Chiral counteranion-directed silver-catalyzed asymmetric synthesis of 1,2-dihydroisoquinolines by Friedel-Crafts alkylation reactions

Article abstract of DOI:10.1016/j.tet.2012.02.058

The reaction of ortho-alkynylaryl aldimines and indoles catalyzed by a silver binol-derived phosphate was realized to afford a series of enantioenriched 1,2-dihydroisoquinolines in moderate to good yields and ee. An interesting phenomenon that highly enantioenriched products could be obtained from their lower ee form by silica gel column chromatography was observed, providing an easy access to the enantiopure form of the product.

Full text of DOI:10.1016/j.tet.2012.02.058

Tetrahedron 68 (2012) 5263e5268
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Chiral counteranion-directed silver-catalyzed asymmetric synthesis of 1,
2-dihydroisoquinolines by FriedeleCrafts alkylation reactions
,
,b,
*
Jun-Wei Zhang a b, Zhe Xu b, Qing Gu b, Xiao-Xin Shi a, Xue-Bing Leng b, Shu-Li You a
a School of Pharmacy, East China University of Science and Technology, 130 Mei-Long Road, Shanghai 200237, PR China
b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of ortho-alkynylaryl aldimines and indoles catalyzed by a silver binol-derived phosphate
was realized to afford a series of enantioenriched 1,2-dihydroisoquinolines in moderate to good yields
and ee. An interesting phenomenon that highly enantioenriched products could be obtained from their
lower ee form by silica gel column chromatography was observed, providing an easy access to the
enantiopure form of the product.
Received 18 December 2011
Received in revised form 16 February 2012
Accepted 24 February 2012
Available online 3 March 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Chiral counteranion
1,2-Dihydroisoquinoline
FriedeleCrafts alkylation
Chiral sliver phosphate
Asymmetric synthesis
1. Introduction
1,2-Dihydroisoquinolines and their derivatives constitute an
important class of heterocyclic compounds and are found in nu-
merous natural products1 and pharmaceuticals2 that exhibit re-
markable biological activities. They also often serve as key building
blocks for natural products synthesis.3 Among them, 1,2-
dihydroisoquinolines bearing a stereogenic carbon center at the
C1 position are particularly interesting structural motif.3a,4 There-
fore, several methodologies have been devoted to the development
of novel 1,2-dihydroisoquinoline-based structures and their effi-
cient synthesis in an asymmetric manner. These include the use of
stoichiometric amount of chiral sources,5 the asymmetric transfer
hydrogenation of dihydroisoquinolines,6 PicteteSpengler re-
actions7 and the catalytic asymmetric addition of carbon nucleo-
philes to C]N bonds of isoquinoline scaffolds.8 Recently, Asao,9
Takemoto,10 Larock,11 Wu,12 and others,13 respectively, reported
Scheme 1. Asymmetric synthesis of 1,2-dihydroisoquinoline using chiral anion
strategy.
also been extended to one-pot procedures that employ 2-(1-
alkynyl)arenecarboxaldehydes and amines to form the required
imines in situ. Notably, all these above-mentioned elegant reports
are limited with racemic studies despite of high efficiency of this
protocol. Consequently, the development of such an asymmetric
variant
providing
chiral
multifunctionalized
1,2-
dihydroisoquinoline is highly desirable but challenging due to the
remote distance between the metal center and nucleophile
(Scheme 1).
AgOTf or other Lewis (p) acid-catalyzed synthesis of multi-
Recently, chiral anions14 have been introduced as a useful
strategy for inducing asymmetry in metal-catalyzed trans-
formations. The strategy has been demonstrated by Toste, List, and
others to be capable of providing products with exceptional
enantioselectivity. As shown in Scheme 1, the above discussed re-
action process involves the nucleophilic attack to the iminium in-
termediate A. We envisioned that with a counteranion bearing
a deep chiral pocket might display efficient enantioselective control
for the nucleophilic attack. Our recent studies disclosed that chiral
substituted binol phosphate could serve as a suitable counteranion
substituted 1,2-dihydroisoquinoline skeletons by nucleophilic ad-
dition to ortho-alkynylaryl aldimines, which were prepared from
ortho-alkynylaldehydes and proper amines (Scheme 1). Particu-
larly, the group of Wu have significantly expanded the catalyst and
reaction types for these reaction patterns.12 Such processes have
* Corresponding author. Fax: þ86 21 54925087; e-mail address: slyou@sioc.ac.cn
(S.-L. You).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2012.02.058

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J.-W. Zhang et al. / Tetrahedron 68 (2012) 5263e5268
Table 2
in silver-catalyzed synthesis of 1,2-dihydroisoquinoline employing
indole as the nucleophile. Herein, we report our detailed studies.
