A novel Fe(II)/diaryl prolinol catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with alkenes

Article abstract of DOI:10.1016/j.tet.2010.11.091

A novel Fe(II)/diaryl prolinol catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with alkenes has been developed. In the presence of FeCl₂ (10 mol %) and α,α-bis(3,5- bistrifluoromethylphenyl)prolinol L1 (10 mol %), [3+2] cycl

Full text of DOI:10.1016/j.tet.2010.11.091

Tetrahedron 67 (2011) 1210e1215
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Tetrahedron
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A novel Fe(II)/diaryl prolinol catalyzed asymmetric 1,3-dipolar cycloaddition
of azomethine ylides with alkenes
,b,
Haisheng Wu a, Bo Wang a, Hongqiang Liu a, Lei Wang a
*
a Department of Chemistry, Huaibei Normal University, Huaibei, Anhui 235000, PR China
b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 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:
Received 28 June 2010
Received in revised form 21 November 2010
Accepted 30 November 2010
Available online 4 December 2010
A novel Fe(II)/diaryl prolinol catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with
alkenes has been developed. In the presence of FeCl2 (10 mol %) and a,a-bis(3,5-bistrifluoromethylphenyl)
prolinol L1 (10 mol %), [3þ2] cycloaddition of azomethine ylides with electronic-deficient olefins un-
derwent smoothly in CH3CN at room temperature to generate the desired endo-adducts in moderate to
good yields and enantioselectivities. This is the first example of Fe(II)/N,O-ligand (L1) catalyzed 1,3-dipolar
enantioselective cycloaddition reaction of azomethine ylides.
Keywords:
Alkenes
Ó 2010 Elsevier Ltd. All rights reserved.
Asymmetric 1,3-dipolar cycloaddition
Azomethine ylides
Diaryl prolinol
Iron
1. Introduction
the desired adducts,5 and high yields and excellent stereo-
selectivities of the desired 1,3-dipolar cycloaddition products of
The 1,3-dipolar cycloaddition reaction constitutes one of the
most fundamental reactions and efficient strategy for the stereo-
selective construction of five-membered heterocyclic compounds.1
Over the past two decades, the development of catalytic asymmet-
ric reactions have been one of the challenging areas within the field
of 1,3-dipolar cycloaddition reactions, and this methodology has
provided organic chemists with the tools necessary to synthesize
a variety of chiral heterocycles in highly enantio-enriched forms.2
Azomethine ylides reacted with electronic-deficient olefins
through a 1,3-dipolar diastereoselective cycloaddition pathway to
form optically active pyrrolidines, as one of the important moiety in
the structures of many biologically active compounds.3 Because of
their great synthetic potential, a few protocols for the metal-cata-
lyzed enantioselective synthesis of 1,3-dipolar cycloaddition prod-
ucts of azomethine ylides with alkenes have been developed. Grigg
and Allway demonstrated that using a stoichiometric amount of
chiral Co(II) or Mn(II)complexes with ephedrinederivatives as chiral
ligands could give the cycloaddition products of azomethine ylides
with up to 96% ee.4 Zhang et al. reported that efficient catalytic
systems, Ag(I) with chiral phosphane ligand, and Ag(I)/P,N-ligand in
the presence of i-Pr2NEt, catalyzed 1,3-dipolar cycloaddition re-
action of azomethine ylides in good yields and stereoselectivities of
azomethine ylides were obtained using AgOAc with chiral N/P- and
S/P-ligands derived from ferrocenyloxazolines and PHOX in the
absence of amine.6 In addition, other metals, such as Zn(II),7 Cu(I)
andCu(II),8 Ni(II),9 and Ca(II)10 in combinationwith avarietyofchiral
N/N-, P/P-, P/N-, and P/S-bidentate ligands were also used as effec-
tive catalysts for asymmetric 1,3-dipolar cycloadditions of azome-
thine ylides. Although iron salts as effective, alternative, and
promising transition-metal catalysts in organic synthesis have re-
ceived much more attention because of their cheap, ubiquitous, and
environmentally benign properties in the recently years,11 there is
not any report on the Fe-catalyzed enantioselective synthesis of the
1,3-dipolar cycloaddition products of azomethine ylides with al-
kenes to the best of our knowledge.
Asymmetric organocatalysis12 has been experiencing a revival
sinceMacMillanetal.,independently, discloseditspotentialin2000.13
For the past decade, L-proline and its derivatives have emerged as one
of the most significant and versatile organocatalysts in the enantio-
selective construction of CeC,14 CeO,15 CeN,16 CeHalogen,17 CeP,18
CeS,19 and CeSe20 bonds, tandem reaction and Aza-DielseAlder re-
action21 through covalent activation modes involving enamines,22
iminium ion,23 and even SOMO mechanisms.24 As a result of our on-
going interest in iron-catalyzed organic reaction,25 we present our
investigation herein for the first time on Fe(II)/N,O-ligand (L1) cata-
lyzed 1,3-dipolar enantioselective cycloaddition reaction. In the
* Corresponding author. E-mail address: leiwang@chnu.edu.cn (L. Wang).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.11.091

H. Wu et al. / Tetrahedron 67 (2011) 1210e1215
1211
presence of FeCl2 (10 mol %) and
a
,
a
-diaryl prolinol L1 (10 mol %),
isolated with 70% yield and 71% ee (Table 1, entry 1). Various chiral
ligands were employed in this [3þ2] cycloaddition reaction and the
experimental results revealed that L1 exhibited the highest cata-
lytic activity among the ligands L1eL11 in Fig. 1, including various
N/N-, N/O-, and O/O-bidentate ones screened in this investigation
(Table 1, entries 1e11). Investigations into the diaryl prolinols
L1eL5 revealed that the steric and electronic properties of the ar-
omatic ring of the catalyst had a combination impact on its per-
formance (Table 1, entries 1e5). Diaryl prolinols, L1 and L2, bearing
an electron-withdrawing group CF3 on the benzene ring, exhibit
the higher reactivity and enantioselectivity than that of its ana-
logue, L3, L4, and L5, respectively (Table 1, entry 1 vs 3 and 4, 2 vs
5). Interestingly, the trimethylsilyl ether L2 resulted in a sharp drop
in both the reactivity and enantioselectivity, comparing to its an-
alogue L1 (Table 1, entry 2 vs 1). Similar phenomena were also
found in L5 and L4 (Table 1, entry 5 vs 4). It is suggested that the
free OH moiety of the ligand is necessary in this process. It is im-
portant to note that more steric hindrance substituted groups are
essential in aromatic rings of diaryl prolinol ligand (Table 1, entry 3
vs 4), as well as in prolinol L6 (Table 1, entry 6 vs 1e5). As expected,
in the absence of chiral ligand, no enantioselectivity was observed
in the model reaction, and 21% yield of the 1,3-dipolar cycloaddi-
tion product was isolated (Table 1, entry 12). In addition, no desired
cycloaddition product was observed in the absence of iron salt even
in the presence of L1 (Table 1, entry 13). However, it should be noted
that no enantioselectivity was found when L11, an O/O-ligand was
used as a chiral one (Table 1, entry 11).
