Enantioselective synthesis of heterocyclic β-aminoalcohols catalysed by a samarium iodo binaphtholate

Article abstract of DOI:10.1016/j.tetasy.2007.10.029

Enantioselective aminolysis of meso-epoxides including a heterocycle catalysed by a samarium iodo binaphtholate has been studied. New β-amino alcohols have been isolated with enantiomeric excesses up to 70%.

Full text of DOI:10.1016/j.tetasy.2007.10.029

Available online at www.sciencedirect.com
Tetrahedron: Asymmetry 18 (2007) 2598–2605
Enantioselective synthesis of heterocyclic b-aminoalcohols catalysed
by a samarium iodo binaphtholate
*
*
´
Myriam Martin, Sophie Bezzenine-Lafollee, Richard Gil and Jacqueline Collin
Laboratoire de Catalyse Mole´culaire, UMR 8182, ICMMO, Universite´ Paris-Sud, 91405 Orsay, France
Received 2 October 2007; accepted 19 October 2007
Abstract—Enantioselective aminolysis of meso-epoxides including a heterocycle catalysed by a samarium iodo binaphtholate has been
studied. New b-amino alcohols have been isolated with enantiomeric excesses up to 70%.
Ó 2007 Elsevier Ltd. All rights reserved.
1. Introduction
with enantiomeric excesses up of to 98%.8 This very effi-
cient procedure avoided the use of solvent and allowed
the reuse of the catalyst.
The synthesis of enantioenriched aminoalcohols is a highly
important topic for chemists since these molecules are
widely employed as chiral auxiliaries, ligands or building
blocks in the design of sophisticated molecules.1,2 Numer-
ous synthetic routes have been reported for their prepara-
tion,3 yet new methods following green chemistry criteria
such as atom economy and/or catalytic reactions are still
being developed.4 Epoxides, which are easily available, can
be readily transformed by reactions with various nucleo-
philes into 1,2-substituted derivatives and especially into
b-aminoalcohols. For the enantioselective catalysed ring-
opening of epoxides, either the desymmetrisation of
meso-epoxides or the kinetic resolution of unsymmetrical
epoxides can be envisaged.5 The first route leading to enan-
tioenriched b-aminoalcohols from meso-epoxides using chi-
ral catalysts involved trimethylsilyl azide as the nucleophile
and afforded b-azidotrimethylsilyl ethers, which were
further reduced. Initial examples based on titanium and
ligands such as tartrates and Schiff bases, catalysed the
formation of b-azidotrimethylsilyl ethers with low enantio-
meric excesses.6 An efficient catalyst was prepared in situ
from Zr(Ot-Bu)4 and (S,S,S)-triisopropanolamine by
Nugent et al. furnished azido silyl ethers with up to 93%
ee, while a similar zirconium-based catalyst with a
bispicolinic amide ligand was less enantioselective.7 The
chiral chromium(III) salen complexes developed by
Jacobsen et al. catalysed the azidolysis of meso-epoxides
However, the enantioselective ring-opening of epoxides by
amines which is more attractive for the preparation of
b-aminoalcohols in terms of atom economy and efficiency
has attracted increased interest only recently. Most of the
chiral catalysts reported up to date are based on lantha-
nides. The first enantioselective aminolyses of meso-
epoxides were described by Wu using in situ prepared
catalysts from (R)-binaphthol and lanthanide chlorides
and by Hou with ytterbium triflate in the presence of
(R)-binaphthol and diphenyl benzyl amine.9 The latter sys-
tem initially developed by Kobayashi et al. for the catalysis
of Diels–Alder reactions,10 allowed the preparation of
b-aminoalcohols from meso-epoxides and aromatic amines
with enantiomeric excesses of up to 80%. Shibasaki and
co-workers studied an in situ prepared catalyst based on
Pr(O-iPr)3, (R)-BINOL and Ph3P@O, which performed
the ring-opening of cyclic epoxides by p-anisidine with up
to 65% ee, and was applied to the formal synthesis of
4-demethoxydaunomycin.11 Schneider et al. examined
various rare earth triflates and different chiral ligands and
found that the system generated in situ from Sc(OTf)3
and a chiral bipyridine ligand, catalysed the desymmetrisa-
tion of aliphatic and aromatic meso-epoxides by aromatic
amines.12 This catalyst provided high asymmetric induc-
tions (up to 97% ee) for aromatic meso-epoxides. Koba-
yashi et al. developed one of the rare enantioselective
Lewis acid catalysed reactions in water with Sc(DS)3 coor-
dinated by the same chiral bipyridine ligand as the previous
group. This system was also highly enantioselective for the
*
Corresponding authors. Fax: +33 (0) 1 69154680 (J.C.); e-mail: jacollin@
icmo.u-psud.fr
0957-4166/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2007.10.029

M. Martin et al. / Tetrahedron: Asymmetry 18 (2007) 2598–2605
2599
aminolysis of aromatic substituted meso-epoxides (up to
tions allowed us to prepare the corresponding b-amino
alcohols with enantiomeric excesses of up to 93%, which
are the highest values reported for these transformations.