Optimization of the reaction conditiona
2. Results and discussion
We began our investigation by testing the FriedeleCrafts type
reaction of ortho-alkynylaryl aldimines with indole,15,16 a privileged
structural core for biologically active compounds and natural
products, with various chiral phosphoric acids and Ag2CO3 (entries
1e13, Table 1). As summarized in Table 1, with 10 mol % of chiral
phosphoric acids (3aem) and 5 mol % of Ag2CO3 in toluene at 60 ꢀC,
most of the reactions proceeded smoothly to give the desired
product 4a in up to 75% yield and 38% ee except those with 3e and
3i. Both 3e and 3i contain triphenylsilyl groups that might be too
sterically bulky for the reaction. Chiral phosphoric acid 3m bearing
2,6-(iPr)2-4-tBuC6H2 group led to the formation of 1,2-
dihydroisoquinoline 4a with best enantioselectivity (38% ee, entry
13, Table 1). Gratifyingly, with the preformed sliver phosphate 3n,
prepared from 3m and Ag2CO3, as the catalyst, the enantiomeric
excess of the product was enhanced to 50% (entry 14, Table 1).
Entry
Solvent
T (ꢀC)
Time (h)
Yieldb (%)
ee (%)c
1
2
3
4
5
6
7
8
Toluene
Benzene
o-Xylene
p-Xylene
DCM
CH3CN
EtOH
i-PrOH
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
60
60
60
60
40
60
40
40
rt
40
80
110
60
60
60
40
10
3
4
4
12
5
12
12
36
10
1
0.5
3
3
80
68
50
52
66
25
25
34
26
73
73
45
72
75
73
83
50
57
59
46
56
57
18
33
52
56
43
21
48
39
48
53
9
10
11
12
13d
14e
15f
16g
Table 1
Screening chiral phosphoric acid catalystsa
3
10
a
All the reactions were performed using 1a (0.10 mmol) and 2a (0.20 mmol) in
1 mL of toluene with 10 mol % of catalyst 3n in dark.
b
Isolated yield.
c
Determined by HPLC.
d
ꢀ
MS (3 A) was added.
e
ꢀ
MS (4 A) was added.
f
ꢀ
MS (5 A) was added.
g
Entry
(S)-3, R
Time (h)
Yieldb (%)
ee (%)c
20 mol % of 3n was used.
1
2
3
4
5
6
7
8
3a, 1-Naphthyl
3b, 2-Naphthyl
3c, 4-Biphenyl
3d, 4-NO2C6H4
5
2
2
1
24
2
1
1
24
1
1
65
71
43
75
8
50
69
57
12
56
71
70
56
80
19
0
12
0
27
16
4
Table 3
Ag(I)-catalyzed enantioselective synthesis of 1,2-dihydroisoquinolinesa
3e, SiPh3
3f, 9-Phenanthryl
3g, 3,5-(CF3)2eC6H3
3h, 4-[3,5-(CF3)2eC6H3]-C6H4
3i, [H]8 SiPh3
3j, [H]8-3,5-(CF3)2-C6H3
3k, 2,6-(iPr)2-4-(9-Anthryl)C6H2
3l, 2,4,6-(iPr)3C6H2
3m, 2,6-(iPr)2-4-tBuC6H2
3n, 2,6-(iPr)2-4-tBuC6H2
4
9
22
19
22
30
38
50
10
11
12
13
14d
2
2.5
10
Entry
1
Product
R
Yield
73
ee
56
a
4a, R1¼H
All the reactions were performed using 1a (0.10 mmol) and 2a (0.20 mmol) in
1 mL of toluene with 10 mol % of catalyst CPA and 5 mol % of Ag2CO3 in dark.
b
Isolated yield.
Determined by HPLC.
Reaction with 3n (sliver phosphate derived from 3m and Ag2CO3).
c
2
3
4
4b, R1¼6-Me
4c, R1¼6,7-(MeO)2
4d, R1¼7-F
67
57
65
63
32
89
d
With 10 mol % of 3n as the catalyst, various solvents were in-
vestigated. The results are summarized in Table 2. Various solvents,
such as toluene, benzene, o-xylene, p-xylene, CH2Cl2, all led to the
formation of the products in good yields and moderate enantio-
selectivities (50e80% yields and 46e59% ee, entries 1e5, Table 2).