[3þ2] cycloaddition of azomethine ylides with electronic-deficient
olefins underwent smoothly to generate the desired endo-adducts in
moderate to good yields and enantioselectivities (Scheme 1).
CF3
F3C
CF3
CF3
L1:
N
H
OH
CO2R
CO2Me
RO2C
Ar
CO2R
L1
FeCl2/ (10 mol%)
Ar
N
CO2Me
+
Et3N, CH3CN
N
H
CO2R
1
2
endo-3
Scheme 1.
2. Results and discussion
Our initial efforts focused on the optimization of 1,3-dipolar
enantioselective cycloaddition. [3þ2] cycloaddition of N-(4-chlor-
obenzylidene)-glycine methyl ester 1a with dibutyl maleate 2a was
chosen as a model reaction. As shown in Table 1, when the model
addition reaction was carried out in the presence of catalytic
amount FeCl2 and L1 in CH3CN at room temperature (20 ꢀC), the
desired 1,3-dipolar cycloaddition product 3a in endo-form was
Table 1
Screening reaction conditions for Fe-catalyzed [3þ2] cycloaddition reaction a
n
CO2 Bu
n
n
CO2 Bu
BuO2C
Fe salt/ Ligand
Et3N, solvent
4-ClC6H4
N
CO2Me
+
4-ClC6H4
CO2Me
n
CO2 Bu
N
H
1a
2a
endo-3a
Entry
Ligand
Fe salt
Solvent
Temp (ꢀC)
Yieldb(%)
eec(%)
1
2
3
4
5
6
7
8
L1
L2
L3
L4
L5
L6
L7
L8
L9
L10
L11
d
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
d
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH2Cl2
Toluene
THF
20
20
20
20
20
20
20
20
20
20
20
20
20
0
0
0
0
0
0
0
0
0
70
51
47
39
31
28
26
35
28
31
30
21
0
46
40
38
42
26
30
51
24
18
13
Trace
Trace
37
22
71
56
45
15
10
2
6
12
14
7
0
0
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25d
26
27
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
0
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeCl2
FeBr2
FeCl3
Fe(OTf)3
Fe2(SO4)3
FeCl2
FeCl2
FeCl2
44
38
30
36
21
28
72
38
6
Hexane
EtOH
EtOEt
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
0
0
0
7
d
d
73
75
ꢁ20
ꢁ40
a
Reaction conditions: N-(4-chlorobenzylidene)-glycine methyl ester 1a (1.0 mmol), dibutyl maleate 2a (1.0 mmol), Fe salt (0.1 mmol), ligand (0.1 mmol), Et3N (1.0 mmol) in
solvent (2.0 mL) at the temperature indicated in Table 1, under nitrogen atmosphere, 24 h.
b
Isolated yields after column chromatography.
Enantiomeric excesses were measured by chiral HPLC.
In the absence of Et3N.
c
d

1212
H. Wu et al. / Tetrahedron 67 (2011) 1210e1215
27). It is interesting to note that both of isolated yields and ee were
L1
L2
Ar
Ar
OR
Ar = 3,5-(CF3)2C6H3, R = H
Ar = 3,5-(CF3)2C6H3, R = TMS
maintained when up 10 mol % of FeCl2 and L1 was added to the
reaction. A lower yield of the product was isolated when less than
10 mol % of FeCl2 and L1 was used in the reaction. It was found that
the reaction was accomplished as the reaction was carried out at
room temperature for 24 h.
OH
L3 Ar = 3,5-(CH3)2C6H3, R = H
N
H
N
L4
Ar = Ph, R = H
H
L5
Ar = Ph, R = TMS
L6
Ph
Ph
Ph
NH2
Ph
H2N
To explore the scope of FeCl2/L1-catalyzed [3þ2] cycloaddition
of azomethine ylides, a number of imino esters (1aef) with di-
methyl, di(n-butyl) and dibenzyl maleates (2a, 2b, and 2c) were
investigated under the optimized reaction conditions. The results
were summarized in Table 2. A variety of imino ester substrates
derived from aromatic aldehyde bearing electron-rich, electron-
neutral, or electron-deficient group, such as F, Cl, H, CH3, and CN on
the benzene ring were able to undergo [3þ2] cycloaddition with
electron-deficient olefin 2a, 2b or 2c in the presence of FeCl2/L1
(10 mol %) in CH3CN at room temperature (20 ꢀC) for 24 h. The
reactions generated the corresponding [3þ2] cycloaddition prod-
ucts endo-3aeh in moderate to good yields (47e70%) and enan-
tioselectivities (53e77% ee). Obviously, steric and electronic
properties have a certain effect on the enantioselectivity of the
model reaction. For imine bearing an electron-withdrawing group
on the benzene ring brought about a slight increase in its enan-
tioselectivity, compared with 1b as substrate (Table 2, entries 1, 2, 3,
5, 7, and 8 vs entry 4). On the other hand, substrate having an
electron-donating substituent, such as methyl group on the ortho-
position of benzene ring, a lower enantioselectivity was observed
(Table 2, entry 6). It should be worth noting that 1f derived from 2-
naphthaldehyde and glycine methyl ester reacted with dibutyl
maleate 2b to generate the corresponding [3þ2] cycloaddition
product 3i in 46% yield and 60% ee (Table 2, entry 9).
Finally, to extend the more application scope and generality of
this iron-catalyzed asymmetric [3þ2] cycloaddition protocol, the
reactions of imino esters (1aed and 1g) with N-methyl and N-
phenyl maleimides (4a and 4b) were investigated using the opti-
mized reaction conditions. As can be seen in Table 3, imino esters
1a, 1b, 1c, and 1g reacted with N-methyl maleimide 4a or N-phenyl
maleimide 4b to give the corresponding [3þ2] cycloaddition
products endo-5ae5d and 5f in moderate to good yields (48e72%)
and enantioselectivities (51e78% ee) (Table 3, entries 1e4 and 6). It
should be noted that a much low enantioselectivity (ee 20%) was
obtained when N-(2-methylbenzylidene)-glycine methyl ester 1d
reacted with N-phenyl maleimide 4b, but 57% yield was obtained
(Table 3, entry 5).
OH
H2N
NH2
H2N
L7
L8
L9
Ph
Ph
Ph
NH2
H
O
O
OH
OH
OH
Ph
L10
L11
Fig. 1. Screened ligands in Fe(II)-catalyzed asymmetric 1,3-dipolar cycloaddition.
The effect of solvents on the model reaction was also examined.
