An N-aryl-substituted oxazolidinone-containing ketone-catalyzed asymmetric epoxidation with hydrogen peroxide as the primary oxidant

Article abstract of DOI:10.1021/jo0708644

(Chemical Equation Presented) Asymmetric epoxidation of various olefins with an N-aryl-substituted oxazolidinone-containing ketone as catalyst and hydrogen peroxide as the primary oxidant has been investigated, and up to 96% ee was obtained.

Full text of DOI:10.1021/jo0708644

reduction product being water.7-9 In addition, ketone-catalyzed
epoxidation reactions with H2O2 require less solvent and salts
than those with Oxone and do not require slow addition of
oxidant.
An N-Aryl-Substituted Oxazolidinone-Containing
Ketone-Catalyzed Asymmetric Epoxidation with
Hydrogen Peroxide as the Primary Oxidant
Fructose-derived ketone 1 has been shown to be an effective
catalyst for the epoxidation of a wide variety of trans- and
trisubstituted olefins.2b,c,10 During our further studies, we have
found that oxazolidinone-containing ketones 2 gave high ee
values for substrates such as cis-olefins,11,12 styrenes,11,13 and
certain trisubstituted olefins11,14 which are not effective with
ketone 1. The question is whether the RCN-H2O2 system can
also be extended to epoxidation with ketone 2. Herein, we wish
to report our efforts on this subject.
Christopher P. Burke, Lianhe Shu, and Yian Shi*
Department of Chemistry, Colorado State UniVersity,
Fort Collins, Colorado 80523
yian@lamar.colostate.edu
ReceiVed April 26, 2007
Early on in the study it became apparent that ketone 2a would
not be useful under these conditions because of its rapid
(7) For a general reference on hydrogen peroxide see: Strukul, G.
Catalytic Oxidations with Hydrogen Peroxide as Oxidant; Kluwer Academic
Publishers: New York, 1992.
(8) For leading reviews on epoxidation of olefins with hydrogen peroxide
see: (a) Grigoropoulou, G.; Clark, J. H.; Elings, J. A. Green Chem. 2003,
5, 1. (b) Noyori, R.; Aoki, M.; Sato, K. Chem. Commun. 2003, 1977. (c)
Burgess, K.; Lane, B. S. Chem. ReV. 2003, 103, 2457. (d) Kelly, D. R.;
Roberts, S. M. Biopolymers 2006, 84, 74. (e) Matsumoto, K. Yuki Gosei
Kagaku Kyokaishi 2006, 64, 869. (f) Arends, I. W. C. E. Angew. Chem.,
Int. Ed. 2006, 45, 6250.
Asymmetric epoxidation of various olefins with an N-aryl-
substituted oxazolidinone-containing ketone as catalyst and
hydrogen peroxide as the primary oxidant has been inves-
tigated, and up to 96% ee was obtained.
(9) For leading references on asymmetric epoxidation with hydrogen
peroxide see: (a) Schwenkreis, T.; Berkessel, A. Tetrahedron Lett. 1993,
34, 4785. (b) Irie, R.; Hosoya, N.; Katsuki, T. Synlett 1994, 255. (c)
Pietika¨inen, P. Tetrahedron Lett. 1994, 35, 941. (d) Sun, H. B.; Hua, W.
Y.; Peng, S. X. Chin. Chem. Lett. 1995, 6, 927. (e) Berkessel, A.;
Frauenkron, M.; Schwenkreis, T.; Steinmetz, A. J. Mol. Catal. A: Chem.
1997, 117, 339. (f) Bolm, C.; Kadereit, D.; Valacchi, M. Synlett 1997, 687.