However, the reaction in polar solvent, such as CH3CN only gave the
product in 25% yield and 57% ee (entry 6, Table 2). The effect of
reaction temperature was also examined, and the reaction at 40 ꢀC
was found to give the best result (73% yield, 56% ee, entry 10, Table
2). Either decreasing or increasing the temperature could damage
the conversion or enantioselectivity of the reaction (entries 9,
11e12, Table 2). The addition of molecular sieves did not lead to any
improved results (entries 13e15, Table 2).
5
6
7
4e, R2¼Cyclopropyl
4f, R2¼n-Butyl
4g, R3¼7-Me
95
80
55
54
10
43
8
9
4h, R3¼5-MeO
4i, R3¼6-Cl
26
50
48
33
10
4j
41
59
Under the above optimized reaction conditions (10 mol % of (S)-
3n, toluene, 40 ꢀC), various substrates were carried out to test the
generality of the current methodology. As summarized in Table 3,
substrate 4b bearing a methyl group at 6 position gave an improved
enantioselectivity (63% ee) and comparable yield (67%) (entry 2,
a
All the reactions were performed using 1 (0.10 mmol) and 2 (0.20 mmol) in 1 mL
of toluene with 10 mol % of catalyst 3n in dark.

J.-W. Zhang et al. / Tetrahedron 68 (2012) 5263e5268
5265
Table 3). By introducing two methoxy groups, substrate 4c led to
decreased yield and enantioselectivity (entry 3, Table 3). In-
terestingly, substrate 4d containing an electron-withdrawing group
(7-F) gave much enhanced enantioselectivity (89% ee, entry 4, Table
3). In addition to the phenyl substituted alkyne, the alkyl groups,
such as cyclopropyl (4e) and n-butyl (4f) could also be well toler-
ated with decent yields but decreased enantioselectivities (entries
5e6, Table 3). For nucleophile, various substituted indoles bearing
either electron-donating or electron-withdrawing groups could be
tolerated with moderate yields and ee values (entries 7e9, Table 3).
Notably, N-methyl indole also gave its desired product 4j in 41%
yield and 59% ee (entry 10, Table 3).
In order to determine the absolute configuration of the product,
the crystal of enantiopure 4a was obtained and a single crystal X-
ray analysis determined its configuration as R (Fig. 1).
Fig. 2. Packing structure of racemic compound 4a.
between racemic and enantiopure compounds will certainly add
interesting flavors in asymmetric synthesis and might provide new
thoughts for the origin of chirality in our nature.
3. Conclusions
In summary, we have developed a silver binol-derived phosphate
catalyzed reaction of ortho-alkynylaryl aldimines and indoles
affording enantioenriched 1,2-dihydroisoquinolines in moderate to
good yields and ee. For product 4a, the racemic form shows better
thermodynamic stability and lower solubility than its optically pure
form due to its intermolecular
pep stacking interactions between
enantiomers, allowing the potential isolation of enantiopure isomer
from product with low ee through silica gel column chromatography.
(R)-4a
4. Experimental section
4.1. General procedure for the enantioselective synthesis of
1,2-dihydroisoquinolines (4aej)
Fig. 1. X-ray structure of enantiopure (R)-4a. Ellipsoids at 30% probability.
During our studies, we have observed an interesting phenom-
enon with product 4a. After the completion of the reaction, a reg-
ular silica gel column chromatography purification afforded
product 4a in 80% yield and 50% ee. However, if the reaction mix-
ture was filtered after staying at room temperature (20 ꢀC) over-
night and then purified by silica gel column chromatography, the
product from filtrate was obtained in 23% yield and 99% ee and that
from filter cake was obtained in 65% yield and 33% ee. Interestingly,
during the purification of the enantioenriched 4a by silica gel col-
umn chromatography, the first collection is in very high ee but the
last collection is almost racemic. This is a rare case that two en-
antiomers could be isolated by regular silica gel column chroma-
tography purification. Obviously in the solid state, optically pure
compounds and their racemates have significantly different crys-
tallographic structures leading to distinctive physical properties,
such as solubility.17,18 Another notable experiment is that the ra-
cemic compound could form crystal much more easily than its
enantiomeric form,19 which also supports the above hypothesis.
To a solution of ortho-alkynylarylimine 1 (0.1 mmol) in toluene
(1 mL) was added indole 2 (0.2 mmol, 2 equiv) and silver phosphate
3n (8.9 mg, 0.01 mmol). The reactionwas stirred overnight at 40 ꢀC in
dark. After the reaction was complete (monitored by TLC), the mix-
turewas purified bysilica gel column chromatography (ethyl acetate/
petroleum ether¼1/10e1/5) to afford 1,2-dihydroisoquinoline 4.
