New multifunctional chiral phosphines and BINOL derivatives co-catalyzed enantioselective aza-Morita-Baylis-Hillman reaction of 5,5-disubstituted cyclopent-2-enone and N-sulfonated imines

Article abstract of DOI:10.1039/c2ob25932j

New multifunctional chiral phosphine (phosphine-amide type) LB8 and BINOL derivative co-catalyzed asymmetric aza-MBH reaction of 5,5-disubstituted cyclopent-2-enones 1 with N-sulfonated imines 2 afforded the corresponding optically active adducts 3 in goo

Full text of DOI:10.1039/c2ob25932j

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PAPER
New multifunctional chiral phosphines and BINOL derivatives co-catalyzed
enantioselective aza-Morita–Baylis–Hillman reaction of 5,5-disubstituted
cyclopent-2-enone and N-sulfonated imines†
Yuan-Liang Yang,a Yin Weib and Min Shi*a,b
Received 15th May 2012, Accepted 18th July 2012
DOI: 10.1039/c2ob25932j
New multifunctional chiral phosphine (phosphine-amide type) LB8 and BINOL derivative co-catalyzed
asymmetric aza-MBH reaction of 5,5-disubstituted cyclopent-2-enones 1 with N-sulfonated imines 2
afforded the corresponding optically active adducts 3 in good to outstanding yields with moderate to good
ee’s under mild conditions. The steric hindrance environment of BINOL derivatives as well as the
nucleophilicity of the phosphorus center and the acidity of free OH which could significantly affect the
stereochemical and chemical outcomes had been discussed, indicating the co-catalyzed system is very
important to this particular asymmetric aza-MBH reaction.
Introduction
Morita–Baylis–Hillman (MBH)/aza-MBH reaction, as one of the
most important carbon–carbon or carbon–heteroatom bond for-
mation and atom economic reactions, has been widely investi-
gated during the past few decades.1 Meanwhile, great progress in
asymmetric MBH or aza-MBH processes in the presence of
chiral organocatalysts has been made.2 However, in contrast to
traditional highly active α,β-unsaturated ketones such as MVK
(methyl vinyl ketone) and EVK (ethyl vinyl ketone), the investi-
gations of 2-cyclopenten-1-one were limited due to its low reac-
tivity.3 Recently, an aza-MBH reaction of 2-cyclopenten-1-one
with N-sulfonated imines has attracted much attention and
satisfied outcomes were obtained.4 Nevertheless, a catalytic
asymmetric aza-MBH reaction was still a challenge.5 To the best
of our knowledge, hydrogen-bonding plays an essential role in a
Scheme 1
wide range of organocatalytic reactions.6 In particular, the utiliz-
ation of chiral diols as promoters has been widely delivered.3h,7
previous work, we wish to report a new multifunctional chiral
phosphine combined with BINOL derivative co-catalyzed asym-
metric aza-MBH reaction using 5,5-disubstituted 2-cyclopenten-
1-ones as the Michael acceptors which affords the corresponding
aza-MBH adducts in high yields with good enantioselectivities
(up to 85% ee) (Scheme 1).
Recently, Sasai and co-workers have developed the novel bifunc-
tional amine and phosphine diol catalysts which were applied in
asymmetric aza-MBH reations.8 Herein, on the basis of our
aKey Laboratory for Advanced Materials and Institute of Fine
Chemicals, East China University of Science and Technology, 130 Mei
Long Road, Shanghai 200237, China
bState Key Laboratory of Organometallic Chemistry, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu,
Shanghai 200032, China. E-mail: Mshi@mail.sioc.ac.cn;
Fax: +86-21-64166128
Results and discussion
Previously, we reported a chiral bifunctional phosphine catalyzed
aza-MBH reaction of 2-cyclopenten-1-one and N-tosyl aldimines
which gave the aza-MBH adducts in high yields, however, with
low to moderate enantioselectivities (up to 62% ee value).2p,5b
Recently, our group has developed a series of new chiral
†Electronic supplementary information (ESI) available: Experimental
procedures and spectroscopic data for all compounds and X-ray crystal
data of compounds syn-D and 3c. CCDC 823459 and 873172. For ESI
and crystallographic data in CIF or other electronic format see DOI:
10.1039/c2ob25932j
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Org. Biomol. Chem., 2012, 10, 7429–7438 | 7429

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multifunctional phosphine catalysts LB1–LB8. This encouraged
us to test their performance in the aza-MBH reaction of 2-cyclo-
penten-1-one and N-tosyl aldimines for improving the enantio-
selectivity. For this purpose, we initiated our screening using
2-cyclopenten-1-one A and N-(4-chlorobenzylidene)-4-methyl-
benzenesulfonamide 2a as model substrates. The results are sum-
marized in the ESI.† On preparing the racemic MBH adduct C,
we found that the MBH–aldol reaction byproduct D was formed
as a diastereomeric mixture, in which the structure of the major
diastereomer was determined by X-ray analysis (Scheme 2).9
Meanwhile, in order to explore the scope of the reaction, further
experiments were conducted using different chiral Lewis bases
(LB1–LB9) and additives (chiral binols) in THF or MTBE (tert-
butyl methyl ether) (Fig. 1). The results are summarized in
Table S1 in the ESI.† Unfortunately, we found that the reaction
conducted at room temperature for 24 h in the presence of chiral
phosphine catalyst LB8 with BINOL derivative BINOL1 with
the optimized conditions, afforded adduct C in 80% yield, but
with only 41% ee value (Table S1,† entry 10).
Based on the above results, we attempted to replace the 5,5-
hydrogen atoms of 2-cyclopenten-1-one with phenyl groups as a
new model substrate to investigate this reaction again. The
results are summarized in Table 1. Firstly, we found that the cor-
responding aza-MBH adduct 3a was produced in poor chemical
yields and enantioselectivities in the presence of LB4 or LB7
without additives (Table 1, entries 1 and 3). Upon using catalyst
LB5,10 the reaction could not proceed. Only LB8 gave better
results, affording 3a in 51% yield and 37% ee than those of LB4
and LB7. Next, we attempted to apply the different additives
combined with the chiral catalyst LB8 to this reaction system. To
our delight, moderate yields and ee values of 3a were obtained
(Table 1, entries 5–8). BINOL1 (R-configuration) gave a slightly
better ee value than that of BINOL2 (S-configuration) under
identical conditions (Table 1, entries 5 vs. 6). However,
BINOL3 and BINOL4 gave better ee values and lower yields
compared with those of BINOL1 and BINOL2 (Table 1, entries
7 and 8).
Then, we screened the effect of temperature in the presence of
BINOL4 and LB8 and found that lower temperatures caused the
reaction to proceed slowly with increasing ee values and dimin-
ishing yields of product 3a (Table 1, entries 9, 11, 12). While at
−30 °C, this co-catalytic system afforded 3a in 70% yield and
80% ee (Table 1, entry 10).
Furthermore, we were pleased to find that enhancing the 3,3′-
substituents’ steric hindrance of the 1,10-binaphthyl framework
of diol proved to be a valuable approach to increase the yields
and enantioselectivities (Table 1, entries 13, 14). Meanwhile, if
the temperature was reduced to −78 °C, the yield was only 46%
and the ee retained (Table 1, entry 16). BINOL5 (R-configur-
ation) again gave a slightly better ee value and higher yield than
that of BINOL6 under identical conditions (Table 1, entries 14
vs. 15). The reaction catalyzed by PPhMe2 and BINOL4 also
went well, but the product was racemic (Table 1, entry 19).
These investigations revealed that the chirality of the product
was controlled by the chiral phosphine catalyst and the chiral
BINOL derivative only played a role in activating the N-sulfo-
nated imine and subsequently offered the steric environment.
However, the additives had a positive influence on the yields
(Table 1, entry 11 vs. 14).
Scheme 2 aza-Morita–Baylis–Hillman reaction of 2-cyclopenten-1-
one A (1.0 equiv) with N-(4-chlorobenzylidene)-4-methylbenzenesulfo-
namide 2a (1.0 equiv) in the presence of PBu3 (20 mol%).
Other than BINAP-derived multifunctional phosphine cata-
lysts, we also tested chiral phosphine catalysts based on an
amino acid skeleton LB9.11 Regardless of addition of an addi-
tive, LB9 could not catalyze the reaction, probably due to its
lower nucleophilicity (Table 1, entries 17 and 18). Our investi-
gations revealed that strong nucleophilicity of the phosphine
Lewis base was essential in this reaction, otherwise the reaction
could not proceed smoothly. In this interesting asymmetric aza-
MBH reaction, the steric hindrance environment of the BINOL
derivative as well as the nucleophilicity of the phosphorus center
and the acidity of free OH could significantly affect the stereo-
chemical and chemical outcomes. The best results were found to
be to carry out the reaction for 5 days in the presence of chiral
phosphine catalyst LB8 with BINOL derivative BINOL5 and
4 Å MS at −50 °C, furnishing 3a in 92% yield and 81% ee.