(g) Kluge, R.; Hocke, H.; Schulz, M. Tetrahedron: Asymmetry 1997, 8,
2513. (h) Pietika¨inen, P. Tetrahedron 1998, 54, 4319. (i) Arai, S.; Tsuge,
H.; Shioiri, T. Tetrahedron Lett. 1998, 39, 7563. (j) Stoop, R. M.; Mezzetti,
A. Green Chem. 1999, 39. (k) Francis, M. B.; Jacobsen, E. N. Angew. Chem.,
Int. Ed. 1999, 38, 937. (l) Kureshy, R. I.; Khan, N. H.; Abdi, S. H. R.;
Patel, S. T.; Jasra, R. V. Tetrahedron: Asymmetry 2001, 12, 433. (m)
Pietikainen, P. J. Mol. Catal. A: Chem. 2001, 165, 73. (n) Arai, S.; Tsuge,
H.; Oku, M.; Miura, M.; Shioiri, T. Tetrahedron 2002, 58, 1623. (o) Tse,
M. K.; Do¨bler, C.; Bhor, S.; Klawonn, M.; Ma¨gerlein, W.; Hugl, H.; Beller,
M. Angew. Chem., Int. Ed. 2004, 43, 5255. (p) Matsumoto, K.; Sawada,
Y.; Saito, B.; Sakai, K.; Katsuki, T. Angew. Chem., Int. Ed. 2005, 44, 4935.
(q) Marigo, M.; Franzen, J.; Poulsen, T. B.; Zhuang, W.; Jorgensen, K. A.
J. Am. Chem. Soc. 2005, 127, 6964. (r) Berkessel, A.; Koch, B.; Toniolo,
C.; Rainaldi, M.; Broxterman, Q. B.; Kaptein, B. Biopolymers 2006, 84,
90. (s) Sunden, H.; Ibrahem, I.; Cordova, A. Tetrahedron Lett. 2006, 47,
99. (t) Tse, M. K.; Bhor, S.; Klawonn, M.; Anilkumar, G.; Jiao, H.;
Spannenberg, A.; Do¨bler, C.; Ma¨gerlein, W.; Hugl, H.; Beller, M. Chem.
Eur. J. 2006, 12, 1875. (u) Kazushige, H.; Tamura, M.; Tani, K.; Nishiwaki,
N.; Ariga, M.; Yasuo, T. Tetrahedron Lett. 2006, 47, 3115. (v) Shitama,
H.; Katsuki, T. Tetrahedron Lett. 2006, 47, 3203. (w) Sawada, Y.;
Matsumoto, K.; Kondo, S.; Watanabe, H.; Ozawa, T.; Suzuki, K.; Saito,
B.; Katsuki, T. Angew. Chem., Int. Ed. 2006, 45, 3478. (x) Colladon, M.;
Scarso, A.; Sgarbossa, P.; Michelin, R. A.; Strukul, G. J. Am. Chem. Soc.
2006, 128, 14006.
(10) (a) Tu, Y.; Wang, Z-X.; Shi, Y. J. Am. Chem. Soc. 1996, 118, 9806.
(b) Wang, Z-X.; Tu, Y.; Frohn, M.; Zhang, J.-R.; Shi, Y. J. Am. Chem.
Soc. 1997, 119, 11224.
(11) (a) Tian, H.; She, X.; Shu, L.; Yu, H.; Shi, Y. J. Am. Chem. Soc.
2000, 122, 11551. (b) Tian, H.; She, X.; Yu, H.; Shu, L.; Shi, Y. J. Org.
Chem. 2002, 67, 2435.
(12) (a) Shu, L.; Wang, P.; Gan, Y.; Shi, Y. Org. Lett. 2003, 5, 293. (b)
Shu, L.; Shi, Y. Tetrahedron Lett. 2004, 45, 8115. (c) Wong, O. A.; Shi,
Y. J. Org. Chem. 2006, 71, 3973. (d) Burke, C. P.; Shi, Y. Angew. Chem.,
Int. Ed. 2006, 45, 4475. (e) Burke, C.P.; Shi, Y. J. Org. Chem. 2007, 72,
4093.