4 .1.1. ( R ) - 1 - ( 1 H - I n d o l - 3 - y l ) - 3 - p h e n y l - 2 - t o s y l - 1, 2 -
dihydroisoquinoline (4a). White solid (76% yield, 56% ee), following
silica gel column chromatography (ethyl acetate/petroleum
ether¼1/10, v/v). Analytical data for 4a: mp¼209e210 ꢀC; ½a D20
ꢁ
þ39.5 (c 0.5 acetone, 99% ee). 1H NMR (300 MHz, CDCl3)
d 2.16 (s,
3H), 5.97 (s, 1H), 6.53 (s, 1H), 6.81e6.84 (m, 4H), 6.93e6.96 (m, 1H),
7.02e7.09 (m, 5H), 7.17e7.18 (m, 2H), 7.20e7.27 (m, 1H), 7.29e7.32
(m, 3H), 7.35 (s, 1H), 7.80 (br, 1H), 8.38 (d, J¼7.5 Hz, 1H); 13C NMR
(75 MHz, CDCl3)
d 21.3, 56.0, 111.1, 114.2, 120.1, 120.2, 120.3, 122.4,
124.7, 125.1, 126.1, 126.3, 127.0, 127.2, 127.4, 127.7, 128.0, 128.1, 128.3,
130.9, 132.0, 134.1, 136.5, 137.0, 138.8, 143.1; IR (film) 3428, 3035,
2266,1593,1489,1455,1419,1269,1350,1340,1294,1165,1085, 972,
806, 767, 738, 694, 683, 657, 623, 551, 540, 488 cmꢂ1; HRMS (EI)
exact mass calcd for (C30H24N2O2S) requires m/z 476.1559, found m/
z 476.1555. The enantiomeric excess was determined by Daicel
The intermolecular
p-p stacking interactions (Fig. 2) were obvi-
ously confirmed by crystal X-ray analysis of racemic compound 4a.
As shown in Fig. 2, the distance of centroids of two six-membered
ꢀ
rings is about 3.912(2) A between S and R enantiomers, and the
distance of centroids of five-membered ring and six-membered
ring is 3.820(2) A between S (or R) and S (or R) enantiomers.
Chiralpak IC (25 cm), hexanes/IPA¼70/30, 0.8 mL/min,
l
¼254 nm,
ꢀ
tR (major)¼12.45 min, tR (minor)¼19.68 min.
Compared with its optically pure form crystal structure, there were
no any intermolecular interactions between two adjacent mole-
cules. All these observations could strongly support that S and R
enantiomers tend to aggregate together. As a result, the racemic
form shows higher thermodynamic stability and lower solubility
than its optically pure form. This observed different properties
4.1.2. (R)-1-(1H-Indol-3-yl)-6-methyl-3-phenyl-2-tosyl-1,2-
dihydroisoquinoline (4b). White solid (67% yield, 63% ee), following
silica gel column chromatography (ethyl acetate/petroleum
ether¼1/10, v/v). Analytical data for 4b: mp¼206e207 ꢀC; ½a D20
ꢁ
þ1.8 (c 0.5 acetone, 63% ee). 1H NMR (300 MHz, CDCl3)
d 2.22 (s,

5266
J.-W. Zhang et al. / Tetrahedron 68 (2012) 5263e5268
3H), 2.25 (s, 3H), 6.11 (s, 1H), 6.54 (s, 1H), 6.66 (s, 1H), 6.84e6.91 (m,
5H), 7.16 (m, 3H), 7.23e7.37 (m, 7H), 7.80 (br, 1H), 8.40 (d, J¼7.5 Hz,
3059, 1545, 1457, 1420, 1338, 1300, 1157, 1087, 1007, 869, 813, 751,
709, 673, 658, 624, 547, 427 cmꢂ1; HRMS (EI) exact mass calcd for
(C27H24N2O2S) requires m/z 440.1559, found m/z 440.1560. The
enantiomeric excess was determined by Daicel Chiralpak IC
1H); 13C NMR (75 MHz, CDCl3)
d 21.0, 21.3, 55.8, 111.0, 114.4, 120.1,
120.2, 120.5, 122.4, 124.6, 125.5, 126.1, 126.2, 127.0, 127.4, 127.9,
128.0, 128.1, 128.3, 129.2, 130.8, 134.0, 136.4, 136.8, 136.9, 138.8,
143.0; IR (film) 3420, 3373, 3053, 2923, 2853, 1595, 1545, 1492,
1458, 1343, 1325, 1305, 1293, 1166, 1156, 1086, 985, 959, 848, 826,
(25 cm), hexanes/IPA¼90/10, 0.8 mL/min,
l¼254 nm, tR (minor)¼
40.54 min, tR (major)¼44.18 min.