Herein we report the enantioselective ring-opening of cyclic
meso-epoxides by amines catalysed by a samarium iodo
binaphtholate to substrates containing an heteroatom in
the cycle for the synthesis of more functionalised enantio-
merically enriched b-amino alcohols. No results concerning
the desymmetrisation of such epoxides by amines had
been described when this study was initiated, the first
examples being reported during the preparation of this
manuscript.16b
96%).13
Enantioselective catalysts for the aminolysis of meso-epox-
ides based on transition metals were also considered.
Through the use of titanium coordinated with binaphthol
up to 93% ee were obtained for the ring-opening of epox-
ides by aliphatic amines, although this catalyst was only
efficient for seven-membered ring cyclic epoxides including
ketal groups.14 Kureshy et al. have extended the use of this
catalyst to reactions involving stilbene oxide and cyclo-
hexene oxide with various aromatic amines.15 The b-amino-
alcohols could be isolated with enantiomeric excesses of up
to 78% and the catalyst could be reused. The reactions were
greatly accelerated under microwave irradiation with
marginal effect on enantioselectivity. The most active and
enantioselective catalysts for the aminolysis of meso-epox-
ides have been recently described by two groups. Schneider
et al. who reported the use of In(OTf)3 coordinated by a
chiral bipyridine ligand, synthesised aminoalcohols from
aromatic epoxides and aromatic amines with enantiomeric
excesses up to 98%.12c The niobium catalyst prepared from
Nb(OMe)5 and a tetradentate binol ligand reported by
Kobayashi et al. afforded high enantiomeric excesses for
the reactions of meso-epoxides with aromatic amines (up
to 96%) and the catalytic ratio was decreased to 0.25%
without lowering the enantioselectivity.16
2. Results and discussion
Over the course of our previous work concerning the enan-
tioselective catalysed aminolysis of cyclic meso-epoxides by
aromatic amines, we had compared the activity and selec-
tivity of lanthanum and samarium iodo binaphtholates
and found higher asymmetric inductions with a samarium
complex.23 The preparation of the catalyst was realised
by the reaction of potassium bis binaphtholate with
samarium triiodide in THF and improved by the use of
potassium diphenyl methide as a potassium source. The
enantioselectivities provided by lanthanide iodo binaphth-
olates are dramatically influenced by temperature, since
enantioselectivity increased with temperature for imino-
aldol reactions,22b and isoinversion effects were observed
for aza-Michael reactions,22c as well as for the aminolysis
of cyclic meso-epoxides.23 To initiate our study we
selected 2,5-dihydrofuran oxide and the electron enriched
aromatic amines, o- and p-anisidine, since these amines
afforded b-aminoalcohols with high enantiomeric excesses
in the case of the ring-opening of cyclohexene, cyclopen-
tene oxide and cyclohexadiene monoxide. The influences
of several parameters on the enantioselectivity of these
two reactions, such as the temperature of the reaction
and the solvent, were examined and the results are shown
in Table 1.
The kinetic resolution of unsymmetrical epoxides was first
investigated by Jacobsen et al. who studied the resolution
of terminal epoxides with trimethylsilyl azide catalysed by
a Cr(III)(salen) azide complex and prepared 1-azido-2-silyl
ethers with 88–98% ee.17 Bartoli et al. reported the kinetic
resolution of aromatic epoxides with aromatic amines with
a similar Cr(III)(salen) chloride catalyst, which led regio-
selectively to 1,2-anti-aminoalcohols in 82–90% ee.18
Carbamates were employed as nucleophiles for the kinetic
resolution of terminal epoxides catalysed by a Co(III)(sa-
len) complex and provided N-Boc or N-Cbz protected
b-aminoalcohols with 99% ee.18b The niobium complex
prepared from Nb(OMe)5 and tetradentate binol ligand
catalysed the ring-opening of unsymmetrical disubstituted
epoxides at the less hindered position with 85–99% ee for
the major product.16b
We first examined the reaction of 2,5-dihydrofuran oxide
2a with o-anisidine 3a under the conditions we have for-
merly described.23 The amine was added to 10 mol %
samarium iodo binaphtholate 1 in methylene chloride in
the presence of molecular sieves, followed by the addition
of epoxide 2a at room temperature (Scheme 1). The
b-aminoalcohol 4aa was obtained with total conversion
and 30% ee after three days (Table 1, entry 1). An increase
in the reaction temperature (entry 2) resulted in a higher
value for the ee (48% at 40 °C) while an increase in the ratio
3a/2a was detrimental to the enantioselectivity (entry 3). In
order to perform the reactions at higher temperature we
investigated the use of dichloroethane as a solvent and
found at 40 °C an enantiomeric excess close to that
obtained in dichloromethane (entry 4). The reactions were
further performed at higher temperature but it led to a
decrease in the enantiomeric excesses (entries 5 and 6).