(13) Goeddel, D.; Shu, L.; Yuan, Y.; Wong, O. A.; Wang, B.; Shi, Y. J.
Org. Chem. 2006, 71, 1715.
Dioxiranes have proven to be valuable agents for the
epoxidation of olefins.1,2 Typically they are prepared by using
a ketone and Oxone (potassium peroxymonosulfate). In our
earlier studies on epoxidation with fructose-derived ketone 1,
we have shown that H2O2 coupled with a nitrile activator
presents a viable alternative to Oxone for the formation of
dioxiranes and subsequent epoxidation of olefins (Scheme 1).3
High yields and ee values were obtained for a wide variety of
trans- and trisubstituted olefins. Further studies have shown that
some other ketones can be effective for the epoxidation with
the RCN-H2O2 system.4,5 In this epoxidation, peroxyimidic acid
is likely the active oxidant for the formation of the dioxirane
(Scheme 1).6 Hydrogen peroxide (H2O2) is a highly desirable
oxidant because of its high active oxygen content and its
* Address correspondence to this author. Phone: 970-491-7424. Fax: 970-
491-1801.
(1) For general leading references on dioxiranes see: (a) Murray, R. W.
Chem. ReV. 1989, 89, 1187. (b) Adam, W.; Curci, R.; Edwards, J. O. Acc.
Chem. Res. 1989, 22, 205. (c) Curci, R.; Dinoi, A.; Rubino, M. F. Pure
Appl. Chem. 1995, 67, 811. (d) Clennan, E. L. Trends Org. Chem. 1995, 5,
231. (e) Adam, W.; Smerz, A. K. Bull. Soc. Chim. Belg. 1996, 105, 581.
(2) For reviews on chiral ketone-catalyzed asymmetric epoxidation see:
(a) Denmark, S. E.; Wu, Z. Synlett 1999, 847. (b) Frohn, M.; Shi, Y.
Synthesis 2000, 1979. (c) Shi, Y. Acc. Chem. Res. 2004, 37, 488. (d) Yang,
D. Acc. Chem. Res. 2004, 37, 497.
(3) (a) Shu, L.; Shi. Y. Tetrahedron Lett. 1999, 40, 8721. (b) Shu, L.;
Shi, Y. Tetrahedron 2001, 57, 5213.
(4) Shu, L.; Shi, Y. J. Org. Chem. 2000, 65, 8807.
(5) Li, W.; Fuchs, P. L. Org. Lett. 2003, 5, 2853.
(6) For leading references on epoxidation with H2O2 and RCN see: (a)
Payne, G. B.; Deming, P. H.; Williams, P. H. J. Org. Chem. 1961, 26, 659.
(b) Payne, G. B. Tetrahedron 1962, 18, 763. (c) McIsaac, J. E., Jr.; Ball,
R. E.; Behrman, E. J. J. Org. Chem. 1971, 36, 3048. (d) Bach, R. D.; Knight,
J. W. Org. Synth. 1981, 60, 63. (e) Arias, L. A.; Adkins, S.; Nagel, C. J.;
Bach, R. D. J. Org. Chem. 1983, 48, 888.
(14) Shen, Y-M.; Wang, B.; Shi, Y. Angew. Chem., Int. Ed. 2006, 45,
1429.
