Asymmetric epoxidation of substituted chalcones and chalcone analogues catalyzed by α-d-glucose- and α-d-mannose-based crown ethers

Article abstract of DOI:10.1016/j.tetasy.2010.05.009

The chiral monoaza-15-crown-5 lariat ethers annellated to methyl-4,6-O-benzylidene-α-d-glucopyranoside-1 or mannopyranoside 2 have been applied as phase-transfer catalysts in the epoxidation of substituted chalcones and chalcone analogues with tert-butylhydroperoxide resulting in significant asymmetric induction. It was found that the position of the substituents in the aromatic ring of the chalcone had an influence both on the chemical yields and enantiomeric excesses. The lowest enantioselectivities (62-83% ee) were found in the case of ortho-substituted model compounds. The highest ee values (ee of 83-97%) were obtained in the case of para-substituted models. From among the chalcone analogues, the maximum ee (90-92%) was detected for the model compound having α-tert-butyl- and β-aryl groups. Using glucose-based crown ether 1, formation of the (-)-enantiomer was preferred, while applying mannose-based 2 as the catalyst, the (+)-enantiomer was in excess.

Full text of DOI:10.1016/j.tetasy.2010.05.009

Tetrahedron: Asymmetry 21 (2010) 919–925
Contents lists available at ScienceDirect
Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
Asymmetric epoxidation of substituted chalcones and chalcone analogues
catalyzed by
a-D-glucose- and a-D-mannose-based crown ethers
a
a
a
b
c
d
}
}
Attila Makó , Zsolt Rapi , György Keglevich , Áron Szöllosy , László Drahos , László Hegedus ,
Péter Bakó a,
*
a Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, PO Box 91, 1521 Budapest, Hungary
b Department of Inorganic and Analytical Chemistry, H-1525 Budapest, Hungary
c Chemical Research Institute for Chemistry, Hungarian Academy of Sciences, H-1525 Budapest, Hungary
d Research Group for Organic Chemical Technology, Hungarian Academy of Sciences, Department of Organic Chemistry and Technology, Budapest University of Technology
and Economics, Budafoki út 8, H-1111 Budapest, Hungary
a r t i c l e i n f o
a b s t r a c t
Article history:
The chiral monoaza-15-crown-5 lariat ethers annellated to methyl-4,6-O-benzylidene-a-D-glucopyrano-
Received 29 March 2010
Accepted 11 May 2010
Available online 11 June 2010
side-1 or mannopyranoside 2 have been applied as phase-transfer catalysts in the epoxidation of substi-
tuted chalcones and chalcone analogues with tert-butylhydroperoxide resulting in significant
asymmetric induction. It was found that the position of the substituents in the aromatic ring of the chal-
cone had an influence both on the chemical yields and enantiomeric excesses. The lowest enantioselec-
tivities (62–83% ee) were found in the case of ortho-substituted model compounds. The highest ee values
(ee of 83–97%) were obtained in the case of para-substituted models. From among the chalcone ana-
logues, the maximum ee (90–92%) was detected for the model compound having a-tert-butyl- and b-aryl
groups. Using glucose-based crown ether 1, formation of the (ꢀ)-enantiomer was preferred, while apply-
ing mannose-based 2 as the catalyst, the (+)-enantiomer was in excess.
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
phase-transfer conditions.4 Later on, a variety of cinchonine or
quinidine alkaloid derivatives were used as catalysts in the reaction
Chiral epoxides are well known as valuable building blocks
which can be potential intermediates and precursors in the prepa-
ration of more complex enantiomerically pure bioactive com-
pounds.1 This explains the great interest in the enantioselective
synthesis of chiral epoxides. A variety of methods have been devel-
oped particularly for the enantioselective epoxidation of electron-
under discussion.5 Similarly, a well established and no less success-
ful is the Julia–Colonna method applying a polyamino acid.6 During
the epoxidation of chalcone the oxidant is NaOH/H2O2 used in the
presence of poly-L-leucine as the chiral inductor in a triphasic sys-
tem.7 It has been shown by us that beside chiral onium salts, mono-
saccharide-based chiral crown ethers are also suitable catalysts in
deficient olefins, such as
a
,b-unsaturated ketones. The epoxidation
the enantioselective epoxidation of a,b-enones by tert-butylhydro-
has been accomplished by homogeneous and heterogeneous cata-
lysts.2 One of the types of the heterogeneous methods is the chiral
phase-transfer catalytic (chiral PTC) reaction, which has been
increasingly useful for asymmetric synthesis, where there is no
need to use special conditions, such as inert atmosphere or dry
circumstances. The most common oxidants (NaOCl, NaOH/H2O2,
or NaOH/t-BuOOH) are readily available and allow a convenient
liquid–liquid phase realization of the reaction.3
peroxide.8 Recently, Hori et al. have applied quaternary ammonium
salts of azacrown ethers as chiral phase-transfer catalysts in the
asymmetric epoxidation of (E)-chalcone with alkaline hydrogen
peroxide.9
During the oxidation of chalcones by tert-butylhydroperoxide,
the glucopyranoside- and mannopyranoside-based monoaza-15-
crown-5 type lariat ethers containing a
c-hydroxypropyl side
arm on the nitrogen atom 1 and 2 were the most efficient phase-
transfer catalysts among the chiral macrocycles synthesized by
us (Fig. 1).8
The utility of chiral quaternary ammonium phase-transfer
catalysts for the asymmetric epoxidation of
a,b-unsaturated
ketones was pioneered by Wynberg et al., who demonstrated that
a quinine derivative was capable of promoting enantioselective
Weitz–Scheffer epoxidation of chalcones under liquid–liquid
Herein, the asymmetric epoxidation of chalcones and chalcone
analogues is described. The epoxidation of a few substituted chal-
cones was investigated in the presence of the modified cinchona
alkaloides,5b,10a dihydrocinchonidine derivatives,5e,10b polyethyl-
ene glycol-supported cinchona ammonium salts,10c quaternary
ammonium salts containing a chiral binaphthyl unit,10d and poly-
* Corresponding author. Fax: +36 1 463 3648.
E-mail address: pbako@mail.bme.hu (P. Bakó).
0957-4166/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2010.05.009

920
A. Makó et al. / Tetrahedron: Asymmetry 21 (2010) 919–925
OCH3
OCH3
O
O
O
O
O
O
O
O
N
(CH2)3OH
N
(CH2)3OH
O
O
O
O
O
O
1
2
Figure 1.