813, 773, 757, 743, 695, 675, 661, 637, 609, 550, 540, 449, 426 cmꢂ1
;
4.1.6. (R)-3-Butyl-1-(1H-indol-3-yl)-2-tosyl-1,2-dihydroisoquinoline
(4f). White solid (80% yield, 10% ee), following silica gel column
chromatography (ethyl acetate/petroleum ether¼1/5, v/v). Analyt-
HRMS (EI) exact mass calcd for (C31H26N2O2S) requires m/z
490.1715, found m/z 490.1709. The enantiomeric excess was de-
termined by Daicel Chiralpak IC (25 cm), hexanes/IPA¼70/30,
ical data for 4f: mp¼176e177 ꢀC; ½a D20
þ10.8 (c 0.5 acetone, 10% ee).
ꢁ
0.8 mL/min,
21.08 min.
l¼254 nm, tR (major)¼14.25 min, tR (minor)¼
1H NMR (300 MHz, CDCl3)
d
0.24 (t, J¼7.5 Hz, 3H), 0.41e0.44 (m,
1H), 0.65e0.70 (m, 1H), 0.79e0.89 (m, 1H), 0.97e1.05 (m, 1H),
2.04e2.14 (m, 1H), 2.20 (s, 3H), 2.79e2.86 (m, 1H), 6.08 (s, 1H), 6.12
(s, 1H), 6.71e6.75 (m, 2H), 6.86 (d, J¼7.5 Hz, 2H), 6.97e7.04 (m, 3H),
7.19e7.30 (m, 3H), 7.40 (d, J¼7.5 Hz, 2H), 7.86 (br,1H), 8.23e8.26 (m,
4.1.3. (R)-1-(1H-Indol-3-yl)-6,7-dimethoxy-3-phenyl-2-tosyl-1,2-
dihydroisoquinoline (4c). White solid (57% yield, 32% ee), following
silica gel column chromatography (ethyl acetate/petroleum
1H); 13C NMR (75 MHz, CDCl3)
d 13.3, 21.3, 21.4, 29.1, 35.8, 56.0,
ether¼1/5, v/v). Analytical data for 4c: mp¼191e192 ꢀC; ½a D20
ꢁ
þ14.8
110.8, 114.5, 119.8, 120.0, 120.4, 122.3, 124.2, 124.6, 126.1, 126.3,
127.0, 127.1, 127.2, 128.3, 130.7, 131.4, 134.7, 136.5, 138.4, 142.9; IR
(film) 3397, 2956, 2930, 2854, 1595, 1539, 1492, 1458, 1429, 1346,
1327, 1168, 1155, 1086, 985, 887, 812, 746, 681, 658, 620, 609, 550,
532, 519 cmꢂ1; HRMS (EI) exact mass calcd for (C28H28N2O2S) re-
quires m/z 456.1872, found m/z 456.1868. The enantiomeric excess
was determined by Daicel Chiralpak AD-H (25 cm), hexanes/
(c 0.5 acetone, 32% ee). 1H NMR (300 MHz, acetone-d6)
d 2.24 (s,
3H), 3.75 (s, 3H), 3.82 (s, 3H), 6.27 (d, J¼1.5 Hz, 1H), 6.58 (s, 1H), 6.74
(s, 1H), 6.77 (s, 1H), 6.84 (s, 1H), 7.04 (d, J¼7.8 Hz, 2H), 7.11e7.13 (m,
3H), 7.17e7.28 (m, 2H), 7.37e7.40 (m, 3H), 7.46 (d, J¼8.1 Hz, 2H),
8.36 (d, J¼7.8 Hz, 1H), 10.00 (br, 1H); 13C NMR (100 MHz, acetone-
d6)
d 20.8, 55.8, 55.9, 56.1, 109.6, 110.9, 112.0, 114.2, 119.7, 120.0,
121.1, 122.2, 124.5, 125.5, 125.6, 126.9, 127.2, 127.7, 127.9, 128.0,
128.8, 135.1, 135.2, 137.6, 140.1, 143.4, 149.1, 150.2; IR (film) 3370,
3320, 2920, 1598, 1512, 1463, 1454, 1341, 1300, 1253, 1229, 1165,
IPA¼80/20, 1.0 mL/min,
l
¼254 nm, tR (major)¼14.29 min, tR
(minor)¼28.78 min.