10.1021/jo0708644 CCC: $37.00 © 2007 American Chemical Society
Published on Web 07/10/2007
6320
J. Org. Chem. 2007, 72, 6320-6323

TABLE 1. Asymmetric Epoxidation of cis-â-Methylstyrene with
SCHEME 1
Ketone 2ba
3 h
10 h
entry
solvent
conv (%)b ee (%)b conv (%)b ee (%)b
1
2
3
4
5
DME
DMM
28
27
28
6
54
28
68
66
65
52
57
54
DME/DMM (1:1)
CH2Cl2
CH2Cl2/EtOH (1:1)
CH2Cl2/EtOH (2:1)
MeOH
6
7
32
67
90
92
100
87
21
47
69
70
74
78
74
73
8
9
EtOH
n-PrOH
i-PrOH
10
11
12
13
14
15
16
17
18
19
20
21
22
n-BuOH
60
73
n-BuOHc
t-BuOH
i-PrCH2CH2OH
C6H6
97
100
13
13
37
14
47
23
57
35d
69
68
68
69
71
70
72
70
PhMe
C6H6/EtOH (1:1)
PhMe/EtOH (1:1)
C6H6/n-BuOH (1:1)
PhMe/n-BuOH
C6H6/n-BuOH (1:6.5)
dioxanec
a The reactions were carried out with olefin (0.5 mmol), ketone 2b (0.025
mmol), and 30% H2O2 (0.20 mL, 2.0 mmol) in CH3CN (0.20 mL, 3.8
mmol)-solvent (0.75 mL)-0.6 M K2CO3 in 4 × 10-4 M aqueous EDTA
(0.75 mL) at 0 °C (bath temperature). b The conversions and ee values were
determined by chiral GC (Chiraldex B-DM). c CH3CN (0.10 mL, 1.9 mmol)
used. d The reaction time is 4 h.
decomposition.15 Ketones 2b,c are more readily available than
2a and appeared to be more robust under the reaction conditions
so further study was conducted with these catalysts. Initial
studies were carried out with cis-â-methylstyrene as a test
substrate. Under the optimum conditions for ketone 1, epoxi-
dation with ketone 2b using H2O2 in CH3CN as solvent gave
poor enantioselectivity (∼50% ee). Subsequently, various
solvents were tested for the epoxidation with 5 mol % ketone
2b. As shown in Table 1, n-BuOH was found to be among the
best solvents (Table 1, entry 11). The ee was increased to 78%
when the amount of CH3CN was reduced (Table 1, entry 12).
After more optimization, it was found that 3.8 equiv of CH3-
CN along with 3 equiv of H2O2 in n-BuOH-0.30 M aq K2CO3
in 4 × 10-4 M EDTA (1:1, v/v) gave the best results overall
for a number of substrates.16 In previous studies of various
olefins, ketone 2c often gave better overall results than 2b,13
so we decided to examine a variety of olefins with this catalyst
(Table 2).17 In many cases the ee values obtained are within a
few percent of if not as high as the corresponding ee values
with Oxone as oxidant. Up to 96% ee was obtained (Table 2,
entry 7). The drop in enantioselectivity observed in some cases
(e.g. Table 2, entry 11) is likely due to a solvent effect since
the asymmetric induction of ketone 2 is largely attributed to
electronic and/or hydrophobic effects which are solvent
dependent.11-14
oxazolidinone is gradually hydrolyzed over time, presumably
due to the nucleophilic action of peroxide anion.15 The major
consequence of this is that relatively unreactive olefins are
difficult to drive to full conversion because the decomposition
process(es) competes with the epoxidation process. However,
for many substrates this system is a viable alternative to the
Oxone protocol.
In summary, a method for asymmetric epoxidation with use
of N-aryl oxazolidinone-containing ketones with H2O2 as
primary oxidant has been described. A variety of olefins can
be epoxidized with good yields and ee values. Use of H2O2
allows for use of less solvent, salts, and eliminates the need for
slow addition of oxidant. The reactions are operationally simple,
and in many cases give results similar to those obtained with
Oxone.
Experimental Section
The general experimental information is similar to that recently
described.10b Hydrogen peroxide (H2O2) is potentially explosive,
and although no incidents occurred in our experience, care must
be taken in handling this compound. In the epoxidation reaction,
EDTA is used to minimize the decomposition of H2O2 catalyzed
by any trace metals. Freshly purchased H2O2 from Aldrich was
used in this study. It was found that vigorous stirring is crucial for
epoxidation efficiency, particularly for less reactive substrates. All
epoxides are known except Table 2, entries 5 and 8, and gave
satisfactory spectroscopic characterization.