The aminolysis of 2a with p-anisidine 3b was first
performed in dichloromethane at 25 °C, which provided
the b-aminoalcohol 4ab with a good enantiomeric excess
(70%) (entry 8). An increase in the temperature and in
Our previous studies investigated the activity of samarium
diiodide as an efficient Lewis acid catalyst for a wide range
of carbon–carbon bond forming reactions, such as
Mukaiyama aldol reactions, Diels–Alder reactions, or tan-
dem Mukaiyama Michael-aldol reactions,19 and carbon–
nitrogen forming reactions, such as aza-Michael reac-
tions.20 We also found that samarium diiodide catalyses
the ring-opening of epoxides with various nucleophiles
such as trimethylsilyl azide, trimethylsilyl cyanide and
amines leading to the corresponding opening products in
mild conditions.21 Next, we developed the enantioselective
version of some of these reactions with lanthanide iodo
binaphtholates as catalysts and isolated the products of
iminoaldol and aza-Michael reactions in high enantiomeric
excesses.22 In a previous report, we described the desym-
metrisation of cyclic meso-epoxides by aromatic amines
catalysed by samarium iodo binaphtholate.23 These reac-

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M. Martin et al. / Tetrahedron: Asymmetry 18 (2007) 2598–2605
Table 1. Enantioselective aminolysis of epoxide 2a catalysed by samarium complex 1
Entry
RNH2
Solvent
Product
T (°C)
t (h)
Yielda (%)
ee (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
CH2Cl2
CH2Cl2
CH2Cl2
C2H4Cl2
C2H4Cl2
C2H4Cl2
C2H4Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
C2H4Cl2
C2H4Cl2
4aa
4aa
4aa
4aa
4aa
4aa
4aa
4ab
4ab
4ab
4ab
4ab
4ab
4ab
25
40
40
40
60
80
40
25
25
40
40
0
80
48
80
48
40
40
48
24
24
48
24
72
48
48
77
55
47
54
55
63
35
32
10d
64
22e
15
70
42
30
48
31
41
34
30
52
70
63
64
69
48
68
66
b
c
b
b
40
40
c
a Isolated yield, 100% conversion, reaction performed with 10% catalyst 1 and ratio 3/2: 1.2.
b Ratio 3/2: 2.
c 5% Catalyst 1.
d 15% Conversion.
e 25% Conversion.
the ratio 3b/2a for reactions realised in dichloromethane
(entries 9–11) led to small variations in the enantiomeric
excesses of 4ab. A decrease in reaction temperature to
0 °C did not allow us to improve the asymmetric induction
(entry 12). The reaction was next carried out in dichloro-
ethane at 40 °C which proved to be the best conditions
for the aminolysis by o-anisidine. Product 4ab was
obtained in good yield and with 68% ee (entry 13). For
the ring-opening of 2,5-dihydrofuran oxide 2a, the highest
asymmetric inductions were obtained with dichloroethane
as solvent and at 40 °C with a ratio 3/2: 1.2. A lower
amount of catalyst of 5% did not decrease the enantioselec-
tivity since in dichloroethane at 40 °C, b-aminoalcohols
4aa and 4ab were isolated with 52% ee and 66% ee, respec-
tively (entries 7 and 14).
have been studied and the results collected in Table 2. All
reactions were performed in dichloroethane using
10 mol % of catalyst 1. The ring-opening of 2,5-dihydro-
furan oxide 2a was realised with aniline 3c under the same
conditions as aromatic amines substituted by electrodonat-
ing groups (40 °C, 48 h) with total conversion and 42% ee
(Table 2, entries 1–3). In reactions involving epoxide 2a,
the highest ee (70%) was obtained with p-anisidine 3b while
o-anisidine 3a and aniline 3c afforded identical values.
Aminolysis with amine 3a of epoxide 2b with a N-Cbz
group included in the five-membered ring was first con-
ducted under the conditions optimised for the desymmetri-
sation of 2a. The b-aminoalcohol 4ba was obtained with
40% ee but conversion was not complete (entry 4). At a
higher temperature, a total conversion was observed with
unchanged enantioselectivity (entry 5). The reaction of
epoxide 2b with p-anisidine 3b afforded lower enantiomeric
excesses than with o-anisidine 3a at different temperatures
(entries 6–8), in contrast to that observed with epoxide
2a, including an oxygen atom in the cycle. Similarly the
ring-opening of 2b with aniline was achieved with very
low enantioselectivity (entry 9).
The presence of heteroatoms in the epoxide results in a
stronger coordination to the Lewis acid catalyst and reac-
tivity of the nucleophiles is decreased. The aminolyses of
2,5-dihydrofuran oxide 2a described above are thus per-
formed at higher temperatures than the similar ring-open-
ing of cyclopentene oxide.23 We next examined the
possibility of including other functions in the cycle of the
epoxide such as carbamates or ketals. Desymmetrisations
of various epoxides by o- and p-anisidine and by aniline
In order to improve the asymmetric induction of the
desymmetrisation of epoxides containing nitrogen func-
OH
10 mol% 1
O
O
.(THF)
Sm I
X
+
Ar NH2
X
O
Ar
CH2Cl2 or C2H4Cl2, MS 4A
N
H
1
4
2
3
(R)
a X = O
a Ar =
b Ar =
o
-MeO-C6H4
-MeO-C6H4
b X = N-Cbz
c X = N-Boc
p
c Ar = Ph
d X = N-Fmoc
e X = (O)2-C(Me)2
Scheme 1.