L
-leucine10e as the phase-transfer catalysts. The epoxidation of
Table 1
Asymmetric epoxidation of chalcone with different Ar1 substituent in the presence of
chalcone analogues (a,b-enones) was accomplished in the pres-
chiral crown ether 1 at 0–2 °C
ence of quaternary ammonium salts derived from cinchoni-
dine.5b,10f In the present study, the effect of substituents on the
chalcone is studied in the presence of glucose-based crown ether
1. Then the role of steric and electronic factors with regard to the
enone substrate 3 is examined, in order to evaluate their role on
the asymmetric epoxidation.
O
O
Ar1
S
R
b
Entry Product Ar1
Time (h) Yielda (%)
[
a
]
D
eec (%)
948b
2. Results and discussion
1
2
4
5
Ph
1
3
2
2
4
2
2
8
2
3
1
1
2
82
65
68
71
72
90
81
69
77
58
66
55
63
ꢀ196
2-Cl–C6H4
ꢀ121.2 69
ꢀ168.1 79
ꢀ182.4 97
In our experiments, the epoxidation of chalcones with tert-
butylhydroperoxide (TBHP, 2 equiv) was carried out in a liquid–
liquid two-phase system employing toluene and 20% aq NaOH
(3.5 equiv) as the base and 7 mol % of chiral crown catalyst at a
temperature of 0–2 °C (Scheme 1). In most cases, the reactions
were complete after 1–10 h. After the usual work-up procedure,
the product was isolated by preparative TLC. The asymmetric
induction, expressed in terms of the enantiomeric excess (ee%),
was determined by 1H NMR spectroscopy using (+)-Eu(hfc)3 as a
chiral shift reagent. The trans epoxyketones were obtained in all
experiments with a high diastereoselectivity (de >98%).
3
6
3-Cl–C6H4
4
7
4-Cl–C6H4
5
6
7
8
8
9
2-CH3–C6H4
3-CH3–C6H4
4-CH3–C6H4
2-CH3O–C6H4
3-CH3O–C6H4
4-CH3O–C6H4
2-NO2–C6H4
3-NO2–C6H4
4-NO2–C6H4
ꢀ167
71
ꢀ188.1 87
ꢀ203.3 92
10
11
12
13
14
15
16
ꢀ98.5
84
9
ꢀ199.4 88
10
11
12
13
ꢀ199.5 95
ꢀ285
80
ꢀ146.6 >99
ꢀ122.6 96
a
b
c
Based on isolation by preparative TLC.
In CH2Cl2 at 22 °C.
Determined by 1H NMR spectroscopy in the presence of Eu(hfc)3 as the chiral
crown catalyst
t-BuOOH
O
O
shift reagent.
O
*
Ar1
Ar2
Ar1
Ar2
20 % NaOH
toluene
12). It can be concluded that the substituents in the aromatic ring
influence the extent of asymmetric induction depending on their
position. With the exception of the nitro series 14–16, the ten-
dency is that the further the substituent is located from the car-
bonyl group, the higher the ee value is. The maximum ee values
were obtained for the para-substituted cases 7, 10, and 13.
*
Scheme 1. Asymmetric epoxidation of a
,b-enones (Ar1 and Ar2 listed in Tables 1–
4).
At first, the effect of substituents in the aromatic ring (Ar1) next
to the carbonyl group was studied keeping Ar2 as a phenyl substi-
tuent. The results of the epoxidation are shown in Table 1.
In the next experiments, the substituents of the b-phenyl group
(Ar2) of the chalcone were varied. Results of the enantioselectivity
of the epoxidation carried out in the presence of catalyst 1 are
listed in Table 2. The chlorophenyl epoxyketones 17–19 isolated
in 74–88% yield were obtained in ee values of 75–83%. For the 2-
chlorophenyl-, 3-chlorophenyl-, and 4-chlorophenyl cases, ee val-
ues of 75%, 82%, and 83%, respectively, were recorded, with good
chemical yields (Table 2, entries 2–4). The trend was quite similar
for the epoxidation of the methylphenyl chalcones: the 2-methyl-
phenyl-, 3-methylphenyl-, and 4-methylphenyl products 20–22
were formed with 76%, 85%, and 86% ee values (Table 2, entries
5–7). A similar tendency can be seen for the methoxyphenyl deriv-
atives: the 2-methoxyphenyl-, 3-methoxyphenyl-, and 4-methoxy-
phenyl products 23–25 were obtained in 62%, 82%, and 85% ee
value, respectively (Table 2, entries 8–10). In the nitro-substituted
cases, the presence of the electron-withdrawing substituents 26–
28 caused a dramatic change: both the chemical yields and enan-
tiomeric excesses were lower, as compared to the previous cases.
For the 2-nitrophenyl-, 3-nitrophenyl-, and 4-nitrophenyl cases
26–28, 14%, 21%, and 63% ee values, respectively, were obtained
As a comparison, the earlier result for the epoxidation of unsub-
stituted chalcone has also been included. (Table 1, entry 1).8b The
chlorophenyl epoxyketones 5–7 obtained in 65–71% yield were
formed in increasing ee in the following order according to the po-
sition of the chloro-substituent: the 2-chlorophenyl-, 3-chloro-
phenyl-, and 4-chlorophenyl products were obtained in an ee of
69%, 79%, and 97%, respectively (Table 1, entries 2–4). In the elec-
tron-donating methyl-substituent cases, the products 8–10 were
obtained in better yields (72–90%) and the ee values increased in
the same order, as in the previous case (71%, 87%, and 92%, respec-
tively) (Table 1, entries 5–7). A similar trend was experienced in
the case of methoxy-substituents 11–13. In the presence of catalyst
1, the yields were 58–77%, while the ee values were in the range of
84–95% (Table 1, entries 8–10). The para-methoxy derivative (13)
was formed in the highest ee (95%). In the electron-withdrawing
nitro-substituted cases, the epoxyketones 14–16 were obtained
in 55–66% yield with high (80–99%) ee values. In these instances,
the 3-nitro derivative 15 was formed >99% ee value. (Table 1, entry

A. Makó et al. / Tetrahedron: Asymmetry 21 (2010) 919–925
921
Table 2
may prevent the asymmetric induction as compared to the epoxi-
dation of unsubstituted chalcone 4. As the substituents get further
from the reaction centrum (as in the meta- and para-substituted
models) the extent of the steric effect becomes less significant. In
the para-substituted models 19, 22, 25, and 26 there is practically
no steric effect, although in these cases the ee values are somewhat
below the ee of 94% detected for the unsubstituted chalcone. This
can be seen well for the nitro-substituted models: as the nitro-
group gets further from the reaction center, the enantiomeric ex-
cess increases from 14% to 63%.