During the course of study it was also observed that the
ketones are susceptible to decomposition under the reaction
conditions. The reaction pH with 0.30 M K2CO3 is about 11.5,
and at such a high pH R-deprotonation of the ketone occurs
subsequently eliminating acetone.18 It is also possible that the
Representative Procedure for Asymmetric Epoxidation (Table
2, entry 2). A mixture of 2-methyl-1-phenyl-1-propene (0.135 g,
1.00 mmol) and ketone 2c21 (0.051 g, 0.15 mmol) in n-BuOH (3.0
mL) was cooled to 0 °C with an ice bath. CH3CN (0.20 mL, 3.8
mmol) and 0.30 M K2CO3 in 4 × 10-4 M aqueous EDTA (3.0
mL) were then added, followed by H2O2 (30%, 0.30 mL, 3.0 mmol)
with vigorous stirring at 0 °C. The mixture was stirred at 0 °C for
(15) For facile hydrolysis of oxazolidinone with LiOOH see: Evans, D.
A.; Britton, T. C.; Ellman, J. A. Tetrahedron Lett. 1987, 28, 6141.
(16) Under these conditions, 28% conversion and 78% ee were obtained
for cis-â-methylstyrene with ketone 2a.
(17) It was observed that olefins containing hydroxy groups are usually
poor substrates under the reaction conditions for reasons that are not well
understood.
(18) The formation of acetone can be detected by NMR.
J. Org. Chem, Vol. 72, No. 16, 2007 6321

TABLE 2. Asymmetric Epoxidation of Olefins with Ketone 2ca
a The reactions were carried out with olefin (1.0 mmol), ketone 2c (0.10-0.30 mmol), CH3CN (0.20 mL, 3.8 mmol), n-BuOH (3.0 mL), aq 0.30 M
K2CO3 in 4 × 10-4 M EDTA (3.0 mL), and 30% H2O2 (0.30 mL, 3.0 mmol) at 0 °C for the time indicated. b Absolute configuration was determined by
comparing the measured optical rotations to the reported ones. c Conversion was determined by GC of the crude reaction mixture. d Enantioselectivity was
determined by chiral GC (Chiraldex B-DM column). e Conversion was determined by 1H NMR of the crude reaction mixture. f Enantioselectivity was
determined by chiral HPLC (Chiralcel OD column).
24 h and was then poured into petroleum ether and extracted with
petroleum ether. The combined organic layers were washed with
water and saturated aqueous Na2S2O3, dried (Na2SO4), filtered,
concentrated, and purified by flash chromatography (silica gel was
buffered with 1% Et3N in petroleum ether; petroleum ether was
used as eluent) to give 2,2-dimethyl-3-phenyloxirane as a colorless
oil (0.121 g, 82% yield, 92% ee).
(d, J ) 4.4 Hz, 1H), 3.39-3.32 (m, 1H), 1.10 (d, J ) 5.2 Hz, 3H);
13C NMR (100 MHz, CDCl3) δ 135.7, 128.2, 127.7, 126.8, 57.8,
55.4, 12.7.
Table 2, entry 2: colorless oil; [R]25D +38.3 (c 0.85, C6H6) (92%
1
ee); H NMR (400 MHz, CDCl3) δ 7.40-7.28 (m, 5H), 3.87 (s,
1H), 1.49 (s, 3H), 1.08 (s, 3H); 13C NMR (100 MHz, CDCl3) δ
136.8, 128.2, 127.6, 126.6, 64.8, 61.3, 25.0, 18.2.
