Diastereoselective and enantioselective epoxidation of acyclic β-trifluoromethyl-β,β-disubstituted enones by hydrogen peroxide with a pentafluorinated quinidine-derived phase-transfer catalyst

Article abstract of DOI:10.1002/adsc.201300249

An efficient catalytic asymmetric epoxidation of β-trifluoromethyl- β,β-disubstituted unsaturated ketones has been achieved by a pentafluorine-substituted phase-transfer catalyst with hydrogen peroxide (30%). Thus, the β-trifluoromethyl-α,β-epoxy ketones with a quaternary carbon centre were obtained in excellent diastereoselectivities (up to 100:1 dr) and excellent enantioselectivities (up to 99.7% ee). Low catalyst loading, recycle of catalyst, environmentally benign oxidant and easy transformation of the epoxides into medicinally important trifluoromethylated intermediate make our protocol much more practical. Copyright

Full text of DOI:10.1002/adsc.201300249

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DOI: 10.1002/adsc.201300249
Diastereoselective and Enantioselective Epoxidation of Acyclic b-
Trifluoromethyl-b,b-Disubstituted Enones by Hydrogen Peroxide
with a Pentafluorinated Quinidine-Derived Phase-Transfer
Catalyst
Shaoxiang Wu,a Dong Pan,a Chengyao Cao,a Qi Wang,a and Fu-Xue Chena,*
a
Department of Applied Chemistry, School of Chemical Engineering & the Environment, Beijing Institute of Technology,
No.5 South Zhongguancun Street, Haidian District, Beijing 100081, Peopleꢀs Republic of China
Fax : (+86)-10-6891-8296; e-mail: fuxue.chen@bit.edu.cn
Received: March 25, 2013; Revised: May 29, 2013; Published online: July 12, 2013
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201300249.
Abstract: An efficient catalytic asymmetric epoxi-
dation of b-trifluoromethyl-b,b-disubstituted unsa-
turated ketones has been achieved by a pentafluor-
ine-substituted phase-transfer catalyst with hydro-
gen peroxide (30%). Thus, the b-trifluoromethyl-
a,b-epoxy ketones with a quaternary carbon centre
were obtained in excellent diastereoselectivities (up
to 100:1 dr) and excellent enantioselectivities (up to
99.7% ee). Low catalyst loading, recycle of catalyst,
environmentally benign oxidant and easy transfor-
mation of the epoxides into medicinally important
trifluoromethylated intermediate make our protocol
much more practical.
phase-transfer catalysts (PTC), chiral ligand-metal
peroxides, polyamino acids, chiral hydroperoxides,
and chiral pyrrolidines.[5] Particularly, asymmetric
phase-transfer catalysis has been extensively studied
and many highly effective reaction systems have been
developed due to the many advantages of the tech-
nique including operational simplicity, mild reaction
conditions, inexpensive, environmentally benign re-
agents, and possibility to conduct large-scale prepara-
tions.[5,6] Despite the wealth of asymmetric epoxida-
tions of cyclic and acyclic a,b-unsaturated ketones,[5,7]
to the best of our knowledge, the highly enantioselec-
tive epoxidation of acyclic b,b-disubstituted enones
has been less described,[5,8] especially for the b,b-di-
Keywords: asymmetric catalysis; epoxidation; hy-
drogen peroxide; phase-transfer catalysts; trifluoro-
methyl group
ACHTUNGTRENsNUGN ubstituted unsaturated ketones having a b-trifluoro-
methyl group. In 2007, Berkessel reported the enan-
tioselective epoxidation of 2-methylnaphthoquinone
catalyzed by PTC giving the quinone epoxide in 85%
ee.[7l] Recently, Yamamoto and co-workers already re-
ported successful results using FeACTHNUTRGENUG(N OTf)2 and phenan-
throline for the catalytic asymmetric epoxidation of
Enantiomerically enriched a,b-epoxy ketones are ver- acyclic b-methyl b,b-disubstituted enones.[8b] This cata-
satile chiral building blocks for access to natural prod- lyst gave ee values up to 92%.