In order to improve the results, we then embarked on further
optimization of the reaction conditions. The solvent effects were
investigated, using substrates 1a and 2a and LB8 and BINOL5
as the catalytic system. The results are summarized in Table 2
Fig. 1 Tested multifunctional chiral phosphines and BINOL deriva-
tives for asymmetric aza-MBH reactions.
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Table 1 Multifunctional chiral phosphines and BINOL derivatives co-catalyzed aza-MBH reaction: 5,5-diphenylcyclopent-2-enone 1a with
N-(4-chlorobenzylidene)-4-methylbenzenesulfonamide 2a in THF
Entry
Catalyst
Additive
Temperature (°C)
Time
Yielda (%)
eeb (%)
1
2
3
4
5
6
7
LB4
LB5
LB7
LB8
LB8
LB8
LB8
LB8
LB8
LB8
LB8
LB8
LB8
LB8
LB8
LB8
LB9
LB9
PhPMe2
—
—
—
—
rt
rt
rt
rt
rt
rt
rt
rt
−10
−30
−50
−78
−30
−50
−50
−78
−30
−30
−30
1 d
1 d
1 d
1 d
1 d
1 d
1 d
1 d
2 d
2 d
5 d
5 d
2 d
5 d
5 d
5 d
2 d
2 d
2 d
19
—
41
51
77
83
60
58
56
70
53
31
85
92
81
46
NR
NR
77
15
—
28
37
61
56
65
64
75
80
80
73
81
81
75
75
—
—
Race
BINOL1
BINOL2
BINOL3
BINOL4
BINOL4
BINOL4
BINOL4
BINOL4
BINOL5
BINOL5
BINOL6
BINOL5
—
8
9c
10c
11c
12c
13c
14c
15c
16c
17c
18c
19c
BINOL4
BINOL4
a Isolated yield. b Determined by chiral HPLC. c 4 Å MS was used.
entry 2). Next, we switched from single solvents to mixed sol-
vents. THF–fluorobenzene (1 : 1), out of all kinds of mixed sol-
vents, afforded the best results (Table 2, entries 8–10; Table S2,†
entries 19–25). When the catalyst and additive loadings were
reduced to 10 mol% respectively, we found the yield and ee
value of 3a decreased remarkably (Table 2, entry 12).
Table 2 Screening of solvent effects on the aza-MBH reaction of 1a
with 2a in the presence of LB8
Under these optimized conditions, we next examined the gen-
erality of this reaction using 5,5-disubstituted cyclopent-2-enone
1a, 1b (R1 = 4-FC6H4), 1c (R1 = 4-CF3C6H4) and N-sulfonated
imines 2. The results are presented in Table 3. The corresponding
products 3 were obtained in high yields and good ee’s, regardless
of the electron-donating or the electron-withdrawing group in
meta or para position of R2 (Table 3, entries 1, 2, 4, 6–9) in
spite of the poor reaction outcomes if R2 were 2-furyl and
2-naphthyl groups (Table 3, entries 5, 10). Moreover, if R2 was
2-thienyl, it worked well to furnish the corresponding adduct 3d
in 94% yield and 76% ee (Table 3, entry 3). Outstanding ee’s
(73%–85%) and yields (88%–99%) were also attained for 1b
and 1c with 2 when substituents were in para position of R2
(Table 3, entries 11–15).
Entry
Solvent
Yielda (%)
eeb (%)
1
2
3
4
DCM
Toluene
CHCl3
Et2O
DMF
THF
Fluorobenzene
Toluene–THF = 1 : 1
Fluorobenzene–THF = 1 : 1
CHCl3–THF = 1 : 1
Fluorobenzene–THF = 1 : 4
THF
92
85
81
—
54
92
92
58
90
81
92
69
50
82
43
—
51
81
64
62
82
62
78
70
5
6
7c
8
9
10
11
12d
a Isolated yield. b Determined by chiral HPLC. Unless otherwise
specified, 1a (0.05 mmol), 2a (0.075 mmol), LB8 (0.01 mmol),
BINOL5 (0.01 mmol) and 50 mg 4 Å MS were used. c The reaction was
conducted at −40 °C. d The catalyst and additive loadings were reduced
by half (10 mol%).
The constitutions and absolute configurations of 3 have been
determined as S-configurations by X-ray diffraction of 3c
bearing a bromine atom on the meta position of the benzene
ring.12 The CIF data for 3c are presented in the ESI.†9
A plausible mechanism for this asymmetric aza-MBH reaction
is outlined in Scheme 3. First, 5,5-disubstituted cyclopent-2-
enone reacts with LB8 to form a phosphonium enolate E,2g,13
which is stabilized by intermolecular hydrogen bonding with
BINOL5. In addition, the intermolecular hydrogen bonding
between the chiral binolic OH and the nitrogen anion stabilized
by sulfonyl group and oxygen atom of carbonyl group can
and Table S2,† respectively. We found that THF or THF–fluoro-
benzene was the solvent of choice (Table 2, entries 6, 9), while
other solvents such as DCM, CHCl3, Et2O, DMF and fluoroben-
zene gave low enantioselectivities or yields (Table 2, entries 1, 3,
4, 5, 7; Table S2,† entries 8–13). The reaction in toluene went
well and offered the product in 85% yield and 82% ee (Table 2,
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Table 3 Multifunctional chiral phosphine LB8-catalyzed aza-MBH reaction: 5,5-disubstituted cyclopent-2-enones 1 with N-sulfonated imines 2
Entry
R1
R2
Yielda (%)
eeb (%)
Absolute configuration
1
2
3
4
5
6
7
8
Ph (1a)
Ph (1a)
Ph (1a)
Ph (1a)
Ph (1a)
Ph (1a)
Ph (1a)
Ph (1a)
Ph (1a)
Ph (1a)
4-FC6H4 (1b)
4-FC6H4 (1b)
4-FC6H4 (1b)
4-CF3C6H4 (1c)
4-CF3C6H4 (1c)
4-NO2C6H4
3-BrC6H4
2-Thienyl
3-MeOC6H4
2-Furyl
4-BrC6H4
4-CF3C6H4
4-CF3C6H4
3-NO2C6H4
2-Naphthyl
4-NO2C6H4
4-CH3C6H4
4-ClC6H4
99 (3b)
96 (3c)
94 (3d)
90 (3e)
61 (3f)
96 (3g)
99 (3h)
84 (3i)
99 (3j)
44 (3k)
99 (3l)
91 (3m)
89 (3n)
99 (3o)
88 (3p)
85
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
79 (88)d
76
75
68
84
80
84
82
60
82
84
75
73
85
9
10
11
12c
13c
14c
15c
4-NO2C6H4
4-CH3C6H4
a Isolated yields. b Determined by chiral HPLC. c The reaction was carried out in THF. d The ee of 3c after recrystallization.
ee’s have been achieved. Multifunctional phosphines and large
sterically hindered chiral binols are required to get good results.
Further efforts are in progress regarding the reaction scope and
mechanistic details.
Experimental section
General remarks
1H NMR spectra were recorded on a Bruker AM-300 or
AM-400 spectrometer for solution in CDCl3 with tetramethylsi-
lane (TMS) as internal standard; J-values are in Hz. Mass
spectra were recorded with a HP-5989 instrument. All of the
compounds reported in this paper gave satisfactory HRMS ana-
lytic data. Melting points were determined on a digital melting
point apparatus and temperatures were uncorrected. Optical
rotations were determined at 589 nm (sodium D line) by using a
Perkin-Elmer-341 MC digital polarimeter; [α]D-values are given
in unit of 10 deg−1 cm2 g−1. Infrared spectra were recorded on a
Scheme 3 A plausible reaction mechanism.
Perkin-Elmer PE-983 spectrometer with absorption in cm−1
.
Chiral HPLC was performed on a SHIMADZU SPD-10A vp
series with chiral columns (Chiralpak AD-H, IC-H columns
4.6 × 250 mm, (Daicel Chemical Ind., Ltd.)). THF, toluene and
Et2O were distilled from sodium (Na) under argon (Ar) atmos-
phere. CH3CN, 1,2-dichloroethane and dichloromethane were
distilled from CaH2 under an argon (Ar) atmosphere. Commer-
cially obtained reagents were used without further purification.
All reactions were monitored by TLC with Huanghai GF254
silica gel coated plates. Flash column chromatography was
carried out using 300–400 mesh silica gel at increased pressure.
produce relatively stable intermediates F and G. While, inter-
mediate F is less stable than G due to that the steric repulsions
between Ar in N-sulfonated imine and phenyl in phosphonium
enolate E. Meanwhile, the fact that the yield of 3k is low when
Ar is 2-naphthyl can also prove the effect of large sterically hin-
dered substituents. Therefore, the favoured intermediate G under-
goes β-elimination to give the target product I with (S)-enriched
configuration instead of H.
In conclusion, we have established a new multifunctional
chiral strong nucleophilic phosphine (phosphine-amides) LB8
combined with BINOL derivative BINOL5 co-catalyzed aza-
MBH reaction of 5,5-disubstituted cyclopent-2-enone 1 with N-
sulfonated imines 2 to provide easy access to optically active
adducts 3 under mild conditions. Good to excellent yields and
Reaction procedure for the preparation of catalysts
Reaction procedures for the preparation of LB1–LB4, LB6,
LB7, and LB8 have been summarized in the ESI† and the spec-
troscopic data are shown below.
