Synthesis and application of diphenyl sulfide linked bis(imidazoline) ligands: Dramatic electronic effect of ligands on catalytic behavior

Article abstract of DOI:10.1002/ejoc.201001347

Diphenyl sulfide linked bis(imidazoline) ligands with electron-withdrawing N-Ts substitution and electron-donating N-alkyl or N-H substitutions were synthesized through different routes. The electronic effects of the ligands were tuned rationally, and dra

Full text of DOI:10.1002/ejoc.201001347

FULL PAPER
DOI: 10.1002/ejoc.201001347
Synthesis and Application of Diphenyl Sulfide Linked Bis(imidazoline)
Ligands: Dramatic Electronic Effect of Ligands on Catalytic Behavior
Xian Du,[a] Han Liu,[b] and Da-Ming Du*[a]
Keywords: Asymmetric catalysis / Imidazoline / Sulfur / Substituent effects / Alkylation
Diphenyl sulfide linked bis(imidazoline) ligands with elec- was observed. N-Alkyl and N-H ligands demonstrated much
tron-withdrawing N-Ts substitution and electron-donating
N-alkyl or N-H substitutions were synthesized through dif-
ferent routes. The electronic effects of the ligands were tuned
rationally, and dramatic variation in their catalytic behavior
higher catalytic activity and improved enantioselectivity than
N-Ts ligands in Pd-catalyzed asymmetric allylic alkylation
reactions.
Since the first report of pyridine-derived imidazoline li-
gands in rhodium-catalyzed asymmetric hydrosilylation of
ketones in 1989,[3] chiral imidazoline ligands with diverse
scaffolds have been developed and applied in a variety of
asymmetric transformations.[4] Compared with the corre-
sponding oxazoline and thiazoline ligands, the introduction
of substituents at the N-1 site of the imidazoline ring pro-
vides the opportunity to fine-tune the electronic effects or-
thogonally to steric effects.[2f,5] As part of our project on the
development of diphenylamine-linked and diphenyl sulfide
linked chiral ligands,[6] we developed diphenylamine-linked
bis(imidazoline) ligands.[6h] Compared with diphenylamine-
linked bis(oxazoline) and bis(thiazoline) ligands,[6e] the bis-
(imidazoline) ligands with electron-withdrawing N-Ts sub-
stitution gave better enantioselectivity and lower catalytic
activity in the asymmetric Friedel–Crafts alkylation. In-
spired by these results, we designed diphenyl sulfide linked
bis(imidazoline) ligands 1 (Figure 1) to realize their elec-
tronic effects in palladium-catalyzed asymmetric allylic al-
kylations. Herein, we would like to document our recent
progress.
Introduction
The development of efficient asymmetric methodologies
for providing enantiomerically pure products is of great
value, due to the increasing demands for chiral compounds
in the development of pharmaceuticals, agrochemicals, and
materials. In order to develop efficient and highly enantio-
selective metal-catalyzed asymmetric reactions, the design
and synthesis of chiral ligands and catalysts is a challenging
task. As an important aspect of ligand structure modifica-
tion, the tuning of electronic effects has attracted the atten-
tion of scientists from coordination chemistry and catalysis.
In order to realize the structure–reactivity relationship and
to optimize the ligand structure with a designated scaffold,
both electron-withdrawing groups and electron-donating
groups are introduced into the ligands at proper sites. Varia-
tion in the ligand electron density can be transferred to the
metal cation through coordination bonds and affects the
crucial properties of the complex, such as the positive
charge density of the metal, the redox potential, the length
of the coordination bonds, and the stability of the complex.
During the past two decades, electronic effects of chiral li-
gands have been investigated by several groups.[1,2] Com-
pared with the variation of the ligand scaffold, the catalytic
activity and stereoselectivity (including enantioselectivity
and diastereoselectivity) of the catalysts were tuned finely.
Dramatic electronic effects such as inversion of diastereo-
selectivity were observed only in some cases.[2i,2j]
[a] School of Chemical Engineering and Environment, Beijing
Institute of Technology,
Beijing 100081, People’s Republic of China
Fax: +86-10-68914985
E-mail: dudm@bit.edu.cn
[b] Beijing National Laboratory for Molecular Sciences (BNLMS),
College of Chemistry and Molecular Engineering, Peking
University,
Beijing 100871, People’s Republic of China
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201001347.
Figure 1. Diphenyl sulfide linked bis(imidazoline) ligands.
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Dramatic Electronic Effect of Ligands on Catalytic Behavior
low activity could not be improved in other solvents
(Table 1, Entries 7–10). When the catalyst loading was
raised to 8 and 10 mol-%, the reaction time could be short-
ened to 5 d with ca. 50% conversion, but the enantio-
selectivity was not affected significantly.
Results and Discussion
After obtaining the encouraging results with the use of
bis(imidazoline) ligands in catalyzed asymmetric Friedel–
Crafts alkylations,[6h] we designed N-Ts ligands 1a–f. The
ligands were synthesized from 2-(2-carboxyphenyl)sulfanyl-
benzoic acid (2), as illustrated in Scheme 1. Mono- and bis-
substituted N-tosyl chiral ethylene diamines 3a–f were syn-
thesized from the corresponding amino alcohols or di-
amines, as we reported before.[6h] Precursors 4a–f were ob-
tained in good yields. Some of the products can precipitate
from the reaction mixture and be isolated in pure form
through filtration as a result of their poor solubility in
CH2Cl2. The desired ligands were obtained in moderate to
good yields through imidazoline formation by using the
Hendrickson’s reagent.[7]
Table 1. Screening of ligands 1a–f, solvents, and catalyst loading in
asymmetric allylic alkylation reactions.[a]
Entry
Ligand
Solvent Time [d] Yield [%][b] ee [%][c]
1
2
3
4
5
6
7
8
9
1a
1b
1c
1d
1e
1f
1b
1b
1b
1b
1b
1b
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
toluene
THF
CH3CN
Et2O
CH2Cl2
CH2Cl2
14
9
14
14
14
8
9
9
9
9
30
55
16
37
7
99
15
37
73
14
42
53
59
85
41
77
63
6
75
73
79
78
80
89
10
11[d]
12[e]
5
5
[a] The reaction was conducted with 5a (0.5 mmol) and 6a
(1.5 mmol) in solvent (3 mL) at room temperature. [b] Isolated
yield. [c] Determined by HPLC by using a Chiralcel IA column
with n-hexane/2-propanol (90:10) as eluent. [d] The catalyst loading
was 8 mol-%. [e] The catalyst loading was 10 mol-%.
Considering the mechanism of allylic alkylation, such a
significant but discouraging electronic effect can be attrib-
uted to the electron-withdrawing nature of the N-Ts substit-
uent. The introduction of N-Ts groups reduces the electron
density at the N-3 sites and the metal center relative to that
of the corresponding bis(oxazoline) ligands. Thus, the rate
of the oxidative addition of the allyl substrate to Pd0 species
is slower. On the basis of this analysis, we concluded that
bis(imidazoline) ligands with electron-donating substituents
at the N-1 position should give enhanced catalytic activity.