ucts and pharmaceuticals in asymmetric synthesis and
In addition, the challenges of sustainable develop-
medicinal chemistry.[1] They can be converted to ment create a demand for environmentally friendly
many types of useful chiral compounds such as a-hy- and cost-effective approaches under the concept of
droxy carbonyls, b-hydroxy carbonyls, a,b-dihydroxy green chemistry.[9] This requires eliminating the use or
carbonyls, epoxy alcohols. Since the breakthrough in generation of hazardous substances in chemical pro-
asymmetric epoxidation of allylic alcohols by Sharp- cesses. From this point of view, hydrogen peroxide is
less in the early 1980s,[2] considerable efforts have probably the best choice of terminal oxidant.[10]
been devoted to the development of efficient catalyst
During the preparation of this manuscript, Shibata
systems for the asymmetric epoxidation of olefins in described in an independent work the asymmetric
the last two decades.[3] In recent years, a variety of ap- aerobic epoxidation of b-trifluoromethyl-b,b-disubsti-
proaches has been surely elaborated for the asymmet- tuted enones induced by methylhydrazine.[11] While
ric epoxidation of electron-deficient olefins, particu- a notable achievement, this method requires the use
larly a,b-unsaturated ketones.[4] Versatile strategies of an equivalent of the highly flammable and toxic
have been developed including the use of chiral methylhydrazine.[12] Herein, we report an efficient cat-
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Table 1. Optimization of the catalyst efficiency.[a]
Entry
PTC (mol%)
Solvent
Time [h]
Yield [%][b]
ee [%][c]
1
3a (10)
3a (10)
3a (10)
3a (10)
3b (10)
3c (10)
3d (10)
3e (10)
3f (10)
3g (10)
3g (10)
3g (10)
3g (10)
3g (3)
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
20
24
24
24
20
20
20
20
20
20
40
6
6
8
8
8
8
8
87
46
41
CM
82
85
92
90
89
83
80
92
90
80
93
85
89
90
51
16
26
ND
39
44
74
71
79
92
91
98
96
98
99
98
98
À99
2[d]
3[e]
4[f]
5
6
7
8
9
10
11
12
13
14
15[g]
16[g,h]
17[g,i]
18[g]
AHCTUNGTERN(GNUN i-Pr)2O
CHCl3
CH2Cl2
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
3g (3)
3g (3)
3g (3)
3h (3)
[a]
Unless otherwise mentioned, all reactions were performed with 1a (0.1 mmol), 30% H2O2 (0.2 mL, 20.0 equiv.), chiral am-
monium salt (x mol%), 50% aqueous KOH (35 mL, 3.0 equiv.) in solvent (0.25M) at 08C. TCCA=trichloroisocyanuric
acid, NCS=N-chlorosuccinimide, ND=not detected., CM=complex mixture.
Isolated yield.
Determined by chiral HPLC on Chiralpak AS-H.
TCCA was used as oxidant.
NCS was used.
NaClO was used.
[b]
[c]
[d]
[e]
[f]
[g]
[h]
[i]
[1a]=1.0M.
2M aqueous KOH (0.15 mL, 3.0 equiv.) was used.
LiOH (7.2 mg, 3.0 equiv) was used.
alytic asymmetric epoxidation of b,b-disubstituted un- methyl)benzyl bromide was used and the results are
saturated ketones 1 bearing a b-trifluoromethyl group listed in Table 1. 30% H2O2 combined with 50%
with an F5-substituted PTC 3g at low catalyst loading aqueous KOH led to the desired product in 51% ee
(3 mol%). The b-trifluoromethyl-a,b-epoxy ketones albeit in good yield (Table 1, entry 1). However, tri-
(2) with a quaternary carbon centre were obtained in chloroisocyanuic acid (TCCA)[7e,f] and NCS were less
excellent yield (up to 96%), remarkable diastereose- effective in conjunction with 50% aqueous KOH
lectivity (up to 100:1 dr), and excellent enantioselec- while NaClO gave merely trace conversion and a com-
tivity (up to 99% ee) using aqueous H2O2 as the oxi- plex mixture (entries 2–4).
dant.