M. Martin et al. / Tetrahedron: Asymmetry 18 (2007) 2598–2605
2601
Table 2. Enantioselective aminolysis of epoxides 2 by aromatic amines catalysed by samarium complex 1
Entry
Epoxide
RNH2
Product
T (°C)
t (h)
Conversion (yield)a
eec (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
2a
2a
2a
2b
2b
2b
2b
2b
2b
2c
2c
2c
2c
2c
2d
2d
2e
2e
2e
2e
2e
3a o-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3c PhNH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3c PhNH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3c PhNH2
3a o-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3a o-MeO–C6H4–NH2
3b p-MeO–C6H4–NH2
4aa
4ab
4ac
4ba
4ba
4bb
4bb
4bb
4bc
4ca
4ca
4cb
4cb
4cc
4da
4db
4ea
4ea
4ea
4ea
4eb
40
40
40
40
80
40
60
80
80
80
60
80
60
60
60
60
25
40
60
80
40
40
48
48
48
48
48
20
48
48
20
65
20
40
48
72
72
72
40
18
18
40
100 (54)
100 (70)
100 (71)
72 (65)
100 (80)
100 (52)
59 (33)
100 (80)
90 (88)
100 (55)
100 (95)
100
100 (74)
100 (93)
(43)b
(47)b
100 (54)
100 (70)
100 (76)
100 (82)
100 (65)
41
68
42
40
43
17
12
10
16
54
58
37
47
42
29
0
15
26
21
18
13
a Conversion % (isolated yield %), reaction performed with 10% catalyst 1 and ratio 3/2: 1.2.
b Conversion could not be measured by 1H NMR of crude product.
c Configuration of the products, indicated in Section 4, have been determined by the comparison of the sign of the specific rotation with the literature or by
analogy.16b
tionalities, we tested substrate 2c with a different nitrogen
protecting group, such as Boc. With o- and p-anisidine,
the ring-opening reactions were performed at 60 °C and
80 °C and slightly higher excesses were found at 60 °C
(entries 10–13). The best values of the enantiomeric
excesses found for 4ca and 4cb were 58% and 47%, respec-
tively. As observed with the N-Cbz substituted epoxide, the
enantioselectivity is higher with o-anisidine than with
p-anisidine. Using aniline, aminolysis of 2c furnished
product 4ca with a total conversion and 42% ee at 60 °C
(entry 14). Substrate 2c with a more bulky N-protecting
group than 2b afforded higher enantiomeric excesses.
Epoxide 2d N-substituted with Fmoc as a bulkier protect-
ing group was therefore examined for the ring-opening
reactions with 3a and 3b. These reactions were achieved,
with low conversions, after three days at 60 °C, and a small
enantiomeric excess was observed for 4da, while 4db was
isolated in racemic form (entries 15 and 16). Comparison
of the aminolysis at 60 °C of epoxides containing N-Boc
and N-Fmoc groups (entries 11 and 15, 13 and 16) indi-
cated a diminution of the rates and the enantioselectivities
of the reactions with the latter. Since epoxide 2d is more
difficult to prepare and to purify than 2b and 2c we did
not conduct further investigations with this substrate.
Better asymmetric inductions have been found for the
aminolyses of N-Boc substituted epoxide 4c compared to
other carbamate derivatives and the highest enantiomeric
excess (58%) was obtained for the ring-opening with
o-anisidine. The only results reported so far for the enan-
tioselective aminolysis of epoxides with heterocycles using
a chiral niobium catalyst have provided higher levels of
enantioselectivity than catalyst 1 for epoxides 2a, 2b and
2c (78–81%). However, reactions were realised with aniline
as the sole amine and no reaction using aromatic amine
with easily deprotecting N-substituent was described.16b
We have also carried out the aminolysis of epoxide 2e
including a ketal function, which afforded the products
with good yields but low enantioselectivities at all
temperatures (entries 17–21). The best result was obtained
using o-anisidine at 40 °C.
The epoxides examined herein are far less active than cyclic
epoxides without a heteroatom in the ring since the latter
reactions have been achieved overnight at ꢀ40 °C with
total conversion. This is not surprising as the presence of
the heteroatom probably enhances the coordination to
samarium and lowers the reaction rate. More unexpected
is the behaviour with temperature of the desymmetrisation
of O and N-substituted cyclic epoxides by aromatic amines.
For simple cyclic epoxides, a dramatic influence of temper-
ature on the enantioselectivity has been observed with an
isoinversion effect.24 The temperature of inversion of
ꢀ40 °C which has been determined carefully for one reac-
tion, allowed us to obtain very high enantiomeric excesses
for various reactions involving similar epoxides and aro-
matic amines.23 In the present case, a small range of tem-
peratures is available and in general, no significant effect
of temperature on asymmetric induction has been noticed.
For the reaction leading to b-aminoalcohol 4aa, only the
variation of the enantiomeric excess with temperature
seems not monotonous with an isoinversion effect and ee
maximal at 40 °C. Optimal temperatures were further
determined for other reactions.
Herein we have succeeded in isolating several new
enantiomerically enriched b-aminoalcohols. Since these
molecules contain both heterocycles and easily remov-
able N-protecting groups,25 the reactions are a useful
tool for the direct preparation of various chiral
synthons.

2602
M. Martin et al. / Tetrahedron: Asymmetry 18 (2007) 2598–2605
3. Conclusion
weighed in a Schlenk tube and dichloroethane (5 mL)
was added. ortho-Anisidine 3b (74 mg, 0.6 mmol) was
added to the solution, which was stirred at room tempera-
ture for 15 min. Outside the glove box, the reaction was
heated at 40 °C and a solution of 2,5-dihydrofuran oxide
2a (43 mg, 0.5 mmol) in dichloroethane (1 mL) was then
added by syringe. After stirring at 40 °C for 48 h, the reac-
tion mixture was hydrolysed with 0.1 M HCl, diluted with
CH2Cl2 and neutralised with 0.1 M NaOH. The aqueous
layer was extracted with EtOAc. The crude product was
purified by preparative thin layer chromatography on silica
gel (heptane/EtOAc 50:50). The enantiomeric excess of 4aa
was determined by HPLC analysis as described below.