To further test our hypothesis of electronic effect, novel li-
gands 1g–i were designed by using optimized 1b as a lead-
ing structure. In this case, the Hendrickson reagent cannot
Scheme 1. Synthesis of N-Ts-substituted diphenyl sulfide linked
bis(imidazoline) ligands.
With the desired ligands 1a–f in hand, we tested their be used for the nucleophiles of the corresponding diamines
catalytic activity in palladium-catalyzed asymmetric allylic (instead of the sulfonamides in 4), as they may destroy the
alkylation reactions by using racemic (E)-1,3-diphenylprop- reagent. Finally, desired ligands 1g–i with electron-donating
2-en-1-yl acetate (5a) and dimethyl malonate (6a) as model substituents were synthesized following Casey’s procedure[8]
substrates; the catalysts were used at a loading of 5 mol- by using bis(β-hydroxy amide) 8 as precursor (Scheme 2),
%. As summarized in Table 1, ligand 1b gave the highest which was the intermediate in our bis(oxazoline) prepara-
enantioselectivity with 85%ee (Table 1, Entry 2). The tion.[6i] Only primary amines with low molecular weights
enantioselectivity is comparable to the optimized result can be successfully used in this transformation. It is feasible
using bis(oxazoline) ligands, whereas the catalytic activity to use large excess amounts of the amines to suppress the
of the bis(imidazoline) ligands is much lower. In most cases, side reactions. When we tried to use a slight excess amount
up to 14 d were needed to observe notable conversion of benzylamine or 4-methylaniline in this reaction, only in-
(Table 1, Entries 1–5). For ligand 1f with less bulky substi- separable mixtures without major components were ob-
tution on the imidazoline ring, though the reaction rate was tained. Other routes toward 1g–i did not give fruitful re-
higher, only 6%ee was obtained (Table 1, Entry 6). Such sults.[9]
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optical rotations of the products and their retention times
on HPLC with literature data. We used other substrates,
such as indole, benzyl alcohol, and morpholine, but they
did not work in our reaction. A simple catalytic enantio-
selectivity comparison between our bis(oxazoline)s and bis-
(imidazoline)s may not be appropriate, because the best li-
gand, bis(oxazoline), contains a 4-tert-butyl group in the
oxazoline ring, whereas the best bis(imidazoline) ligand
contains a 4-benzyl group. The scientific value of this re-
search is the direct observation of a dramatic electronic ef-
fect in the bis(imidazoline) ligands on the catalytic behavior.
Scheme 2. Synthesis of bis(imidazoline) ligands through chlorina-
tion/substitution.
Ligands 1g–i were tested in the model asymmetric allylic
alkylation by using 5 mol-% of the catalysts. As we ex-
pected, the catalytic activity increased dramatically. As
summarized in Table 2, full conversion was achieved within
1 d at room temperature (Table 2, Entries 1–3). To our sur-
prise, ligand 1h with an N-CH3 substituent was so active
that the product was obtained in 96% yield with 93%ee
within only 1 h (Table 2, Entry 2). In contrast, the opti-
mized bis(oxazoline) ligand reported previously[6i] gave 84%
yield and 89%ee after 48 h. When the temperature was fur-
ther reduced to 0 °C, no improvement in the enantio-
selectivity and a decreased yield were observed (Table 2, En-
try 4).
Table 3. Scope of substrates for Pd-1h- catalyzed asymmetric allylic
alkylations.[a]
Table 2. Catalytic behavior of ligands 1g–i in the model asymmetric
allylic alkylation reaction.[a]
Entry
Ligand
T [°C]
Time [h] Yield [%][b] ee [%][c]
1
2
3
4
1g
1h
1i
25
25
25
0
16
1
17
24
99
96
94
59
87
93
86
93
1h
[a] The reaction was conducted with 5a (0.5 mmol) and 6a
(1.5 mmol) in solvent (3 mL) at room temperature. [b] Isolated
yield. [c] Determined by HPLC by using a Chiralcel IA column
with n-hexane/2-propanol (90:10) as eluent.
To illustrate the generality of the high reactivity of ligand
1h, other substrates were tested under the optimized condi-
tion (Table 3). For the phenyl-containing model substrate,
diethyl and dibenzyl malonates gave comparable activity to
dimethyl malonate, whereas the enantioselectivity was 91
and 90%, respectively (Table 3, Entries 2 and 3). When
bulky 1,3-bis(1-naphthyl)prop-2-en-1-yl acetate[10] was
used, full conversion was achieved within 1 h for all three
malonates (Table 3, Entries 4–6). When substrates with elec-
tron-withdrawing groups were tested,[10] comparable ac-
[a] The reaction was conducted with allyl acetate 5 (0.5 mmol) and
nucleophile 6 (1.5 mmol) in CH2Cl2 (3 mL) at room temperature
using 1h (6 mol-%) and [Pd(η3-C3H5)Cl]2 (2.5 mol-%) as catalyst.
[b] Isolated yield. [c] Determined by HPLC by using a Chiralcel IA
column. [d] Dibenzyl malonate (1.0 mmol) was used. [e] The data
in parentheses were obtained by using the optimized bis(oxazoline)
ligand with a tert-butyl group on the oxazoline ring.
On the basis of the absolute configurations of the prod-
tivity but lower enantioselectivities were obtained (Table 3, ucts, a transition-state model of the asymmetric allylic alk-
Entries 7 and 8). In all the cases, ligand 1h gave much ylation reaction was proposed (Figure 2). Considering the
higher reactivity and comparable enantioselectivity than coordination number of the Pd center and the results ob-
those reported for the optimized bis(oxazoline) ligand (data tained by Schulz by using sulfur-containing monooxazoline
in parentheses in Table 3).[6i] The absolute configurations of ligands[11] and Gomez by using diphenyl ether linked bis-
the products were determined to be S by comparison of the (oxazoline) ligands,[12] we envisioned that chelation of the S
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Eur. J. Org. Chem. 2011, 786–793

Dramatic Electronic Effect of Ligands on Catalytic Behavior
2,2Ј-Bis{N-[(S)-1-phenyl-2-(4-methylbenzenesulfonamido)ethyl]carb-
amoyl}diphenyl Sulfide (4a): To a round-bottomed flask was added
2 (1.151 g, 4.2 mmol) and SOCl2 (10 mL). The mixture was heated
at reflux for 4 h, and the excess amount of SOCl2 was removed
under vacuum. The diacyl chloride residue was dissolved in CH2Cl2
(10 mL). To a round-bottomed flask was added 3a (2.436 g,
8.4 mmol), Et3N (3.0 mL, 21 mmol), and CH2Cl2 (20 mL). The
mixture was cooled to 0 °C, and the solution of the diacyl chloride
was added dropwise. After completion of the addition, the mixture
was stirred at room temperature overnight. During the reaction the
and N atoms to Pd with one imidazoline free is not a favor-
able transition state, because bis(oxazoline) is more power-
ful than monooxazoline in Schulz’s report.[11] The weak in-
teraction between the sulfur atom and Pd cannot be exclu-
sively abandoned. The sulfur atom may function as an ad-
ditional chelation point to stabilize the complex. The nu-
cleophile attacks the η3-allyl complex as illustrated in Fig-
ure 2 to release the steric hindrance and gives the S config-
ured product. Electron-poor substrates 5c and 5d will give
looser complexes with larger bond lengths between the η3- product precipitated from the mixture. The reaction was quenched
allyl ligands and the PdII center, which will lead to weaker
with saturated NH4Cl (aq.), and the white precipitate was filtered
and washed thoroughly with water. After being dried by lamp heat-
stereochemical information transfer and lower enantio-
selectivities.
ing, the desired product (3.43 g, Ͼ99% yield) was obtained as a
white powder. M.p. 269–271 °C. [α]2D0 = +4.74 (c = 0.49, DMSO).