Subsequently, the effect of catalyst structure was
Initially, the model reaction was conducted with screened in the asymmetric epoxidation of enones. N-
(E)-4,4,4-trifluoro-1,3-diphenylbut-2-en-1-one (1a) by (4-Methylbenzyl)ammonium bromide salt (3b) led to
10 mol% of PTCs in toluene at 08C. To evaluate oxi- the desired product in 39% ee and good yield
dants, the widely used chiral quaternary ammonium (entry 5). When 3c possessing a 4-trifluoromethylben-
salt 3a derived from quinidine and 3,5-bis(trifluoro- zyl group at the nitrogen atom of quinidine was used,
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Diastereoselective and Enantioselective Epoxidation of Acyclic b-Trifluoromethyl-b,b-Disubstituted Enones
Table 2. Effect of hydroxy groups at C-6 and C-9 on the
the reaction afforded 2a with an increased 44% ee
(entry 6). It is noteworthy that when the reaction was
carried out in the presence of 3d bearing a hindering
N-9-anthrylmethylene group, a promising result (74%
ee) was achieved (entry 7). Comparing the above re-
sults and structures of 3a–3d, steric and electronic fac-
tors might have a great significance on the enantiose-
lectivity. This led us to employ the quaternary ammo-
nium salt with both appropriate steric hindrance and
strong electron-withdrawing property. As we all
known, fluorine has the highest electronegativity
value among all the elements,[13] while the size of fluo-
rine falls in between that of hydrogen and oxygen.
Therefore, a series of F-substituted quinidine-derived
ammonium salts (3e–g) was prepared and evaluated
(entries 8–10). To our delight, electron-deficient 2,4,5-
trifluorobenzylammonium salt 3f improved the enan-
tioselectivity to 79% ee. Furthermore, in the presence
of the F5-substituted catalyst 3g, the product was ob-
tained in excellent enantioselectivity (92% ee,
entry 10). This excellent enantioselectivity might
result from an F effect which was previously observed
in (S)-binaphthol derived C2-symmetric chiral cata-
lysts[14] and the binding of enzyme inhibitors.[15] This
enantioselectivity.[a]
Entry PTC (mol%) Time [h] Yield [%][b] ee [%][c]
1
2
3
4
3g (3)
4a (3)
4b (3)
4c (3)
8
93
23
18
trace
99
6
90
–
16
16
16
[a]
Reaction conditions (unless otherwise mentioned): 1a
(0.1 mmol), 30% H2O2 (0.2 mL, 20.0 equiv.), PTC
(0.003 mmol, 3 mol%), 50% aqueous KOH (35 mL,
3.0 equiv.) in CHCl3 (0.10 mL) at 08C.
Isolated yield.
Determined by chiral HPLC on Chiralpak AS-H.
[b]
[c]
was in accordance with the concept that an electron- For all evaluated b,b-disubstituted unsaturated ke-
withdrawing group might increase the enantioselectiv- tones bearing a b-trifluoromethyl group we obtained
ity by the formation of a tighter binding ion pair,[16] excellent diastereoselectivity and enantioselectivity. A
which would lead to a more rigid conformation.
series of trifluoromethylated enones bearing fluoro,
Upon screening solvents, CHCl3 was found giving chloro, bromo, methyl, methoxy and phenyl groups
the best ee value (98%) and yield (92%) (Table 1, en- on the aromatic rings (1a–1r) was selected to establish
tries 11–13). Furthermore, reducing the catalyst load- the generality of this process. We were pleased to find
ing to 3 mol% resulted in the retention of the enan- that the reaction tolerated a wide range of functional
tioselectivity (99% ee) and excellent yield albeit with groups on either aromatic ring including electron-neu-
a concentrated reaction medium and a longer reaction tral, electron-withdrawing, and electron-donating
time (entries 14 and 15). Bases hardly affected the groups with 95–99% ee and diastereoselectivity rang-
catalyst efficiency in the current methodology (en- ing from 20:1 to 100:1 (entries 1–17). Notably, a sub-
tries 16 and 17). As anticipated, quinine-derived cata- strate containing an aromatic heterocycle 1r was also
lyst (3h) also gave excellent enantioselectivity for converted to the product in excellent yield, diastereo-
(2R,3R)-2a with the opposite stereochemistry.