We have found that a samarium iodo binaphtholate cata-
lyses the desymmetrisation by aromatic amines of cyclic
meso-epoxides containing O and N functionalities leading
to new enantiomerically enriched heterocyclic b-amino-
alcohols with up to 70% ee. p-Anisidine afforded the high-
est enantioselectivity for an epoxide, containing an oxygen
as heteroatom while the reaction of N-Boc substituted
epoxide with o-anisidine gave the highest ee for the ring-
opening of epoxides including a nitrogen heterocycle. We
are currently working to improve the activity and enantio-
selectivity of the catalysts for the preparation of b-amino-
alcohols by aminolytic desymmetrisation of epoxides and
studying the synthetic applications of these reactions.
4.3. (1R,2R)-4-Oxa-2-(2-methoxyphenylamino)cyclo-
pentanol 4aa
20
4. Experimental
4.1. General
Oil. ½aꢁD ¼ þ7:9 (c 1.0, CHCl3) for 48% ee; IR (CaF2,
CHCl3) (cmꢀ1): m 3618, 3021, 2977, 1515, 1215, 1047; H
1
NMR (360 MHz, CDCl3): d 3.74 (1H, dd, J = 9.5 Hz,
J = 2.5 Hz), 3.77–3.80 (1H, m), 3.84 (3H, s, CH3), 3.81–
3.89 (1H, m, CH2), 4.04 (1H, dd, J = 10.1 Hz,
J = 4.4 Hz), 4.32 (2H, m), 6.72–6.81 (3H, m), 6.89–6.93
(1H, m); 13C NMR (75 MHz, CDCl3): d 55.3, 61.5, 72.5,
74.3, 75.9, 109.5, 110.4, 117.3, 121.2, 136.4, 146.8; HRMS
calcd for C11H15O3NNa (MNa+): 232.0944, found:
232.0949; HPLC (Welk O1 column, flow rate:
0.8 mL minꢀ1, hexane/ethanol 95:5, column temperature:
15 °C, k: 254 nm, tR(minor) = 24.9 min, tR(major) = 26.4 min).
All manipulations were carried out under an argon atmo-
sphere using standard Schlenk or glove box techniques.
Dichloromethane and dichloroethane were distilled from
CaH2 and degassed immediately prior to use. The method
for preparing samarium iodobinaphtholate had been previ-
ously described.23 All catalysts have been prepared from
enantiopure (R)-1,1-binaphthol. Epoxides 2a and 2b were
synthesised according to the literature procedures.26–28
The tert-butyl 6-oxa-3-aza-bicyclo[3.1.0]hexane-3-carbox-
ylate 2c was obtained by the reaction of commercially
available 3-pyrroline with t-butyl dicarbonate followed by
epoxidation. Epoxides and amines were distilled and
degassed or recrystallised prior to use.
4.4. (1R,2R)-4-Oxa-2-(4-methoxyphenylamino)cyclo-
pentanol 4ab
20
Mp: 130–132 °C. ½aꢁD ¼ þ8:1 (c 1.0, CHCl3) for 66% ee; IR
(CaF2, CHCl3) (cmꢀ1): m 3684, 3622, 3021, 2977, 2930,
1364, 1216, 1046; 1H NMR (360 MHz, CDCl3): d 3.67
(1H, dd, J = 9.6 Hz, J = 2.5 Hz), 3.76 (3H, s), 3.73–3.79
(1H, m), 3.82–3.86 (1H, m), 4.04 (1H, dd, J = 11.3 Hz,
J = 4.3 Hz), 4.24–4.29 (2H, m), 6.64 (2H, d, J = 9.0 Hz),
6.81 (2H, d, J = 8.8 Hz); 13C NMR (75 MHz, CDCl3): d
55.7, 62.6, 72.5, 74.5, 76.0, 114.6, 115.0, 140.5, 152.6;
HRMS (EI) calcd for C11H15O3N (M): 209.1046, found:
209.1054; HPLC (Chiralpak AD column, flow rate:
1H and 13C NMR spectra were recorded on Bruker AM
360, AM 300 and AM 250 spectrometers, operating at
360, 300 and 250 MHz for 1H and at 90.6, 75 and
62.5 MHz for 13C in CDCl3. Chemical shifts for H and
1
13C spectra were referenced internally according to the
residual solvent resonances and reported in ppm relative
1
to CDCl3 (7.27 ppm for H and 77 ppm for 13C). Infrared
spectra were recorded on a Perkin Elmer 1000 FT-IR spec-
trometer as KBr disks or in CHCl3 solution using CaF2
cells and reported in cmꢀ1. High resolution mass spectra
were measured on a Finnigan MAT 95 S spectrometer or
at 70 eV (EI) with a Trace DSQ Thermo Electron spec-
trometer. Optical rotations were measured by using a Per-
kin Elmer 241 polarimeter at room temperature in a cell of
0.5 mL minꢀ1
tR(major) = 37.4 min, tR(minor) = 42.6 min).