1H NMR (300 MHz, [D6]DMSO): δ = 2.34 (s, 6 H, CH3), 3.01–
3.11 (m, 4 H, CH2), 3.34–3.37 (m, 2 H, NH), 5.05–5.09 (m, 2 H,
CH), 7.11–7.14 (m, 2 H, ArH), 7.20–7.28 (m, 6 H, ArH), 7.32–7.35
(m, 10 H, ArH), 7.55–7.58 (m, 2 H, ArH), 7.64 (d, J = 8.1 Hz, 4
H, ArH), 7.73 (t, J = 6.0 Hz, 2 H, ArH), 8.77 (d, J = 8.4 Hz, 2 H,
NH) ppm. 13C NMR (75 MHz, [D6]DMSO): δ = 20.9, 47.3, 52.9,
126.4, 126.8, 126.9, 127.0, 128.0, 128.1, 129.6, 130.3, 132.6, 134.7,
137.1, 138.4, 140.3, 142.6, 166.9 ppm. IR (neat): ν = 3315, 3269,
˜
1634, 1512, 1330, 1160, 1092, 928, 810 cm–1. HRMS (ESI): calcd.
for C44H42N4NaO6S3 [M + Na]+ 841.21587; found 841.21373.
2,2Ј-Bis{N-[(S)-1-(4-methylbenzenesulfonamido)-3-phenylprop-2-
yl]carbamoyl}diphenyl Sulfide (4b): Compound 4b was prepared fol-
lowing the procedure outlined for 4a from 2 (419 mg, 1.53 mmol)
and 3b (1.003 g, 3.3 mmol). The desired product was obtained as a
white solid (1.125 g, 87% yield). M.p. 155–158 °C. [α]2D0 = –52.6 (c
Figure 2. Proposed transition-state model.
1
= 0.41, DMSO). H NMR (300 MHz, [D6]DMSO): δ = 2.34 (s, 6
H, CH3), 2.70 (dd, J = 13.7, 8.9 Hz, 2 H, CH), 2.86–2.92 (m, 6 H,
CH), 3.34 (d, J = 7.2 Hz, 2 H, NH), 4.12 (br., 2 H, CH), 7.05–7.08
(m, 2 H, ArH), 7.13–7.24 (m, 10 H, ArH), 7.26–7.36 (m, 8 H, ArH),
7.65–7.68 (m, 4 H, ArH), 7.73–7.74 (m, 2 H, ArH), 8.25 (d, J =
8.4 Hz, 2 H, NH) ppm. 13C NMR (75 MHz, [D6]DMSO): δ = 20.9,
36.6, 45.5, 50.4, 126.0, 126.4, 126.6, 127.6, 128.0, 129.0, 129.6,
130.1, 132.6, 134.7, 137.4, 138.4, 138.9, 142.6, 167.2 ppm. IR
Conclusions
In conclusion, we designed and synthesized diphenyl sul-
fide linked bis(imidazoline) ligands 1a–f having electron-
withdrawing N-Ts substituents. According to their low cata-
lytic activity in asymmetric allylic alkylation reactions, we
rationally designed and synthesized bis(imidazoline)s 1g–i
with benzyl groups on the imidazoline rings. These ligands
demonstrated much higher catalytic activity than ligands
1a–f and the corresponding bis(oxazoline) ligands we re-
ported before, as well as significantly improved enantio-
selectivity in some cases. Further application of these li-
gands in other asymmetric transformations is under way in
our laboratory.
(neat): ν = 3295, 2979, 2603, 2498, 1639, 1526, 1334, 1157, 1096,
˜
869, 851 cm–1. HRMS (ESI): calcd. for C46H47N4O6S3 [M + H]+
847.26522; found 847.26394.
2,2Ј-Bis{N-[(S)-1-(4-methylbenzenesulfonamido)-3-methylbut-2-
yl]carbamoyl}diphenyl Sulfide (4c): Compound 4c was prepared fol-
lowing the procedure outlined for 4a from 2 (685 mg, 2.5 mmol)
and 3c (1.280 g, 5.0 mmol). The crude product was purified by sil-
ica gel column chromatography (CH2Cl2/MeOH, 20:1). The desired
product was obtained as a white solid (1.710 g, 95% yield). M.p.
103–106 °C. [α]2D0 = –10.9 (c = 0.40, CH2Cl2). 1H NMR (300 MHz,
[D6]DMSO): δ = 0.81 (d, J = 6.6 Hz, 6 H, CH3), 0.85 (d, J =
6.9 Hz, 6 H, CH3), 1.79–1.90 (m, 2 H, CH), 2.37 (s, 6 H, CH3),
2.78–2.86 (m, 4 H, CH), 3.36–3.39 (m, 2 H, NH), 3.79–3.89 (m, 2
H, CH), 7.14–7.19 (m, 2 H, ArH), 7.29–7.34 (m, 4 H, ArH), 7.37–
7.40 (m, 4 H, ArH), 7.48–7.51 (m, 2 H, ArH), 7.69 (d, J = 8.1 Hz,
4 H, ArH), 8.10 (d, J = 9 Hz, 2 H, NH) ppm. 13C NMR (75 MHz,
[D6]DMSO): δ = 17.6, 19.5, 21.0, 28.7, 43.9, 53.6, 126.5, 126.8,
127.9, 129.6, 130.0, 132.7, 134.3, 137.3, 139.5, 142.6, 167.6 ppm.
Experimental Section
General Remarks: Commercially available compounds were used
without further purification. Solvents were dried according to stan-
dard procedures. Column chromatography was carried out by using
silica gel (200–300 mesh). Melting points were measured with a XT-
1
4 melting point apparatus. H NMR spectra were recorded with a
Mercury 300 MHz spectrometer, whereas 13C NMR spectra were
recorded at 75 MHz. Infrared spectra were obtained with a Nicolet
AVATAR 330 FTIR spectrometer. ESI mass spectra were obtained
with a Thermo Finnigan LCQ Deca XP Plus mass spectrometer.
Optical rotations were measured with a Perkin–Elmer 341 LC or
WZZ-3 spectrometer. The enantiomeric excess values of the prod-
ucts were determined by chiral HPLC by using an Agilent HP 1200
instrument on a Chiralpak IA column.
IR (neat): ν = 3275, 2961, 1636, 1534, 1464, 1326, 1158, 1093,
˜
841 cm–1. HRMS (ESI): calcd. for C38H47N4O6S3 [M + H]+
751.26522; found 751.26480.