Among the solvents, such as CH2Cl2, C6H5CH3, THF, hexane,
C2H5OH, C2H5OC2H5, and CH3CN tested in the model reaction,
CH3CN was found to be the best of choice. When the model reaction
was carried out in CH3CN, it gave the desired product not only in
the highest isolated yield, but also in the best of enantioselectivity
(Table 1, entries 14e20). In order to further understand the role of
iron salts, a number of iron salts were investigated in the model
reaction using Fe/L1 catalytic system in CH3CN at 0 ꢀC. It was found
that the activity of Fe(II) salts tested in the experiment, such as
FeCl2 and FeBr2 is more active than that of Fe(III) salts, such as FeCl3,
Fe(OTf)3, and Fe2(SO4)3. The use of Fe(III) salts including FeCl3, Fe
(OTf)3, and Fe2(SO4)3 displayed in low reactivity and poor enan-
tioselectivity (Table 1, entries 20e24).
Only trace amount of desired was obtained when the model
reaction was performed in the absence of additional organic amine
triethylamine (Table 1, entry 25). In order to find the best reaction
conditions for the reaction, the effect of reaction temperature on
the cycloaddition reaction was also surveyed. As can be seen from
Table 1, at the room temperature (20 ꢀC), the reaction took place
smoothly with both good isolated yield and enantioselectivity. A
slightly higher ee was obtained along with sacrificing yield when
the reaction was performed at 0 to ꢁ40 ꢀC (Table 1, entries 26 and
Table 2
Fe(II)/L1-catalyzed enantioselective cycloaddition of azomethine ylides (1) with dialkyl maleates (2)a
CO2R
CO2Me
RO2C
Ar
CO2R
L1
FeCl2/ (10 mol%)
Ar
N
CO2Me +
Et3N, CH3CN
N
H
CO2R
endo-3
1
2
Entry
Ar
R
3
Yieldb(%)
eec(%)
1
2
3
4
5
6
7
8
9
4-ClC6H4 (1a)
4-ClC6H4 (1a)
4-ClC6H4 (1a)
C6H5 (1b)
4-FC6H4 (1c)
2-CH3C6H4 (1d)
4-CNC6H4 (1e)
4-CNC6H4 (1e)
2-Naphthyl (1f)
n-C4H9 (2a)
CH3 (2b)
C6H5CH2 (2c)
CH3 (2b)
CH3 (2b)
CH3 (2b)
n-C4H9 (2a)
CH3 (2b)
CH3 (2b)
3a
3b
3c
3d
3e
3f
3g
3h
3i
70
51
62
47
52
51
68
61
46
71
77
69
62
70
53
74
67
60
a
Reaction conditions: 1 (1.0 mmol), 2 (1.0 mmol), FeCl2 (0.1 mmol), L1 (0.1 mmol), Et3N (1.0 mmol) in CH3CN (2.0 mL) at room temperature (20 ꢀC) under nitrogen
atmosphere for 24 h.
b
Isolated yields after column chromatography.
Enantiomeric excesses were measured by chiral HPLC.
c

H. Wu et al. / Tetrahedron 67 (2011) 1210e1215
1213
Table 3
Fe(II)/L1-catalyzed enantioselective cycloaddition of azomethine ylides (1) with N-substituted maleimides (4)a
R
N
O
O
FeCl2/L1 (10 mol%)
Ar
N
CO2Me +
O
O
N
Et3N, CH3CN
R
4
Ar
CO2Me
N
H
1
5
endo-
Entry
Ar
R
5
Yieldb(%)
eec(%)
1
2
3
4
5
6
4-ClC6H4 (1a)
4-ClC6H4 (1a)
C6H5 (1b)
4-FC6H4 (1c)
2-CH3C6H4 (1d)
3-BrC6H4 (1g)
CH3 (4a)
C6H5 (4b)
CH3 (4a)
C6H5 (4b)
C6H5 (4b)
C6H5 (4b)
5a
5b
5c
5d
5e
5f
54
48
60
49
57
72
51
78
75
65
20
57
a
Reaction conditions: 1 (1.0 mmol), 4 (1.0 mmol), FeCl2 (0.1 mmol), L1 (0.1 mmol), Et3N (1.0 mmol) in CH3CN (2.0 mL) at room temperature (20 ꢀC) under nitrogen
atmosphere for 24 h.
b
Isolated yields after column chromatography.
Enantiomeric excesses were measured by chiral HPLC.
c
A plausible mechanism for the cycloaddition reaction of azo-
methine ylides is shown in Scheme 2. Coordination of the imino
ester to chiral N,O-ligand L1 and Fe(II) catalyst, followed by
deprotonation with base to form the reactive metal-bound azo-
methine ylide dipole, which reacts with dipolarophiles in a chiral
environment, was followed by elimination of cycloadduct to afford
the expected endo-cycloadduct stereoselectively, and regenerate
the chiral catalyst.
4. Experimental section
4.1. General remarks
All reactions were carried out under a nitrogen atmosphere. All 1H
and 13C NMR spectra were recorded on a 400 MHz Bruker FT-NMR
spectrometers. All chemical shifts are given as
d value (ppm) with
reference to tetramethylsilane (TMS) as an internal standard. IR
spectra were obtained on a Nicolet NEXUS 470 spectrophotometer.
Enantiomeric excesses were determined on Agilent 1100 HPLC using
Daicel Chiralpak AS-H, AD-H and Chiralcel OD-H columns with race-
mic compound as standard. Products were purified by flash chroma-
tography on 230e400 meshsilicagel, SiO2.Thechemicalsandsolvents
were purchased from commercial suppliers either from Aldrich, Fluka,
Fisher Scientific and Novabiochem, USA, or Shanghai Chemical Com-
pany, China and were used without purification prior to use.
CO2R
CO2Me
RO2C
Ar
O
L1
FeCl2/
Ar
N
OMe
Et3N
N
H
endo-Product
*
O
N
Et3N
*
Fe
Cl2
O
N
Et3NH Cl
Fe
Cl2
4.2. General procedure for the FeCl2-catalyzed [3D2]
cycloaddtion reaction
*
*
O
N
O
N
CO2R
RO2C
Cl
O
Fe
Cl
O
Under nitrogen atmosphere, FeCl2 (12.7 mg, 0.1 mmol) and
ligand L1 (52.5 mg, 0.1 mmol) were placed in a dried Schlenk tube
and CH3CN (1.0 mL) was added. The mixture was stirred at room
temperature (20 ꢀC) for 1 h. Then imine substrate 1 (1.0 mmol),
electronic-deficient olefin 2 or 4 (1.0 mmol) and Et3N (101 mg,
1.0 mmol) were added as solution in CH3CN (1.0 mL). The mixture
was stirred at room temperature (20 ꢀC) and the progress of the
cycloaddition reaction was typically monitored by TLC analysis.
After the reaction proceeded for 24 h, the reaction was quenched
with saturated ammonium chloride solution and then washed with
ethyl acetate (3.0 mLꢂ3), the combined ethyl acetate was concen-
trated. The obtained residue was purified by column chromatog-
raphy on silica gel using hexane/ethyl acetate as eluent to provide
the desired [3þ2] cycloaddtion product.