The disubstituted halogen derivatives 29–31 were formed in a
wide range of enantioselectivity: in the case of 2,4-dichloro-
phenyl-29, 2,6-dichlorophenyl-30, and 2-chloro-6-fluorophenyl
epoxyketones ee values of 99%, 70%, and 24%, respectively, were
obtained. Besides the steric effects of the substituents, the elec-
tronic properties are also prevailing as is shown by the comparison
of compounds 30 and 31: the ee value of 70% obtained for 2,6-di-
chloro derivative 30 decreased to an ee of 24% in case one of the
chloro atoms was replaced by a fluoro atom as in 31.
Asymmetric epoxidation of chalcone with different Ar2 substituents in the presence of
chiral crown ether 1 at 0–2 °C
O
O
S
Ar2
R
Entry Product Ar2
Time (h) Yielda (%)
[a]
D
eec (%)
948b
b
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
4
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Ph
1
2
2
2
4
2
2
4
3
2
2
1
1
2
2
2
82
74
88
78
75
79
88
49
78
79
55
59
52
50
60
54
ꢀ196
2-Cl–C6H4
3-Cl–C6H4
4-Cl–C6H4
ꢀ7.4 75
ꢀ196.4 82
ꢀ209.5 83
ꢀ75.7 76
ꢀ201.1 85
ꢀ183.9 86
ꢀ63.4 62
ꢀ203.8 82
ꢀ175.1 85
ꢀ30.8 14
2-CH3–C6H4
3-CH3–C6H4
4-CH3–C6H4
2-CH3O–C6H4
3-CH3O–C6H4
4-CH3O–C6H4
2-NO2–C6H4
3-NO2–C6H4
4-NO2–C6H4
2,4-DiCl–C6H3
2,6-DiCl–C6H3
2-Cl-6-F–C6H3
ꢀ68
21
In all cases, the (2R,3S)-enantiomer with a negative specific
rotation was formed in excess.10e There was only one exception,
the 2,6-dichloro derivative 30 was formed with the predominance
of the enantiomer with positive specific rotation.
ꢀ152.6 63
ꢀ47.1 99
+48.3 70
ꢀ20
24
a
b
c
Based on isolation by preparative TLC.
Table 3 includes the results of the epoxidation of a few a,b-
enones (chalcone analogues). In the first cases the effect of the Y1
moiety (with Y2 = Ph) was studied. In the instance of benzylidene-
acetone (Y1 = Me) there was no reaction (Table 3, entry 2). Replac-
ing the Me group by But, epoxyketone 33 was, however, obtained
in good yield and with an ee of 90% (Table 3, entry 3). It is interest-
ing to compare the results obtained for the 1 and 2-naphthyl-
substituted models: product 34 was obtained in 64% yield and in
an ee of 67%, while epoxyketone 35 was formed in low yield and
in an ee of 87% (Table 3, entries 4 and 5). Then the Y2 moiety
was changed as shown by entries 6–9 of Table 3 (Y1 = Ph). Product
36 (Y2 = Me) was obtained with an ee value of 55%. The replace-
ment of the Me group by But resulted in a decreased ee value of
34% and the enantiomer with positive specific rotation was formed
in excess (Table 3, entry 7). In this case, the sterically demanding
substituent in the proximity of the reaction center may prevent
an efficient asymmetric induction. The 1- and 2-naphthyl-epoxy-
ketones 38 and 39 were formed in an ee value of 83% and 66%,
respectively (Table 3, entries 8 and 9). In the latter cases again
the relevance of steric effects may be deduced. Finally, in the case
of Y2 = 1- and 2-naphthyl with Y1 = But, the corresponding prod-
ucts 40 and 41 were formed in 85% and 92% ee, respectively
In CH2Cl2 at 22 °C.
Determined by 1H NMR spectroscopy in the presence of Eu(hfc)3 as the chiral
shift reagent.
(Table 2, entry 11–13). It can be seen from the data of Table 2 that
the substituents of the b-phenyl ring prevent the asymmetric
induction to a greater extent than those of the other phenyl ring:
products 17–28 were obtained in lower enantioselectivities than
epoxyketones 5–16 (for these latter data see Table 1). It is also
clear that independent of the electronic effect, position of the sub-
stituent in the b-aryl ring plays also a significant role in the asym-
metric induction presumably due to steric effects. The
enantioselectivity is the lowest for ortho-substituted models 17,
20, 23, and 26 and the highest (83%, 86%, 85%, and 63%) for the
para-substituted cases 19, 22, 25, and 28. The meta-substituted
epoxyketones 18, 21, 24, 27 were obtained in intermediate ee val-
ues. The reason for this experience is clear if the first step of the
oxidation that is the attack of the hydroperoxy anion (the nucleo-
philic addition of the peroxy anion) on the b-carbon atom of the
chalcone is considered as the configuration determining step.8c It
is probable that the ortho-substituents close to this reaction center
Table 3
Asymmetric epoxidation of chalcone analogues catalyzed by chiral crown ether 1 at 0–2 °C
O
O
Y1
*
Y2
*
b
Entry
Product
Y1
Y2
Time (h)
Yielda (%)
[
a
]
D
eec (%)
1
2
3
4
5
6
7
8
9
4
32
33
34
35
36
37
38
39
40
41
Ph
Ph
Ph
Ph
Ph
1
20
16
10
3
6
18
9
82
—
ꢀ196
—
94
—
CH3
But
86
64
30
60
53
68
33
60
52
ꢀ239.3
ꢀ188.4
ꢀ137.7
ꢀ3.4
90
67
87
55
34
83
66
85
92
1-Naphthyl
2-Naphthyl
Ph
Ph
Ph
Ph
Ph
But
But
CH3
But
+9.2
1-Naphthyl
2-Naphthyl
1-Naphthyl
2-Naphthyl
ꢀ167
ꢀ61.6
ꢀ47.8
ꢀ253.2
6
12
12
10
11
a
b
c
Based on isolation by preparative TLC.
In CH2Cl2 at 22 °C.
Determined by 1H NMR spectroscopy in the presence of Eu(hfc)3 as the chiral shift reagent.

922
A. Makó et al. / Tetrahedron: Asymmetry 21 (2010) 919–925
Table 4
Asymmetric epoxidation of substituted chalcones and chalcone analogues catalyzed by chiral crown ether 2 at 0–2 °C
O
O
Ar1
Ar2
*
*
b
Entry
Product
Ar1
Ar2
Time (h)
Yielda (%)
[a
]
D
eec (%)
1
2
3
4
5
6
7
4a
7a
Ph
Ph
Ph
Ph
8
3
4
3
2
47
70
57
72
75
80
61
+171.4
+167.1
+176.8
+194.7
+160.5
+221.1
+174.3
828b
89
86
77
78
4-Cl–C6H4
4-CH3O–C6H4
Ph
13a
19a
25a
33a
34a
4-Cl–C6H4
4-CH3O–C6H4
Ph
Ph
Ph
But
8
10
83
62
1-Naphthyl
a
b
c
Based on isolation by preparative TLC.
