Lanthanide complexes combined with chiral salen ligands: Application in the enantioselective epoxidation reaction of α,β-unsaturated ketones

Article abstract of DOI:10.1039/c9ra01529a

Readily available lanthanide amides Ln[N(SiMe₃)₂]₃ (Ln = Nd (1), Sm (2), Eu (3), Yb (4), La (5)), combined with chiral salen ligands H₂L^a ((S,S)-N,N′-di-(3,5-disubstituted-salicylidene)-1,2-cyclohexan

Full text of DOI:10.1039/c9ra01529a

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Lanthanide complexes combined with chiral salen
ligands: application in the enantioselective
Cite this: RSC Adv., 2019, 9, 13749
epoxidation reaction of a,b-unsaturated ketones†
a
a
ab
ab
*
*
Xuexiu Xia, Chengrong Lu, Bei Zhao
and Yingming Yao
Readily available lanthanide amides Ln[N(SiMe3)2]3 (Ln ¼ Nd (1), Sm (2), Eu (3), Yb (4), La (5)), combined with
chiral salen ligands H2La ((S,S)-N,N0-di-(3,5-disubstituted-salicylidene)-1,2-cyclohexanediamine) and H2Lb
((S,S)-N,N0-di-(3,5-disubstituted-salicylidene)-1,2-diphenyl-1,2-ethanediamine) were employed in the
enantioselective epoxidation of a,b-unsaturated ketones. It was found that the salen–La complex shows
the highest efficiency and enantioselectivity. A relatively broad scope of a,b-unsaturated ketones was
investigated, and excellent yields (up to 99%) and moderate to good enantioselectivities (37–87%) of the
target molecules were achieved.
Received 28th February 2019
Accepted 17th April 2019
DOI: 10.1039/c9ra01529a
rsc.li/rsc-advances
and enantioselectivities.6 Epoxidation of non-functionalised
alkenes catalyzed by Mn–salen was investigated by Vyas.7
Introduction
However, to the best of our knowledge, examples of highly
active lanthanide complexes bearing chiral salen ligands are
limited, and their applications are restricted to ring–opening
reaction of epoxides,8 aminoalkene hydroamination/cyclisa-
tion,9 and nitro–mannich reaction.10 Shibasaki developed
asymmetric epoxidation of the electron-decient C]C bonds in
enones, a,b-unsaturated amides and esters, using the combi-
nation of lanthanide-BINOL-Ph3As]O as catalyst.11 Some
lanthanide–BINOL and its derivatives have also been investi-
gated in such a transformation, which gave rise to high enan-
tioselectivities in many cases.12 Feng employed Sc(OTf)3/N,N0-
dioxide as catalyst to realize the asymmetric epoxidation of a,b-
unsaturated ketones with excellent enantioselectivities.13
Recently, our group reported a series of rare-earth metal
complexes together with phenoxy-functionalized chiral proli-
nols which are highly efficient catalysts in the epoxidation of
a,b-unsaturated ketones. Both bisubstituted and trisubstituted
chalcones produced the corresponding epoxides in excellent
yields (up to 99%) and enantioselectivities (up to 99%) using
tert-butylhydroperoxide (TBHP) as the oxidant.14 As a continua-
tion of our research on the lanthanide-mediated asymmetric
transformation, we herein report rare-earth metal complexes
bearing chiral salen ligands and their catalytic potential in the
enantioselective epoxidation of a,b-unsaturated ketones.
Salen ligands are a particular class of Schiff bases, which are
produced by condensation of two salicylaldehydes with
a diamine. The use of salen metal complexes for a large variety
of catalytic transformations has emerged, mainly because the
salen ligands are easily available and highly tunable, and are
capable of coordinating to many different metals to form
various catalysts.1 In recent years, chiral salen ligands have
become one of the most popular chiral ligands and a series of
salen-transition metal catalysts have found application in
enantioselective synthesis. In 2001, Kozlowski developed a set
of modular bifunctional salen ligands, which showed enhanced
reactivity in the asymmetric addition of diethylzinc to aldehydes
and achieved excellent yield (up to 99%) with high enantiose-
lectivity (up to 91%).2 In 2003, Jiang used salen-Ti complexes to
catalyze the enantioselective addition of TMSCN to ketones.3
Rawal reported that the enantioselective carbonyl–ene reactions
were catalyzed by a salen–Co complex, which generated chiral
homoallylic alcohols in excellent yields, enantioselectivities and
diastereoselectivities.4 In 2014, the asymmetric conia-ene-type
cyclization of a-functionalized ketones was catalyzed by
a chiral salen–Fe complex.5 Salen–Zr complexes catalyzed
enantioselective a-hydroxylation of b-ketones esters using
cumene hydroperoxide (CHP) as the oxidant in excellent yields
aCollege of Chemistry, Chemical Engineering and Materials Science, Dushu Lake
Campus, Soochow University, Suzhou 215123, People's Republic of China. E-mail:
zhaobei@suda.edu.cn
Results and discussion
bKey Laboratory of Organic Synthesis of Jiangsu Province, People's Republic of China.