Fe
Ar
N
Ar
N
OMe
OMe
CO2R
RO2C
AzomethineYlideComplex
Scheme 2. Plausible mechanism of the 1,3-dipolar cycloaddition of azomethine ylides
catalyzed by chiral L1-Fe(II) complexes.
3. Conclusions
In summary, a novel Fe(II)/diaryl prolinol catalyzed asymmetric
1,3-dipolar cycloaddition of azomethine ylides with alkenes has
been developed. In the presence of FeCl2 (10 mol %) and a,a-bis
(3,5-bistrifluoromethylphenyl)prolinol L1 (10 mol %), [3þ2] cyclo-
addition of azomethine ylides with electronic-deficient olefins,
including dialkyl maleates and N-substituted maleimides un-
derwent smoothly in CH3CN at room temperature (20 ꢀC) to gen-
erate the desired the endo-adducts in moderate to good yields and
enantioselectivities in the most cases. Efforts to elucidate the
mechanistic details of this asymmetric 1,3-dipolar cycloaddition
reaction and extension of this protocol to other substrates and re-
actions are under current investigation in our laboratory.
4.2.1. (2R,3S,4R,5S)-3,4-Dibutyl,2-methyl 5-(4-chlorophenyl)pyrroli-
dine-2,3,4-tricarboxylate (3a). White solid; SiO2 chromatography:
n-hexaneeEtOAc 1:1; 71% ee. HPLC: Daicel Chiralpak AS-H column,
i-PrOH/hexane 50:50, flow rate 0.8 mL/min, tR¼7.07 min and
8.98 min,
l
¼205 nm; 1H NMR (400 MHz, CDCl3):
¼7.30 (s, 4H),
d
4.43 (d, J¼6.7 Hz, 1H), 4.11e4.03 (m, 3H), 3.80 (s, 3H), 3.73e3.55 (m,
4H), 1.62e1.56 (m, 2H), 1.39e1.34 (m, 2H), 1.21e1.15 (m, 2H),
1.09e1.03 (m, 2H), 0.92 (t, J¼7.4 Hz, 3H), 0.78 (t, J¼7.2 Hz, 3H); 13C

1214
H. Wu et al. / Tetrahedron 67 (2011) 1210e1215
NMR (100 MHz, CDCl3):
d
¼170.9, 170.4, 170.3, 135.8, 133.5, 128.4,
J¼8.4 Hz, 2H), 7.52 (d, J¼8.4 Hz, 2H), 4,58 (d, J¼6.2 Hz, 1H), 4.22 (d,
J¼9.1 Hz, 1H), 4.13e4.02 (m, 2H), 3.81 (s, 3H), 3.80e3.58 (m, 4H),
1.63e1.56 (m, 2H), 1.42e1.32 (m, 2H), 1.24e1.15 (m, 2H), 1.11e1.01
(m, 2H), 0.93 (t, J¼7.4 Hz, 3H), 0.79 (t, J¼7.2 Hz, 3H); 13C NMR
128.3, 65.2, 64.7, 64.5, 62.1, 52.6, 51.2, 30.4, 30.2, 19.1, 18.9, 13.7, 13.5.
IR (KBr, cmꢁ1): 3281, 2961, 1737, 1708, 1498, 1460, 1430, 1402, 1381,
1342, 1308, 1293, 1238, 1204, 1178, 1112, 1093, 1078, 1016, 935, 833,
775. Anal. Calcd for C22H30ClNO6: C, 60.06; H, 6.87; N, 3.18. Found:
C, 60.33; H, 6.73; N, 3.29.
(100 MHz, CDCl3):
d¼170.6, 170.0, 169.8, 142.8, 132.1, 127.8, 118.5,
111.6, 65.3, 64.7, 64.6, 61.8, 52.4, 52.2, 51.0, 30.4, 30.1, 19.0, 18.8, 13.6,
13.5. IR (KBr, cmꢁ1): 3272, 2953, 2924, 2849, 2228, 1743, 1692, 1463,
1431, 1411, 1378, 1369, 1332, 1301, 1284, 1227, 1195, 1164, 1101, 1076,
1052, 1012, 929, 825, 763. Anal. Calcd for C23H30N2O6: C, 64.17; H,
7.02; N, 6.51. Found: C, 64.29; H, 6.91; N, 6.37.
4.2.2. (2R,3S,4R,5S)-Trimethyl 5-(4-chlorophenyl)pyrrolidine-2,3,4-
tricarboxylate (3b)6a. White solid; SiO2 chromatography: n-
hexaneeEtOAc 1:1; 77% ee. HPLC: Daicel Chiralpak AS-H column,
i-PrOH/hexane 50:50, flow rate 0.8 mL/min, tR¼9.22 min and
11.62 min,
l
¼205 nm; 1H NMR (400 MHz, CDCl3):
d¼7.29 (s, 4H),
4.2.8. (2R,3S,4R,5S)-Trimethyl 5-(4-cyanophenyl)pyrrolidine-2,3,4-
tricarboxylate (3h)8d. Colorless solid; SiO2 chromatography: n-
hexaneeEtOAc 1:1; 67% ee. HPLC: Daicel Chiralpak AD-H column,
i-PrOH/hexane 50:50, flow rate 0.8 mL/min, tR¼8.84 min and
4.45 (d, J¼7.0 Hz, 1H), 4.14 (d, J¼8.9 Hz, 1H), 3.79 (s, 3H), 3.75e3.70
(m, 1H), 3.68 (s, 3H), 3.60e3.56 (m, 1H), 3.27 (s, 3H), 3.08 (br, 1H);
13C NMR (100 MHz, CDCl3):
d¼170.8,170.6, 170.5,135.7,133.3, 128.3,
128.1, 64.4, 61.9, 52.2, 52.1, 51.9, 51.3, 50.7.
15.40 min,
l
¼205 nm; 1H NMR (400 MHz, CDCl3):
d
¼7.63 (d,
J¼8.1 Hz, 2H), 7.51 (d, J¼7.8 Hz, 2H), 4.54 (d, J¼6.3 Hz, 1H), 4.18 (d,
J¼8.7 Hz, 1H), 3.80 (s, 3H), 3.79e3.73 (m, 1H), 3.69 (s, 3H),
3.67e3.61 (m, 1H), 3.27 (s, 3H); 13C NMR (100 MHz, CDCl3):
4.2.3. (2R,3S,4R,5S)-3,4-Dibenzyl-2-methyl-5-(4-chlorophenyl)pyr-
rolidine-2,3,4-tricarboxylate (3c). White solid;SiO2 chromatography:
n-hexaneeEtOAc 3:1; 69% ee. HPLC: Daicel Chiralpak AS-H column,
i-PrOH/hexane 50:50, flow rate 0.8 mL/min, tR¼6.15 min and
d
¼171.0, 170.8, 170.6, 143.3, 132.2, 128.0, 118.8, 111.7, 64.8, 62.2, 52.7,
52.5, 52.2, 51.8, 51.0.