, hexane/isopropanol 90:10, k: 254 nm,
4.5. (1R,2R)-4-Oxa-2-phenylaminocyclopentanol 4ac
20
Mp: 102–104 °C. ½aꢁD ¼ þ11:0 (c 0.7, CHCl3) for 44% ee,
20
1 dm length at the sodium D line (k = 589 nm) and were re-
lit.16b ½aꢁD ¼ þ27:4 (c 0.54, CHCl3) for 75% ee; HPLC
20
ported as follows: ½aꢁD (c in g per 100 mL, CHCl3). HPLC
(Chiralcel OJ column, flow rate: 0.7 mL minꢀ1, hexane/iso-
analyses were performed on a Thermo Separation Product
Pompe P100 with an UV detector and chiral stationary-
phase columns (Whelk O1, Chiralcel OD-H or Chiralcel
OJ, Chiralpak AD or Chiralpak IA). All the crude prod-
ucts were purified by preparative thin layer chromatogra-
phy on silica gel 60 PF254 (heptane/ethyl acetate 50:50).
propanol
tR(minor) = 15.3 min).
75:25,
k:
254 nm,
tR(major) = 13.1 min,
4.6. (3R,4R)-Benzyl 3-hydroxy-4-(2-methoxyphenyl-
amino)pyrrolidine-1-carboxylate 4ba
20
Oil. ½aꢁD ¼ þ12:1 (c 1.0, CHCl3) for 43% ee; IR (CaF2,
4.2. Typical procedure for the aminolysis of epoxides
CHCl3) (cmꢀ1): m 3616, 3425, 3021, 2976, 1693, 1603,
1515, 1456, 1428, 1358, 1207; 1H NMR (250 MHz, CDCl3):
In the glove box, samarium iodo binaphtholate 1 (32.5 mg,
0.05 mmol) and molecular sieves 4 A (100 mg) were
d
3.37–3.55 (2H, m), 3.71 (1H, dd, J = 12.0 Hz,
˚
J = 4.4 Hz), 3.83 (3H, s), 3.89–3.97 (2H, m), 4.26–4.30

M. Martin et al. / Tetrahedron: Asymmetry 18 (2007) 2598–2605
2603
(2H, m), 5.16 (2H, s), 6.70–6.94 (4H, m), 7.28–7.44 (5H,
m); 13C NMR (62.5 MHz, CDCl3, rotamers): d 50.4,
50.7, 51.9, 52.3, 55.7, 58.6, 59.1, 67.0, 73.0, 73.8, 109.5,
110.1, 117.4, 121.1, 127.8, 128.4, 136.1, 136.4, 146.7,
155.2; HRMS calcd for C19H22O4N2Na (MNa+):
365.1472, found: 365.1469; HPLC (Chiralpak AD column,
flow rate: 0.8 mL minꢀ1, hexane/isopropanol 85:15, k:
254 nm, tR(minor) = 16.4 min, tR(major) = 20.6 min).
152.6, 154.8; MS (ESI) m/z: 331.1 (MNa+, 100%); HPLC
(Chiralpak IA column, flow rate: 0.5 mL minꢀ1, hexane/
isopropanol 95:5, k: 254 nm, tR(minor) = 44.7 min,
tR(major) = 47.6 min).
4.11. (3R,4R)-tert-Butyl 3-hydroxy-4-(phenylamino)pyrroli-
dine-1-carboxylate 4cc
20
Mp: 144–147 °C. ½aꢁD ¼ þ12:5 (c 0.82, CHCl3) for 42% ee,
20
4.7. (3R,4R)-Benzyl 3-hydroxy-4-(4-methoxyphenyl-
amino)pyrrolidine-1-carboxylate 4bb
lit.16b ½aꢁD ¼ þ19:3 (c 1.72, CHCl3) for 89% ee; HPLC
(Chiralcel OD-H column, flow rate: 0.7 mL minꢀ1, hex-
ane/isopropanol 75:25, k: 254 nm, tR(minor) = 8.4 min,
tR(major) = 10.7 min).
20
Mp: 129–132 °C. ½aꢁD ¼ þ3:0 (c 1.0, CHCl3) for 10 ee%; IR
(CaF2, CHCl3) (cmꢀ1): m 3684, 3622, 3019, 2977, 1699,
1
1514, 1424, 1211, 1046; H NMR (250 MHz, CDCl3): d
4.12. 9H-Fluoren-9-ylmethyl 3-hydroxy-4-(2-methoxy-
phenyl-amino)pyrrolidine-1-carboxylate 4da
3.34–3.54 (2H, m), 3.75 (3H, s), 3.68–3.85 (2H, m), 3.86–
3.98 (1H, m), 4.24–4.33 (1H, m), 5.15 (2H, s), 6.61 (2H,
d, J = 8.6 Hz), 6.80 (2H, d, J = 8.6 Hz), 7.29–7.42 (5H,
m); 13C NMR (62.5 MHz, CDCl3, rotamers): d 50.3,
50.7, 51.9, 52.3, 55.7, 59.6, 60.2, 67.0, 73.1, 73.9, 114.7,
115.0, 127.9, 128.0, 128.5, 136.5, 140.2, 152.8, 155.2;
HRMS calcd for C19H22O4N2Na (MNa+): 365.1472,
found: 365.1473; HPLC (Chiralcel OD-H column, flow
rate: 0.8 mL minꢀ1, hexane/ethanol 85:15, k: 254 nm,
tR(major) = 24.1 min, tR(minor) = 28.1 min).