E-mail: yaoym@suda.edu.cn; Fax: +86 51265880305; Tel: +86 512 65880305
† Electronic supplementary information (ESI) available. CCDC 1888891 (for 7e)
contains the supplementary crystallographic data for this paper. For ESI and
crystallographic data in CIF or other electronic format see DOI:
10.1039/c9ra01529a
To test the reactivity and selectivity of lanthanide amides in
combination with chiral salen ligands, ve amides Ln
[N(SiMe3)2]3 (Ln ¼ Nd (1), Sm (2), Eu (3), Yb (4), La (5)), two
series of phenoxy-functionalized chiral salen ligands [(S,S)-N,N0-
di-(3-R1-5-R2-salicylidene)-1,2-cyclohexanediamine, [R1 ¼ R2
¼
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Me (H2L1); R1 ¼ R2 ¼ tBu (H2L2); R1 ¼ H, R2 ¼ Cl (H2L3); R1 ¼ H; studied, and the lanthanum amide 5 gave the best result. The ee
R2 ¼ tBu (H2L4); R1 ¼ tBu, R2 ¼ H (H2L5); R1 ¼ Me, R2 ¼ H value of 7a reached 41% without sacricing yield (Table 1,
(H2L6); R1 ¼ tBu; R2 ¼ 1-adam (H2L7)] and (S,S)-N,N0-(3-R1-5-R2- entries 1 and 10–13).
salicylidene)-1,2-diphenyl-1,2-ethanediamine [R1 ¼ R2 ¼ Me
To further improve enantioselectivity, different solvents were
(H2L8); R1 ¼ R2 ¼ tBu (H2L9)] were synthesized according to the screened. Fortunately, when acetonitrile was used as the solvent
previous study.15 With the neodymium amide 1 and the salen in the model reaction, the ee value increased to 57%, while the
ligand H2L1 in hand, the epoxidation reaction of chalcone was yield of 99% was maintained (Table 1, entries 13–17). Some
carried out in the presence of TBHP in THF. The results are successful cases in the asymmetric epoxidation reactions also
listed in Table 1. The model reaction underwent quantitatively achieved high ee values in acetonitrile.14a,16 Perhaps the weak
with unsatisfying enantioselectivity (99% yield and 31% ee). On coordination of acetonitrile to the central lanthanide metal
the basis of this nding, the inuence of the chiral salen ligands changes the coordination environment. And it leads to better
on enantioselectivity was carefully investigated via the modi- match for the catalyst and substrate, which may plays an
cation of the phenol moiety. The yields of the corresponding important role in the metal-based catalytic asymmetric reac-
epoxides remained excellent and the ee values varied from 11– tion. A relatively low temperature is usually helpful to improve
31% (Table 1, entries 1–7). If the chiral linkage was changed to the enantioselectivity of the asymmetric reaction. To our
(S,S)-1,2-diphenyl-1,2-ethanediamine (H2L8 and H2L9), no delight, attempts to lower the reaction temperature have
signicant improvement is observed (Table 1, entries 1–9).
a positive effect on the enantioselectivity. The ee value signi-
Thus, the chiral salen ligand H2L1 was the optimal choice for cantly increased when the reaction temperature decreased, and
ꢁ
the model reaction considering both yield and enantiose- the 80% ee of the epoxide 7a was obtained at ꢀ20 C (Table 1,
lectivity. Lanthanide amides of different metal centers were entries 17–20). Finally, the ratio of the lanthanum amide 5 to
the chiral salen ligand H2L1 was studied in CH3CN and the
results showed that the 1 : 1.2 molar ratio was optimal for the
model reaction (Table 1, entries 19, 21–22). Thus, 10 mol% of La
Table 1 Optimization of the reaction conditionsa
amide 5 in the combination of 12 mol% of chiral salen ligand
H2L1 was an optimal catalytic system for the asymmetric epox-
ꢁ
idation of chalcone with TBHP in CH3CN at ꢀ20 C.