2,2Ј-Bis{N-[(S)-1-(4-methylbenzenesulfonamido)-3,3-dimethylbut-2-
yl]carbamoyl}diphenyl Sulfide (4d): Compound 4d was prepared fol-
lowing the procedure outlined for 4a from 2 (548 mg, 2.0 mmol)
Eur. J. Org. Chem. 2011, 786–793
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X. Du, H. Liu, D.-M. Du
FULL PAPER
and 3d (1.141 g, 4.2 mmol). The crude product was purified by sil-
ica gel column chromatography (CH2Cl2/MeOH, 20:1). The desired
product was obtained as a white solid (1.55 g, Ͼ99% yield). M.p.
130–131 °C. [α]2D0 = –12.3 (c = 0.90, CH2Cl2). 1H NMR (300 MHz,
[D6]DMSO): δ = 0.86 (s, 18 H, CH3), 2.38 (s, 6 H, CH3), 2.77–2.85
(m, 2 H, CH), 2.94–2.98 (m, 2 H, CH), 3.36–3.40 (m, 2 H, NH),
3.85–3.91 (m, 2 H, CH), 7.21–7.22 (m, 2 H, ArH), 7.31–7.34 (m, 4
H, ArH), 7.38–7.41 (m, 4 H, ArH), 7.57–7.61 (m, 2 H, ArH), 7.72
CH3), 3.79 (t, J = 9.0 Hz, 2 H, CH), 4.37 (t, J = 10.2 Hz, 2 H,
CH), 5.21 (t, J = 9.0 Hz, 2 H, CH), 7.17–7.20 (m, 12 H, ArH),
7.25–7.34 (m, 6 H, ArH), 7.38–7.41 (m, 2 H, ArH), 7.46–7.48 (m, 2
H, ArH), 7.59 (d, J = 7.8 Hz, 4 H, ArH) ppm. 13C NMR (75 MHz,
CDCl3): δ = 21.6, 55.8, 68.4, 126.4, 126.6, 127.3, 127.7, 128.6,
129.8, 130.0, 130.9, 132.7, 132.8, 134.7, 137.2, 141.5, 144.5,
157.2 ppm. HRMS (ESI): calcd. for C44H39N4O4S3 [M + H]+
783.21279; found 783.21175.
(d, J = 8.1 Hz, 4 H, ArH), 8.15 (d, J = 9.6 Hz, 2 H, NH) ppm. 13
C
2,2Ј-Bis[(S)-1-(4-methylbenzenesulfonyl)-4-benzylimidazolin-2-yl]-
diphenyl Sulfide (1b): Compound 1b was prepared following the
procedure outlined for 1a from 4b (874 mg, 1.03 mmol). The de-
sired product was obtained as a pale yellow oil (663 mg, 79 %
yield). [α]2D0 = –45.8 (c = 0.56, CH2Cl2). 1H NMR (300 MHz,
CDCl3): δ = 2.40 (s, 6 H, CH3), 2.47 (dd, J = 13.7, 8.9 Hz, 2 H,
CH2), 3.03 (dd, J = 13.8, 6.0 Hz, 2 H, CH2), 3.64 (dd, J = 12.0,
6.6 Hz, 2 H, CH), 3.86 (t, J = 9.9 Hz, 2 H), 4.33–4.43 (m, 2 H,
CH), 7.06–7.09 (m, 4 H, ArH), 7.15–7.38 (m, 18 H, ArH), 7.57 (d,
J = 8.4 Hz, 4 H, ArH) ppm. 13C NMR (75 MHz, CDCl3): δ =
21.6, 41.4, 52.2, 66.5, 126.3, 126.4, 127.7, 128.4, 129.2, 129.7, 130.7,
131.8, 132.6, 132.9, 135.2, 137.0, 137.5, 144.4, 156.0 ppm. IR
NMR (75 MHz, [D6]DMSO): δ = 20.9, 26.6, 34.1, 43.2, 57.2, 126.5,
128.1, 129.6, 129.9, 132.9, 134.6, 137.55, 137.63, 140.0, 142.5,
168.0 ppm. IR (neat): ν = 3260, 2962, 1638, 1534, 1466, 1327, 1157,
˜
1092, 1025, 952, 814 cm–1. HRMS (ESI): calcd. for C40H51N4O6S3
[M + H]+ 779.29652; found 779.29607.
2,2Ј-Bis{N-[(1S,2S)-1,2-diphenyl-2-(4-methylbenzenesulfonamido)-
ethyl]carbamoyl}diphenyl Sulfide (4e): Compound 4e was prepared
following the procedure outlined for 4a from 2 (822 mg, 3.0 mmol)
and 3e (2.206 g, 6.0 mmol). The desired product was obtained as a
white solid (2.360 g, 81% yield). M.p. 290–292 °C. [α]2D0 = +20.2 (c
1
= 0.66, DMSO). H NMR (300 MHz, [D6]DMSO): δ = 2.23 (s, 6
H, CH3), 3.34 (d, J = 6.9 Hz, 2 H, NH), 4.83 (d, J = 5.4 Hz, 2 H,
CH), 5.32–5.37 (m, 2 H, CH), 6.96–6.99 (m, 4 H, ArH), 7.03–7.05
(m, 12 H, ArH), 7.13–7.19 (m, 8 H, ArH), 7.26 (br., 4 H, ArH),
7.33 (br., 6 H, ArH), 8.24 (d, J = 9.6 Hz, 2 H, ArH), 8.68 (d, J =
9.0 Hz, 2 H, NH) ppm. 13C NMR (75 MHz, [D6]DMSO): δ = 20.8,
57.7, 61.7, 125.9, 126.6, 127.1, 127.5, 127.7, 128.8, 130.3, 132.6,
(neat): ν = 3062, 2922, 1636, 1493, 1361, 1167, 1099, 1030,
˜
814 cm–1. HRMS (ESI): calcd. for C46H43N4O4S3 [M + H]+
811.24409; found 811.24302.
2,2Ј-Bis[(S)-1-(4-methylbenzenesulfonyl)-4-isopropylimidazolin-2-
yl]diphenyl Sulfide (1c): Compound 1c was prepared following the
procedure outlined for 1a from 4c (750 mg, 1.0 mmol). The desired
product was obtained as a colorless oil (510 mg, 71% yield). [α]2D0
= –53.3 (c = 1.08, CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 0.81
(d, J = 6.6 Hz, 6 H, CH3), 0.90 (d, J = 6.6 Hz, 6 H, CH3), 1.62–
1.68 (m, 2 H, CH), 2.41 (s, 6 H, CH3), 3.54–3.63 (m, 2 H, CH),
3.86–3.95 (m, 4 H, CH), 7.24–7.38 (m, 12 H, ArH), 7.62 (d, J =
8.1 Hz, 4 H, ArH) ppm. 13C NMR (75 MHz, CDCl3): δ = 18.3,
18.8, 21.6, 32.8, 50.7, 71.4, 126.2, 127.8, 129.7, 129.8, 130.6, 132.5,
134.7, 138.3, 138.5, 139.1, 139.5, 141.6, 166.7 ppm. IR (neat): ν =
˜
3320, 3279, 1636, 1526, 1322, 1159, 1085, 920 cm–1. HRMS (ESI):
calcd. for C56H51N4O6S3 [M + H]+ 971.29652; found 971.29576.