selectivity and enantioselectivity (entry 18). In addi-
Hydrogen bonding is believed to have a great tion, b-CF3-b-alkyl disubstituted substrates (1s, 1t)
effect in the asymmetric epoxidation of a,b-unsaturat- were oxidized to give the corresponding products
ed ketones.[5,7k] Catalyst 4a, without a free hydroxy with good enantiomeric excess and excellent yield
group, nearly lost its catalytic capability with 23% (entries 19 and 20). However, when Ar2 was replaced
yield and 6% ee (Table 2, entry 2), suggesting that by an alkyl substituent (Ar1 =Ph, Ar2 =t-Bu; Ar1 =
a hydrogen bond and a possible p-p stacking between C6H5CH2, Ar2 =t-Bu) complex mixtures were ob-
the benzyl moiety of catalyst and the aromatic portion tained.
of substrate act as well.[7f,g,17] Moreover, deprotection
The construction of the trifluoromethyl alcohol unit
of C-6 methyl affording catalyst 4b with two free hy- exemplified by CF3C(OH)RR’ is particularly impor-
droxy groups gave 90% ee but 18% yield (entry 3) tant as it is frequently a constituent of biologically
while a free OH at C-6 and C-9-O-benzylated catalyst active molecules.[18] On the other hand, chemoselec-
4c yielded traces of product (entry 4). Consequently, tive reduction of a,b-epoxy ketones to b-hydroxy ke-
the free hydroxyl group at C-9 governs both the con- tones has attracted much attention for several de-
version and enantioselectivity while a second free OH cades because the reduction products (b-hydroxy ke-
at C-6 destroys the catalytic activity but maintains the tones) are very important intermediates in organic
chiral inductivity (entry 1 vs. entries 2–4).
synthesis.[19] Due to the difficulty to get optically pure
With the optimized conditions in hand, the sub- trifluoromethylated compounds and the significance
strate generality was investigated as shown in Table 3. of these compounds,[20] the obtained b-CF3-a,b-epoxy
Adv. Synth. Catal. 2013, 355, 1917 – 1923
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Table 3. Substrate scope of the asymmetric epoxidation.[a]
Entry
2
Ar1
Ar2
Yield [%][b]
dr[c]
ee [%][d]
1
2
3
4
5
6
7
8
2a
2b
2c
2d
2e
2f
2g
2h
2i
2j
2k
2l
2m
2n
2o
2p
2q
2r
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
93
84
82
96
86
87
81
84
94
87
81
94
81
96
95
86
90
95
88
90
50:1
50:1
50:1
20:1
20:1
50:1
100:1
25:1
50:1
50:1
33:1
50:1
33:1
50:1
25:1
20:1
50:1
20:1
100:1
100:1
99[e]
98
98
95
98
98
99
99
99.7
98.6
97
98
98
97
96
99
96
4-FC6H4
4-ClC6H4
4-BrC6H4
4-CF3C6H4
2-naphthyl
4-PhC6H4
4-MeC6H4
2-MeOC6H4
3-MeOC6H4
4-MeOC6H4
Ph
9
Ph
Ph
Ph
10
11
12
13
14
15
16
17
18
19
20
4-FC6H4
4-ClC6H4
4-BrC6H4
4-CF3C6H4
4-MeC6H4
2-thiophthyl
3,5-Cl2C6H3
C2H5
Ph
Ph
Ph
Ph
Ph
4-Br-3-MeC6H3
Ph
Ph
99
82
81
2s
2t
C6H5CH2
[a]
Unless otherwise mentioned, all reactions were performed with 1a (0.1 mmol), 30% H2O2 (0.2 mL, 20.0 equiv.), 3g
(1.8 mg, 0.003 mmol, 3 mol%), 50% aqueous KOH (35 mL, 3.0 equiv.) in CHCl3 (0.10 mL) at 08C.
Isolated yield.
Determined by H NMR of the crude product.
Determined by chiral HPLC.