7432 | Org. Biomol. Chem., 2012, 10, 7429–7438
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Amine precursor of LB1: (R)-2′-(phospholan-1-yl)-1,1′-
binaphthyl-2-amine
8.8 Hz, J2 = 2.0 Hz), 7.48 (1H, t, J = 7.2 Hz), 7.39 (1H, t, J =
7.2 Hz), 7.26–7.25 (1H, m), 7.10 (2H, t, J = 10.0 Hz), 7.03 (1H,
s), 1.97–1.90 (1H, m), 1.83–1.69 (7H, m), 1.82 (3H, s),
1.62–1.54 (6H, m), 1.41–1.30 (10H, m); 31P NMR (162 MHz,
CDCl3, 85% H3PO4): δ −22.0; MS (ESI) m/z (%) 518.3 [M+ +
H]; HRMS (ESI) Calcd for C35H37NOP+1 [M+ + H] requires
518.2535, Found 518.2537.
(R)-2′-(Phospholan-1-yl)-1,1′-binaphthyl-2-amine.Procedure:
This compound was prepared according to the previous litera-
ture.10 A white solid. m.p. 178–180 °C; [α]2D0 = −92.9 (c 0.6,
CH2Cl2). IR (CH2Cl2) ν 3378, 3050, 2927, 2855, 1618, 1511,
1471, 1431, 1379, 1351, 1262, 1211, 1144, 1094, 1022, 963,
933, 810, 773, 734 cm−1; 1H NMR (400 MHz, CDCl3, TMS): δ
7.92 (1H, d, J = 8.4 Hz), 7.89 (1H, d, J = 8.0 Hz), 7.82 (1H, d,
J = 8.8 Hz), 7.77 (1H, d, J = 8.0 Hz), 7.67 (1H, d, J = 8.4 Hz),
7.45 (1H, qu, J = 8.4 Hz), 7.25 (1H, s), 7.24 (1H, s), 7.22–7.18
(1H, m), 7.16–7.14 (1H, m), 7.11 (1H, d, J = 9.2 Hz), 6.82 (1H,
d, J = 8.4 Hz), 3.56 (2H, brs), 2.17–2.11 (1H, m), 1.87–1.29
(7H, m); 31P NMR (162 MHz, CDCl3, 85% H3PO4): δ −22.0;
MS (ESI) m/z (%) 356.1 [M+ + H]; HRMS (ESI) Calcd for
C24H23NP+1 [M+ + H] requires 356.1490, Found 356.1488.
LB4: (R)-2′-(Phospholan-1-yl)-1,1′-binaphthyl-2-ol. Procedure:
This compound was prepared according to the previous litera-
ture.2p,15 A white solid. m.p. 188–200 °C; [α]2D0 = −120.6 (c 1.0,
CHCl3). IR (KBr): ν 3506, 3425, 3054, 2933, 2856, 1619, 1594,
1514, 1501, 1345, 1265, 1203, 1143, 866, 812, 735, 683 cm−1
;
1H NMR (400 MHz, CDCl3, TMS): δ 7.98 (1H, d, J = 8.8 Hz),
7.95 (1H, d, J = 8.8 Hz), 7.92 (1H, d, J = 8.0 Hz), 7.87 (1H, d,
J = 8.0 Hz), 7.70 (1H, dd, J1 = 8.8 Hz, J2 = 2.4 Hz), 7.48 (1H,
dt, J1 = 8.0 Hz, J2 = 1.2 Hz), 7.36 (1H, d, J = 8.8 Hz),
7.34–7.26 (2H, m), 7.25–7.20 (2H, m), 6.92 (1H, d, J = 8.4 Hz),
4.84 (1H, s, OH), 2.10–2.01 (1H, m), 1.89–1.64 (5H, m),
1.44–1.25 (2H, m); 31P NMR (CDCl3, 121.5 MHz, 85%
H3PO4): δ −21.69, −21.71; MS (EI) m/z (%): 356 (34.94) [M+],
355 (18.83), 340 (27.25), 399 (100), 281 (14.69), 268 (29.67),
252 (17.67), 239 (20.96); HRMS (EI) Calcd For C24H21PO+1
(M+) requires 356.1330, Found: 356.1324.
LB1: (R)-N-(2′-(phospholan-1-yl)-1,1′-binaphthyl-2-yl)acetamide.
Procedure: This compound was prepared according to the pre-
vious literature.10 Awhite solid. m.p. 102–104 °C; [α]2D0 = −81.0
(c 0.3, CH2Cl2). IR (CH2Cl2) ν 3411, 3064, 2959, 2925, 2857,
1693, 1596, 1496, 1424, 1263, 1096, 1016, 867, 798, 733 cm−1
;
1H NMR (400 MHz, CDCl3, TMS): δ 8.57 (1H, d, J = 9.2 Hz),
8.01 (2H, t, J = 9.2 Hz), 7.91 (2H, t, J = 8.8 Hz), 7.70 (1H, d,
J = 8.8 Hz), 7.49 (1H, t, J = 8.0 Hz), 7.39 (1H, t, J = 7.8 Hz),
7.26 (1H, t, J = 7.8 Hz), 7.21 (1H, t, J = 7.8 Hz), 7.10 (1H, d,
J = 7.2 Hz), 6.88 (1H, d, J = 8.4 Hz), 6.82 (1H, s), 2.06–2.02
(1H, m), 1.86–1.68 (4H, m), 1.82 (3H, s), 1.57–1.50 (2H, m),
1.30–1.23 (1H, m); 31P NMR (162 MHz, CDCl3, 85% H3PO4):
δ −21.7; MS (ESI) m/z (%) 398.2 [M+ + H]; HRMS (ESI) Calcd
for C26H25NOP+1 [M+ + H] requires 398.1596, Found 398.1595.
LB6: (R)-3-(2-(Phospholan-1-yl)phenyl)-5,5′,6,6′,7,7′,8,8′-
octahydro-1,1′-binaphthyl-2,2′-diamine. Procedure: Compound
VI (2.52 g, 4.5 mmol) was dissolved in 85 mL of EtOH, and
then 85 mL 50% potassium hydroxide aqueous solution was
added into the mixture. The resulting solution was heated to
120 °C overnight and the reaction was quenched by addition of
saturated 10% HCl solution, washed with water, extracted by
CH2Cl2 twice, dried by anhydrous Na2SO4. The solution was
concentrated for the next step without further purification (quan-
titative yield). Triphenylphosphine (5.98 g, 22.8 mmol) in
toluene (50 mL) was added into this product mixture (2.12 g,
4.57 mmol) and then trichlorosilane (2.31 mL, 22.8 mmol) was
added. The resulting mixture was heated at 110 °C for three
days. After being cooled to room temperature, the product
mixture was diluted with dichloromethane, quenched with a
small amount of saturated NaHCO3 solution. The resulting sus-
pension was filtered through Celite, and washed with dichloro-
methane. The combined extracts were dried over anhydrous
Na2SO4, and the residue was chromatographed on silica gel
(PE–EA = 8 : 1 as eluent) to provide compound LB6 as white
solid (1.56 g, 75% yield). m.p. 171–172 °C; [α]2D0 = +76 (c 0.5,
CH2Cl2). IR (CH2Cl2) ν 3458, 3363, 2926, 2854, 2833, 1606,
1482, 1447, 1422, 1353, 1302, 1286, 1262, 1219, 1106, 1028,
LB2: tert-Butyl (R)-3-methyl-1-oxo-1-((R)-2′-(phospholan-1-
yl)-1,1′-binaphthyl-2-ylamino)butan-2-ylcarbamate. Procedure:
This compound was prepared according to the previous litera-
ture.14 A white solid. m.p. 98–100 °C; [α]2D0 = +12 (c 0.3,
CH2Cl2). IR (CH2Cl2) ν 3402, 3369, 3054, 2960, 2931, 2871,
1691, 1500, 1427, 1366, 1331, 1264, 1168, 1019, 895,
736 cm−1 1H NMR (400 MHz, CDCl3, TMS): δ (rotamer:
;
major/minor = 5/1) 8.50 (1H, d, J = 8.8 Hz), 8.03 (1H, d, J =
9.2 Hz), 7.98 (1H, d, J = 8.4 Hz), 7.90 (2H, t, J = 7.2 Hz), 7.69
(1H, dd, J1 = 8.8 Hz, J2 = 2.4 Hz), 7.49–7.39 (2H, m),
7.27–7.19 (3H, m), 7.05 (1H, d, J = 8.4 Hz), 6.98 (1H, d, J =
8.4 Hz), 4.88 (0.68H, d, J = 8.4 Hz), 4.34 (0.14H, d, J = 8.4
Hz), 3.83–3.77 (0.15H, m), 3.73–3.70 (0.74H, m), 2.16–2.09
(1H, m), 1.89–1.42 (7H, m), 1.35–1.13 (10H, m), 0.46 (3H, d,
J = 7.8 Hz), 0.40 (3H, d, J = 7.8 Hz); 31P NMR (162 MHz,
CDCl3, 85% H3PO4): δ −22.2, −22.6; MS (ESI) m/z (%) 555.3
[M+ + H]; HRMS (ESI) Calcd for C34H40N2O3P+1 [M+ + H]
requires 555.2689, Found 555.2701.