2,2Ј-Bis{N-[(1S,2S)-2-(4-methylbenzenesulfonamido)cyclohexan-1-
yl]carbamoyl}diphenyl Sulfide (4f): Compound 4f was prepared fol-
lowing the procedure outlined for 4a from 2 (822 mg, 3.0 mmol)
and 3f (1.779 g, 6.6 mmol). The desired product was obtained as a
white solid (2.050 g, 86% yield). M.p. 240–241 °C. [α]2D0 = –43.2 (c
133.0, 135.2, 137.2, 144.3, 155.4 ppm. IR (neat): ν = 2958, 2927,
˜
1
1638, 1597, 1467, 1361, 1168, 1092, 1025 cm–1. HRMS (ESI): calcd.
for C38H43N4O4S3 [M + H]+ 715.24409; found 715.24392.
= 0.48, DMSO). H NMR (300 MHz, [D6]DMSO): δ = 0.97–1.32
(m, 8 H, CH2), 1.42–1.53 (m, 6 H, CH2), 1.74–1.78 (m, 2 H, CH2),
2.36 (s, 6 H, CH3), 3.02 (d, J = 8.1 Hz, 2 H, CH), 3.35 (d, J =
6.9 Hz, 2 H, NH), 3.66 (d, J = 6.3 Hz, 2 H, CH), 7.15 (d, J =
7.2 Hz, 2 H, ArH), 7.33 (m, 8 H, ArH), 7.47 (d, J = 6.6 Hz, 2 H,
ArH), 7.70 (d, J = 7.8 Hz, 4 H, ArH), 8.02 (d, J = 8.1 Hz, 2 H,
NH) ppm. 13C NMR (75 MHz, [D6]DMSO): δ = 20.9, 23.9, 24.1,
31.3, 31.9, 51.8, 56.1, 126.2, 126.5, 127.9, 129.4, 130.0, 132.2, 134.5,
2,2Ј-Bis[(S)-1-(4-methylbenzenesulfonyl)-4-tert-butylimidazolin-2-yl-
]diphenyl Sulfide (1d): Compound 1d was prepared following the
procedure outlined for 1a from 4d (778 mg, 1.0 mmol). The desired
product was obtained as a white solid (394 mg, 53% yield). M.p.
176–180 °C. [α]2D0 = –54.6 (c = 0.47, CH2Cl2). 1H NMR (300 MHz,
CDCl3): δ = 0.83 (s, 18 H, CH3), 2.40 (s, 6 H, CH3), 3.61 (t, J =
7.7 Hz, 2 H, CH), 3.82–3.95 (m, 4 H, CH), 7.22–7.32 (m, 8 H,
ArH), 7.35–7.38 (m, 2 H, ArH), 7.42–7.45 (m, 2 H, ArH), 7.64 (d,
J = 8.1 Hz, 4 H, ArH) ppm. 13C NMR (75 MHz, CDCl3): δ = 21.6,
25.9, 34.0, 49.1, 74.9, 126.1, 127.8, 129.7, 129.9, 130.5, 132.5, 132.9,
138.8, 139.6, 142.1, 167.1 ppm. IR (neat): ν = 3285, 2936, 2856,
˜
1635, 1534, 1325, 1158, 1089, 816 cm–1. HRMS (ESI): calcd. for
C40H47N4O6S3 [M + H]+ 775.26522; found 775.26498.
2,2Ј-Bis[(S)-1-(4-methylbenzenesulfonyl)-4-phenylimidazolin-2-yl]-
diphenyl Sulfide (1a): To a flame-dried Schlenk tube was added
triphenylphosphane oxide (1.668 g, 6.0 mmol) and CH2Cl2
(15 mL). The solution was cooled to 0 °C, and trifluoromethanesul-
fonic anhydride (0.5 mL, 3.0 mmol) was added in one portion. The
134.8, 137.3, 144.4, 155.4 ppm. IR (neat): ν = 2957, 2869, 1638,
˜
1477, 1362, 1186, 1109, 1042 cm–1. HRMS (ESI): calcd. for
C40H47N4O4S3 [M + H]+ 743.27539; found 743.27481.
mixture was stirred at 0 °C for 0.5 h, then 4a (818 mg, 1.0 mmol) 2,2Ј-Bis[(4S,5S)-1-(4-methylbenzenesulfonyl)-4,5-diphenylimid-
was added in several portions. After completion of the addition,
the mixture was stirred at 0 °C for 2 h. The reaction was quenched
with saturated NaHCO3 (aq.). The organic phase was separated,
and the water phase was extracted with CH2Cl2 (2ϫ10 mL). The
combined organic phase was dried with anhydrous Na2SO4, and
the solvent was removed under vacuum. The residue was purified
by silica gel (buffered with Et3N) column chromatography
(CH2Cl2). The desired product was obtained as a white solid
(517 mg, 66% yield). M.p. 107–110 °C. [α]2D0 = –40.7 (c = 0.72,
azolin-2-yl]diphenyl Sulfide (1e): Compound 1e was prepared fol-
lowing the procedure outlined for 1a from 4e (649 mg, 0.67 mmol).
The desired product was obtained as a white solid (512 mg, 82%
yield). M.p. 115–117 °C. [α]2D0 = +11.4 (c = 0.25, CH2Cl2). 1H NMR
(300 MHz, CDCl3): δ = 2.30 (s, 6 H, CH3), 5.03 (d, J = 5.4 Hz, 2
H, CH), 5.14–5.29 (m, 2 H, CH), 6.98–7.58 (m, 36 H, ArH) ppm.
13C NMR (75 MHz, CDCl3): δ = 21.4, 72.1, 79.0, 126.1, 126.5,
127.2, 127.8, 128.5, 128.9, 129.3, 130.2, 130.8, 134.5, 141.3, 141.6,
144.3, 157.1 ppm. IR (neat): ν = 3061, 2923, 1632, 1494, 1365,
˜
CH Cl ). IR (neat): ν = 3094, 2925, 1633, 1494, 1362, 1167, 1092, 1135, 1000 cm–1. HRMS (ESI): calcd. for C56H47N4O4S3
˜
2
2
1017, 814 cm–1. 1H NMR (300 MHz, CDCl3): δ = 2.37 (s, 6 H,
[M + H]+ 935.27539; found 935.27392.
790
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 786–793

Dramatic Electronic Effect of Ligands on Catalytic Behavior
2,2Ј-Bis[(4S,5S)-4,5-butylidenyl-1-(4-methylbenzenesulfonyl)imid- 129.4, 129.7, 131.8, 133.7, 135.3, 138.7, 163.3 ppm. IR (neat): ν =
˜
azolin-2-yl]diphenyl Sulfide (1f): Compound 1f was prepared fol-
lowing the procedure outlined for 1a from 4f (433 mg, 0.50 mmol).