Table 2, entry 3: colorless oil; [R]25 +99.3 (c 0.46, EtOH)
Table 2, entry 1: colorless oil; [R]25 -40.0 (c 0.77, CHCl3)
D
D
1
(82% ee); 1H NMR (400 MHz, CDCl3) δ 7.40-7.28 (m, 5H), 4.07
(88% ee); H NMR (400 MHz, CDCl3) δ 7.50-7.30 (m, 10H),
3.98 (s, 1H), 1.48 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 142.5,
136.1, 128.7, 128.4, 127.9, 127.7, 126.7, 125.4, 67.3, 63.3, 16.9.
Table 2, entry 4: colorless oil; [R]25 -17.3 (c 0.60, CHCl3)
(19) (a) Witkop, B.; Foltz, C. M. J. Am. Chem. Soc. 1957, 79, 197. (b)
Zhang, W.; Loebach, J. L.; Wilson, S. R.; Jacobsen, E. N. J. Am. Chem.
Soc. 1990, 112, 2801.
D
(83% ee); 1H NMR (400 MHz, CDCl3) δ 7.28-7.23 (m, 1H), 7.14-
7.08 (m, 3H), 3.84 (dd, J ) 4.2, 2.8 Hz, 1H), 3.14 (dd, J ) 5.6,
4.2 Hz, 1H), 2.81 (dd, J ) 5.6, 2.8 Hz, 1H), 2.35 (s, 3H); 13C
NMR (100 MHz, CDCl3) δ 138.5, 137.7, 129.2, 128.6, 126.2, 122.9,
52.6, 51.4, 21.6.
(20) Brandes, B. D.; Jacobsen, E. N. J. Org. Chem. 1994, 59, 4378.
(21) Ketones 2b and 2c used in this study were prepared by the PDC
oxidation of the alcohol precursors (for less reactive olefins, best results
were obtained with freshly recrystallized ketones). It was observed that lower
conversions were obtained with the ketone prepared from the TEMPO-
bleach oxidation of the alcohol.22 It appears that some residual impurities
from TEMPO-bleach oxidation somehow affect the epoxidation.
(22) Zhao, M-X.; Goeddel, D.; Li, K.; Shi, Y. Tetrahedron 2006, 62,
8064.
Table 2, entry 5: colorless oil; [R]25 -13.8 (c 0.48, CHCl3)
D
(80% ee); IR (NaCl) 1587, 1152 cm-1; 1H NMR (400 MHz, CDCl3)
δ 7.30-7.24 (m, 1H), 7.01-6.92 (m, 3H), 5.18 (s, 2H), 3.84 (dd,
J ) 4.2, 2.8 Hz, 1H), 3.48 (s, 3H), 3.14 (dd, J ) 5.6, 4.2 Hz, 1H),
6322 J. Org. Chem., Vol. 72, No. 16, 2007

2.79 (dd, J ) 5.6, 2.8 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ
157.7, 139.6, 129.9, 119.2, 116.3, 113.4, 94.6, 56.3, 52.5, 51.4.
Anal. Calcd for C10H12O3: C, 66.65; H, 6.71. Found: C, 66.90; H,
6.94.
Table 2, entry 10: colorless oil; [R]25 -31.2 (c 0.41, CHCl3)
D
1
(90% ee); H NMR (400 MHz, CDCl3) δ 3.42 (dt, J ) 4.4, 1.6
Hz, 1H), 3.13 (qd, J ) 5.2, 4.4 Hz, 1H), 2.22 (td, J ) 7.2, 1.6 Hz,
2H), 1.53-1.47 (m, 2H), 1.42-1.22 (m, 8H), 1.40 (d, J ) 5.2 Hz,
3H), 0.89 (t, J ) 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
86.9, 75.1, 54.2, 46.1, 31.5, 28.7, 28.6, 22.8, 19.0, 14.9, 14.3.