[b]
[c]
[d]
[e]
1
The absolute configuration of 2a was determined to be (2S,3S) by comparing HPLC retention time and the sign of optical
rotation value of 5a with that in the literature.[18d]
ketones were converted into other trifluoromethyl- forming the carbon–oxygen bond. Subsequently, the
containing intermediates, such as b-trifluoromethyl-b- nucleophilic a-carbon atom attacks the electrophilic
hydroxy ketones. Gratifyingly, treatment of 2a with
Zn and NH4Cl in EtOH for 2 h led to 5a in 79% yield
and 99% ee as shown in Eq. (1) (Scheme 1). b-Tri-
fluoromethyl b-hydroxy ketone 5b is one of an impor-
tant class of compounds for new agrochemicals and
veterinary medicines.[21] Similarly, b-trifluoromethyl-b-
hydroxyl ketone 5b was obtained with retained enan-
tioselectivity (97% ee) [Scheme 1, Eq. (2)].
In addition, to further evaluate the efficiency and
utility of this catalyst system, the catalyst was recov-
ered by simple filtration and reused with retained ca-
pability of asymmetric induction [Scheme 2, Eq. (3)].
Also, the reaction has been enlarged to a gram scale
under the optimized conditions and the product was
obtained in excellent enantioselectivity [Scheme 2,
Eq. (4)].
It is noteworthy that excellent enantioselectivity for
(2R,3R)-2a with the opposite stereochemistry was
achieved from (Z)-1a (Scheme 3). This indicates that
the peroxide adds as a nucleophile to the electrophilic
b-carbon atom of the b-CF3-b,b-disubstituted ketones a,b-epoxy ketones.
Scheme 1. Chemoselective reduction of b-trifluoromethyl-
1920
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Adv. Synth. Catal. 2013, 355, 1917 – 1923

Diastereoselective and Enantioselective Epoxidation of Acyclic b-Trifluoromethyl-b,b-Disubstituted Enones
Scheme 2. Catalyst recycling and scale-up experiments.
and hydrogen peroxide are efficient for the asymmet-
ric epoxidation of b-trifluoromethyl b,b-disubstituted
enones. The methodology described is significant as:
(i) a wide range of optical active trifluoromethyl ep-
oxides (2a–t) bearing a quaternary trifluoromethylat-
ed carbon centre were obtained in excellent enantio-
selectivity (up to 99.7% ee), and excellent diastereose-
lectivity (up to 100:1 dr) at low catalyst loading
(3 mol%); and (ii) the readily available and recyclable
Scheme 3. Asymmetric epoxidation of (Z)-1a.
peroxygen atom to produce the desired b-trifluoro- catalyst, environmental benign oxidant (H2O2), with
methyl-a,b-epoxy ketones.[7j,22]
mild, easy-to-handle reaction conditions make our
Based on the result of the asymmetric epoxidation protocol much more practical under the concept of
of (Z)-b-CF3-b,b-disubstituted enone, as well as the green chemistry; and (iii) the subsequent transforma-
essential role of the hydroxyl group at C-9 of the qui- tion into tetrasubstituted trifluoromethyl alcohol 5b,
nidine-derived F5-substituted quaternary ammonium a medicinally important intermediate was achieved
salt, a plausible transition state of the catalytic asym- with unprecedentedly high enantioselectivity. Further
metric epoxidation was proposed (Figure 1). The free investigations would be directed toward extension of
hydroxy group in the quaternary ammonium hydro- this catalyst for epoxidation to other kind of trifluoro-
peroxide of 3g[16] captures enone 2a through an inter- methylated olefins.
molecular hydrogen-bond with the carbonyl oxygen
atom of the substrate, together with a possible p-p
stacking of the fluorinated benzyl moiety and the aro-
matic portion of the substrate. Subsequent attack of
hydroperoxide to the b-carbon from the Re face fol-
lowed by an intramolecular cyclization leads to the
formation of the epoxide product.
In summary, we have demonstrated that an F5-sub-
stituted quinidine-derived quaternary ammonium salt
Experimental Section
Typical Procedure; Synthesis of 2a
Aqueous hydrogen peroxide (30%, 0.20 mL, 2.0 mmol) and
50% aqueous KOH (35 mL, 0.3 mmol) were added to a solu-
tion of (E)-4,4,4-trifluoro-1,3-diphenylbut-2-en-1-one (1a)
(27.6 mg, 0.10 mmol), catalyst 3g (1.8 mg, 0.003 mmol,
3 mol%), in CHCl3 (0.1 mL), and the reaction mixture was
stirred vigorously at 08C for 8 h. The reaction was quenched
with water, the aqueous layer was extracted with EtOAc
(15 mLꢂ3), and the combined organic layer was washed
with brine, dried over Na2SO4 and concentrated under re-
duced pressure. The residue was purified by column chroma-
tography with silica gel (petroleum ether/EtOAc=50/1, v/v)
to give the product (2a). The enantioselectivity was deter-
mined by chiral HPLC (Chiralpak AS-H, n-hexane/i-
PrOH=95:5, 0.5 mLminÀ1, l=254 nm):
t
(major)=
12.9 min, t (minor)=31.5 min, 99% ee. The diastereoselec-
1
tivity was determined by H NMR spectroscopy of the crude
Figure 1. Proposed transition state.