The desired product was obtained as a white solid (260 mg, 71%
yield). M.p. 125–127 °C. [α]2D0 = –41.0 (c = 0.30, CH2Cl2). 1H NMR
(300 MHz, CDCl3): δ = 1.25–1.37 (m, 4 H, CH2), 1.41–1.48 (m, 2
H, CH2), 1.58–1.62 (m, 2 H, CH2), 1.83–1.91 (m, 4 H, CH2), 2.30–
2.34 (m, 2 H, CH2), 2.42 (s, 6 H, CH3), 2.46–2.51 (m, 2 H, CH2),
3.33 (br., 4 H, CH), 7.19–7.31 (m, 12 H, ArH), 7.57 (d, J = 7.8 Hz,
4 H, ArH) ppm. 13C NMR (75 MHz, CDCl3): δ = 21.6, 24.5, 25.0,
30.1, 30.5, 69.3, 71.1, 126.2, 127.7, 129.0, 129.5, 130.3, 132.7, 134.4,
3091, 2966, 2931, 2871, 1726, 1603, 1580, 1453, 1406, 1364, 1287,
1121, 1073, 1046 cm–1. HRMS (ESI): calcd. for C38H43N4S3 [M +
H]+ 587.32029; found 587.32031.
(S)-Dimethyl 2-[(E)-1,3-Diphenylprop-2-en-1-yl]malonate (7aa): To
a flame-dried Schlenk tube was added [Pd(allyl)Cl]2 (4.6 mg,
0.0125 mmol) and ligand 1h (15.9 mg, 0.03 mmol) under an argon
atmosphere, followed by the addition of CH2Cl2 (2.0 mL). The
solution was stirred at room temperature for 0.5 h. Then, a solution
of 5a (126 mg, 0.50 mmol) in CH2Cl2 (1 mL) was added, and the
mixture was stirred for 10 min before the addition of 6a (0.17 mL,
1.5 mmol), N,O-bis(trimethylsilyl)acetamide (BSA; 0.37 mL,
1.5 mmol) and anhydrous KOAc (10 mg, 0.10 mmol). After being
stirred for 1 h (full conversion of the substrate was monitored by
TLC), water (10 mL) was added, and the mixture was extracted
with EtOAc (2ϫ20 mL). The combined organic phase was dried
with anhydrous Na2SO4. The solvent was removed under vacuum,
and the residue was purified by silica gel flash chromatography
(petroleum ether/ethyl acetate, 20:1). The desired product was ob-
tained as a colorless oil (155 mg, 96% yield). The ee was deter-
mined by chiral HPLC. HPLC (Daicel Chiralpak IA column, n-
136.0, 136.8, 144.1, 158.5 ppm. IR (neat): ν = 2931, 2857, 1621,
˜
1466, 1363, 1264, 1168, 1047, 1079, 1025 cm–1. HRMS (ESI): calcd.
for C40H43N4O4S3 [M + H]+ 739.24409; found 739.24395.
2,2Ј-Bis[(S)-4-benzylimidazolin-2-yl]diphenyl Sulfide (1g): To
a
round-bottomed flask was added 8[6i] (270 mg, 0.5 mmol) and
SOCl2 (2 mL). The mixture was heated at reflux for 10 h, and the
excess amount of SOCl2 was removed under vacuum. The residue
was dissolved in CHCl3 (10 mL). Et3N (0.6 mL, 4.2 mmol) was
added, followed by a saturated solution of ammonia in CHCl3
(30 mL). The mixture was stirred at room temperature overnight
and then was treated with 10% NaOH (aq.) (10 mL) for 1 h. The
organic phase was separated, and the aqueous phase was extracted
with CH2Cl2 (3ϫ 50 mL). The combined organic phase was dried
with anhydrous NaSO4. The solvent was removed under vacuum,
and the residue was purified by silica gel (buffered with Et3N) col-
umn chromatography (CH2Cl2/MeOH, 20:1). The desired product
was obtained as a pale yellow oil (166 mg, 66% yield). [α]2D0 = –63.1
hexane/2-propanol
= 90:10, 0.5 mL/min, 254 nm): tminor =
15.2 min, tmajor = 18.3 min. [α]2D0 = –13.7 (c = 1.8, CH2Cl2; 93%ee)
{ref.[13] [α]2D0 = –11.2; c = 1.04, CHCl3; 86%ee}. 1H NMR
(300 MHz, CDCl3): δ = 3.51 (s, 3 H, CH3), 3.69 (s, 3 H, CH3), 3.96
(d, J = 10.8 Hz, 1 H, CH), 4.27 (dd, J = 10.8, 8.4 Hz, 1 H, CH),
6.33 (dd, J = 15.6, 8.4 Hz, 1 H, =CH), 6.48 (d, J = 15.6 Hz, 1 H,
=CH), 7.19–7.30 (m, 10 H, ArH) ppm. 13C NMR (75 MHz,
CDCl3): δ = 49.1, 52.4, 52.6, 57.6, 126.3, 127.1, 127.5, 127.8, 128.4,
128.7, 129.1, 131.8, 136.8, 140.1, 167.7, 168.1 ppm.
1
(c = 0.69, CH2Cl2). H NMR (300 MHz, CDCl3): δ = 2.59 (dd, J
= 13.5, 7.2 Hz, 2 H, CH), 2.84 (dd, J = 13.5, 6.6 Hz, 2 H, CH),
3.38 (dd, J = 12.0, 7.2 Hz, 2 H, CH), 3.61 (t, J = 11.0 Hz, 2 H,
CH), 4.03–4.14 (m, 2 H, CH), 5.29 (br., 2 H, NH), 7.12–7.30 (m,
16 H, ArH), 7.64–7.67 (m, 2 H, ArH) ppm. 13C NMR (75 MHz,
CDCl3): δ = 41.8, 55.7, 62.3, 126.2, 127.3, 128.4, 129.0, 130.2,
(S)-Diethyl 2-[(E)-1,3-Diphenylprop-2-en-1-yl]malonate (7ab): Com-
pound 7ab was prepared according to the procedure outlined for
7aa by using 5a (126 mg, 0.50 mmol) and 6b (240 mg, 1.5 mmol).
The desired product was obtained as a colorless oil (174 mg, 99%
yield). The ee was determined by chiral HPLC. HPLC (Daicel Chi-
ralcel IA column, n-hexane/2-propanol = 90:10, 0.5 mL/min,
254 nm): tminor = 14.1 min, tmajor = 16.9 min. [α]2D0 = –7.9 (c = 2.3,
CH2Cl2; 91%ee) {ref.[14] [α]2D5 = –17.2; c = 1.02, CHCl3; 97%ee}.
130.5, 131.9, 132.5, 134.2, 138.3, 163.2 ppm. IR (neat): ν = 3169,
˜
2919, 2849, 1726, 1603, 1583, 1494, 1453, 1287, 1121, 977 cm–1.
HRMS (ESI): calcd. for C32H31N4S [M + H]+ 503.22639; found
503.22680.