13.33 min, 205 nm; 1H NMR (400 MHz, CDCl3):
d¼7.36e7.29 (m, 6H),
7.26e7.13 (m, 8H), 5.22e5.12 (m, 2H), 4.71 (d, J¼12.1 Hz, 1H),
4.61e4.56 (m, 2H), 4.20e4.16 (m, 1H), 3.73e3.69 (m, 1H), 3.64e3.61
(m,1H), 3.21(t, J¼7.2 Hz, 3H), 2.76 (br,1H); 13C NMR (100 MHz, CDCl3):
4.2.9. (2R,3S,4R,5S)-Trimethyl 5-(2-naphthyl)pyrrolidine-2,3,4-tri-
carboxylate (3i)5a. White solid; SiO2 chromatography: n-hex-
aneeEtOAc 1:1; 60% ee. HPLC: Daicel Chiralpak AS-H column, i-
PrOH/hexane 50:50, flow rate 0.8 mL/min, tR¼10.19 and 24.29 min,
d
¼171.7,171.3,170.6,136.7,135.3,134.6,133.5,128.9,128.6,128.4,128.2,
127.8, 127.3, 126.7, 126.1, 67.0, 66.8, 64.4, 63.2, 61.5, 53.5, 50.7. IR (KBr,
cmꢁ1): 3345, 3032, 2978, 2334, 1954, 1893, 1735, 1721, 1599, 1494,
1455, 1381, 1201, 1014, 908, 751, 698. Anal. Calcd for C28H26ClNO6: C,
66.21; H, 5.16; N, 2.76. Found: C, 66.37; H, 5.09; N, 2.87.
l
¼205 nm; 1H NMR (400 MHz, CDCl3):
d
¼7.78e7.83 (m, 4H),
7.47e7.41 (m, 3H), 4.63 (d, J¼6.5 Hz, 1H), 4.23 (d, J¼9.0 Hz, 1H), 3.83
(s, 3H), 3.81e3.76 (m, 1H), 3.69 (s, 3H), 3.69e3.66 (m, 1H), 3.16 (s,
3H); 13C NMR (100 MHz, CDCl3):
d
¼170.9, 170.8, 170.6, 134.3, 133.1,
132.8, 128.0, 127.9, 127.5, 126.1, 125.9, 125.5, 124.7, 65.4, 62.0, 52.4,
52.1, 51.3, 51.2, 51.1.
4.2.4. (2R,3S,4R,5S)-Trimethyl 5-phenylpyrrolidine-2,3,4-tricarbox-
ylate (3d)6a. White solid; SiO2 chromatography: n-hexaneeEtOAc 1:1;
62% ee. HPLC: Daicel Chiralpak AS-H column, i-PrOH/hexane 50:50,
4.2.10. (1S,3R,3S,6R)-Methyl 5-methyl-4,6-dioxo-3-(4-chlorophenyl)-
octahydropyrrole[3,4-c]pyrrole-1-carboxylate (5a)5f. White solid;
SiO2 chromatography: n-hexaneeEtOAc 1:1; 51% ee. HPLC: Daicel
Chiralpak AS-H column, i-PrOH/hexane 50:50, flow rate 1.5 mL/
flow rate 0.8 mL/min, tR¼7.04 and 14.39 min,
l
¼205 nm; 1H NMR
(400 MHz, CDCl3):
d
¼7.34e7.26 (m, 5H), 4.49 (d, J¼7.0 Hz, 1H), 4.17 (d,
J¼9.1 Hz,1H), 3.81 (s, 3H), 3.80e3.72 (m,1H), 3.70 (s, 3H), 3.60e3.56 (m,
1H), 3.24 (s, 3H); 13C NMR (100 MHz, CDCl3):
d¼171.0,170.9,170.8,137.0,
min, tR¼6.20 and 25.92 min,
l
¼205 nm; 1H NMR (400 MHz, CDCl3):
128.3, 127.7, 126.7, 65.4, 62.1, 52.5, 52.4, 52.1, 51.3, 50.9.
d
¼7.30e7.21 (m, 4H), 4.45 (d, J¼8.5 Hz, 1H), 4.03 (d, J¼6.9 Hz, 1H),
3.87 (s, 3H), 3.55 (t, J¼7.4 Hz, 1H), 3.41 (t, J¼8.1 Hz, 1H), 2.86 (s, 3H),
4.2.5. (2R,3S,4R,5S)-Trimethyl 5-(4-fluorophenyl)pyrrolidine-2,3,4-
tricarboxylate (3e)6a. White solid; SiO2 chromatography: n-hex-
aneeEtOAc 1:1; 70% ee. HPLC: Daicel Chiralpak AS-H column,
i-PrOH/hexane 50:50, flow rate 0.8 mL/min, tR¼7.56 and 11.89 min,
2.39 (br, 1H); 13C NMR (100 MHz, CDCl3):
d¼175.7, 174.5, 169.9,
135.2, 133.9, 128.6, 128.4, 63.2, 61.5, 52.3, 49.2, 47.9, 24.9.
4.2.11. (1S,3R,3S,6R)-Methyl 4,6-dioxo-3-(4-chlorophenyl)-5-phenyl-
octahydropyrrole[3,4-c]pyrrole-1-carboxylate (5b)9. White solid;
SiO2 chromatography: n-hexaneeEtOAc 1:1; 78% ee. HPLC: Daicel
Chiralpak AS-H column, i-PrOH/hexane 50:50, flow rate 1.5 mL/
l
¼205 nm; 1H NMR (400 MHz, CDCl3):
d¼7.35e7.31 (m, 2H),
7.03e6.99 (m, 2H), 4.47 (d, J¼7.0 Hz, 1H), 4.15 (d, J¼8.8 Hz, 1H), 3.81
(s, 3H), 3.73e3.71 (m, 1H), 3.69 (s, 3H), 3.58e3.54 (m, 1H), 3.26 (s,
3H); 13C NMR (100 MHz, CDCl3):
d¼170.9, 170.8, 170.7, 162.1 (d,
min, tR¼7.11 and 19.85 min,
l
¼220 nm; 1H NMR (400 MHz, CDCl3):
J¼245.8 Hz), 132.9 (d, J¼3.0 Hz), 128.4 (d, J¼8.1 Hz), 115.1 (d,
d
¼7.40e7.36 (m, 4H), 7.33e7.30 (m, 3H), 7.12 (d, J¼7.1 Hz, 2H), 4.52
J¼21.2 Hz), 64.6, 62.1, 52.4, 52.1, 52.0, 51.3, 50.8.