In CH2Cl2 at 22 °C.
Determined by 1H NMR spectroscopy in the presence of Eu(hfc)3 as the chiral shift reagent.
(Table 3, entries 10 and 11). It can be seen that the best enantio-
meric excesses were obtained for the models with Y1 = But and
Y2 = Ph, as product 33 or Y2 = 2-naphthyl as in product 41.
A few experiments were also carried out using the related, but
mannopyranozide-based, catalyst 2. The results are listed in
Table 4.
Comparing the data obtained for products 7a, 13a, 19a, 25a, 33a,
and 34a with those measured in the presence of the glucose-based
catalyst 1 (Table 1–3), the following tendencies can be seen. In the
case of catalyst 2, both the chemical yields and enantiomeric ex-
cesses are somewhat lower. The main difference is that while the
glucose-based catalyst 1 results in most cases the formation of the
enantiomer with negative specific rotation in excess that is the anti-
pode with (2R,3S)-configuration, the mannose-based catalyst 2 pro-
motes the predominant formation of the enantiomer with positive
specific rotation. The reason for this may be that already in the first
step of the epoxidation of the chalcone, transient complexes of dif-
ferent types are formed with crown ethers 1 and 2.8c
241 polarimeter at 22 °C. 1H and 13C NMR spectra were recorded
on a Bruker 300 and a Bruker DRX-500 or a Varian Inova 500
instrument in CDC13 with TMS as the internal standard. Analytical
and preparative thin layer chromatography was performed on sil-
ica gel plates (60 GF-254, Merck), while column chromatography
was carried out using 70–230 mesh silica gel (Merck). Chemicals
and the shift reagent Eu(hfc)3 were purchased from Aldrich Chem.
Co.
4.2. General procedure for the epoxidation of chalcones
To a solution of
a,b-enones (1.44 mmol) and the appropriate
catalyst (0.1 mmol) in toluene (3 mL) was added 20% aq NaOH
(1 mL) and the mixture was treated with 0.5 mL 5.5 M tert-butyl
hydroperoxide in decane (2.88 mmol). The mixture was stirred at
0–2 °C for 1–10 h. A fresh portion of toluene (7 mL) and water
(10 mL) was added and the mixture was stirred for several min-
utes. The organic phase was washed with 10% aqueous hydrochlo-
ric acid (2 ꢁ 10 mL) and then with water (10 mL). The organic
phase was dried (Na2CO3). The crude product obtained after evap-
orating the solvent was purified by preparative TLC (silica gel,
hexane–ethyl acetate, 10:1 as the eluant) to give the chiral epoxyk-
etone in a pure form. The enantiomer excess was determined by 1H
NMR spectroscopy in the presence of Eu(hfc)3 as the chiral shift
reagent.
3. Conclusion
The use of glucopyranoside-based crown ether 1 as a catalyst in
the asymmetric epoxidation of substituted chalcones and
a,b-
enones led to comparable and, in a few cases, better results with
respect to enantioselectivities, compared to those obtained in the
presence of cinchona alkaloids. The significantly shorter reaction
times (1–10 h vs 48–120 h) represent the major advantage for
the use of crown catalyst 1. Applying lariat ether 1, the position
of the substituents in the aromatic ring had a great impact on
the chemical yield and enantiomeric excesses. The results suggest
that the substituents close to the reaction center prevent the asym-
metric induction, hence the further the substituents are placed
from the reaction center, the higher the extent of enantioselectiv-
The configuration of the major enantiomer was in each case
determined by comparison with the literature data. For products
5–13, 16–28, 33–39 the 1H NMR data were practically identical
with those reported in the literature earlier.
4.2.1. trans-(2R,3S)-2,3-Epoxy-1-(2-chlorophenyl)-3-
phenylpropan-1-one 510e
Yield: 65%; oil; ½a D22
ꢂ
¼ ꢀ121:2 (c 1, CH2Cl2, 69% ee). 1H NMR
(500 MHz, CDCl3) d 4.09 (d, J = 1.7 Hz, 1H), 4.15 (d, J = 1.7 Hz, 1H),
ity. The epoxyketones substituted on the
a-aryl unit 5–16 were
7.33–7.36 (m, 5H, Ar-H), 7.37–7.62 (m, 4H, Ar-H).
generally formed in a higher ee value than those substituted on
the b-site 17–28. The monosaccharide unit of the catalyst is deci-
sive with respect to the configuration of the epoxiketone. The glu-
cose-based catalyst 1 promoted mostly the formation of the
(2R,3S)-enantiomer with negative specific rotation, while the man-
nose-based crown 2 enhanced the predominant formation of the
enantiomer with positive specific rotation.
4.2.2. trans-(2R,3S)-2,3-Epoxy-1-(3-chlorophenyl)-3-
phenylpropan-1-one 610e
Yield: 68%; mp 86–88 °C; ½a D22
¼ ꢀ168:1 (c 1, CH2Cl2, 79% ee).
ꢂ
1H NMR (500 MHz, CDCl3) d 4.08 (d, J = 1.5 Hz, 1H), 4.23 (d,
J = 1.5 Hz, 1H), 7.36–7.42 (m, 5H, Ar-H), 7.44–8.0 (m, 4H, Ar-H).
4.2.3. trans-(2R,3S)-2,3-Epoxy-1-(4-chlorophenyl)-3-
4. Experimental
phenylpropan-1-one 710e
Yield: 71%; mp 92–94 °C; ½a D22
ꢂ
¼ ꢀ182:4 (c 1.0, CH2Cl2, 97% ee).
4.1. General procedures
25
577
Lit. ½
a
ꢂ
¼ ꢀ202 (c 2, CH2Cl2, 98% ee).6d 1H NMR (500 MHz, CDCl3)
d 4.08 (d, J = 1.6 Hz, 1H), 4.23 (d, J = 1.8 Hz, 1H), 7.35–7.42 (m, 5H,
Melting points were taken using a Büchi 510 apparatus and are
uncorrected. Optical rotations were measured with a Perkin–Elmer
Ar-H), 7.47–7.97 (m, 4H, Ar-H).

