=2.3, 1H), 6.77–6.64 (m, 3H), 6.25 (s, 1H), 3.63 (m, 5H),
3.08 (dt, J=15.4, 7.5, 1H), 2.91 ppm (dt, J=16.2, 4.7, 1H); 13C NMR
(100 MHz, acetone): d=154.7, 151.1, 139.2, 136.4, 133.1, 130.0, 129.5,
129.0, 128.0, 127.4, 126.5, 126.1, 118.8, 118.7, 116.6, 112.8, 112.4, 102.6,
57.5, 55.8, 42.8, 27.9 ppm; MS (EI, 70 eV): m/z (%): 354 [M+], 261 (100),
217, 206, 93.
1-(6-Methyl-1H-indol-3-yl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline (4c):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=20:1, Rf =0.5). 1H NMR (400 MHz, acetone): d=9.88 (s,
1H), 7.41 (d, J=8.2, 1H), 7.39–7.32 (m, 1H), 7.23–7.12 (m, 6H), 7.06 (d,
J=8.0, 2H), 6.78 (d, J=8.1, 1H), 6.72–6.64 (m, 2H), 6.23 (s, 1H), 3.65
(dd, J=8.9, 4.7, 2H), 3.13–3.00 (m, 1H), 2.89 (dt, J=16.2, 4.8, 1H),
2.36 ppm (s, 3H); 13C NMR (100 MHz, acetone): d=150.9, 139.1, 138.6,
136.4, 131.7, 130.0, 129.0, 127.4, 126.5, 125.6, 124.8, 121.6, 120.4, 119.3,
1-(6-Chloro-1H-indol-3-yl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline (4h):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=20:1, Rf =0.6). 1H NMR (400 MHz, acetone): d=10.20 (s,
1H), 7.49 (d, J=8.5, 1H), 7.40 (d, J=1.5, 1H), 7.36 (d, J=5.6, 1H),
7.25–7.13 (m, 5H), 7.07 (d, J=8.0, 2H), 6.94 (dd, J=8.5, 1.8, 1H), 6.82
(s, 1H), 6.71 (t, J=7.2, 1H), 6.26 (s, 1H), 3.68–3.57 (m, 2H), 3.13–3.01
6448
www.chemeurj.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 6443 – 6450

Cross-Dehydrogenative-Coupling Reaction
FULL PAPER
118.6, 116.3, 112.2, 112.1, 57.4, 43.0, 27.6, 21.8 ppm; MS (EI): m/z (%):
338.1 [M+], 244 (100), 232, 217, 121, 93.
1-(1H-Indol-3-yl)-2-(4-cyanophenyl)-1,2,3,4-tetrahydroisoquinoline (4q):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=20:1, Rf =0.3). 1H NMR (400 MHz, acetone): d=11.13 (s,
1H), 8.41 (dd, J=6.4, 2.8, 1H), 7.67 (d, J=3.1, 1H), 7.60–7.54 (m, 1H),
7.53–7.43 (m, 3H), 7.38–7.25 (m, 5H), 6.65–6.58 (m, 2H), 6.36 (s, 1H),
3.50–3.39 (m, 2H), 2.99 ppm (t, J=7.2, 2H); 13C NMR (100 MHz, ace-
tone): d=153.3, 138.9, 138.7, 136.7, 134.7, 129.8, 129.2, 128.4, 127.4, 125.7,
123.0, 121.2, 120.7, 120.5, 118.5, 114.7, 113.0, 99.4, 57.1, 43.4, 28.4 ppm;
MS (EI): m/z (%): 349 [M+], 230 (100), 218, 118; HRMS (ESI): m/z
calcd for C24H20N3: 350.16527 [M+H]; found: 350.16506 [M+H].
1-(1-Methyl-1H-indol-3-yl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline (4e):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=20:1, Rf =0.4). 1H NMR (400 MHz, acetone): d=7.57 (d,
J=8.0, 1H), 7.34 (dd, J=21.6, 6.8, 2H), 7.23–7.10 (m, 6H), 7.06 (d, J=
8.1, 2H), 6.96 (t, J=7.5, 1H), 6.73–6.66 (m, 2H), 6.26 (s, 1H), 3.69 (s,
3H), 3.68–3.58 (m, 2H), 3.06 (ddd, J=15.1, 8.8, 5.9, 1H), 2.89 ppm (dt,
J=16.2, 4.8, 1H); 13C NMR (100 MHz, acetone): d=150.7, 139.0, 138.5,
136.4, 130.0, 129.6, 129.6, 129.0, 128.0, 127.5, 126.6, 122.3, 120.8, 119.7,
118.5, 118.5, 116.2, 110.3, 57.1, 42.9, 32.8, 27.5 ppm; MS (EI): m/z (%):
338 [M+], 245 (100), 232.