product.
Adv. Synth. Catal. 2013, 355, 1917 – 1923
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asc.wiley-vch.de
1921

Shaoxiang Wu et al.
COMMUNICATIONS
Acknowledgements
Biomol. Chem. 2007, 5, 2283–2290; j) Y. Chu, X. Liu,
W. Li, X. Hu, L. Lin, X. Feng, Chem. Sci. 2012, 3,
1996–2000; k) S. Arai, H. Tsuge, T. Shioiri, Tetrahedron
Lett. 1998, 39, 7563–7566; l) A. Berkessel, M. Guixꢃ, F.
Schmidt, J. M. Neudçrfl, J. Lex, Chem. Eur. J. 2007, 13,
4483–4498.
We thank NSFC (21172018) and Beijing Institute of Technol-
ogy for the financial support.
[8] a) W. Adam, P. B. Rao, H.-G. Degen, C. R. Saha-
Mçller, Eur. J. Org. Chem. 2002, 630–639; b) Y. Nishi-
kawa, H. Yamamoto, J. Am. Chem. Soc. 2011, 133,
8432–8435.
References
[1] a) D. P. Curran, J. Am. Chem. Soc. 1983, 105, 5826–
5833; b) M. J. Porter, J. Skidmore, Chem. Commun.
2000, 1215–1225; c) C. Lauret, Tetrahedron: Asymmetry
2001, 12, 2359–2383.
[2] a) J. T. Katsuki, K. B. Sharpless, J. Am. Chem. Soc.
1980, 102, 5974–5976; b) R. M. Hanson, K. B. Sharpless,
J. Org. Chem. 1986, 51, 1922–1925.
[3] For recent reviews, see: a) O. A. Wong, Y. Shi, Chem.
Rev. 2008, 108, 3958–3987; b) E. M. McGarrigle, D. G.
Gilheany, Chem. Rev. 2005, 105, 1563–1602; c) Q.-H.
Xia, H.-Q. Ge, C.-P. Ye, Z.-M. Liu, K.-X. Su, Chem.
Rev. 2005, 105, 1603–1662; d) B. S. Lane, K. Burgess,
Chem. Rev. 2003, 103, 2457–2474; e) W. Adam, C. R.
Saha-Mçller, P. A. Ganeshpure, Chem. Rev. 2001, 101,
3499–3548.
[9] a) J. O. Metzger, Angew. Chem. 1998, 110, 3145–3148;
Angew. Chem. Int. Ed. 1998, 37, 2975–2978; b) P. T.
Anastas, J. C. Warner, Green Chemistry, Theory and
Practice, Oxford University Press, New York, 1998;
c) J. M. DeSimone, Science 2002, 297, 799–803.
[10] a) K. A. Jørgensen, Chem. Rev. 1989, 89, 431–458;
b) C. W. Jones, Applications of Hydrogen Peroxide and
Derivatives, MPG Books Ltd., Cornwall, U.K., 1999;
c) W. Adam, Peroxide Chemistry Mechanistic and Prep-
arative Aspects of Oxygen Transfer, Wiley-VCH, Darm-
stadt, 2000; d) W. R. Sanderson, Pure Appl. Chem.
2000, 72, 1289–1304.
[11] H. Kawai, S. Okusu, Z. Yuan, E. Tokunaga, A.
Yamano, M. Shiro, N. Shibata, Angew. Chem. 2013,
125, 2277–2281; Angew. Chem. Int. Ed. 2013, 52, 2221–
2225.