(d, J¼8.7 Hz, 1H), 4.01 (d, J¼6.6 Hz, 1H), 3.84 (s, 3H), 3.67 (t,
J¼7.2 Hz, 1H), 3.49 (t, J¼8.2 Hz, 1H), 2.48 (br s, 1H); 13C NMR
4.2.6. (2R,3S,4R,5S)-Trimethyl 5-(2-methylphenyl)pyrrolidine-2,3,4-
tricarboxylate (3f)5a. Colorless oil; SiO2 chromatography: n-hex-
aneeEtOAc 1:1; 53% ee. HPLC: Daicel Chiralpak AS-H column,
i-PrOH/hexane 50:50, flow rate 0.8 mL/min, tR¼6.56 and 16.22 min,
(100 MHz, CDCl3):
128.6, 128.5, 128.4, 126.0, 63.3, 61.7, 52.3, 49.0, 47.9.
d
¼174.9, 173.5, 169.9, 135.3, 133.9, 131.4, 129.1,
4.2.12. (1S,3R,3S,6R)-Methyl 5-methyl-4,6-dioxo-3-phenyl-octahy-
dropyrrole[3,4-c]pyrrole-1-carboxylate (5c)5f. White solid; SiO2
chromatography: n-hexaneeEtOAc 1:1; 75% ee. HPLC: Daicel
Chiralpak AD-H column, i-PrOH/hexane 50:50, flow rate 0.7 mL/
l
¼205 nm; 1H NMR (400 MHz, CDCl3):
d¼7.39e7.36 (m, 1H),
7.18e7.14 (m, 3H), 4.61 (d, J¼6.6 Hz, 1H), 4.11 (d, J¼8.7 Hz, 1H), 3.83
(s, 3H), 3.77e3.71 (m, 1H), 3.67 (s, 3H), 3.69e3.64 (m, 1H), 3.12 (s,
3H), 2.34 (s, 3H); 13C NMR (100 MHz, CDCl3):
d
¼171.5, 171.0, 135.8,
min, tR¼9.09 and 10.85 min,
l
¼220 nm; 1H NMR (400 MHz, CDCl3):
135.1, 130.4, 127.8, 126.2, 62.2, 61.9, 52.6, 52.3, 51.6, 51.4, 51.0.
d
¼7.34 (m, 5H), 4.50 (d, J¼8.6 Hz, 1H), 4.06 (d, J¼6.8 Hz, 1H), 3.88 (s,
3H), 3.57 (t, J¼7.2 Hz, 1H), 3.43 (t, J¼8.2 Hz, 1H), 2.87 (s, 3H); 2.73(br
4.2.7. (2R,3S,4R,5S)-3,4-Dibutyl, 2-methyl 5-(4-cyanophenyl)pyrro-
lidine-2,3,4-tricarboxylate (3g). White solid; SiO2 chromatography:
n-hexaneeEtOAc 1:1; 74% ee. HPLC: Daicel Chiralpak AD-H column,
i-PrOH/hexane 50:50, flow rate 0.8 mL/min, tR¼12.85 min and
s, 1H); 13C NMR (100 MHz, CDCl3):
d
¼175.9, 174.6, 170.1, 136.6,
128.4, 128.3, 126.9, 64.0, 61.6, 52.1, 49.5, 48.2, 24.9.
4.2.13. (1S,3R,3S,6R)-Methyl 4,6-dioxo-3-(4-fluorophenyl)-5-phenyl-
octahydropyrrole[3,4-c]pyrrole-1-carboxylate (5d)9. White solid;
21.28 min,
l
¼205 nm; 1H NMR (400 MHz, CDCl3):
d¼7.64 (d,

H. Wu et al. / Tetrahedron 67 (2011) 1210e1215
1215
ꢀ
Carreira, E. M. Angew. Chem., Int. Ed. 2004, 43, 5971e5973; (d) Najera, C.;
Retamosa, M. D. G.; Sansano, J. Angew. Chem., Int. Ed. 2008, 47, 6055e6058; (e)
SiO2 chromatography: n-hexaneeEtOAc 1:1; 65% ee. HPLC: Daicel
Chiralpak AS-H column, i-PrOH/hexane 50:50, flow rate 0.8 mL/
ꢀ
Alemparte, C.; Blay, G.; Jørgensen, K. A. Org. Lett. 2005, 7, 4569e4572; (f) Najera,
C.; Retamosa, M. D. G.; Sansano, J. Org. Lett. 2007, 9, 4025e4028; (g) Ogata, K.;
Fukuzawa, S.-i. Org. Lett. 2010, 12, 1752e1755.
min, tR¼5.98 and 11.65 min,
l
¼220 nm; 1H NMR (400 MHz, CDCl3):
d
¼7.45e7.38 (m, 5H), 7.15e7.13 (m, 2H), 7.07e7.03 (m, 2H), 4.60 (d,
6. (a) Zeng, W.; Zhou, Y.-G. Org. Lett. 2005, 7, 5055e5058; (b) Zeng, W.; Chen, G.-
Y.; Zhou, Y.-G.; Li, Y.-X. J. Am. Chem. Soc. 2007, 129, 750e751; (c) Zeng, W.; Zhou,
Y.-G. Tetrahedron Lett. 2007, 48, 4619e4622; (d) Stohler, R.; Wahl, F.; Pfaltz, A.
Synthesis 2005, 1431e1436; (e) Xue, Z.-Y.; Liu, T.-L.; Lu, Z.; Huang, H.; Tao, H.-Y.;
Wang, C.-J. Chem. Commun. 2010, 46, 1727e1729.
7. (a) Gothelf, A. S.; Gothelf, K. V.; Hazell, R. G.; Jørgensen, K. A. Angew. Chem., Int.
Ed. 2002, 41, 4236e4238; (b) Dogan, O.; Koyuncu, H.; Garner, P.; Bulut, A.;
Youngs, W. J.; Panzner, M. Org. Lett. 2006, 8, 4687e4690.
J¼8.8 Hz, 1H), 4.14 (d, J¼6.7 Hz, 1H), 3.87 (s, 3H), 3.73 (t, J¼7.1 Hz,
1H), 3.55 (t, J¼8.3 Hz, 1H), 2.49 (br s, 1H); 13C NMR (100 MHz,
CDCl3):
d
¼174.9, 173.5, 169.9, 162.6 (d, J¼245.5 Hz), 132.4, 131.6,
129.1, 128.8 (d, J¼8.2 Hz), 128.6, 128.0, 115.5 (d, J¼21.3 Hz), 63.5,
61.8, 52.3, 49.2, 48.1.
ꢀ
8. (a) Lopez-Pírez, A.; Adrio, J.; Carretero, J. C. Angew. Chem., Int. Ed. 2009, 48,
340e343; (b) Hernandez-Toribio, J.; Arrayas, R. G.; Martín-Matute, B.; Carre-
tero, J. C. Org. Lett. 2009, 11, 393e396; (c) Lopez-Pírez, A.; Adrio, J.; Carretero, J.
4.2.14. (1S,3R,3S,6R)-Methyl 4,6-dioxo-3-(2-methylphenyl)-5-phe-
ꢀ
ꢀ
nyl-octahydropyrrole[3,4-c]pyrrole-1-carboxylate
(5e)8i. White
ꢀ
solid; SiO2 chromatography: n-hexaneeEtOAc 1:1; 20% ee. HPLC:
Daicel Chiralpak AS-H, i-PrOH/hexane 50:50, flow rate 0.8 mL/min,
C. J. Am. Chem. Soc. 2008, 130, 10084e10085; (d) Wang, C. J.; Liang, G.; Xue, Z.-Y.;
Gao, F. J. Am. Chem. Soc. 2008, 130, 17250e17251; (e) Stanley, L. M.; Sibi, M. P.