2,2Ј-Bis[(S)-1-methyl-4-benzylimidazolin-2-yl]diphenyl Sulfide (1h): 1H NMR (300 MHz, CDCl3): δ = 1.00 (t, J = 7.2 Hz, 3 H, CH3),
Compound 1h was prepared following the procedure outlined for
1g from 8 (270 mg, 0.5 mmol) and a saturated solution of methyl-
amine in CHCl3 (5 mL). The desired product was obtained as a
pale yellow oil (161 mg, 61% yield). [α]2D0 = –63.9 (c = 0.41,
1.20 (t, J = 7.2 Hz, 3 H, CH3), 3.92 (d, J = 9.0 Hz, 1 H, CH), 3.96
(q, J = 7.2 Hz, 2 H, CH2), 4.16 (q, J = 7.2 Hz, 2 H, CH2), 4.27
(dd, J = 10.8, 8.7 Hz, 1 H, CH), 6.34 (dd, J = 15.6, 8.1 Hz, 1 H,
=CH), 6.48 (d, J = 15.6 Hz, 1 H, =CH), 7.16–7.31 (m, 10 H, ArH)
CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 2.66 (s, 6 H, CH3), ppm. 13C NMR (75 MHz, CDCl3): δ = 13.7, 14.0, 49.2, 57.7, 61.3,
2.72 (dd, J = 13.5, 8.7 Hz, 2 H, CH), 3.11 (dd, J = 13.7, 5.0 Hz, 2
61.5, 126.3, 127.0, 127.4, 127.9, 128.4, 128.6, 129.3, 131.6, 136.8,
H, CH), 3.27 (t, J = 8.9 Hz, 2 H, CH), 3.50 (t, J = 9.9 Hz, 2 H, 140.3, 167.3, 167.8 ppm.
CH), 4.18–4.29 (m, 2 H, CH), 7.18–7.31 (m, 10 H, ArH), 7.33–7.43
(S)-Dibenzyl 2-[(E)-1,3-Diphenylprop-2-en-1-yl]malonate (7ac):
(m, 8 H, ArH) ppm. 13C NMR (75 MHz, CDCl3): δ = 34.1, 41.4,
Compound 7ac was prepared according to the procedure outlined
for 7aa by using 5a (126 mg, 0.50 mmol) and 6c (284 mg,
1.0 mmol). The desired product was obtained as a colorless oil
(236 mg, 99% yield). The ee was determined by chiral HPLC.
HPLC (Daicel Chiralcel IA column, n-hexane/2-propanol = 95:5,
56.6, 63.3, 126.3, 127.7, 128.3, 129.4, 130.0, 130.7, 131.1, 132.5,
134.0, 137.7, 164.5 ppm. IR (neat): ν = 3061, 2922, 1610, 1580,
˜
1493, 1453, 1388, 1291, 1250, 1291, 1044 cm–1. HRMS (ESI): calcd.
for C34H35N4S [M + H]+ 531.25769; found 531.25783.
2,2Ј-Bis[(S)-1-(1-methylethyl)-4-benzylimidazolin-2-yl]diphenyl Sulf- 1.0 mL/min, 254 nm): tminor = 19.8 min, tmajor = 23.0 min. [α]2D0
=
ide (1i): Compound 1i was prepared following the procedure out-
lined for 1g from 8 (270 mg, 0.5 mmol) and isopropylamine (1.18 g,
20 mmol). The desired product was obtained as a pale yellow oil
(130 mg, 44% yield). [α]2D0 = –56.3 (c = 0.39, CH2Cl2). 1H NMR
(300 MHz, CDCl3): δ = 0.95 (d, J = 5.1 Hz, 6 H, CH3), 1.01 (d, J
–6.7 (c = 3.0, CH2Cl2; 90%ee) {ref.[10] [α]2D5 = –7.1; c = 1.0, CHCl3;
1
95%ee}. H NMR (300 MHz, CDCl3): δ = 4.05 (d, J = 11.1 Hz, 1
H, CH), 4.30 (dd, J = 10.8, 8.1 Hz, 1 H, CH), 4.92 (ABq, J =
12 Hz, 2 H), 5.10 (ABq, J = 12 Hz, 2 H), 6.30 (dd, J = 15.9, 8.1 Hz,
1 H, =CH), 6.42 (d, J = 15.9 Hz, 1 H, =CH), 7.02–7.05 (m, 2 H,
= 6.6 Hz, 6 H, CH3), 2.74 (dd, J = 13.5, 8.7 Hz, 2 H, CH), 3.12– ArH), 7.20–7.28 (m, 18 H, ArH) ppm. 13C NMR (75 MHz,
3.18 (m, 4 H, CH), 3.34–3.45 (m, 4 H, CH), 4.31–4.42 (m, 2 H,
CH), 7.18–7.31 (m, 18 H, ArH) ppm. 13C NMR (75 MHz, CDCl3): 128.1, 128.2, 128.31, 128.35, 128.43, 128.7, 128.9, 131.8, 135.01,
δ = 20.0, 20.5, 42.2, 46.2, 46.7, 65.0, 125.9, 126.8, 128.1, 129.1, 135.05, 136.6, 140.0, 167.1, 167.5 ppm.
CDCl3): δ = 49.2, 57.7, 67.1, 67.3, 126.4, 127.1, 127.5, 127.9, 128.0,
Eur. J. Org. Chem. 2011, 786–793
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
791

X. Du, H. Liu, D.-M. Du
2-[(E)-1,3-Bis(1-naphthyl)prop-2-en-1-yl]malonate HPLC (Daicel Chiralcel IA column, n-hexane/2-propanol = 85:15,
FULL PAPER
(S)-Dimethyl
(7ba): Compound 7ba was prepared according to the procedure
outlined for 7aa by using 5b (176 mg, 0.50 mmol) and 6a (0.17 mL,
1.5 mmol). The desired product was obtained as a yellowish oil
1.0 mL/min, 254 nm): tminor = 9.9 min, tmajor = 13.6 min. [α]2D0
=
+1.5 (c = 2.0, CH2Cl2; 86%ee) {ref.[10] [α]2D5 = –3.1; c = 1.0, CHCl3;
97%ee}. 1H NMR (300 MHz, CDCl3): δ = 3.54 (s, 3 H, CH3), 3.70
(240 mg, 99% yield). The ee was determined by chiral HPLC. (s, 3 H, CH3), 3.92 (d, J = 10.8 Hz, 1 H, CH), 4.25 (dd, J = 10.5,
HPLC (Daicel Chiralpak IA column, n-hexane/2-propanol = 80:20,
8.4 Hz, 1 H, CH), 6.29 (dd, J = 15.9, 8.4 Hz, 1 H, =CH), 6.42 (d,
J = 15.9 Hz, 1 H, =CH), 7.17–7.34 (m, 8 H, ArH) ppm. 13C NMR
(75 MHz, CDCl3): δ = 48.3, 52.4, 52.6, 57.2, 127.5, 128.5, 128.8,
129.08, 129.13, 130.9, 132.9, 133.2, 134.9, 138.4, 167.4, 167.8 ppm.
1.0 mL/min, 254 nm): tminor = 9.2 min, tmajor = 13.5 min. [α]2D0
=
+41.2 (c = 1.5, CH2Cl2; 99%ee) {ref.[6i] [α]2D0 = +46.9; c = 0.6,
CH2Cl2; 94%ee}. 1H NMR (300 Hz, CDCl3): δ = 3.40 (s, 3 H,
CH3), 3.71 (s, 3 H, CH3), 4.33 (d, J = 10.5 Hz, 1 H, CH), 5.34 (t,
J = 9.6 Hz, 1 H, CH), 6.42 (dd, J = 15.6, 8.7 Hz, 1 H, =CH), 7.27–
7.58 (m, 9 H, ArH, =CH), 7.66 (d, J = 8.1 Hz, 1 H, ArH), 7.71–
7.75 (m, 2 H, ArH), 7.82 (d, J = 8.1 Hz, 1 H, ArH), 7.95 (d, J =
7.5 Hz, 1 H, ArH), 8.40 (d, J = 8.7 Hz, 1 H, ArH) ppm. 13C NMR
(75 MHz, CDCl3): δ = 44.1, 52.4, 52.6, 57.2, 123.2, 123.6, 123.9,
124.2, 125.3, 125.4, 125.6, 125.9, 126.3, 127.77, 127.83, 128.3,
128.9, 129.8, 131.0, 131.3, 132.2, 133.3, 134.1, 134.5, 136.1, 167.7,
168.5 ppm.