[12] a) H. Pyysalo, A. Niskanen, A. v. Wright J. Food
Safety 1978, 1, 295–299; b) F. Vçgtte, W. M. Mtiller,
Naturwissenschaften 1980, 67, 255–256; c) S. Turchetta,
L. D. Ferra, M. Zenoni, M. Anibaldi, U.S. Patent
8,232,392 B2, 2012.
[4] a) T. Nemoto, T. Ohshima, M. Shibasaki, J. Synth. Org.
Chem. Jpn. 2002, 60, 94–105; b) A. Lattanzi, Curr. Org.
Synth. 2008, 5, 117–133.
[5] a) K. Maruoka, Asymmetric Phase Transfer Catalysis,
Wiley-VCH, Weinheim, 2008; b) D. Diez, M. G. Nunez,
A. B. Anton, P. Garcia, R. F. Moro, N. M. Garrido, I. S.
Marcos, P. Basabe, J. G. Urones, Curr. Org. Synth. 2008,
5, 186–216; c) T. Hashimoto, K. Maruoka, Chem. Rev.
2007, 107, 5656–5682; d) T. Ooi, K. Maruoka, Angew.
Chem. 2007, 119, 4300–4345; Angew. Chem. Int. Ed.
2007, 46, 4222–4266; e) J. Novacek, M. Waser, Eur. J.
Org. Chem. 2013, 637–648.
[6] a) A. Nelson, Angew. Chem. 1999, 111, 1685–1687;
Angew. Chem. Int. Ed. 1999, 38, 1583–1585; b) T.
Shioiri, S. Arai, in: Stimulating Concepts in Chemistry,
(Eds.: F. Vçgtle, J. F. Stoddart, M. Shibasaki), Wiley-
VCH, Weinheim, 2000, pp 123–143; c) M. J. OꢀDonnell,
in: Catalytic Asymmetric Syntheses, 2nd edn., (Ed.: I.
Ojima), Wiley-VCH, New York, 2000, Chap. 10;
d) M. J. OꢀDonnell, Aldrichimica Acta 2001, 34, 3–15;
e) M. J. OꢀDonnell, Acc. Chem. Res. 2004, 37, 506–517;
f) B. Lygo, B. I. Andrews, Acc. Chem. Res. 2004, 37,
518–525; g) J. Vachon, J. Lacour, Chimia 2006, 60, 266–
275.
[7] a) X. Wang, C. M. Reisinger, B. List, J. Am. Chem. Soc.
2008, 130, 6070–6071; b) B. Lygo, P. G. Wainwright, Tet-
rahedron 1999, 55, 6289–6300; c) E. J. Corey, F.-Y.
Zhang, Org. Lett. 1999, 1, 1287–1290; d) S. Arai, H.
Tsuge, M. Oku, M. Miura, T. Shioiri, Tetrahedron 2002,
58, 1623–1630; e) J. Ye, Y. Wang, R. Liu, G. Zhang, Q.
Zhang, J. Chen, X. Liang, Chem. Commun. 2003, 2714–
2715; f) J. Ye, Y. Wang, X. Liang, Adv. Synth. Catal.
2004, 346, 691–696; g) T. Ooi, D. Ohara, M. Tamura, K.
Maruoka, J. Am. Chem. Soc. 2004, 126, 6844–6845;
h) S.-s. Jew, J.-H. Lee, B.-S. Jeong, M.-S. Yoo, M. J.
Kim, Y.-J. Lee, J. Lee, S.-H. Choi, K. Lee, M.-S. Lah,
H.-g. Park, Angew. Chem. 2005, 117, 1407–1409;
Angew. Chem. Int. Ed. 2005, 44, 1383–1385; i) B. Lygo,
S. D. Gardiner, M. C. McLeod, D. C. M. To, Org.
[13] a) L. Pauling, The Nature of the Chemical Bond and the
Structure of Molecules and Crystals: An Introduction to
Modern Structural Chemistry, Cornell University Press,
Ithaca, NY, 1939; b) D. OꢀHagan, Chem. Soc. Rev.
2008, 37, 308–319.
[14] T. Ooi, M. Takeuchi, M. Kameda, K. Maruoka, J. Am.
Chem. Soc. 2000, 122, 5228–5229.