A. Makó et al. / Tetrahedron: Asymmetry 21 (2010) 919–925
923
4.2.4. trans-(2R,3S)-2,3-Epoxy-1-(2-methylphenyl)-3-
4.2.14. trans-(2R,3S)-2,3-Epoxy-3-(3-chlorophenyl)-1-
phenylpropan-1-one 810e
phenylpropan-1-one 1810e
Yield: 72%; oil; ½a D22
ꢂ
¼ ꢀ167:0 (c 1, CH2Cl2, 71% ee). 1H NMR
Yield: 88%; mp 72–74 °C; ½a D22
ꢂ
¼ ꢀ196:4 (c 1, CH2Cl2, 82% ee).
(500 MHz, CDCl3) d 2.55 (s, 3H, CH3), 4.04 (d, J = 1.6 Hz, 1H), 4.10
(d, J = 1.8 Hz, 1H), 7.27–7.68 (m, 9H, Ar-H).
1H NMR (300 MHz, CDCl3) d 4.06 (d, J = 1.6 Hz, 1H), 4.26 (d,
J = 1.8 Hz, 1H), 7.30–7.37 (m, 4H, Ar-H), 7.50–8.01 (m, 5H, Ar-H).
4.2.15. trans-(2R,3S)-2,3-Epoxy-3-(4-chlorophenyl)-1-
4.2.5. trans-(2R,3S)-2,3-Epoxy-1-(3-methylphenyl)-3-
phenylpropan-1-one 1910e
phenylpropan-1-one 910e
Yield: 78%; mp 112–114 °C; ½a D22
ꢂ
¼ ꢀ209:5 (c 1.0, CH2Cl2, 83%
Yield: 90%; oil; ½a D22
ꢂ
¼ ꢀ188:1 (c 1.0, CH2Cl2, 87% ee). 1H NMR
20
578
ee). Lit. ½
aꢂ
¼ ꢀ148 (c 2, CH2Cl2, 66% ee).6b 1H NMR (300 MHz,
(500 MHz, CDCl3) d 2.41 (s, 3H, CH3), 4.07 (d, J = 1.4 Hz, 1H), 4.29
(d, J = 1.5 Hz, 1H), 7.35–7.82 (m, 9H, Ar-H).
CDCl3) d 4.05 (d, J = 1.7 Hz, 1H), 4.24 (d, J = 1.8 Hz, 1H), 7.30–7.38
(m, 4H, Ar-H), 7.49–7.99 (m, 5H, Ar-H).
4.2.6. trans-(2R,3S)-2,3-Epoxy-1-(4-methylphenyl)-3-
4.2.16. trans-(2R,3S)-2,3-Epoxy-3-(2-methylphenyl)-1-
phenylpropan-1-one 1010e
phenylpropan-1-one 2010e
Yield: 81%; mp 57–59 °C; ½a D22
¼ ꢀ203:3 (c 1, CH2Cl2, 92% ee).
ꢂ
Yield: 75%; oil; ½a D22
ꢂ
¼ ꢀ75:7 (c 1, CH2Cl2, 76% ee). 1H NMR
1H NMR (500 MHz, CDCl3) d 2.42 (s, 3H, CH3), 4.07 (d, J = 1.6 Hz,
1H), 4.27 (d, J = 1.8 Hz, 1H), 7.28–7.93 (m, 9H, Ar-H).
(300 MHz, CDCl3) d 2.37 (s, 3H, CH3), 4.21 (d, J = 1.8 Hz, 1H), 4.23
(d, J = 1.6, 1H), 7.19–7.30 (m, 4H, Ar-H), 7.51–8.05 (m, 5H, Ar-H).
4.2.7. trans-(2R,3S)-2,3-Epoxy-1-(2-methoxyphenyl)-3-
4.2.17. trans-(2R,3S)-2,3-Epoxy-3-(3-methylphenyl)-1-
phenylpropan-1-one 1110e
phenylpropan-1-one 2110e
Yield: 69%; oil; ½a D22
ꢂ
¼ ꢀ98:5 (c 1, CH2Cl2, 84% ee). 1H NMR
Yield: 79%; mp 41–42 °C; ½a D22
¼ ꢀ201:1 (c 1, CH2Cl2, 85% ee).
ꢂ
1H NMR (300 MHz, CDCl3) d 2.38 (s, 3H, CH3), 4.04 (d, J = 1.9 Hz,
1H), 4.30 (d, J = 2.0 Hz, 1H), 7.19–7.31 (m, 4H, Ar-H), 7.47–7.53
(m, 2H, Ar-H), 7.58–7.65 (m, 1H, Ar-H), 8.02–8.05(m, 2H, Ar-H).
(500 MHz, CDCl3) d 3.61 (s, 3H, OCH3), 4.01 (d, J = 1.8 Hz, 1H),
4.31 (d, J = 1.8 Hz, 1H), 7.0–7.83 (m, 9H, Ar-H).
4.2.8. trans-(2R,3S)-2,3-Epoxy-1-(3-methoxyphenyl)-3-
phenylpropan-1-one 1210e
4.2.18. trans-(2R,3S)-2,3-Epoxy-3-(4-methylphenyl)-1-
phenylpropan-1-one 2210e
Yield: 77%; oil; ½a D22
ꢂ
¼ ꢀ199:4 (c 1, CH2Cl2, 88% ee). 1H NMR
Yield: 88%; mp 71–72 °C; ½a D22
¼ ꢀ183:9 (c 1, CH2Cl2, 86% ee).
ꢂ
(500 MHz, CDCl3) d 3.85 (s, 3H, OCH3), 4.07 (d, J = 1.8 Hz, 1H),
4.27 (d, J = 1.8 Hz, 1H), 7.15–7.85 (m, 9H, Ar-H).
1H NMR (300 MHz, CDCl3) d 2.37 (s, 3H, CH3), 4.03 (d, J = 1.6 Hz,
1H), 4.28 (d, J = 1.7 Hz, 1H), 7.21–7.26 (m, 4H, Ar-H), 7.47–8.0 (m,
5H, Ar-H).
4.2.9. trans-(2R,3S)-2,3-Epoxy-1-(4-methoxyphenyl)-3-
phenylpropan-1-one 1310e
Yield: 58%; mp 60–62 °C; ½a D22
¼ ꢀ199:5 (c 1, CH2Cl2, 95% ee).
ꢂ
4.2.19. trans-(2R,3S)-2,3-Epoxy-3-(2-methoxyphenyl)-1-
phenylpropan-1-one 2310e
Lit. ½a 2D2
ꢂ
¼ ꢀ164 (c 2, CH2Cl2, 87% ee).6d 1H NMR (500 MHz, CDCl3)
Yield: 49%; oil;
½
a 2D2
ꢂ
¼ ꢀ63:4 (c 1, CH2Cl2, 62% ee). Lit.
d 3.88 (s, 3H, OCH3), 4.07 (d, J = 1.7 Hz, 1H), 4.25 (d, J = 1.8 Hz, 1H),
25
½
aꢂ
¼ ꢀ22 (c 2, CH2Cl2, 76% ee).6d 1H NMR (300 MHz, CDCl3) d
577
6.96–8.02 (m, 9H, Ar-H).