1126, 1088, 985, 853, 816, 768, 747, 666, 594, 564, 548, 541 cmꢂ1
;
4.1.7. (R)-3-Phenyl-1-(7-methyl-1H-indol-3-yl)-2-tosyl-1,2-
dihydroisoquinoline (4g). White solid (55% yield, 43% ee), following
silica gel column chromatography (ethyl acetate/petroleum
HRMS (ESI) exact mass calcd for (C32H28N2NaO4S) requires m/z
559.1662, found m/z 559.1679. The enantiomeric excess was de-
termined by Daicel Chiralpak IC-H (25 cm), hexanes/IPA¼70/30,
ether¼1/10, v/v). Analytical data for 4g: mp¼188e189 ꢀC; ½a D20
ꢁ
0.8 mL/min,
28.61 min.
l¼254 nm, tR (major)¼18.71 min, tR (minor)¼
þ28.3 (c 0.5 acetone, 43% ee). 1H NMR (300 MHz, CDCl3)
d 2.20 (s,
3H), 2.35 (s, 3H), 6.05 (s, 1H), 6.57 (s, 1H), 6.85e6.86 (m, 4H),
7.00e7.10 (m, 4H), 7.16e7.20 (m, 3H), 7.22e7.24 (m, 1H), 7.35e7.37
(m, 4H), 7.67 (br, 1H), 8.26 (d, J¼7.8 Hz, 1H); 13C NMR (75 MHz,
4.1.4. (R)-7-Fluoro-1-(1H-indol-3-yl)-3-phenyl-2-tosyl-1,2-
dihydroisoquinoline (4d). White solid (65% yield, 89% ee), following
silica gel column chromatography (ethyl acetate/petroleum
CDCl3) d 16.5, 21.3, 56.0, 114.7, 117.9, 120.1, 120.2, 120.5, 123.0, 124.3,
125.0, 125.7, 126.3, 127.1, 127.2, 127.4, 127.6, 127.9, 128.1, 128.2, 130.8,
132.1, 134.1, 136.0, 137.1, 138.7, 143.0; IR (film) 3373, 3053, 2922,
2853, 1704, 1596, 1493, 1449, 1433, 1342, 1165, 1085, 978, 796, 783,
762, 685, 675, 657, 563, 549, 543, 459 cmꢂ1; HRMS (ESI) exact mass
calcd for (C31H26N2NaO2S) requires m/z 513.1607, found m/z
513.1621. The enantiomeric excess was determined by Daicel
Chiralpak IC-H (25 cm), hexanes/IPA¼70/30, 0.8 mL/min,
ether¼1/10, v/v). Analytical data for 4d: mp¼201e202 ꢀC; ½a D20
ꢁ
þ28.2 (c 0.5 acetone, 89% ee). 1H NMR (300 MHz, CDCl3)
d 2.24 (s,
3H), 6.11 (s, 1H), 6.56 (s, 1H), 6.74e6.84 (m, 4H), 6.94 (d, J¼8.1 Hz,
2H), 7.16e7.18 (m, 3H), 7.25e7.33 (m, 5H), 7.40 (d, J¼8.1 Hz, 2H),
7.86 (br, 1H), 8.39 (d, J¼7.8 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d 21.3,
55.7 (d, J¼1.6 Hz), 111.1, 113.4, 113.5 (d, J¼22.1 Hz), 114.2 (d,
J¼21.4 Hz), 119.0, 119.1, 120.1, 120.4, 122.6, 124.4, 126.0, 126.6 (d,
J¼8.3 Hz), 127.0, 127.3 (d, J¼3.1 Hz), 127.5, 128.0, 128.2, 128.4, 134.2,
134.3, 136.5, 136.7, 136.8, 138.6, 143.4, 162.2 (d, J¼246.9 Hz); 19F
l¼254 nm, tR (major)¼12.92 min, tR (minor)¼18.99 min.
4.1.8. (R)-3-Phenyl-1-(5-methoxy-1H-indol-3-yl)-2-tosyl-1,2-
dihydroisoquinoline (4h). White solid (26% yield, 48% ee), following
silica gel column chromatography (ethyl acetate/petroleum
NMR (282 MHz, CDCl3)
d
ꢂ113.6 (m); IR (film) 3415, 3373, 3053,
2925, 1597, 1492, 1457, 1447, 1420, 1343, 1167, 1087, 985, 812, 774,
748, 695, 674, 660, 638, 610, 551, 540 cmꢂ1; HRMS (ESI) exact mass
calcd for (C30H23FN2NaO2S) requires m/z 517.1357, found m/z
517.1373. The enantiomeric excess was determined by Daicel Chir-
ether¼1/5, v/v). Analytical data for 4h: mp¼171e172 ꢀC; ½a D20
ꢂ19.6
ꢁ
(c 0.4 acetone, 48% ee). 1H NMR (300 MHz, CDCl3)
d 2.21 (s, 3H), 4.03
(s, 3H), 6.09 (s, 1H), 6.59 (s, 1H), 6.82 (s, 1H), 6.88e6.93 (m, 4H),
7.01e7.02 (m, 1H), 7.07e7.10 (m, 2H), 7.16e7.26 (m, 4H), 7.35e7.42
alpak IC (25 cm), hexanes/IPA¼70/30, 0.8 mL/min,
l¼254 nm, tR
(major)¼9.73 min, tR (minor)¼13.93 min.