Dimethyl 2-(1,2,3,4-tetrahydro-2-phenylisoquinolin-1-yl)malonate (4v):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=15:1, Rf =0.2). 1H NMR (400 MHz, CDCl3): d=7.31–7.06
(m, 7H), 6.98 (d, J=8.1 Hz, 2H), 6.76 (t, J=7.3 Hz, 1H), 5.70 (d, J=
9.4 Hz, 1H), 3.95 (d, J=9.4 Hz, 1H), 3.77–3.57 (m, 5H), 3.54 (s, 3H),
3.07 (ddd, J=15.6, 8.9, 6.3 Hz, 1H), 2.87 ppm (dt, J=16.5, 5.1 Hz, 1H);
13C NMR (100 MHz, CDCl3) d=168.5, 167.6, 148.9, 135.8, 135.0, 129.3,
129.2, 127.8, 127.2, 126.2, 118.8, 115.4, 77.6, 77.2, 76.9, 59.3, 58.3, 52.7,
42.3, 26.2 ppm; MS (EI): m/z (%): 339 [M+], 209 (100), 193, 115, 77.
1-(1H-Indol-3-yl)-2-(4-bromophenyl)-1,2,3,4-tetrahydroisoquinoline (4p):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=15:1, Rf =0.3). 1H NMR (400 MHz, acetone): d=10.08 (s,
1H), 7.54 (d, J=8.0, 1H), 7.44–7.34 (m, 2H), 7.34–7.26 (m, 2H), 7.22–
7.13 (m, 3H), 7.11–7.05 (m, 1H), 7.05–6.99 (m, 2H), 6.99–6.90 (m, 1H),
6.84 (s, 1H), 6.26 (s, 1H), 3.74–3.55 (m, 2H), 3.08 (ddd, J=14.6, 8.7, 5.8,
1H), 2.93 ppm (dt, J=16.2, 5.0, 1H); 13C NMR (100 MHz, acetone): d=
150.4, 139.2, 138.6, 136.7, 133.1, 130.0, 129.4, 128.1, 127.9, 127.1, 125.9,
122.9, 121.0, 120.4, 119.4, 118.3, 112.9, 110.2, 57.7, 43.6, 28.1 ppm; MS
(EI): m/z (%): 402 [M+], 338, 245, 232 (100), 218; HRMS (ESI): m/z
calcd for C23H20N2Br: 403.08044 [M+H]; found: 403.08000.
1-Nitromethyl-2-phenyl-1,2,3,4-tetrahydroisoquinoline (4r): Purified by
column chromatography on silica gel (eluting with hexane/ethyl acetate=
5:1, Rf =0.5). 1H NMR (400 MHz, CDCl3): d=2.77 (dt, J=16.4 Hz,
4.8 Hz, 1H), 3.03–3.11 (m, 1H), 3.56–3.63 (m, 2H), 4.54 (dd, J=12.0 Hz,
6.8 Hz, 1H), 4.85 (dd, J=12.0 Hz, 8.0 Hz, 1H), 5.54 (t, J=8.0 Hz, 1H),
6.84 (t, J=7.2 Hz, 1H), 6.97 (d, J=8.2 Hz, 2H), 7.11–7.28 ppm (m, 7H);
13C NMR (100 MHz, CDCl3): d =26.7, 42.3, 58.4, 79.0, 115.3, 119.7,
126.9, 127.2, 128.3, 129.4, 129.7, 133.2, 135.5, 148.6 ppm; MS (EI): m/z
(%): 268 [M+], 208 (100), 77.