Chem. Rev. 2008, 108, 2887e2902; (f) Fukuzawa, S.-i.; Oki, H. Org. Lett. 2008, 10,
tR¼11.21 min and 52.07 min,
l
¼220 nm; 1H NMR (400 MHz, CDCl3):
ꢀ
1747e1750; (g) Liamas, T.; Arrayas, R. G.; Carretero, J. C. Org. Lett. 2006, 8,
d
¼7.68e7.64 (m, 1H), 7.37e7.18 (m, 6H), 7.09e7.03 (m, 2H),
1795e1798; (h) Yan, X.-X.; Peng, Q.; Zhang, Y.; Zhang, K.; Hong, W.; Hou, X.-L.;
ꢀ
Wu, Y.-D. Angew. Chem., Int. Ed. 2006, 45, 1979e1983; (i) Cabrera, S.; Gomez
4.76e4.73 (m, 1H), 4.17e4.14 (m, 1H), 3.90 (s, 3H), 3.73 (t, J¼6.2 Hz,
ꢀ
Arrayas, R.; Carretero, J. C. J. Am. Chem. Soc. 2005, 127, 16394e16395; (j)
1H), 3.64 (t, J¼8.5 Hz, 1H), 2.47 (s, 3H); 13C NMR (100 MHz, CDCl3):
Oderaotoshi, Y.; Cheng, W.; Fujitomi, S.; Kasano, Y.; Minakata, S.; Komatsu, M.
d¼175.2, 173.53, 170.2, 135.7, 135.53, 131.3, 130.1, 128.9, 128.5, 128.1,
Org. Lett. 2005, 5, 5043e5046; (k) Gao, W.; Zhang, X.; Raghunath, M. Org. Lett.
ꢀ
2005, 7, 4241e4244; (l) Robles-Machín, R.; Gonzalez-Esgevillas, M.; Adrio, J.;
126.3, 126.2, 125.5, 61.4, 60.5, 52.5, 48.3, 47.1, 19.3.
Carretero, J. C. J. Org. Chem. 2010, 75, 233e236; (m) Arai, T.; Mishiro, A.; Yo-
koyama, N.; Suzuki, K.; Sato, H. J. Am. Chem. Soc. 2010, 132, 5338e5339.
9. Shi, J.-W.; Zhao, M.-X.; Lei, Z.-Y.; Shi, M. J. Org. Chem. 2008, 73, 305e308.
10. Saito, S.; Tsubogo, T.; Kobayashi, S. J. Am. Chem. Soc. 2007, 129, 5364e5365.
11. (a) Enthaler, S.; Junge, K.; Beller, M. Angew. Chem., Int. Ed. 2008, 47, 3317e3321;
(b) Correa, A.; Garcia Mancheno, O.; Bolm, C. Chem. Soc. Rev. 2008, 37,
1108e1117; (c) Bolm, C.; Legros, J.; Le Paih, J.; Zani, L. Chem. Rev. 2004, 104,
4.2.15. (1S,3R,3S,6R)-Methyl 4,6-dioxo-3-(3-bromophenyl)-5-phe-
nyl-octahydropyrrole[3,4-c]pyrrole-1-carboxylate (5f)9. White solid;
SiO2 chromatography: n-hexaneeEtOAc 1:1; 57% ee. HPLC: Daicel
Chiralcel OD-H column, i-PrOH/hexane 50:50, flow rate 1 mL/min,
¼230 nm; 1H NMR (400 MHz,
€
tR¼19.22 min and 35.37 min,
l
6217e6254; (d) Sherry, B. D.; Furstner, A. Acc. Chem. Res. 2008, 41, 1500e1511.
€
12. For recent reviews, see: (a) Berkessel, A.; Groer, H. Asymmetric Organocatalysis;
CDCl3):
d
¼7.67 (s, 1H), 7.48e7.35 (m, 5H), 7.25e7.14(m, 3H), 4.57
Wiley-VCH: Weinheim, 2005; (b) Special Issue: ‘Asymmetric Organocatalysis’:
Acc. Chem. Res. 2004, 37, 487e631; (c) Special Issue: ‘Organocatalysis’:Chem.
Rev. 2007, 107, 5413e5883; (d) Dondoni, A.; Massi, A. Angew. Chem., Int. Ed.
2008, 47, 4638e4660.
(dd, J¼4.5, 9.0 Hz, 1H), 4.14 (dd, J¼4.5, 6.6 Hz, 1H), 3.88 (s, 3H), 3.75
(t, J¼6.9 Hz, 1H), 3.57 (t, J¼8.4 Hz, 1H), 2.52 (br s, 1H); 13C NMR
(100 MHz, CDCl3):
d
¼174.9, 173.7, 169.8, 145.5, 139.4, 131.8, 131.7,
13. (a) Ahrendt, K. A.; Borths, C. J.; MacMillan, D. W. C. J. Am. Chem. Soc. 2000, 122,
4243e4244; (b) List, B.; Lerner, R. A.; Barbas, C. F., III. J. Am. Chem. Soc. 2000, 122,
130.3, 129.5, 128.8, 126.4, 126.2, 122.9, 63.6, 61.8, 52.6, 49.2, 47.9.
2395e2396.
ˇ
Acknowledgements
ꢀ
14. For examples, see: (a) García-García, P.; Ladepeche, A.; Halder, R.; List, B. Angew.
Chem., Int. Ed. 2008, 47, 4719e4721; (b) Hayashi, Y.; Itoh, T.; Ohkubo, M.; Ishikawa,
H. Angew. Chem., Int. Ed. 2008, 47, 4722e4724; (c) Kim, H.; MacMillan, D. W. C. J.
Am. Chem. Soc. 2008, 130, 398e399; (d) Reyes, E.; Jiang, H.; Milelli, A.; Elsner, P.;
Hazell, R. G.; Jøgensen, K. A. Angew. Chem., Int. Ed. 2007, 46, 9202e9205; (e) Tang,
Z.; Yang, Z.-H.; Chen, X.-H.;Cun, L.-F.; Mi, A.-Q.; Jiang, Y.-Z.; Gong, L.-Z. J. Am. Chem.
Soc. 2005, 127, 9285e9289; (f) Tang, Z.; Jiang, F.; Yu, L.-T.; Gong, L.-Z.; Mi, A.-Q.;
Jiang, Y.-Z.; Wu, Y.-D. J. Am. Chem. Soc. 2003, 125, 5262e5263.
We gratefully acknowledge financial support by the National
Natural Science Foundation of China (No. 20972057, 20772043).
Supplementary data
15. For CeO bond, see: Lu, M.; Zhu, D.; Lu, Y.; Hou, Y.; Tan, B.; Zhong, G. Angew.
Chem., Int. Ed. 2008, 47, 10187e10191.