(m, 4H), 7.74 (br, 1H), 7.93 (s, 1H); 13C NMR (100 MHz, CDCl3)
d 21.3,
56.0, 56.1, 101.2, 112.0, 113.2, 114.0, 120.1, 125.0, 125.2, 126.3, 126.6,
127.1, 127.2, 127.4, 127.6, 128.0, 128.1, 128.4, 130.9, 131.5, 132.0, 134.6,
137.2, 138.9, 143.1, 154.5; IR (film) 3362, 2924, 2853, 1624, 1586,
1488, 1457, 1442, 1340, 1208, 1162, 1086, 1055, 1002, 916, 801, 788,
765, 734, 680, 659, 625, 649 cmꢂ1; HRMS (MALDI) exact mass calcd
for (C31H26N2O3SNa) requires m/z 529.1556, found m/z 529.1551.
The enantiomeric excess was determined by Daicel Chiralpak AS-H
4.1.5. (R)-3-Cyclopropyl-1-(1H-indol-3-yl)-2-tosyl-1,2-
dihydroisoquinoline (4e). White solid (95% yield, 54% ee), following
silica gel column chromatography (ethyl acetate/petroleum
ether¼1/5, v/v). Analytical data for 4e: mp¼183e184 ꢀC; ½a D20
ꢁ
þ115.6 (c 0.5 acetone, 54% ee). 1H NMR (300 MHz, CDCl3)
d
ꢂ0.34e0.30 (m, 1H), 0.25e0.27 (m, 2H), 0.59e0.64 (m, 1H),
1.77e1.83 (m, 1H), 2.12 (s, 3H), 5.90 (s, 1H), 6.01 (s, 1H), 6.61e6.64
(m, 2H), 6.79 (d, J¼7.8 Hz, 2H), 6.90e6.95 (m, 3H), 7.10e7.12 (m,
2H), 7.17e7.18 (m, 1H), 7.36 (d, J¼7.8 Hz, 2H), 7.84 (br, 1H), 8.15e8.17
(25 cm), hexanes/IPA¼70/30, 0.8 mL/min,
l¼254 nm, tR (major)¼
18.00 min, tR (minor)¼32.41 min.
(m, 1H); 13C NMR (75 MHz, CDCl3)
d
7.2, 8.4, 16.1, 21.3, 56.1, 110.9,
4.1.9. (R)-3-Phenyl-1-(6-chloro-1H-indol-3-yl)-2-tosyl-1,2-
dihydroisoquinoline (4i). White solid (50% yield, 33% ee), following
silica gel column chromatography (ethyl acetate/petroleum
114.5, 116.1, 119.9, 120.4, 122.2, 124.3, 124.4, 126.0, 126.1, 126.9, 127.1,
127.2, 128.3, 130.6, 131.5, 135.0, 136.4, 140.2, 142.9; IR (film) 3420,

J.-W. Zhang et al. / Tetrahedron 68 (2012) 5263e5268
5267
ether¼1/10, v/v). Analytical data for 4i: mp¼226e227 ꢀC; ½a D20
ꢁ
6. Uematsu, N.; Fujii, A.; Hashiguchi, S.; Ikariya, T.; Noyori, R. J. Am. Chem. Soc.
1996, 118, 4916.
þ11.7 (c 0.5 acetone, 33% ee). 1H NMR (300 MHz, CDCl3)
d 2.22 (s,
7. (a) Taylor, M. S.; Jacobsen, E. N. J. Am. Chem. Soc. 2004, 126, 10558; (b) Seayad, J.;
Seayad, A. M.; List, B. J. Am. Chem. Soc. 2006, 128, 1086; (c) Wanner, M. J.; Van der
Haas, R. N. S.; De Cuba, K. R.; Van Maarseveen, J. H.; Hiemstra, H. Angew. Chem., Int.
Ed. 2007, 46, 7485; (d) Raheem, I. T.; Thiara, P. S.; Peterson, E. A.; Jacobsen, E. N. J.