1-(1H-Indol-3-yl)-2-(2-methoxyphenyl)-1,2,3,4-tetrahydroisoquinoline
(4n): Purified by column chromatography on silica gel (eluting with
hexane/ethyl acetate=15:1, Rf =0.3). 1H NMR (400 MHz, acetone): d=
9.93 (s, 1H), 7.27 (d, J=8.1, 1H), 7.24–7.12 (m, 3H), 7.07 (d, J=3.8,
2H), 7.01–6.93 (m, 2H), 6.88 (td, J=7.8, 1.5, 1H), 6.78 (t, J=7.5, 1H),
6.65 (qd, J=7.8, 1.3, 3H), 6.16 (s, 1H), 3.88 (s, 3H), 3.53 (ddd, J=12.6,
9.1, 5.5, 1H), 3.37 (dt, J=12.5, 4.6, 1H), 3.04–2.90 ppm (m, 2H);
13C NMR (100 MHz, acetone): d=155.0, 142.2, 140.3, 138.2, 136.4, 130.0,
129.6, 128.9, 127.3, 126.8, 126.3, 124.0, 123.3, 122.4, 122.0, 121.4, 119.9,
119.1, 113.4, 112.4, 57.9, 56.5, 45.2 ppm; MS (EI): m/z (%): 354.1 [M+],
231 (100), 218, 123, 108, 80 ppm; HRMS (ESI): m/z calcd for C24H23N2O:
355.18049 [M+H]; found: 355.18009.
2-(4-Methoxyphenyl)-1-nitromethyl-1,2,3,4-tetrahydroisoquinoline (4s):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=5:1, Rf =0.4). 1H NMR (400 MHz, CDCl3): d=2.69 (dt,
J=16.0 Hz, 4.0 Hz, 1H), 2.96–3.02 (m, 1H), 3.50–3.56 (m, 2H), 3.74 (s,
3H), 4.55 (dd, J=12 Hz, 5.8 Hz, 1H), 4.81 (dd, J=12 Hz, 8.6 Hz, 1H),
5.38 (dd, J=5.8 Hz, 8.6 Hz, 1H), 6.81 (d, J=9.0 Hz, 2H), 6.91 (d, J=
9.0 Hz, 2H), 7.09–7.33 ppm (m, 4H); 13C NMR (100 MHz, CDCl3): d=
25.8, 43.1, 55.5, 58.9, 78.9, 114.7, 118.8, 126.6, 126.9, 127.9, 129.4, 132.9,
135.4, 143.0, 153.9 ppm; MS (EI): m/z (%): 298 [M+], 239 (100), 223,
115, 91, 77.
1-(1H-Indol-3-yl)-2-(4-fluorophenyl)-1,2,3,4-tetrahydroisoquinoline (4o):
Purified by column chromatography on silica gel (eluting with hexane/
ethyl acetate=20:1, Rf =0.4). 1H NMR (400 MHz, acetone): d=9.11 (s,
1H), 7.48 (d, J=8.0, 1H), 7.35 (d, J=8.2, 1H), 7.28 (d, J=7.1, 1H),
7.24–6.99 (m, 7H), 6.95 (t, J=7.5, 1H), 6.83–6.66 (m, 2H), 6.23 (s, 1H),
3.69–3.51 (m, 2H), 3.05 (dt, J=14.9, 7.4, 1H), 2.92 ppm (dt, J=16.4, 4.9,
1H); 13C NMR (100 MHz, acetone) d=158.3 (d, J=233.8 Hz), 148.0(d,
J=1.9 Hz), 138.9, 138.0, 136.1, 129.5, 129.0, 127.4, 126.5, 125.6, 122.3,
120.6, 119.8, 118.9 (d, J=7.4 Hz), 118.9, 116.2 (d, J=21.9 Hz), 116.0,
112.3, 58.2, 44.0, 27.7 ppm; MS (EI): m/z (%)=342 (100) [M+], 231, 218,
217, 111; HRMS (ESI): m/z calcd for C23H20N2F: 343.16050 [M+H];
found: 343.15996 [M+H].
2-(4-Bromophenyl)-1-nitromethyl-1,2,3,4-tetrahydroisoquinoline (4t): Pu-
rified by column chromatography on silica gel (eluting with hexane/ethyl
1
acetate=15:1, Rf =0.4). H NMR (400 MHz, CDCl3): d=2.79 (dt, J=4.8,
16.0 Hz, 1H), 3.01–3.15 (m, 1H), 3.57–3.65 (m, 1H), 4.57 (dd, J=6.4,
12.0 Hz, 1H), 4.82 (dd, J=8.0, 12.0 Hz, 1H), 5.47 (t, J=8.0 Hz, 1H), 6.84
(d, J=9.1 Hz, 2H), 7.16–7.31 (m, 4H), 7.34 ppm (d, J=9.1 Hz, 2H);
13C NMR (100 MHz, CDCl3): d=26.1, 42.0, 58.1, 78.6, 111.5, 116.7, 126.8,
126.9, 128.2, 129.2, 132.2, 132.4, 135.0, 147.5 ppm; MS (EI): m/z (%): 346
[M+] , 288 (100), 118, 90, 77.