943, 872, 811, 767, 743 cm−1 1H NMR (400 MHz, CDCl3,
;
TMS): δ 7.45–7.41 (1H, m), 7.33–7.25 (3H, m), 6.91 (1H, d, J =
8.4 Hz), 6.87 (1H, d, J = 12.0 Hz), 6.62 (1H, dd, J1 = 8.0 Hz,
J2 = 3.6 Hz), 3.25 (4H, brs), 2.77–2.71 (4H, m), 2.40–2.23 (4H,
m), 1.96–1.60 (16H, m); 31P NMR (162 MHz, CDCl3, 85%
H3PO4): δ −19.9, −21.1; MS (ESI) m/z (%) 455.3 [M+ + H];
HRMS (ESI) Calcd for C30H36N2P+1 [M+ + H] requires
455.2604, Found 455.2611.
LB3: (R)-N-(2′-(Phospholan-1-yl)-1,1′-binaphthyl-2-yl)adamantane-
carboxamide. Procedure: This compound was prepared accord-
ing to the previous literature.15 A white solid. m.p. 187–190 °C;
[α]2D0 = −147.9 (c 0.5, CH2Cl2). IR (CH2Cl2) ν 3417, 3055,
2924, 2851, 1727, 1683, 1620, 1594, 1499, 1453, 1426, 1376,
1332, 1263, 1219, 1103, 937, 814, 736 cm−1
;
1H NMR
LB7: (R)-N,N′-(3-(2-(Phospholan-1-yl)phenyl)-5,5′,6,6′,7,7′,8,8′-
octahydro-1,1′-binaphthyl-2,2′-diyl)diacetamide. Procedure: This
compound was prepared according to the previous literature.16
(400 MHz, CDCl3, TMS): δ 8.63 (1H, d, J = 8.8 Hz), 8.01 (2H,
t, J = 8.8 Hz), 7.91 (2H, t, J = 8.8 Hz), 7.71 (1H, dd, J1 =
This journal is © The Royal Society of Chemistry 2012
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A white solid (70% yield). m.p. 144–146 °C; [α]2D0 = −236.5
(c 1.0, CH2Cl2). IR (CH2Cl2) ν 3287, 3256, 2929, 2856, 1688,
1665, 1592, 1524, 1434, 1401, 1366, 1292, 1263, 1092, 1060,
Compound 1c: 5,5-Bis(4-(trifluoromethyl)phenyl)cyclopent-2-
enone. Procedure: This compound was prepared according to
the previous literature.19,20 A mixture of 5 and 5′ (400 mg,
0.8 mmol) was dissolved in 15 mL toluene and potassium car-
bonate (336 mg, 2.4 mmol) was added. The resulting solution
was heated to reflux for three hours. The solvent was removed
under reduced pressure and the residue was purified by flash
column chromatography on silica gel (EtOAc–PE = 1 : 4 as
eluent) to furnish product 1c as white solid (150 mg, 51% yield).
m.p. 97–99 °C; IR (CH2Cl2) ν 2926, 1707, 1616, 1595, 1410,
1
1015, 799 cm−1; H NMR (400 MHz, CDCl3, TMS): δ 8.30
(0.5H, s), 7.56–7.27 (5.5H, m), 7.09–7.04 (2H, m), 2.86–2.76
(4H, m), 2.31–2.25 (2H, m), 2.05–1.94 (5H, m), 1.86–1.41
(15H, m), 1.32–1.27 (4H, m); 31P NMR (162 MHz, CDCl3,
85% H3PO4): δ −16.0; MS (ESI) m/z (%) 539.3 [M+ + H];
HRMS (ESI) Calcd for C34H40N2O2P+1 [M+ + H] requires
539.2812, Found 539.2822.
1320, 1261, 1163, 1112, 1017, 958, 936, 831, 802, 766 cm−1
;
1H NMR (400 MHz, CDCl3, TMS): δ 7.93–7.90 (1H, m), 7.58
(4H, d, J = 8.4 Hz), 7.32 (4H, d, J = 8.4 Hz), 6.33–6.31 (1H,
m), 3.53 (2H, d, J = 2.0 Hz); 13C NMR (100 MHz, CDCl3): δ
207.0, 162.4 (d, JC–F = 1.5 Hz), 146.3 (d, JC–F = 1.1 Hz), 132.7,
129.4 (q, JC–F = 32.4 Hz), 128.3, 125.6 (q, JC–F = 3.7 Hz),
123.9 (q, JC–F = 270.3 Hz), 59.6, 46.9; 19F NMR (376 MHz,
CDCl3, CFCl3): δ −62.7; (EI) m/z (%) 370 (100.00) [M+], 351
(17.56), 301 (33.68), 273 (40.35), 225 (40.90), 202 (14.32), 183
(11.08), 177 (16.41), 159 (34.82); HRMS (EI) Calcd for
C19H12OF6 [M+] requires 370.0792, Found 370.0786.
LB8: (R)-N,N′-(3-(2-(Phospholan-1-yl)phenyl)-5,5′,6,6′,7,7′,8,8′-
octahydro-1,1′-binaphthyl-2,2′-diyl)diadamantanecarboxamide.
Procedure: This compound was prepared according to the pre-
vious literature.17 To a solution of resolved LB6 (454 mg,
1.0 mmol) and pyridine (320 mg, 4.0 mmol) in toluene (10 mL)
was added 1-adamantanecarboxylic acid chloride (794 mg,
4.0 mmol) in one portion. The reaction mixture was stirred at
90 °C for 12 h. The reaction mixture was cooled to room temp-
erature and the toluene was removed under high vacuum. The
remaining residue was chromatographed on silica gel (PE–EA =
8 : 1 as eluent) to provide compound LB8 as white solid
(355 mg, 45% yield). m.p. >320 °C; [α]2D0 = −193.6 (c 0.5,
CH2Cl2). IR (CH2Cl2) ν 3312, 2905, 2850, 1725, 1700, 1661,
1590, 1486, 1452, 1344, 1264, 1180, 1102, 1079, 975, 802, 764,
General procedure for the preparation of 3 from the reaction of
1a with 2a using 3a as an example in the presence of LB8
1
739 cm−1; H NMR (400 MHz, CDCl3, TMS): δ 8.06 (1H, s),
To a mixture of 1a (0.075 mmol, 18 mg), 2a (0.1125 mmol,
33 mg), catalyst LB8 (10 mg, 0.015 mmol), BINOL5 (12 mg,
0.015 mmol) and 50 mg 4 Å MS was added 1.0 mL of THF–
fluorobenzene (1 : 1) at −50 °C under argon. The reaction sol-
ution was stirred for about 5 days and monitored by TLC. After
the reaction completed, the solution was concentrated under
reduced pressure and the residue was further purified by silica
gel column chromatography (EtOAc–PE = 1 : 4) to give the
target product 3a.
7.38 (1H, d, J = 8.4 Hz), 7.34–7.25 (4H, m), 7.18–7.15 (1H, m),
7.04 (1H, d, J = 8.4Hz), 7.01 (1H, s), 2.82–2.77 (4H, m),
2.37–2.18 (5H, m), 1.98 (3H, s), 1.87–1.41 (36H, m), 1.57 (6H,
s); 31P NMR (162 MHz, CDCl3, 85% H3PO4): δ −15.9, −23.9;
MS (ESI) m/z (%) 779.7 [M+ + H]; HRMS (ESI) Calcd for
C52H64N2O2P+1 [M+ + H] requires 779.4695, Found 779.4699.
Typical procedure for the preparation of Boc-protected
Morita–Baylis–Hillman adducts
(S)-N-((4-Chlorophenyl)(5-oxo-4,4-diphenylcyclopent-1-enyl)-
methyl)-4-methylbenzenesulfonamide 3a. Following the general
procedure, the mixture was purified by column chromatography
using silica gel to give the target product 3a (36 mg, 90% yield).
A white solid. m.p. for racemic 3a = 206–208 °C; m.p. for 3a =
169–170 °C; [α]D20 = +18.0 (c 0.3, CH2Cl2). IR (CH2Cl2): ν
3277, 3057, 2923, 2585, 1694, 1634, 1596, 1490, 1328, 1157,
The reaction procedure for the preparation of 5,5-disubstituted
cyclopent-2-enones has been summarized in the ESI† and their
spectroscopic data are shown below.
Compound 1a: 5,5-Diphenylcyclopent-2-enone. Procedure:
1
This is a known compound. A white solid. H NMR (400 MHz,
CDCl3, TMS): δ 7.86–7.83 (1H, m), 7.32–7.20 (10H, m),
6.29–6.26 (1H, m), 3.51 (2H, t, J = 2.8 Hz); 13C NMR
(100 MHz, CDCl3): δ 208.8, 162.3, 143.1, 132.7, 128.4, 127.9,
126.7, 59.9, 47.8.