16. For CeN bond, see: (a) Vesely, J.; Ibrahem, I.; Zhao, G.-L.; Rios, R.; Cordova, A.
Supplementary data associated with this article can be found in
online version at doi:10.1016/j.tet.2010.11.091.
ꢀ
Angew. Chem., Int. Ed. 2007, 46, 778e781; (b) Chen, Y. K.; Yoshida, M.; Mac-
Millan, D. W. C. J. Am. Chem. Soc. 2006, 128, 9328e9329; (c) Diner, P.; Nielsen,
ꢀ
M.; Marigo, M.; Jøgensen, K. A. Angew. Chem., Int. Ed. 2007, 46, 1983e1987.
17. For Cehalogen bond, see: (a) Brochu, M. P.; Brown, S. P.; MacMillan, D. W. C. J.
Am. Chem. Soc. 2004, 126, 4108e4109; (b) Shibatomi, K.; Yamamoto, H. Angew.
Chem., Int. Ed. 2008, 47, 5796e5798.
References and notes
1. (a) Synthetic Applications of Dipolar Cycloaddition Chemistry towards Heterocyclic
and Natural Products; Padwa, A., Pearson, W., Eds.; Wiley-VCH: Weinheim,
2002; (b) Wade, P. A. In Comprehensive Organic Synthesis; Trost, B. M.,
Fleming, I., Semmelhack, M. F., Eds.; Pergamon: Oxford, 1991; Vol 4; p 1111; (c)
Torssell, K. B. G. Nitrile Oxides, Nitrones and Nitronates in Organic Synthesis; VCH:
Weinheim, 1988.
18. For CeS bond, see: (a) Marigo, M.; Wabnitz, T. C.; Fielenbach, D.; Jøgensen, K. A.
Angew. Chem., Int. Ed. 2005, 44, 794e797; (b) Zhao, G.-L.; Rios, R.; Vesely, J.;
ꢀ
Eriksson, L.; Cordova, A. Angew. Chem., Int. Ed. 2008, 47, 8468e8472.
19. For CeP bond, see: (a) Carlone, A.; Bartoli, G.; Bosco, M.; Sambri, L.; Melchiorre,
P. Angew. Chem., Int. Ed. 2007, 46, 4504e4506; (b) Ibrahem, I.; Rios, R.; Vesely, J.;
2. For reviews of asymmetric 1,3-dipolar cycloadditions, see: (a) Gothelf, K. V.;
Jørgensen, K. A. Chem. Rev. 1998, 98, 863e910; (b) Pellissier, H. Tetrahedron
2007, 63, 3235e3285.
ꢀ
Hammar, P.; Eriksson, L.; Himo, F.; Cordova, A. Angew. Chem., Int. Ed. 2007, 46,
4507e4510.
20. For CeSe bond, see: Tiecco, M.; Carlone, A.; Sternativo, S.; Marini, F.; Bartoli, G.;
Melchiorre, P. Angew. Chem., Int. Ed. 2007, 46, 6882e6885.
ꢀ
ꢀ
3. (a) Barluenga, J.; Fernandez-Rodríguez, M. A.; Aguilar, E.; Fernandez-Mari, F.;
Salinas, A.; Olano, B. Chem.dEur. J. 2001, 7, 3533e3544; (b) Sebahar, P. R.;
Williams, R. M. J. Am. Chem. Soc. 2000, 122, 5666e5667; (c) Denhart, D. J.;
Griffith, D. A.; Heathcock, C. H. J. Org. Chem. 1998, 63, 9616e9617; (d) Garner, P.;
Cox, P. B.; Anderson, J. T.; Protasiewicz, J.; Zaniewski, R. J. Org. Chem. 1997, 62,
493e498; (e) Alvarez-Ibarra, C.; Csaky, A. G.; Lopez, I.; Quiroga, M. L. J. Org.
Chem. 1997, 62, 479e484; (f) Bianco, A.; Maggini, M.; Scorrano, G.; Toniolo, C.;
Marconi, G.; Villani, C.; Prato, M. J. Am. Chem. Soc. 1996, 118, 4072e4080; (g)
Kopach, M. E.; Fray, A. H.; Meuers, A. I. J. Am. Chem. Soc. 1996, 118, 9876e9883;
(h) Waldmann, H.; Blaeser, E.; Jansen, M.; Letschert, H.-P. Chem.dEur. J. 1995, 1,
150e154; (i) Garner, P.; Ho, W. B.; Shin, H. J. Am. Chem. Soc. 1993, 115,
10742e10753.
21. (a) Reyes, E.; Talavera, G.; Vicario, J. L.; Badía, D.; Carrillo, L. Angew. Chem., Int.
Ed. 2009, 48, 5701e5704; (b) Han, B.; Li, J.-L.; Ma, C.; Zhang, S.-J.; Chen, Y.-C.
Angew. Chem., Int. Ed. 2008, 47, 9971e9974; (c) Han, B.; He, Z.-Q.; Li, J.-L.; Li, R.;
Jiang, K.; Liu, T.-Y.; Chen, Y.-C. Angew. Chem., Int. Ed. 2009, 48, 5474e5477; (d)
Xie, H.-X.; Zu, L.-S.; Li, H.; Wang, J.; Wang, W. J. Am. Chem. Soc. 2007, 129,
10886e10894; (e) Zu, L.-S.; Wang, J.; Li, H.; Xie, H.-X.; Jiang, W.; Wang, W. J. Am.
Chem. Soc. 2007, 129, 1036e1037.
22. Mukherjee, S.; Yang, J.; Hoffmann, S.; List, B. Chem. Rev. 2007, 107, 5471e5569.
€
23. Erkkila, A.; Majander, I.; Pihko, P. M. Chem. Rev. 2007, 107, 5416e5470.
24. (a) Beeson, T. D.; Mastracchio, A.; Hong, J. B.; Ashton, K.; MacMillan, D. W. C.
Science 2007, 316, 582e585; (b) Nicewicz, D. A.; MacMillan, D. W. C. Science
2008, 322, 77e80.
25. (a) Li, P.; Zhang, Y.; Wang, L. Chem.dEur. J. 2009, 15, 2045e2049; (b) Wang, M.;
Ren, K.; Wang, L. Adv. Synth. Catal. 2009, 351, 1586e1594; (c) Ren, K.; Wang, M.;
Wang, L. Eur. J. Org. Chem. 2010, 565e571.
4. (a) Allway, P.; Grigg, R. Tetrahedron Lett. 1991, 32, 5817e5820; (b) Grigg, R.
Tetrahedron: Asymmetry 1995, 6, 2475e2486.
5. (a) Longmire, J. M.; Wang, B.; Zhang, X. J. Am. Chem. Soc. 2002, 124,
13400e13401; (b) Chen, C.; Li, X.; Schreiber, S. L. J. Am. Chem. Soc. 2003, 125,
10174e10175; (c) Knopfel, T. F.; Aschwanden, P.; Ichikawa, T.; Watanabe, T.;