Table 2, entry 6: white solid; [R]25 +14.8 (c 1.80, CHCl3)
D
(91% ee); 1H NMR (400 MHz, CDCl3) δ 7.15-7.14 (m, 1H), 7.05-
7.02 (m, 1H), 6.70 (d, J ) 8.4 Hz, 1H), 3.86 (d, J ) 4.2 Hz, 1H),
3.48 (d, J ) 4.2 Hz, 1H), 2.29 (s, 3H), 1.57 (s, 3H), 1.24 (s, 3H);
13C NMR (100 MHz, CDCl3) δ 150.5, 131.0, 130.6, 130.2, 119.9,
118.0, 73.0, 63.1, 51.3, 25.9, 22.7, 20.7.
Table 2, entry 11: colorless oil; [R]25 -19.1 (c 0.33, CHCl3)
D
1
(82% ee); H NMR (400 MHz, CDCl3) δ 6.02 (dt, J ) 15.4, 4.4
Hz, 1H), 5.60 (ddt, J ) 15.4, 7.6, 1.7 Hz, 1H), 4.22 (dd, J ) 4.4,
1.7 Hz, 2H), 3.43 (dd, J ) 7.6, 4.0 Hz, 1H), 3.22 (quint., J ) 5.4
Hz, 1H), 1.29 (d, J ) 5.4 Hz, 3H), 0.91 (s, 9H), 0.07 (s, 6H); 13C
NMR (100 MHz, CDCl3) δ 136.3, 123.9, 63.2, 56.9, 54.7, 26.1,
18.6, 13.6, -5.1.
Table 2, entry 7: colorless oil; [R]25 +106.9 (c 1.38, CHCl3)
D
(96% ee); 1H NMR (400 MHz, CDCl3) δ 7.34-7.31 (m, 2H), 7.13-
7.10 (m, 2H), 3.83 (s, 1H), 2.67-2.57 (m, 1H), 2.51-2.36 (m,
2H), 1.99-1.83 (m, 2H), 1.76-1.60 (m, 1H); 13C NMR (100 MHz,
CDCl3) δ 135.5, 133.7, 128.6, 127.7, 66.9, 62.0, 31.5, 28.5, 12.6.
Acknowledgment. We are grateful for the generous financial
support from the General Medical Sciences of the National
Institutes of Health (GM59705-08). We thank Mei-Xin Zhao,
O. Andrea Wong, Yu-Mei Shen, and Bin Wang for kindly
providing some of the substrates described in Table 2 (entries
5-8).
Table 2, entry 8: colorless oil; [R]25 +52.4 (c 0.67, CHCl3)
D
(90% ee); IR (NaCl) 1604, 1497, 1455 cm-1; 1H NMR (400 MHz,
CDCl3) δ 7.38-7.32 (m, 2H), 7.30-7.24 (m, 3H), 4.02 (s, 1H),
2.10-1.96 (m, 1H), 1.89-1.74 (m, 3H), 1.74-1.40 (m, 4H); 13C
NMR (100 MHz, CDCl3) δ 137.4, 128.3, 127.7, 126.4, 72.8, 63.5,
34.2, 28.6, 25.5, 25.4. Anal. Calcd for C12H14O: C, 82.72; H, 8.10.
Found: C, 82.56; H, 7.99.
Supporting Information Available: The data for the determi-
nation of the enantiomeric excess of the epoxides obtained with
Table 2, entry 9: colorless oil; [R]25 -34.8 (c 0.43, CHCl3)
D
1
ketone 2c along with the H and 13C NMR spectra of epoxides.
(88% ee); 1H NMR (400 MHz, CDCl3) δ 7.48-7.45 (m, 2H), 7.35-
7.30 (m, 3H), 3.65 (d, J ) 4.4 Hz, 1H), 3.27 (qd, J ) 5.2, 4.4 Hz,
1H), 1.51 (d, J ) 5.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
132.1, 129.0, 128.6, 122.4, 85.5, 84.3, 54.7, 46.2, 15.1.
This material is available free of charge via the Internet at
http://pubs.acs.org.
JO0708644
J. Org. Chem, Vol. 72, No. 16, 2007 6323