1088, 1034, 1013, 919, 883, 812, 756, 734 cm−1 1H NMR
;
(400 MHz, CDCl3, TMS): δ 7.58 (2H, d, J = 8.0 Hz), 7.47 (1H,
s), 7.26–7.21 (6H, m), 7.11–6.99 (10H, m), 6.05 (1H, d, J =
8.4 Hz), 5.32 (1H, d, J = 8.4 Hz), 3.32 (1H, d, J = 19.2 Hz),
3.14 (1H, d, J = 19.2 Hz), 2.31 (3H, s); 13C NMR (CDCl3,
100 MHz): δ 206.9, 158.0, 143.4, 142.3, 142.2, 141.4, 137.2,
136.8, 133.7, 129.6, 128.6, 128.5, 128.4, 128.1, 127.8, 127.6,
127.1, 127.0, 126.9, 61.0, 54.5, 45.4, 21.4; MS (ESI) m/e 550.0
(M+ + Na); HRMS (ESI) for C31H26ClNO3SNa+1 (M+ + Na):
550.1223, Found: 550.1214. The ee of the 3a was determined to
be 82% [determined by HPLC, Chiralpak AD-H, n-hexane–
isopropanol = 70 : 30, 0.5 mL min−1, λ = 214 nm, t (major) =
25.55 min, t (minor) = 34.47 min].
Compound 1b: 5,5-Bis(4-fluorophenyl)cyclopent-2-enone.
Procedure: This compound was prepared according to the pre-
vious literature.18 A yellow solid. m.p. 64–66 °C; IR (CH2Cl2)
ν 3074, 2919, 1702, 1597, 1505, 1436, 1407, 1342, 1229, 1162,
1
1108, 1015, 951, 830, 738 cm−1; H NMR (400 MHz, CDCl3,
TMS): δ 7.86–7.83 (1H, m), 7.26–7.14 (4H, m), 7.01–6.96 (4H,
m), 6.28–6.26 (1H, m), 3.46 (2H, t, J = 2.8 Hz); 13C NMR
(100 MHz, CDCl3): δ 208.4, 162.3, 160.5 (d, JC–F = 244.6 Hz),
138.7 (d, JC–F = 2.6 Hz), 132.5, 129.4 (d, JC–F = 7.8 Hz), 115.2
(d, JC–F = 21.2 Hz), 58.5, 47.6; 19F NMR (376 MHz, CDCl3,
CFCl3): δ −115.8; (EI) m/z (%) 270 (100) [M+], 241 (33.37),
227 (18.15), 201 (43.45), 175 (20.67), 146 (31.31), 133 (13.27),
120 (17.11), 109 (64.97); HRMS (EI) Calcd for C17H12OF2
[M+] requires 270.0856, Found 270.0860.
(S)-4-Methyl-N-((4-nitrophenyl)(5-oxo-4,4-diphenylcyclopent-
1-enyl)methyl)benzenesulfonamide 3b. Following the general
procedure, the mixture was purified by column chromatography
using silica gel to give the target product 3b (40 mg, 99% yield).
7434 | Org. Biomol. Chem., 2012, 10, 7429–7438
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A white solid. m.p. for racemic 3b = 160–162 °C; m.p. for 3b =
145–148 °C; [α]D20 = +13.6 (c 0.6, CH2Cl2). IR (CH2Cl2):
ν 3279, 3058, 2923, 2583, 1697, 1634, 1597, 1492, 1444, 1345,
n-hexane–isopropanol = 70 : 30, 0.5 mL min−1, λ = 214 nm,
t (major) = 30.22 min, t (minor) = 26.58 min].
1159, 1089, 1034, 1015, 927, 883, 814, 757, 734 cm−1 1H
;
(S)-N-((3-Methoxyphenyl)(5-oxo-4,4-diphenylcyclopent-1-enyl)-
methyl)-4-methylbenzenesulfonamide 3e. Following the general
procedure, the mixture was purified by column chromatography
using silica gel to give the target product 3e (35 mg, 90% yield).
A white solid. m.p. for racemic 3e = 153–154 °C; m.p. for 3e =
141–143 °C; [α]D20 = +27.3 (c 0.4, CH2Cl2). IR (CH2Cl2): ν
3277, 2923, 2853, 1700, 1599, 1492, 1444, 1331, 1262, 1160,
NMR (400 MHz, CDCl3, TMS): δ 7.98 (2H, d, J = 8.4 Hz),
7.60 (2H, d, J = 8.0 Hz), 7.52 (1H, s), 7.30–7.20 (8H, m), 7.08
(2H, d, J = 8.0 Hz), 7.01–6.97 (4H, m), 6.25 (1H, d, J =
9.2 Hz), 5.46 (1H, d, J = 8.8 Hz), 3.35 (1H, d, J = 18.0 Hz),
3.14 (1H, d, J = 17.2 Hz), 2.30 (3H, s); 13C NMR (CDCl3,
100 MHz): δ 206.7, 158.6, 147.3, 145.4, 143.8, 142.0, 141.8,
140.5, 137.0, 129.7, 128.6, 128.5, 127.7, 127.6, 127.5, 127.2,
127.1, 123.6, 60.9, 54.3, 45.5, 21.4; MS (ESI) m/e 561.0
(M+ + Na); HRMS (ESI) for C31H26N2O5SNa+1 (M+ + Na):
561.1460, Found: 561.1454. The ee of the 3b was determined to
be 85% [determined by HPLC, Chiralpak AD-H, n-hexane–
isopropanol = 70 : 30, 0.5 mL min−1, λ = 214 nm, t (major) =
51.21 min, t (minor) = 56.76 min].
1
1091, 1036, 917, 814, 698 cm−1; H NMR (400 MHz, CDCl3,
TMS): δ 7.60 (2H, d, J = 8.0 Hz), 7.50 (1H, s), 7.26–7.20 (6H,
m), 7.09–7.01 (7H, m), 6.71 (1H, dd, J1 = 8.0 Hz, J2 = 2.0 Hz),
6.66 (1H, d, J = 6.8 Hz), 6.61 (1H, s), 5.95 (1H, d, J = 8.4 Hz),
5.32 (1H, d, J = 8.4 Hz), 3.60 (3H, s), 3.36–3.31 (1H, m), 3.17
(1H, dd, J1 = 19.6 Hz, J2 = 2.8 Hz), 2.30 (3H, s); 13C NMR
(CDCl3, 100 MHz): δ 206.9, 159.7, 157.9, 143.2, 142.5, 141.9,
139.8, 137.3, 129.6, 129.5, 128.4, 127.8, 127.6, 127.2, 126.9,
118.9, 113.9, 111.8, 60.9, 55.0, 45.5, 21.4; MS (ESI) m/z 546.0
(M+ + Na); HRMS (ESI) for C32H29NO4SNa+1 (M+ + Na):
546.1711, Found: 546.1710. The ee of the 3e was determined to
be 75% [determined by HPLC, Chiralpak AD-H, n-hexane–
isopropanol = 70 : 30, 0.5 mL min−1, λ = 214 nm, t (major) =
31.59 min, t (minor) = 27.87 min].
(S)-N-((3-Bromophenyl)(5-oxo-4,4-diphenylcyclopent-1-enyl)-
methyl)-4-methylbenzenesulfonamide 3c. Following the general
procedure, the mixture was purified by column chromatography
using silica gel to give the target product 3c (41 mg, 96% yield).
A white solid. m.p. for racemic 3c = 146–148 °C; m.p. for 3c =
150–152 °C; [α]D20 = +22.0 (c 0.3, CH2Cl2). IR (CH2Cl2):
ν 3273, 3058, 2961, 2923, 2846, 1698, 1634, 1595, 1492, 1473,
(S)-N-(Furan-2-yl(5-oxo-4,4-diphenylcyclopent-1-enyl)methyl)-
4-methylbenzenesulfonamide 3f. Following the general pro-
cedure, the mixture was purified by column chromatography
using silica gel to give the target product 3f (23 mg, 61% yield).