3.84 (s, 3H, CH3O), 4.19 (d, J = 1.9 Hz, 1H), 4.39 (d, J = 1.8 Hz, 1H),
6.92–7.31 (m, 4H, Ar-H), 7.49–8.0 (m, 5H, Ar-H).
4.2.10. trans-(2R,3S)-2,3-Epoxy-1-(2-nitrophenyl)-3-
phenylpropan-1-one 14
4.2.20. trans-(2R,3S)-2,3-Epoxy-3-(3-methoxyphenyl)-1-
Yield: 66%; mp 74–75 °C; ½a D22
¼ ꢀ285:0 (c 1, CH2Cl2, 80% ee).
ꢂ
phenylpropan-1-one 2410e
1H NMR (300 MHz, CDCl3) d 3.72 (d, J = 1.7 Hz, 1H), 3.87 (d,
J = 1.8 Hz, 1H), 7.22–7.35 (m, 5H, Ar-H), 7.53–8.18 (m, 4H, Ar-H).
HRMS calcd for C15H11NO4 269.0690, found 269.0686.
Yield: 78%; oil; ½a D22
ꢂ
¼ ꢀ203:8 (c 1, CH2Cl2, 82% ee). 1H NMR
(300 MHz, CDCl3) d 3.83 (s, 3H, CH3O), 4.06 (d, J = 1.7 Hz, 1H),
4.27 (d, J = 1.8 Hz, 1H), 6.90–7.32 (m, 4H, Ar-H), 7.62–8.01 (m,
5H, Ar-H).
4.2.11. trans-(2R,3S)-2,3-Epoxy-1-(3-nitrophenyl)-3-
phenylpropan-1-one 15
4.2.21. trans-(2R,3S)-2,3-Epoxy-3-(4-methoxyphenyl)-1-
Yield: 55%; mp 189–191 °C; ½a D22
¼ ꢀ146:6 (c 1, CH2Cl2, 99% ee).
ꢂ
phenylpropan-1-one 2510e
1H NMR (300 MHz, CDCl3) d 3.87 (d, J = 1.8 Hz, 1H), 3.72 (d,
J = 1.7 Hz, 1H), 7.22–7.35 (m, 5H, Ar-H), 7.53–8.18 (m, 4H, Ar-H);
HRMS calcd for C15H11NO4 269.0690, found 269.0688.
Yield: 79%; oil;
½
a 2D2
ꢂ
¼ ꢀ175:1 (c 1, CH2Cl2, 85% ee). Lit.
25
½
aꢂ
¼ ꢀ305 (c 2, CH2Cl2, 90% ee).6d 1H NMR (300 MHz, CDCl3) d
577
3.8 (s, 3H, CH3O), 4.0 (d, J = 1.9 Hz, 1H), 4.28 (d, J = 1.9 Hz, 1H),
6.91–7.27 (m, 4H, Ar-H), 7.49–7.99 (m, 5H, Ar-H).
4.2.12. trans-(2R,3S)-2,3-Epoxy-1-(4-nitrophenyl)-3-
phenylpropan-1-one 168b
4.2.22. trans-(2R,3S)-2,3-Epoxy-3-(2-nitrophenyl)-1-
Yield: 63%; mp 120–122 °C; ½a D22
¼ ꢀ122:6 (c 1, CH2Cl2, 96% ee).
ꢂ
phenylpropan-1-one 2611
Lit. ½a 2D2
ꢂ
¼ ꢀ37:8 (c 1, CH2Cl2, 16% ee).8b 1H NMR (300 MHz, CDCl3)
Yield: 55%; mp 105–107 °C; ½a D22
¼ ꢀ30:8 (c 1, CH2Cl2, 14% ee).
ꢂ
Lit. ½a 2D2
ꢂ
¼ ꢀ48:7 (c 1, CH2Cl2, 29% ee).11 1H NMR (300 MHz, CDCl3)
d 4.21 (d, J = 1.7 Hz, 1H), 4.25 (d, J = 1.8 Hz, 1H), 7.35–7.44 (m, 5H,
Ar-H), 8.19–8.34 (m, 4H, Ar-H).
d 4.22 (d, J = 2.0 Hz, 1H), 4.65 (d, J = 2.0 Hz, 1H), 7.50–8.23 (m, 9H,
Ar-H).
4.2.13. trans-(2R,3S)-2,3-Epoxy-3-(2-chlorophenyl)-1-
phenylpropan-1-one 1710e
4.2.23. trans-(2R,3S)-2,3-Epoxy-3-(3-nitrophenyl)-1-
Yield: 74%; mp 48–50 °C; ½a D22
ꢂ
¼ ꢀ7:4 (c 1, CH2Cl2, 75% ee). 1H
phenylpropan-1-one 2712
Yield: 59%; mp 118–119 °C; ½a D22
ꢂ
¼ ꢀ68:0 (c 1, CH2Cl2, 21% ee).
NMR (300 MHz, CDCl3)
d 4.17 (d, J = 1.9 Hz, 1H), 4.41 (d,
1H NMR (300 MHz, CDCl3) d 4.22 (d, J = 1.6 Hz, 1H), 4.31 (d,
J = 1.8 Hz, 1H), 7.52–8.25 (m, 9H, Ar-H).
J = 1.8 Hz, 1H), 7.31–7.42 (m, 4H, Ar-H), 7.51–8.06 (m, 5H,
Ar-H).

924
A. Makó et al. / Tetrahedron: Asymmetry 21 (2010) 919–925
4.2.24. trans-(2R,3S)-2,3-Epoxy-3-(4-nitrophenyl)-1-
CDCl3) d 4.30 (d, J = 1.5 Hz, 1H), 4.72 (d, J = 1.6, 1H), 7.40–7.68
(m, 7H, Ar-H), 7.82–7.92 (m, 2H, Ar-H), 7.93–8.0 (m, 1H, Ar-H),
8.01–8.11 (m, 2H, Ar-H).
phenylpropan-1-one 2811
Yield: 52%; mp 124 °C; ½a D22
¼ ꢀ169:6 (c 1, CH2Cl2, 63% ee). Lit.