(S)-Dimethyl 2-[(E)-1,3-Bis(4-bromophenyl)prop-2-en-1-yl]malonate
(7da): Compound 7da was prepared according to the procedure
outlined for 7aa by using 5d (205 mg, 0.50 mmol) and 6a (0.17 mL,
1.5 mmol). The desired product was obtained as a colorless oil
(202 mg, 84% yield). The ee was determined by chiral HPLC.
HPLC (Daicel Chiralcel IA column, n-hexane/2-propanol = 85:15,
1.0 mL/min, 254 nm): tminor = 11.6 min, tmajor = 15.9 min. [α]2D0
=
+7.2 (c = 3.5, CH2Cl2; 89%ee) {ref.[10] [α]2D5 = +3.1; c = 1.0, CHCl3;
97%ee}. 1H NMR (300 MHz, CDCl3): δ = 3.55 (s, 3 H, CH3), 3.70
(s, 3 H, CH3), 3.91 (d, J = 10.8 Hz, 1 H, CH), 4.23 (dd, J = 10.8,
8.4 Hz, 1 H, CH), 6.29 (dd, J = 15.9, 8.1 Hz, 1 H, =CH), 6.40 (d,
J = 15.6 Hz, 1 H, =CH), 7.17 (d, J = 6.9 Hz, 4 H, ArH), 7.39 (d,
J = 8.4 Hz, 2 H, ArH), 7.45 (d, J = 8.4 Hz, 2 H, ArH) ppm. 13C
NMR (75 MHz, CDCl3): δ = 48.3, 52.5, 52.6, 57.1, 121.0, 121.4,
127.8, 129.1, 129.5, 131.0, 131.5, 131.8, 135.3, 138.9, 167.4,
167.8 ppm.
(S)-Diethyl 2-[(E)-1,3-Bis(1-naphthyl)prop-2-en-1-yl]malonate (7bb):
Compound 7bb was prepared according to the formerly described
procedure outlined for 7aa by using 5b (176 mg, 0.50 mmol) and
6b (240 mg, 1.5 mmol). The desired product was obtained as a col-
orless oil (215 mg, 95% yield). The ee was determined by chiral
HPLC. HPLC (Daicel Chiralcel IA column, n-hexane/2-propanol
= 85:15, 0.8 mL/min, 254 nm): tminor = 7.9 min, tmajor = 10.4 min.
[α]2D0 = +39.2 (c = 2.6, CH2Cl2; 90%ee) {ref.[6i] [α]2D0 = +33.6; c =
Supporting Information (see footnote on the first page of this arti-
cle): 1H and 13C NMR spectra of new compounds and HPLC dia-
grams of the alkylation products.
1
0.8, CH2Cl2; 94%ee}. H NMR (300 MHz, CDCl3): δ = 0.80 (t, J
= 7.2 Hz, 3 H, CH3), 1.19 (t, J = 7.2 Hz, 3 H, CH3), 3.85 (q, J =
7.2 Hz, 2 H, CH2), 4.21 (qd, J = 7.2, 2.1 Hz, 2 H, CH2), 4.29 (d, J
= 10.8 Hz, 1 H, CH), 5.34 (t, J = 9.6 Hz, 1 H, CH), 6.45 (dd, J =
15.6, 8.4 Hz, 1 H, =CH), 7.29–7.59 (m, 9 H, ArH, =CH), 7.66 (d,
J = 8.1 Hz, 1 H, ArH), 7.71–7.75 (m, 2 H, ArH), 7.82 (d, J =
8.1 Hz, 1 H, ArH), 7.96 (d, J = 7.5 Hz, 1 H, ArH), 8.42 (d, J =
8.7 Hz, 1 H, ArH) ppm. 13C NMR (75 MHz, CDCl3): δ = 13.4,
14.0, 44.0, 57.6, 61.3, 61.6, 123.4, 123.6, 123.8, 124.4, 125.2, 125.4,
125.6, 125.9, 126.2, 127.6, 127.8, 128.3, 128.8, 129.5, 131.0, 131.4,
132.4, 133.4, 124.0, 134.5, 136.3, 167.3, 168.1 ppm.
Acknowledgments
We thank the National Natural Science Foundation of China
(Grant Nos. 20772006 and 21072020), the Development Program
for Distinguished Young and Middle-aged Teachers of Beijing In-
stitute of Technology, and the Program for New Century Excellent
Talents in University (NCET-07–0011) for financial support.
(S)-Dibenzyl
2-[(E)-1,3-Bis(1-naphthyl)prop-2-en-1-yl]malonate
(7bc): Compound 7bc was prepared according to the procedure
outlined for 7aa by using 5b (176 mg, 0.50 mmol) and 6c (284 mg,
1.0 mmol). The desired product was obtained as a colorless oil
(284 mg, 99% yield). The ee was determined by chiral HPLC.
HPLC (Daicel Chiralcel IA column, n-hexane/2-propanol = 95:5,
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1
+24.5 (c = 2.6, CH2Cl2; 91%ee). H NMR (300 MHz, CDCl3): δ
= 4.41 (d, J = 10.8 Hz, 1 H, CH), 4.83 (ABq, J = 12.3 Hz, 2 H,
CH), 5.15 (s, 2 H, CH), 5.35 (t, J = 9.6 Hz, 1 H, CH), 6.40 (dd, J
= 15.3, 8.4 Hz, 1 H, =CH), 6.89 (d, J = 6.6 Hz, 2 H, =CH), 7.09–
7.23 (m, 8 H, ArH), 7.28–7.56 (m, 9 H, ArH), 7.68–7.79 (m, 3 H,
ArH), 7.83–7.92 (m, 2 H, ArH), 8.35 (d, J = 8.4 Hz, 1 H, ArH)
ppm. 13C NMR (75 MHz, CDCl3): δ = 44.2, 57.5, 67.2, 67.4, 123.3,
123.7, 123.9, 124.4, 125.3, 125.4, 125.6, 125.7, 126.0, 126.3, 127.8,
127.9, 128.0, 128.25, 128.34, 128.4, 128.9, 129.8, 131.0, 131.4,
132.0, 133.4, 134.1, 134.4, 134.8, 135.0, 136.1, 167.1, 167.9 ppm.
IR (neat): ν = 3061, 1754, 1735, 1597, 1510, 1456, 1376, 1264, 1218,
˜
1152, 1003, 968, 908 cm–1. HRMS (ESI): calcd. for C40H32O4Na
[M + Na]+ 599.21928; found 599.21904.
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Received: September 28, 2010
Published Online: December 9, 2010
Eur. J. Org. Chem. 2011, 786–793
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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