A white solid. m.p. for racemic 3f = 160–163 °C; m.p. for 3f =
167–168 °C; [α]D20 = +22.0 (c 0.8, CH2Cl2). IR (CH2Cl2):
ν 3278, 3059, 1701, 1638, 1597, 1493, 1444, 1332, 1184, 1106,
1090, 1012, 917, 753 cm−1; 1H NMR (400 MHz, CDCl3, TMS):
δ 7.63 (2H, d, J = 8.0 Hz), 7.56 (1H, s), 7.30–7.18 (7H, m),
7.10–7.04 (6H, m), 6.16–6.15 (1H, m), 5.95 (1H, d, J = 3.2 Hz),
5.88 (1H, d, J = 8.8 Hz), 5.45 (1H, d, J = 8.8 Hz), 3.34 (1H, dd,
J1 = 19.6 Hz, J2 = 2.0 Hz), 3.19 (1H, dd, J1 = 19.6 Hz, J2 =
2.4 Hz), 2.30 (3H, s); 13C NMR (CDCl3, 100 MHz): δ 206.5,
158.2, 150.4, 143.3, 142.6, 142.4, 139.9, 137.2, 129.5, 128.4,
127.9, 127.6, 127.1, 126.9, 110.5, 107.7, 60.9, 49.2, 45.6, 21.5;
1
1443, 1330, 1259, 1158, 1090, 1018, 931, 797, 759 cm−1; H
NMR (400 MHz, CDCl3, TMS): δ 7.58 (2H, d, J = 6.8 Hz),
7.49 (1H, s), 7.29–7.20 (7H, m), 7.15 (1H, s), 7.08–7.02 (8H,
m), 6.06 (1H, d, J = 8.8 Hz), 5.33 (1H, d, J = 8.4 Hz),
3.35–3.31 (1H, m), 3.16 (1H, dd, J1 = 19.6 Hz, J2 = 2.0 Hz),
2.30 (3H, s); 13C NMR (CDCl3, 100 MHz): δ 206.8, 158.2,
143.5, 142.3, 142.2, 141.1, 140.4, 137.1, 130.9, 130.1, 129.7,
129.6, 128.53, 128.50, 127.8, 127.5, 127.1, 127.0, 126.9, 125.4,
122.6, 60.9, 54.4, 45.5, 21.4; MS (ESI) m/e 594.0 (M+ + Na);
HRMS (ESI) for C31H26NO3SBrNa+1 (M+ + Na): 594.0715,
Found: 594.0709. The ee of the 3c was determined to be 79%
[determined by HPLC, Chiralpak AD-H, n-hexane–isopropanol
= 70 : 30, 0.5 mL min−1, λ = 214 nm, t (major) = 19.96 min,
t (minor) = 12.36 min].
MS (ESI) m/z 506.0 (M+
+ Na); HRMS (ESI) for
C29H25NO4SNa+1 (M+ + Na): 506.1396, Found: 506.1397.
The ee of the 3f was determined to be 68% [determined
by HPLC, Chiralpak AD-H, n-hexane–isopropanol = 70 : 30,
0.5 mL min−1, λ = 214 nm, t (major) = 29.53 min, t (minor) =
25.44 min].
(S)-4-Methyl-N-((5-oxo-4,4-diphenylcyclopent-1-enyl)(thiophen-
2-yl)methyl)benzenesulfonamide 3d. Following the general pro-
cedure, the mixture was purified by column chromatography
using silica gel to give the target product 3d (35 mg, 94% yield).
A white solid. m.p. for racemic 3d = 185–187 °C; m.p. for 3d =
182–184 °C; [α]D20 = +51.6 (c 0.4, CH2Cl2). IR (CH2Cl2): ν
3275, 3060, 2923, 2852, 1697, 1635, 1597, 1492, 1443, 1331,
(S)-N-((4-Bromophenyl)(5-oxo-4,4-diphenylcyclopent-1-enyl)-
methyl)-4-methylbenzenesulfonamide 3g. Following the general
procedure, the mixture was purified by column chromatography
using silica gel to give the target product 3g (41 mg, 96% yield).
A white solid. m.p. for racemic 3g = 200–201 °C; m.p. for 3g =
183–185 °C; [α]D20 = +30.8 (c 0.8, CH2Cl2). IR (CH2Cl2): ν
3280, 3059, 2923, 2853, 1701, 1635, 1597, 1491, 1444, 1331,
1304, 1259, 1106, 1089, 921, 814, 758 cm−1 1H NMR
;
(400 MHz, CDCl3, TMS): δ 7.63 (2H, d, J = 8.4 Hz), 7.55 (1H,
t, J = 2.4 Hz), 7.30–7.21 (6H, m), 7.12–7.05 (7H, m), 6.77 (1H,
dd, J1 = 5.2 Hz, J2 = 3.6 Hz), 6.65–6.64 (1H, m), 6.04 (1H, d,
J = 8.8 Hz), 5.60 (1H, d, J = 8.8 Hz), 3.38–3.32 (1H, m), 3.17
(1H, dd, J1 = 19.6 Hz, J2 = 2.4 Hz), 2.29 (3H, s); 13C NMR
(CDCl3, 100 MHz): δ 206.6, 157.9, 143.4, 142.4, 142.3, 142.1,
141.4, 137.2, 129.6, 128.44, 128.42, 127.8, 127.7, 127.1, 126.9,
126.8, 125.7, 125.4, 60.9, 51.1, 45.5, 21.5; MS (ESI) m/z 522.0
(M+ + Na); HRMS (ESI) for C29H25NO3S2Na+1 (M+ + Na):
522.1174, Found: 522.1186. The ee of the 3d was determined
to be 76% [determined by HPLC, Chiralpak AD-H,
1
1262, 1184, 1160, 1090, 1010, 755 cm−1; H NMR (400 MHz,
CDCl3, TMS): δ 7.58 (2H, d, J = 8.4 Hz), 7.47 (1H, s),
7.30–7.20 (8H, m), 7.08 (2H, d, J = 8.4 Hz), 7.04–7.00 (4H, m),
6.96 (2H, d, J = 8.4 Hz), 6.05 (1H, d, J = 8.4 Hz), 5.30 (1H,
d, J = 8.8 Hz), 3.37–3.31 (1H, m), 3.15 (1H, dd, J1 = 19.6 Hz,
J2 = 2.4 Hz), 2.32 (3H, s); 13C NMR (CDCl3, 100 MHz): δ
This journal is © The Royal Society of Chemistry 2012
Org. Biomol. Chem., 2012, 10, 7429–7438 | 7435

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206.9, 158.0, 143.4, 142.3, 142.2, 141.3, 137.3, 137.2, 131.6,
130.0, 128.5, 128.4, 127.8, 127.6, 127.1, 127.0, 126.9, 121.9,
61.0, 54.6, 45.4, 21.5; MS (ESI) m/z 594.0 (M+ + Na); HRMS
(ESI) for C31H26NO3SBrNa+1 (M+ + Na): 594.0700, Found:
594.0709. The ee of the 3g was determined to be 84% [deter-
mined by HPLC, Chiralpak AD-H, n-hexane–isopropanol =
70 : 30, 0.5 mL min−1, λ = 214 nm, t (major) = 40.85 min,
t (minor) = 28.32 min].
ν 3273, 3060, 2923, 1700, 1636, 1529, 1493, 1444, 1347, 1265,
1
1159, 1089, 1018, 912, 781, 732 cm−1; H NMR (400 MHz,
CDCl3, TMS): δ 7.99 (1H, dd, J1 = 8.4 Hz, J2 = 1.6 Hz), 7.87
(1H, t, J = 1.6 Hz), 7.60 (1H, s), 7.58–7.56 (3H, m), 7.33 (1H, t,
J = 8.0 Hz), 7.28–7.18 (6H, m), 7.06–6.98 (6H, m), 6.35 (1H, d,
J = 9.2 Hz), 5.47 (1H, d, J = 8.8 Hz), 3.37–3.31 (1H, m), 3.15
(1H, dd, J1 = 19.6 Hz, J2 = 2.4 Hz), 2.27 (3H, s); 13C NMR
(CDCl3, 100 MHz): δ 206.6, 158.8, 148.0, 143.7, 142.0, 141.8,
140.6, 140.3, 136.9, 133.0, 129.7, 129.5, 128.5, 128.4, 127.7,
127.4, 127.0, 126.3, 122.7, 121.5, 60.8, 54.1, 45.7, 21.4; MS
(ESI) m/z 561.1 (M+ + Na); HRMS (ESI) for C31H26N2O5SNa+1
(M+ + Na): 561.1453, Found: 561.1455. The ee of the 3j was
determined to be 82% [determined by HPLC, Chiralpak AD-H,
n-hexane–isopropanol = 60 : 40, 0.5 mL min−1, λ = 230 nm,
t (major) = 27.18 min, t (minor) = 17.87 min].
(S)-4-Methyl-N-((5-oxo-4,4-diphenylcyclopent-1-enyl)(4-(trifluoro-
methyl)phenyl)methyl)benzenesulfonamide 3h. Following the
general procedure, the mixture was purified by column chrom-
atography using silica gel to give the target product 3h (42 mg,
99% yield). Awhite solid. m.p. for racemic 3h = 96–98 °C; m.p.
for 3h = 116–118 °C; [α]2D0 = +20.2 (c 0.5, CH2Cl2). IR
(CH2Cl2): ν 3279, 2962, 1695, 1617, 1596, 1493, 1444, 1324,
1260, 1160, 1090, 1017, 798 cm−1 1H NMR (400 MHz,
;
(S)-4-Methyl-N-(naphthalen-2-yl(5-oxo-4,4-diphenylcyclopent-
1-enyl)methyl)benzenesulfonamide 3k. Following the general
procedure, the mixture was purified by column chromatography
using silica gel to give the target product 3k (18 mg, 44% yield).