1-(1-Nitroethyl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline (4u): Purified by
column chromatography on silica gel (eluting with hexane/ethyl acetate=
20:1, Rf =0.6). H NMR (400 MHz, CDCl3): d=[1.53 (d, J=8.0 Hz), 1.69
(d, J=8.0 Hz), 3H], [2.83–2.94 (m), 2.99–3.09 (m), 2H], [3.51–3.61 (m),
3.80–3.86 (m), 2H], [4.84–4.92 (m), 5,01–5.08 (m), 1H], 5.22–5.26 (m,
1H), 6.79–6.84 (m, 1H), 6.97–7.01 (m, 2H), 7.08–7.29 ppm (m, 6H);
13C NMR (100 MHz, CDCl3): d=(16.4, 17.4), (26.4, 26.7), (42.7, 43.5),
(61.1, 62.7), (85.4, 88.9), (114.5, 115.4), (118.8, 119.3), 126.1, 126.6, 127.2,
128.2, 128.3, 128.7, 129.1, 129.3, 129.4, 129.6, 132.0, 133.8, 134.8, 135.6,
148.9, 49.2 ppm; MS (EI): m/z (%): 282 [M+], 208 (100), 104, 77.
1-(1H-Indol-3-yl)-2-(4-methoxyphenyl)-1,2,3,4-tetrahydroisoquinoline
(4m): Purified by column chromatography on silica gel (eluting with
hexane/ethyl acetate=20:1, Rf =0.4). 1H NMR (400 MHz, acetone): d=
9.98 (s, 1H), 7.45 (d, J=8.0, 1H), 7.34 (d, J=8.2, 1H), 7.23 (d, J=7.4,
1H), 7.20–6.94 (m, 6H), 6.95–6.84 (m, 1H), 6.84–6.65 (m, 3H), 6.04 (s,
1H), 3.68 (s, 3H), 3.62–3.41 (m, 2H), 3.02 (ddd, J=15.3, 9.3, 5.7, 1H),
2.94–2.80 ppm (m, 1H); 13C NMR (100 MHz, acetone): d=154.3, 145.7,
139.2, 138.0, 136.2, 129.6, 129.1, 127.9, 127.2, 126.4, 125.7, 122.2, 120.9,
120.1, 119.6, 119.3, 115.2, 112.2, 58.7, 55.7, 44.8, 27.9 ppm; MS (EI): m/z
(%): 354 [M+], 230 (100), 218, 202, 123, 108.
1
1-(1H-Indol-3-yl)-2-(4-methyl-phenyl)-1,2,3,4-tetrahydroisoquinoline
(4l): Purified by column chromatography on silica gel (eluting with
hexane/ethyl acetate=20:1, Rf =0.5). 1H NMR (400 MHz, acetone): d=
9.99 (s, 1H), 7.52 (d, J=8.0, 1H), 7.33 (dd, J=15.1, 7.2, 2H), 7.15 (dt, J=
7.1, 4.0, 3H), 7.06 (t, J=7.6, 1H), 7.02–6.88 (m, 5H), 6.74 (d, J=1.9,
1H), 6.19 (s, 1H), 3.59 (dd, J=9.0, 4.7, 2H), 3.04 (ddd, J=15.6, 8.8, 6.4,
1H), 2.86 (s, 1H), 2.18 ppm (s, 3H); 13C NMR (100 MHz, acetone): d=
149.4, 139.6, 138.6, 136.9, 130.9, 130.1, 129.6, 128.4, 128.3, 127.8, 126.9,
126.0, 122.8, 121.3, 120.2, 120.0, 117.7, 112.7, 58.1, 43.9, 27.9, 21.0 ppm;
MS (EI): m/z (%): 338 [M+], 231 (100), 218, 202, 115, 106; HRMS (ESI):
m/z calcd for C24H21N2 [MꢀH]; 337.16993; found: 337.16894.
Acknowledgements
Financial support from the Ministry of Science and Technology of China
(2009CB220008, 2013CB834505 and 2013CB834804), the National Natu-
ral Science Foundation of China (21090343 and 91027041), the Knowl-
edge Innovation Program of the Chinese Academy of Sciences is grate-
fully acknowledged.
Chem. Eur. J. 2013, 19, 6443 – 6450
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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Received: December 23, 2012
Revised: February 2, 2013
Published online: March 15, 2013
6450
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