ꢂ
½
a 2D2
ꢂ
¼ ꢀ161 (c 1, CH2Cl2, 61% ee)11 1H NMR (300 MHz, CDCl3) d
4.21 (d, J = 1.4 Hz, 1H), 4.27 (d, J = 1.8 Hz, 1H), 7.52–8.28 (m, 9H,
4.2.34. trans-(ꢀ)-2,3-Epoxy-3-(naphth-2-yl)-1-phenylpropan-1-
Ar-H).
one 3910f
Yield: 33%; mp: 101–103 °C; ½a D22
¼ ꢀ61:7 (c 1, CH2Cl2, 66% ee).
ꢂ
4.2.25. trans-(2R,3S)-2,3-Epoxy-3-(2,4-dichlorophenyl)-1-
Lit. ½a 2D2
ꢂ
¼ ꢀ84:0 (c 1.6, CH2Cl2, 93% ee).5e 1H NMR (500 MHz,
phenylpropan-1-one 29
CDCl3) d 4.25 (d, J = 1.6 Hz, 1H), 4.40 (d, J = 1.8 Hz, 1H), 7.50–7.63
(m, 8H, Ar-H), 7.84–7.91 (m, 3H, Ar-H), 8.03 (d, J = 8.0, 1H, Ar-H).
Yield: 50%; mp 106 °C; ½a D22
ꢂ
¼ ꢀ47:1 (c 1, CH2Cl2, 99% ee). 1H
NMR (300 MHz, CDCl3)
d 4.14 (d, J = 1.8 Hz, 1H), 4.37 (d,
J = 1.4 Hz, 1H), 7.31–7.41 (m, 3H, Ar-H), 7.51–8.04 (m, 5H, Ar-H);
HRMS calcd for C15H10Cl2O2 292.0060 found 292.0057.
4.2.35. (ꢀ)-4,4-Dimethyl-1,2-epoxy-1-(naphth-1-yl)pentan-3-
one 40
Yield: 60%; oil; ½a D22
ꢂ
¼ ꢀ47:8 (c 1, CH2Cl2, 85% ee). 1H NMR
4.2.26. trans-(+)-2,3-Epoxy-3-(2,6-dichlorophenyl)-1-
(500 MHz, CDCl3) d 1.29 (s, 9H, But), 3.86 (d, J = 1.9 Hz, 1H), 4.55
(d, J = 1.9 Hz, 1H), 7.48 (m, 1H, H-3, Ar-H), 7.52–7.56 (m, 3H, H-
2,6,7, Ar-H), 7.85–8.0 (m, 3H, H-4,5,8, Ar-H); HRMS calcd for
phenylpropan-1-one 30
Yield: 60%; mp 99–10 °C; ½a D22
ꢂ
¼ þ48:3 (c 1, CH2Cl2, 70% ee). 1H
NMR (300 MHz, CDCl3) d 4.30 (d, J = 1.9 Hz, 1H), 4.53 (d, J = 2.0 Hz,
1H), 7.27–7.35 (m, 3H, Ar-H), 7.55–8.18 (m, 5H, Ar-H); HRMS calcd
for C15H10Cl2O2 292.0060 found 292.0056.
C17H18O2 254.1306, found 254.1305.
4.2.36. (ꢀ)-4,4-Dimethyl-1,2-epoxy-1-(naphth-2-yl)pentan-3-
one 41
4.2.27. trans-(ꢀ)-2,3-Epoxy-3-(2-chloro-6-fluorophenyl)-1-
Yield: 52%; mp: 99–101 °C; ½a D22
¼ ꢀ253:2 (c 1, CH2Cl2, 92% ee).
ꢂ
phenylpropan-1-one 31
1H NMR (500 MHz, CDCl3) d 1.25 (s, 9H, But), 3.96 (d, J = 1.8 Hz, 1H),
4.02 (d, J = 1.8 Hz, 1H), 7.35 (m, 1H, H-3, Ar-H), 7.50–7.52 (m, 2H,
H-6,7, Ar-H), 7.82–7.87 (m, 4H, H-1,4,5,8, Ar-H); HRMS calcd for
Yield: 54%; mp 121–123 °C; ½a D22
¼ ꢀ20:0 (c 1, CH2Cl2, 24% ee).
ꢂ
1H NMR (300 MHz, CDCl3) d 4.27 (d, J = 1.7 Hz, 1H), 4.69 (d,
J = 1.9 Hz, 1H), 7.05–7.34 (m, 3H, Ar-H), 7.53–8.14 (m, 5H, Ar-H);
HRMS calcd for C15H10ClFO2 276.0353 found 276.0356.
C17H18O2 254.1306, found 254.1307.
Acknowledgments
4.2.28. (1S,2R)-4,4-Dimethyl-1,2-epoxy-1-phenylpentan-3-one
337a
Financial support by the Hungarian Scientific Research Found
(OTKA No. K 75098 and K 81127) is gratefully acknowledged.
Yield: 86%; mp: 66–67 °C; ½a D22
¼ ꢀ239:3 (c 1, CH2Cl2, 90% ee).
ꢂ
Lit. ½a 2D2
ꢂ
¼ ꢀ261:2 (c 1.05 CH2Cl2, 97% ee).7a 1H NMR (500 MHz,
t
CDCl3) d 1.23 (s, 9H, Bu), 3.85 (d, J = 1.6 Hz, 1H), 3.87 (d, J = 1.8),
References
7.31–7.38 (m, 5H, Ar-H).
1. (a) Lohray, B. B. Synthesis 1992, 1035; (b) Katsukis, T. J. Synth. Org. Chem. Jpn.
1995, 53, 940; (c) Besses, P.; Veschambre, H. Tetrahedron 1994, 50, 8885; (d)
Schuring, V.; Bestschinger, F. Chem. Rev. 1992, 92, 873; (e) Archelas, A.;
Furstoss, R. Top. Curr. Chem. 1992, 200, 159.
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1109; Elliott, M. C. J. Chem. Soc., Perkin Trans. 1 1998, 4175; (d) Polter, M. J.;
Skidmore, J. Chem. Commun. 2000, 1215.
4.2.29. trans-(ꢀ)-2,3-Epoxy-1-(naphth-1-yl)-3-phenylpropan-1-
one 345b
Yield: 64%; mp: 127–129 °C; ½a D22
¼ ꢀ188:4 (c 1, CH2Cl2, 67%
ꢂ
ee). Lit. ½a 2D2
ꢂ
¼ ꢀ188 (c 1, CHCl3, 71% ee).5b 1H NMR (500 MHz,
CDCl3) d 4.14 (d, J = 1.7 Hz, 1H), 4.25 (d, J = 1.8 Hz, 1H), 7.37–7.42
3. Maruoka, K. Asymmetric Phase Transfer Catalysis; Wiley-VCH, Verlag GmbH &
Co. KGaA: Weinheim, 2008.