A white solid. m.p. for racemic 3k = 214–216 °C; m.p. for 3k =
227–229 °C; [α]2D0 = +7.0 (c 0.2, CH2Cl2). IR (CH2Cl2): ν 3278,
2962, 1699, 1635, 1598, 1493, 1444, 1330, 1260, 1160, 1091,
CDCl3, TMS): δ 7.56 (2H, d, J = 8.0 Hz), 7.52 (1H, s), 7.37
(2H, d, J = 8.0 Hz), 7.25–7.20 (8H, m), 7.05–7.00 (6H, m), 6.29
(1H, d, J = 8.8 Hz), 5.43 (1H, d, J = 8.8 Hz), 3.32 (1H, d, J =
19.2 Hz), 3.17 (1H, dd, J1 = 19.6 Hz, J2 = 2.0 Hz), 2.29 (3H, s);
13C NMR (CDCl3, 100 MHz): δ 206.8, 158.1, 143.5, 142.2,
142.1, 141.2, 137.1, 129.9 (q, JC–F = 32.4 Hz), 129.5, 128.5,
128.4, 127.7, 127.5, 127.1, 127.03, 127.00, 126.9, 125.3 (q, JC–
1
1018, 860, 798, 756 cm−1; H NMR (400 MHz, CDCl3, TMS):
= 3.7 Hz), 123.4 (q, JC–F = 270.7 Hz), 60.9, 54.6, 45.5, 21.3;
F
δ 7.74 (1H, d, J = 8.4 Hz), 7.65 (1H, d, J = 8.4 Hz), 7.60 (1H, d,
J = 8.0 Hz), 7.54–7.50 (2H, m), 7.45–7.39 (2H, m), 7.37 (1H,
s), 7.27–7.21 (7H, m), 7.06–7.03 (4H, m), 7.00 (2H, d, J = 8.4
Hz), 6.13 (1H, d, J = 8.8 Hz), 5.52 (1H, d, J = 8.8 Hz),
3.39–3.33 (1H, m), 3.16 (1H, dd, J1 = 19.6 Hz, J2 = 2.4 Hz),
2.30 (3H, s); 13C NMR (CDCl3, 100 MHz): δ 207.0, 158.1,
143.3, 142.5, 142.3, 141.5, 137.2, 135.4, 132.9, 132.7, 129.7,
129.5, 128.5, 128.4, 127.9, 127.8, 127.7, 127.4, 127.1, 127.0,
126.9, 126.4, 126.2, 125.6, 124.7, 61.1, 55.0, 45.4, 21.4; MS
(ESI) m/z 566.1 (M+ + Na); HRMS (ESI) for C35H29NO3SNa+1
(M+ + Na): 566.1868, Found: 566.1853. The ee of the 3k was
determined to be 60% [determined by HPLC, Chiralpak AD-H,
n-hexane–isopropanol = 60 : 40, 0.5 mL min−1, λ = 230 nm,
t (major) = 48.73 min, t (minor) = 55.92 min].
19F NMR (376 MHz, CDCl3, CFCl3): δ −62.7; MS (ESI) m/z
584.0 (M+ + Na); HRMS (ESI) for C32H26NO3SF3Na+1 (M+ +
Na): 584.1479, Found: 584.1478. The ee of the 3h was deter-
mined to be 80% [determined by HPLC, Chiralpak AD-H,
n-hexane–isopropanol = 70 : 30, 0.5 mL min−1, λ = 214 nm,
t (major) = 27.69 min, t (minor) = 21.37 min].
(S)-4-Methyl-N-((5-oxo-4,4-diphenylcyclopent-1-enyl)(p-tolyl)-
methyl)benzenesulfonamide 3i. Following the general pro-
cedure, the mixture was purified by column chromatography
using silica gel to give the target product 3i (32 mg, 84% yield).
A white solid. m.p. for racemic 3i = 223–224 °C; m.p. for 3i =
220–222 °C; [α]D20 = +24.5 (c 0.5, CH2Cl2). IR (CH2Cl2): ν
3289, 2923, 1693, 1615, 1592, 1498, 1444, 1335, 1288, 1157,
1100, 1035, 1018, 931, 863, 813, 754 cm−1
;
1H NMR
(S)-N-((4,4-Bis(4-fluorophenyl)-5-oxocyclopent-1-enyl)(4-nitro-
phenyl)methyl)-4-methylbenzenesulfonamide 3l. Following the
general procedure, the mixture was purified by column chrom-
atography using silica gel to give the target product 3l (43 mg,
99% yield). A white solid. m.p. for racemic 3l = 95–98 °C; m.p.
for 3l = 77–80 °C; [α]D20 = +15.0 (c 0.3, CH2Cl2). IR (CH2Cl2):
ν 3281, 2924, 1701, 1635, 1598, 1520, 1507, 1434, 1233, 1184,
(400 MHz, CDCl3, TMS): δ 7.60 (2H, d, J = 8.4 Hz), 7.49 (1H,
t, J = 2.4 Hz), 7.28–7.20 (6H, m), 7.08–7.02 (6H, m), 7.00 (4H,
s), 5.86 (1H, d, J = 8.4 Hz), 5.29 (1H, d, J = 8.4 Hz), 3.36–3.31
(1H, m), 3.16 (1H, dd, J1 = 19.6 Hz, J2 = 2.0 Hz), 2.31 (3H, s),
2.26 (3H, s); 13C NMR (CDCl3, 100 MHz): δ 206.8, 157.7,
143.2, 142.5, 142.0, 137.6, 137.2, 135.3, 129.5, 129.2, 128.4,
128.3, 127.9, 127.6, 127.2, 126.83, 126.81, 126.6, 60.9, 54.8,
45.4, 21.4, 20.1; MS (ESI) m/z 530.0 (M+ + Na); HRMS (ESI)
for C32H29NO3SNa+1 (M+ + Na): 530.1761, Found: 530.1760.
The ee of the 3i was determined to be 84% [determined by
1
1161, 1091, 1015, 817, 735 cm−1; H NMR (400 MHz, CDCl3,
TMS): δ 7.97 (2H, d, J = 8.8 Hz), 7.60 (3H, d, J = 8.0 Hz), 7.28
(2H, d, J = 8.8 Hz), 7.10 (2H, d, J = 8.4 Hz), 6.97–6.88 (8H,
m), 6.40 (1H, d, J = 8.4 Hz), 5.46 (1H, d, J = 8.0 Hz),
3.33–3.28 (1H, m), 3.15 (1H, dd, J1 = 19.6 Hz, J2 = 2.4 Hz),
2.31 (3H, s); 13C NMR (CDCl3, 100 MHz): δ 206.1, 161.6 (dd,
J1C–F = 245.7 Hz, J2C–F = 2.6 Hz), 158.5, 147.3, 145.3, 143.9,
140.9, 137.6 (dd, J1C–F = 16.7 Hz, J2C–F = 3.7 Hz), 136.8, 129.2
(dd, J1C–F = 12.6 Hz, J2C–F = 7.8 Hz), 127.6, 127.0, 123.6,
115.4 (dd, J1C–F = 21.2 Hz, J2C–F = 3.0 Hz), 59.5, 54.0, 45.5,
21.4; 19F NMR (376 MHz, CDCl3, CFCl3): δ −114.8 to −114.9
(m); MS (ESI) m/z 597.0 (M+ + Na); HRMS (ESI) for
C31H24N2O5SF2Na+1 (M+ + Na): 597.1251, Found: 597.1266.
HPLC, Chiralpak AD-H, n-hexane–isopropanol
= 70 : 30,
0.5 mL min−1, λ = 214 nm, t (major) = 24.68 min, t (minor) =
27.06 min].
(S)-4-Methyl-N-((3-nitrophenyl)(5-oxo-4,4-diphenylcyclopent-
1-enyl)methyl)benzenesulfonamide 3j. Following the general
procedure, the mixture was purified by column chromatography
using silica gel to give the target product 3j (40 mg, 99% yield).
A white solid. m.p. for racemic 3j = 153–155 °C; m.p. for 3j =
172–174 °C; [α]D20 = +31.3 (c 1.0, CH2Cl2). IR (CH2Cl2):
7436 | Org. Biomol. Chem., 2012, 10, 7429–7438
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1
The ee of the 3l was determined to be 82% [determined by
1348, 1324, 1161, 1118, 1092, 1070, 1017, 833 cm−1; H NMR
HPLC, Chiralpak AD-H, n-hexane–isopropanol
=
70 : 30,
(400 MHz, CDCl3, TMS): δ 7.98 (2H, d, J = 8.8 Hz), 7.71–7.70
(1H, m), 7.60 (2H, d, J = 8.4 Hz), 7.51 (4H, dd, J1 = 8.4 Hz, J2
= 5.6 Hz), 7.29 (2H, d, J = 8.8 Hz), 7.11 (6H, t, J = 8.8 Hz),
6.38 (1H, d, J = 6.0 Hz), 5.47 (1H, d, J = 4.4 Hz), 3.42–3.37
(1H, s), 3.24 (1H, dd, J1 = 19.6 Hz, J2 = 2.0 Hz), 2.31 (3H, s);
13C NMR (CDCl3, 100 MHz): δ 204.8, 158.7, 147.4, 145.3 (dd,
J1C–F = 8.5 Hz, J2C–F = 1.1 Hz), 145.0, 144.1, 141.5, 136.7,
129.67, 129.65 (dq, J1C–F = 32.7 Hz, J2C–F = 3.7 Hz), 128.0,
127.9, 127.6, 127.0, 125.6 (dq, J1C–F = 3.8 Hz, J2C–F = 2.6 Hz),
123.8, 123.7 (dq, J1C–F = 270.6 Hz, J2C–F = 1.5 Hz), 60.5, 53.9,
44.9, 21.3; 19F NMR (376 MHz, CDCl3, CFCl3): δ −62.7; MS
0.5 mL min−1, λ = 214 nm, t (major) = 45.42 min, t (minor) =
52.19 min].