Am. Chem. Soc. 2007,129,13404; (e) Sewgobind, N. V.; Wanner, M. J.; Ingemann, S.;
De Gelder, R.; Van Maarseveen, J. H.; Hiemstra, H. J. Org. Chem. 2008, 73, 6405; (f)
Bou-Hamdan, F. R.; Leighton, J. L. Angew. Chem., Int. Ed. 2009, 48, 2403; (g) Mur-
atore, M. E.; Holloway, C. A.; Pilling, A. W.; Storer, R. I.; Trevitt, G.; Dixon, D. J. J. Am.
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Dixon, D. J. Org. Lett. 2010, 12, 4720.
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Yudha, S. S.; Asao, N. Synthesis 2008, 820.
10. (a) Yanada, R.; Obika, S.; Kono, H.; Takemoto, Y. Angew. Chem., Int. Ed. 2006, 45,
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3H), 6.10 (s, 1H), 6.59 (s, 1H), 6.84 (s, 1H), 6.87e6.90 (m, 3H),
7.04e7.12 (m, 3H), 7.20e7.22 (m, 3H), 7.28e7.39 (m, 6H), 7.79 (br,
1H), 8.35 (d, J¼9.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d 21.3, 55.8,
111.1, 114.7, 120.2, 121.1, 121.2, 124.8, 125.1, 125.3, 126.3, 127.0, 127.4,
127.5,127.7,128.0,128.2,128.3, 128.4, 130.9,131.6,134.1,136.9, 137.0,
138.6, 143.2; IR (film) 3402, 3059, 2956, 2923, 2853, 1590, 1539,
1493, 1455, 1401, 1336, 1164, 1082, 991, 948, 816, 801, 771, 762, 702,
674, 655, 632, 565, 550 cmꢂ1; HRMS (ESI) exact mass calcd for
(C30H23ClN2NaO2S) requires m/z 533.1061, found m/z 533.1076. The
enantiomeric excess was determined by Daicel Chiralpak IC
(25 cm), hexanes/IPA¼70/30, 0.8 mL/min,
l¼254 nm, tR (major)¼
7.15 min, tR (minor)¼9.20 min.
4.1.10. (R)-3-Phenyl-1-(1-methyl-1H-indol-3-yl)-2-tosyl-1,2-
dihydroisoquinoline (4j). White solid (41% yield, 59% ee), following
silica gel column chromatography (ethyl acetate/petroleum
ether¼1/10, v/v). Analytical data for 4j: mp¼211e212 ꢀC; ½a D20
ꢁ
þ23.5 (c 0.5 acetone, 59% ee). 1H NMR (300 MHz, CDCl3)
d 2.21 (s,
11. Markina, N. A.; Mancuso, R.; Neuenswander, B.; Lushington, G. H.; Larock, R. C.
3H), 3.49 (s, 3H), 5.93 (s, 1H), 6.60 (s, 1H), 6.86e6.89 (m, 4H),
7.04e7.11 (m, 3H), 7.18e7.20 (m, 3H), 7.23e7.25 (m, 1H), 7.28e7.32
(m, 2H), 7.34e7.39 (m, 4H), 8.42 (d, J¼6.9 Hz, 1H); 13C NMR
ACS Comb. Sci. 2011, 13, 265.
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7339; (b) Su, S.; Porco, J. A., Jr. Org. Lett. 2007, 9, 4983; (c) Su, S.; Porco, J.
A., Jr. J. Am. Chem. Soc. 2007, 129, 7744; (d) Nakamura, H.; Saito, H.; Nanjo,
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(75 MHz, CDCl3)
d 21.3, 32.6, 56.0, 109.2, 112.6, 119.8, 120.2, 120.3,
122.0,125.0,126.3,126.7,127.2,127.4,127.6,127.9,128.1, 128.3, 129.1,
130.9, 132.2, 134.3, 137.1, 137.4, 138.9, 143.0; IR (film) 3053, 2920,
1595, 1548, 1495, 1484, 1474, 1456, 1348, 1331, 1304, 1184, 1159,
1085, 974, 950, 870, 813, 798, 780, 761, 747, 730, 694, 683, 653, 639,
627, 616, 552, 540, 519, 419 cmꢂ1; HRMS (EI) exact mass calcd for
(C31H26N2O2S) requires m/z 490.1715, found m/z 490.1718. The en-
antiomeric excess was determined by Daicel Chiralpak IC (25 cm),
hexanes/IPA¼70/30, 0.8 mL/minꢂ1
,
l¼254 nm, tR (major)¼
26.10 min, tR (minor)¼40.93 min.
Acknowledgements
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We thank MOST (973 Program 2010CB833300) and NSFC
(21121062, 21025209, 21002111) for financial support.
Supplementary data
Supplementary data related to this article can be found online at
doi:10.1016/j.tet.2012.02.058.
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