Mp: 129–132 °C. IR (KBr) (cmꢀ1): m 3422, 2926, 1674,
1
1603, 1513, 1448, 1425, 1349, 1223, 1116, 737; H NMR
(360 MHz, CDCl3): d 3.35–3.59 (2H, m), 3.68–3.79 (1H,
m), 3.85 (3H, s), 3.80–4.05 (2H, m), 4.19–4.30 (1H, m),
4.31–4.57 (3H, m), 6.64–6.97 (4H, m), 7.25–7.50 (4H, m),
7.53–7.69 (2H, m), 7.72–7.88 (2H, m); 13C NMR
(90.6 MHz, CDCl3, rotamers): d 47.3, 50.3, 50.7, 52.0,
52.4, 55.4, 58.7, 59.2, 67.4, 73.3, 74.1, 109.7, 110.2, 117.6,
119.9, 121.2, 125.1, 127.0, 127.7, 136.1, 141.3, 143.9,
146.8, 155.2; HRMS calcd for C26H26O4N2Na (MNa+):
453.1785, found: 453.1803; HPLC (Chiralpak IA column,
flow rate: 0.8 mL minꢀ1, hexane/isopropanol 75:25, k:
254 nm, tR(minor) = 12.0 min, tR(major) = 20.1 min).
4.8. (3R,4R)-Benzyl 3-hydroxy-4-(phenylamino)pyrrolidine-
1-carboxylate 4bc
20
Mp: 109–112 °C. ½aꢁD ¼ þ5:1 (c 1.0, CHCl3) for 16% ee,
20
lit.16b ½aꢁD ¼ þ16:9 (c 1.67, CHCl3) for 87% ee; HPLC
(Chiralcel OD-H column, flow rate: 0.8 mL minꢀ1, hex-
ane/ethanol 75:25, k: 254 nm, tR(minor) = 9.4 min,
tR(major) = 10.8 min).
4.13. 9H-Fluoren-9-ylmethyl 3-hydroxy-4-(4-methoxy-
phenyl-amino)pyrrolidine-1-carboxylate 4db
Mp: 106–110 °C. IR (KBr) (cmꢀ1): m 3355, 2946, 1671,
1513, 1452, 1350, 1243, 1124, 758, 740; 1H NMR
(360 MHz, CDCl3): d 3.26–3.56 (2H, m), 3.63–3.98 (3H,
m), 3.76 (3H, s), 4.18–4.34 (2H, m), 4.36–4.51 (2H, m),
6.56–6.69 (2H, d, J = 8.8 Hz), 6.72–6.88 (2H, m), 7.23–
7.48 (4H, m), 7.52–7.67 (2H, m), 7.69–7.85 (2H, m); 13C
NMR (90.6 MHz, CDCl3, rotamers): d 47.3, 50.3, 50.6,
51.9, 52.3, 55.8, 59.6, 60.2, 67.3, 73.1, 74.0, 114.7, 115.0,
119.9, 125.0, 127.0, 127.7, 140.2, 141.3, 143.9, 152.8,
155.1; HRMS calcd for C26H26O4N2Na (MNa+):
453.1785, found: 453.1798; HPLC (Chiralpak IA column,
flow rate: 0.8 mL minꢀ1, hexane/isopropanol 75:25, k:
254 nm, tR(minor) = 14.5 min, tR(major) = 18.8 min).
4.9. (3R,4R)-tert-Butyl 3-hydroxy-4-(2-methoxyphenyl-
amino)pyrrolidine-1-carboxylate 4ca
20
Mp: 123–126 °C. ½aꢁD ¼ þ11:4 (c 1.0, CHCl3) for 58% ee;
IR (KBr) (cmꢀ1): m 3478, 2945, 1682, 1601, 1513, 1413,
1
1233, 1161, 1120, 1024, 742; H NMR (300 MHz, CDCl3):
d 1.48 (9H, s), 3.26–3.50 (2H, m), 3.58–3.71 (1H, m), 3.73–
3.98 (2H, m), 3.84 (3H, s), 4.21–4.33 (1H, m), 6.68–6.88
(4H, m); 13C NMR (62.5 MHz, CDCl3, rotamers): d 28.5,
50.1, 50.5, 51.7, 52.3, 55.3, 58.7, 59.0, 73.0, 73.8, 79.8,
109.5, 110.1, 117.2, 121.2, 136.3, 146.7, 154.9; HRMS calcd
for C16H24O4N2 (M): 308.1731, found: 308.1725; HPLC
(Chiralpak IA column, flow rate: 0.5 mL minꢀ1, hexane/
isopropanol 85:15, k: 254 nm, tR(minor) = 13.1 min,
tR(major) = 14.2 min).