(S)-N-((4,4-Bis(4-fluorophenyl)-5-oxocyclopent-1-enyl)(p-tolyl)-
methyl)-4-methylbenzenesulfonamide
3m. Following
the
general procedure, the mixture was purified by column chrom-
atography using silica gel to give the target product 3m (37 mg,
91% yield). A white solid. m.p. for racemic 3m = 182–184 °C;
m.p. for 3m = 181–183 °C; [α]2D0 = +19.8 (c 0.4, CH2Cl2). IR
(CH2Cl2): ν 3248, 2961, 2923, 1702, 1633, 1598, 1506, 1439,
1326, 1259, 1186, 1160, 1092, 1016, 804, 740 cm−1; H NMR
1
(ESI) m/e 697.0 (M+
+
Na); HRMS (ESI) for
C33H24N2O5SF6Na+1 (M+ + Na): 697.1202, Found: 697.1202. The
(400 MHz, CDCl3, TMS): δ 7.60 (2H, d, J = 8.0 Hz), 7.56–7.55
(1H, m), 7.09 (2H, d, J = 8.4 Hz), 7.00–6.89 (12H, m), 5.92
(1H, d, J = 8.4 Hz), 5.28 (1H, d, J = 8.0 Hz), 3.30–3.24 (1H, s),
3.17–3.11 (1H, m), 2.32 (3H, s), 2.25 (3H, s); 13C NMR
(CDCl3, 100 MHz): δ 206.3, 161.6 (dd, J1C–F = 245.0 Hz, J2C–F
= 3.0 Hz), 157.3, 143.3, 142.5, 138.2 (d, J1C–F = 3.3 Hz), 137.7,
137.1, 135.1, 129.4 (dd, J1C–F = 13.4 Hz, J2C–F = 5.6 Hz),
129.24, 129.21, 127.1, 126.5, 115.2 (dd, J1C–F = 21.6 Hz, J2C–F
= 1.5 Hz), 60.0, 54.5, 45.4, 21.4, 20.9; 19F NMR (376 MHz,
CDCl3, CFCl3): δ −115.4 to −115.5 (m); MS (ESI) m/z 566.1
(M+ + Na); HRMS (ESI) for C32H27NO3SF2Na+1 (M+ + Na):
566.1561, Found: 566.1571. The ee of the 3m was determined
to be 84% [determined by HPLC, Chiralpak AD-H, n-hexane–
isopropanol = 80 : 20, 0.5 mL min−1, λ = 214 nm, t (major) =
38.68 min, t (minor) = 41.74 min].
ee of the 3o was determined to be 73% [determined by HPLC,
Chiralpak AD-H, n-hexane–isopropanol = 80 : 20, 0.5 mL min−1
,
λ = 214 nm, t (major) = 40.71 min, t (minor) = 46.40 min].
(S)-4-Methyl-N-((5-oxo-4,4-bis(4-(trifluoromethyl)phenyl)-
cyclopent-1-enyl)(p-tolyl)methyl)benzenesulfonamide 3p. Fol-
lowing the general procedure, the mixture was purified by
column chromatography using silica gel to give the target
product 3p (42 mg, 88% yield). A white solid. m.p. for racemic
3p = 203–204 °C; m.p. for 3p = 186–188 °C; [α]2D0 = +18.7
(c 0.4, CH2Cl2). IR (CH2Cl2): ν 3282, 2960, 2925, 1701, 1615,
1513, 1410, 1323, 1261, 1160, 1117, 1070, 1017, 813,
1
737 cm−1; H NMR (400 MHz, CDCl3, TMS): δ 7.69 (1H, t,
J = 2.8 Hz), 7.61 (2H, d, J = 7.6 Hz), 7.50 (4H, d, J = 8.4 Hz),
7.14 (6H, q, J = 8.4 Hz), 6.96 (2H, d, J = 8.4 Hz), 6.90 (2H, d,
J = 7.2 Hz), 5.80 (1H, d, J = 7.8 Hz), 5.27 (1H, d, J = 7.2 Hz),
3.40–3.34 (1H, m), 3.27–3.22 (1H, m), 2.32 (3H, s), 2.25 (3H,
s); 13C NMR (CDCl3, 100 MHz): δ 205.0, 157.4 (d, JC–F = 3.0
Hz), 145.8, 143.5 (d, JC–F = 0.8 Hz), 143.1 (t, JC–F = 1.1 Hz),
138.0, 137.0 (t, JC–F = 2.2 Hz), 134.8 (d, JC–F = 1.1 Hz), 129.5,
129.4 (q, JC–F = 32.4 Hz), 129.38, 128.2, 128.1, 127.1, 126.5,
(S)-N-((4,4-Bis(4-fluorophenyl)-5-oxocyclopent-1-enyl)(4-chloro-
phenyl)methyl)-4-methylbenzenesulfonamide 3n. Following the
general procedure, the mixture was purified by column chrom-
atography using silica gel to give the target product 3n (38 mg,
89% yield). A white solid. m.p. for racemic 3n = 198–201 °C;
m.p. for 3n = 179–181 °C; [α]2D0 = +10.0 (c 0.3, CH2Cl2). IR
(CH2Cl2): ν 3278, 2961, 1701, 1634, 1598, 1506, 1434, 1328,
125.5 (dq, J1C–F = 3.7 Hz, J2C–F = 1.5 Hz), 123.4 (q, JC–F
=
1260, 1233, 1184, 1160, 1089, 1014, 806, 736 cm−1; H NMR
1
270.0 Hz), 60.7, 54.5, 45.8, 21.4 (d, JC–F = 1.2 Hz), 21.0 (d,
(400 MHz, CDCl3, TMS): δ 7.58 (2H, d, J = 8.0 Hz), 7.55–7.54
(1H, m) 7.12–7.09 (4H, m), 7.00–6.89 (10H, m), 6.05 (1H, d,
J = 8.4 Hz), 5.31 (1H, d, J = 8.4 Hz), 3.31–3.26 (1H, m),
3.17–3.12 (1H, m), 2.33 (3H, s); 13C NMR (CDCl3, 100 MHz):
δ 206.4, 161.7 (dd, J1C–F = 245.4 Hz, J2C–F = 2.6 Hz), 157.8,
143.6, 141.8, 137.9 (dd, J1C–F = 17.1 Hz, J2C–F = 3.4 Hz),
JC–F = 1.2 Hz); 19F NMR (376 MHz, CDCl3, CFCl3): δ −62.7;
MS (ESI) m/z 666.0 (M+
+ Na); HRMS (ESI) for
C34H27NO3SF6Na+1 (M+ + Na): 666.1496, Found: 666.1508.
The ee of the 3p was determined to be 85% [determined by
HPLC, Chiralpak AD-H, n-hexane–isopropanol
= 80 : 20,
0.5 mL min−1, λ = 214 nm, t (major) = 25.86 min, t (minor) =
137.0, 136.6, 133.9, 129.6, 129.3 (dd, J1C–F = 15.2 Hz, J2C–F
=
23.99 min].
7.8 Hz), 128.7, 128.0, 127.1, 115.4 (dd, J1C–F = 21.6 Hz, J2C–F
= 2.6 Hz), 60.0, 54.3, 45.5, 21.5; 19F NMR (376 MHz, CDCl3,
CFCl3): δ −115.1 to −115.2 (m); MS (ESI) m/z 586.0
(M+ + Na); HRMS (ESI) for C31H24NO3SF2ClNa+1 (M+ + Na):
586.1033, Found: 586.1025. The ee of the 3n was determined to
be 75% [determined by HPLC, Chiralpak AD-H, n-hexane–
isopropanol = 70 : 30, 0.5 mL min−1, λ = 214 nm, t (major) =
21.53 min, t (minor) = 27.05 min].
Acknowledgements
Financial support from the National Basic Research Program of
China (973)-2010CB833302, the Shanghai Municipal Commit-
tee of Science and Technology (11JC1402600), the Fundamental
Research Funds for the Central Universities and the National
Natural Science Foundation of China for financial support
(20902019, 20872162, 20672127, 21121062, 20732008,
20772030 and 20702059) is greatly acknowledged.
(S)-4-Methyl-N-((4-nitrophenyl)(5-oxo-4,4-bis(4-(trifluoromethyl)-
phenyl)cyclopent-1-enyl)methyl)benzenesulfonamide 3o. Fol-
lowing the general procedure, the mixture was purified by
column chromatography using silica gel to give the target
product 3o (50 mg, 99% yield). A white solid. m.p. for racemic
3o = 110–113 °C; m.p. for 3o = 70–73 °C; [α]2D0 = +6.3 (c 0.9,
CH2Cl2). IR (CH2Cl2): ν 3283, 2926, 1704, 1615, 1522, 1410,
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7438 | Org. Biomol. Chem., 2012, 10, 7429–7438
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