(m, 5H, Ar-H), 7.50–8.67 (m, 7H, Ar-H).
4. (a) Helder, R.; Hummelen, J. C.; Laane, R. W. P.; Wiering, J. S.; Wynberg, H.
Tetrahedron Lett. 1976, 1831; (b) Wynberg, H.; Greijdanus, B. Chem. Commun.
1978, 427; (c) Wynberg, H.; Marsman, B. J. Org. Chem. 1980, 45, 158; (d) Plium,
H.; Wynberg, H. J. Org. Chem. 1980, 45, 2498.
5. (a) Arai, S.; Tsuge, H.; Shioiri, T. Tetrahedron Lett. 1998, 39, 7563; (b) Lygo, B.;
Wainwright, P. G. Tetrahedron 1999, 55, 6289; (c) MacDonald, G.; Alcaraz, L.;
Lewis, N. J.; Taylor, J. K. Tetrahedron Lett. 1998, 39, 5433; (d) Adam, W.; Bheema
Rao, P.; Degen, H.-G.; Saha-Möller, C. R. Tetrahedron: Asymmetry 2001, 12, 121;
(e) Corey, E. J.; Zhang, F.-Y. Org. Lett. 1999, 1, 1287.
4.2.30. trans-(2R,3S)-Epoxy-1-(naphth-2-yl)-3-phenylpropan-1-
one 3510g
Yield: 30%; mp: 101–103 °C; ½a D22
¼ ꢀ137:7 (c 1, CH2Cl2, 87%
ꢂ
ee). Lit. ½a 2D2
ꢂ
¼ ꢀ100 (c 1, CH2Cl2, 73% ee).10g 1H NMR (500 MHz,
CDCl3) d 4.16 (d, J = 1.7 Hz, 1H), 4.30 (d, J = 1.8 Hz, 1H), 7.39–7.44
(m, 5H, Ar-H), 7.56–8.56 (m, 7H, Ar-H).
6. (a) Juliá, S.; Masana, J.; Vega, J. C. Angew. Chem., Int. Ed. Engl. 1980, 19, 929; (b)
Juliá, S.; Guixer, J.; Masana, J.; Rocas, J.; Colonna, S.; Annuziata, R.; Molinari, H. J.
Chem. Soc., Perkin Trans. 1 1982, 1317; (c) Kroutil, W.; Lasterra-Sanchez, M. E.;
Maddrell, S. J.; Mayon, P.; Morgan, P.; Roberts, S. M.; Thornton, S. R.; Todd, C. J.;
Tüter, M. J. Chem. Soc., Perkin Trans. 1 1996, 2837; (d) Itsuno, S.; Sakakura, M.;
Ito, K. J. Org Chem. 1990, 55, 6047; (e) Pu, L. Tetrahedron: Asymmetry 1998, 9,
1457; (f) Ebrahim, S.; Wills, M. Tetrahedron: Asymmetry 1997, 8, 3163; (g)
Porter, M. J.; Roberts, S. M.; Skidmore, J. Bioorg. Med. Chem. 1999, 7, 2145.
7. (a) Adger, B. M.; Barkley, J. V.; Bergeron, S.; Cappi, M. W.; Flowerdew, B. E.;
Jackson, M. P.; McCague, R.; Nugent, T. J.; Roberts, S. M. J. Chem. Soc., Perkin
Trans. 1 1997, 3501; (b) Allen, J. V.; Drauz, K.-H.; Roberts, S. M.; Skidmore, J.
Tetrahedron Lett. 1999, 40, 5417; (c) Cappi, M. W.; Chen, W.-P.; Flood, R. W.;
Liao, Y.-W.; Roberts, S. M.; Skidmore, J.; Smith, J. A.; Williamson, N. M. J. Chem.
Soc., Chem. Commun. 1998, 1159.
4.2.31. trans-(2R,3S)-Epoxy-1-phenylbutan-1-one 3610g
Yield: 60%; oil; ½a D22
ꢂ
¼ ꢀ3:4 (c 1, CH2Cl2, 55% ee). Lit. ½a D22
¼ ꢀ10
ꢂ
(c 0.6, CHCl3 63% ee).10g 1H NMR (500 MHz, CDCl3) d 1.52 (d,
J = 5.1 Hz, 3H, CH3), 3.22 (dq, J = 4.9, 1.8 Hz, 1H), 3.99 (d,
J = 1.6 Hz, 1H), 7.5–8.01 (m, 5H, Ar-H).
4.2.32. trans-(+)-2,3-Epoxy-3-(tert-butyl)-1-phenylpropan-1-
one 3710h
Yield: 53%; oil; ½a D22
ꢂ
¼ þ9:2 (c 1, CH2Cl2, 34% ee). Lit. ½a D22
¼ þ10
ꢂ
(c 0.53, CHCl3, 76% ee).10h 1H NMR (500 MHz, CDCl3) d 1.04 (s, 9H,
But), 2.96 (d, J = 2.2, 1H), 4.12 (d, J = 2.2 Hz, 1H), 7.5–8.01 (m, 5H,
Ar-H).
}
8. (a) Bakó, P.; Bakó, T.; Mészáros, A.; Keglevich, Gy.; Szöllosy, Á.; Bodor, S.; Makó,
}
A.; Toke, L. Synlett 2004, 643; (b) Bakó, T.; Bakó, P.; Keglevich, Gy.; Bombicz, P.;
}
Kubinyi, M.; Pál, K.; Bodor, S.; Makó, A.; Toke, L. Tetrahedron: Asymmetry 2004,
}
15, 1589; (c) Makó, A.; Menyhárd, K. D.; Bakó, P.; Keglevich, Gy.; Toke, L. J. Mol.
Struct. 2008, 892, 336.
9. Hori, K.; Tamura, M.; Tani, K.; Nishiwaki, N.; Ariga, M.; Tohda, Y. Tetrahedron
Lett. 2006, 47, 3115.
10. (a) Arai, S.; Tsuge, H.; Oku, M.; Miura, M.; Shioiri, T. Tetrahedron 2002, 58, 1623;
(b) Lygo, B.; Gardiner, S. D.; McLeod, M. C.; To, D. C. M. Org. Biomol. Chem. 2007, 5,
4.2.33. trans-(ꢀ)-2,3-Epoxy-3-(naphth-1-yl)-1-phenylpropan-1-
one 385b
Yield: 68%; mp: 109–111 °C; ½a D22
¼ ꢀ167:0 (c 1, CH2Cl2, 83%
ꢂ
ee). Lit. ½a 2D5
ꢂ
¼ ꢀ67:0 (c 2, CHCl3, 78% ee)10f 1H NMR (500 MHz,

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