4.14. 2,2-Dimethyl-6-(2-methoxyphenylamino)-1,3-dioxe-
pan-5-ol 4ea
20
4.10. (3R,4R)-tert-Butyl 3-hydroxy-4-(4-methoxyphenyl-
amino)pyrrolidine-1-carboxylate 4cb
Oil. ½aꢁD ¼ þ4:7 (c 1, CHCl3) for 26% ee; IR (CaF2,
CHCl3) (cmꢀ1): m 3620, 3568, 3434, 2976, 2944, 1602,
1515, 1457, 1430; 1H NMR (250 MHz, CDCl3): d 1.41
(6H, s), 3.45–3.72 (4H, m), 3.86 (3H, s), 3.92–4.07 (2H,
m), 6.60–6.96 (4H, m); 13C NMR (75 MHz, CDCl3): d
24.5, 55.4, 56.4, 59.9, 61.2, 69.4, 101.8, 109.7, 110.1,
116.7, 121.2, 136.1, 146.7; HRMS (EI) calcd for
C14H21O4N (M): 267.1465, found: 267.1460; HPLC
(Chiralpak IA column, flow rate: 0.6 mL minꢀ1, hexane/
20
Mp: 103–106 °C. ½aꢁD ¼ þ7:5 (c 0.94, CHCl3) for 47% ee;
IR (KBr) (cmꢀ1): m 3385, 3338, 2975, 2923, 1685, 1662,
1
1515, 1424, 1246, 1122; H NMR (300 MHz, CDCl3): d
1.47 (9H, s), 3.21–3.42 (2H, m), 3.62–3.65 (1H, m), 3.75
(3H, s), 3.74–3.97 (2H, m), 4.24 (1H, br s), 6.61 (2H, d,
J = 8.7 Hz), 6.79 (2H, d, J = 8.7 Hz); 13C NMR
(75 MHz, CDCl3, rotamers): d 28.4, 50.1, 50.5, 51.7, 52.0,
55.7, 59.7, 60.2, 73.2, 73.9, 79.8, 114.6, 114.9, 140.5,
isopropanol 90:10, k: 254 nm, tR(minor)
tR(major) = 13.8 min).
=
12.9 min,

2604
M. Martin et al. / Tetrahedron: Asymmetry 18 (2007) 2598–2605
Karl, J.; Jacobsen, E. N. J. Am. Chem. Soc. 1998, 120, 10780–
10781.
4.15. 2,2-Dimethyl-6-(4-methoxyphenylamino)-1,3-dioxe-
pan-5-ol 4eb
9. (a) Fu, X. L.; Wu, S. H. Synth. Commun. 1997, 27, 1677–
1683; (b) Hou, X. L.; Wu, J.; Dai, L. X.; Xia, L. J.; Tang, M.
H. Tetrahedron: Asymmetry 1998, 9, 1747–1752.
10. Kobayashi, S.; Ishitani, H.; Hachiya, I.; Araki, M. Tetrahe-
dron 1994, 50, 11623–11636.
11. Sekine, A.; Oshima, T.; Shibasaki, M. Tetrahedron 2002, 58,
75–82.
12. (a) Schneider, C.; Sreekanth, A. R.; Mai, E. Angew. Chem.,
Int. Ed. 2004, 43, 5691–5694; (b) Mai, E.; Schneider, C. Chem.
Eur. J. 2007, 2729–2741; (c) Mai, E.; Schneider, C. Synlett
2007, 2136–2138.
20
Oil. ½aꢁD ¼ þ6:8 (c 0.68, CHCl3) for 13% ee; IR (CaF2,
CHCl3) (cmꢀ1): m 3650, 3616, 3564, 3430, 2945, 2902,
1618, 1513, 1465, 1386, 1286; 1H NMR (300 MHz, CDCl3):
d 1.38 (6H, s), 3.30–3.40 (1H, m), 3.48–3.62 (2H, m), 3.66–
3.76 (1H, m), 3.74 (3H, s), 3.95 (2H, dd, J = 30.1 Hz,
J = 12.4 Hz), 6.62 (2H, d, J = 8.6 Hz), 6.78 (2H, d,
J = 8.6 Hz); 13C NMR (75 MHz, CDCl3): d 24.6, 55.8,
57.7, 59.8, 61.2, 69.6, 101.8, 114.3, 115.1, 140.4, 152.1;
HRMS (EI) calcd for C14H21O4N (M): 267.1465, found:
267.1459; HPLC (Chiralcel OD-H column, flow rate:
13. Azoulay, S.; Manabe, K.; Kobayashi, S. Org. Lett. 2005, 7,
4593–4595.
14. Sagawa, S.; Abe, H.; Hase, Y.; Inaba, T. J. Org. Chem. 1999,
64, 4962–4965.
0.5 mL minꢀ1
tR(major) = 46.4 min, tR(minor) = 55.7 min).
,
hexane/isopropanol 98/2, k: 254 nm,
15. (a) Kureshy, R. I.; Singh, S.; Khan, N. H.; Abdi, S. H. R.;
Suresh, E.; Jasra, R. V. Eur. J. Chem. 2006, 1303–1309; (b)
Kureshy, R. I.; Singh, S.; Khan, N. H.; Abdi, S. H. R.;
Agrawal, S.; Jasra, R. V. Tetrahedron Lett. 2006, 47, 5277–
5279.
16. (a) Arai, K.; Salter, M. M.; Yamashita, Y.; Kobayashi, S.
Angew. Chem., Int. Ed. 2007, 46, 955–957; (b) Arai, K.;
Lucarini, S.; Salter, M. M.; Yamashita, Y.; Kobayashi, S. J.
Am. Chem. Soc. 2007, 129, 8103–8111.
Acknowledgements
We thank CNRS for financial support and MENERS for
PhD Grant for M.M.
17. Larrow, J. F.; Schaus, S. E.; Jacobsen, E. N. J. Am. Chem.
Soc. 1996, 118, 7420–7421.
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