[15] a) C.-Y. Kim, P. P. Chandra, A. Jain, D. W. Christian-
son, J. Am. Chem. Soc. 2001, 123, 9620–9627; b) J. B.
Doyon, A. Jain, Org. Lett. 1999, 1, 183–186; c) S. Jew,
M.-S. Yoo, B.-S Jeong, Y. Park, H. G. Park, Org. Lett.
2002, 4, 4245–4248.
[16] a) E. J. Corey, F. Xu, M. C. Noe, J. Am. Chem. Soc.
1997, 119, 12414–12415; b) E. J. Corey, F.-Y. Zhang,
Angew. Chem. 1999, 111, 2057–2059; Angew. Chem.
Int. Ed. 1999, 38, 1931–1934; c) K. Brak, E. N. Jacob-
sen, Angew. Chem. 2013, 125, 558–588; Angew. Chem.
Int. Ed. 2013, 52, 534–561.
[17] a) T. Perrard, J.-C. Plaquevent, J.-R. Desmurs, D. Hꢄ-
brault, Org. Lett. 2000, 2, 2959–2962; b) T. Ooi, K.
Doda, K. Maruoka, Org. Lett. 2001, 3, 1273–1276; c) T.
Ooi, D. Ohara, K. Fukumoto, K. Maruoka, Org. Lett.
2005, 7, 3195–3197; d) C. Palomo, M. Oiarbide, A.
Laso, R. Lꢅpez, J. Am. Chem. Soc. 2005, 127, 17622–
17623; e) M. Lian, Z. Li, J. Du, Q. Meng, Z. Gao, Eur.
J. Org. Chem. 2010, 6525–6530; f) C. D. Fiandra, L.
Piras, F. Fini, P. Disetti, M. Moccia, M. F. A. Adamo,
Chem. Commun. 2012, 48, 3863–3865.
[18] a) X. Rabasseda, L. A. Sorbera, J. Castaner, Drugs
Future 1999, 24, 1057–1067; b) R. S. Meissner, J. J. Per-
kins, Y. Kim, B. Hanney, C. A. McVean, Patent
1922
asc.wiley-vch.de
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 1917 – 1923

Diastereoselective and Enantioselective Epoxidation of Acyclic b-Trifluoromethyl-b,b-Disubstituted Enones
WO2007016358, 2007; c) S. Wu, W. Zeng, Q. Wang, F.-
X. Chen, Org. Biomol. Chem. 2012, 10, 9334–9337;
d) Y. Zheng, H.-Y. Xiong, J. Nie, M.-Q. Hua, J.-A. Ma,
Chem. Commun. 2012, 48, 4308–4310.
[20] a) I. Ojima, Fluorine in Medicinal Chemistry and
Chemical Biology, Blackwell, Oxford, 2009; b) S.
Purser, P. R. Moore, S. Swallow, V. Gouverneur, Chem.
Soc. Rev. 2008, 37, 320–330; c) J.-P. Bꢄguꢄ, D. Bonnet-
Delpon, J. Fluorine Chem. 2006, 127, 992–1012.
[21] a) M. Takashi, S. Yasuhiro, M. Kazutaka, Y. Manabu,
Patent WO2007074789, 2007; b) Y. Manabu, U. Tomo-
hisa, M. Yuji, M. Tomohiro, M. Kazutaka, Patent
WO2009001942, 2008.
[19] a) C. H. Robinson, R. Henderson, J. Org. Chem. 1972,
37, 565–568; b) J. D. McChesney, T. N. Thompson, J.
Org. Chem. 1985, 50, 3473–3481; c) L. Engman, D.
Stern, J. Org. Chem. 1994, 59, 5179–5183; d) C. Har-
douin, F. Chevallier, B. Rousseau, E. Doris, J. Org.
Chem. 2001, 66, 1046–1048; e) N. Duangdee, W. Harny-
ing, G. Rulli, J.-M. Neudçrfl, H. Grçger, A. Berkessel,
J. Am. Chem. Soc. 2012, 134, 11196–11205.
[22] H. Pluim, H. Wynberg, J. Org. Chem. 1980, 45, 2498–
2502.
Adv. Synth. Catal. 2013, 355, 1917 – 1923
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1923