Subsequently, various a,b-unsaturated ketones were synthe-
sized and investigated, and the results are summarized in Chart
1. Most of the disubstituted a,b-unsaturated ketones underwent
the transformation to give epoxides in excellent yields (92–99%)
and good to high enantioselectivities (57–83%), with the
exception of 7h (37% ee) (Chart 1, 7a–7o). Delightedly, much
better enantioselectivities, ranging from 80–87%, were observed
in reactions of trisubstituted a,b-unsaturated ketones, which
are in general bulky and challenging substrates (Chart 1, 7p–7y).
It is noteworthy that these substrates are not only trisubstituted,
but also cyclic with restricted mobility, hence more rigid tran-
sition states are supposed to generate, which may play a critical
role in controlling the enantioselectivity. Relatively high results
include the lanthanide–BINOL and its derivatives by Shibasaki,
Entry Cat
n
Ligand
X
Solvent T/ꢁC Yieldb (%) eec (%)
1
2
3
4
5
6
7
8
Nd-1 10 H2L1
Nd-1 10 H2L2
Nd-1 10 H2L3
Nd-1 10 H2L4
Nd-1 10 H2L5
Nd-1 10 H2L6
Nd-1 10 H2L7
Nd-1 10 H2L8
Nd-1 10 H2L9
Sm-2 10 H2L1
Eu-3 10 H2L1
Yb-4 10 H2L1
La-5 10 H2L1
La-5 10 H2L1
La-5 10 H2L1
La-5 10 H2L1
La-5 10 H2L1
La-5 10 H2L1
La-5 10 H2L1
La-5 10 H2L1
La-5 10 H2L1
La-5 10 H2L1
12 THF
12 THF
12 THF
12 THF
12 THF
12 THF
12 THF
12 THF
12 THF
12 THF
12 THF
12 THF
12 THF
12 Tol
12 Hex
12 DME
12 CH3CN rt
12 CH3CN
12 CH3CN -20
12 CH3CN -40
15 CH3CN -20
20 CH3CN -20
12 CH3CN -20
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
99
99
86
99
99
99
86
99
99
99
89
35
99
99
87
89
99
99
99
82
99
99
99
31
23
31
27
30
27
11
13
23
33
35
4
11
Inanaga12a and Ding,12b and Sc(OTf)3/N,N0-dioxide catalyst by
Feng,13 and rare-earth metal complexes together with phenoxy-
functionalized chiral prolinols reported by us.14
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
The real active species in the current system was investi-
gated. La amide 5 was treated with 1.2 equiv. chiral salen ligand
H2L1 in THF. Aer workup, complex 8 was isolated as yellow
crystals (Scheme 1). Its 1H NMR spectrum shows absence of
a peak at 0.1980 ppm, which is ascribed to the coordinated
–N(SiMe3)2 group. Signals at 3.87–3.55, 1.60 and 1.02 ppm are
assigned to cyclohexyl linkage. The peaks at 8.10, 7.91, 7.63, and
7.57 ppm are ascribed to the CH ¼ N double bond. These
observations prove the formation of complex 8 bearing the
chiral salen ligand. Finally, the ratio of the lanthanum atom to
chiral salen ligand is determined to be 2 : 3, based on results of
elemental analysis and complex titration.
41
5
37
35
57
70
80
56
71
75
57
0
La-5
5
H2L1
a
The reaction was performed with chalcone (0.3 mmol), TBHP (0.36
b
c
To nd out whether complex 8 is the active species, it was
tested in the model asymmetric epoxidation of chalcone under
mmol) in 1 mL of solvent. HPLC yield. Determined by chiral HPLC
analysis.
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Table 2 The effect of additives on the asymmetric epoxidation of
chalconea
Entry
Additive
Y
Yeildb (%)
eec (%)
1
2
3
4
5
6
7
8
9
—
20
20
20
20
20
20
10
30
50
91
98
93
88
86
85
93
95
90
70
78
15
59
60
56
73
75
66
HN(SiMe3)2
DBU
Pyridine
Et3N
2,2-Bipyridine
HN(SiMe3)2
HN(SiMe3)2
HN(SiMe3)2
a
Reactions were performed with chalcone (0.3 mmol), TBHP (0.36
b
c
mmol), 1 mL CH3CN. HPLC yield. Determined by chiral HPLC
analysis.
Chart
1 Epoxidation of a,b-unsaturated ketones catalyzed by
complex 5a. aReactions were performed with the substrate (0.3 mmol),
TBHP (0.36 mmol) in 1 mL CH3CN at ꢀ20 ꢁC for 10 h; isolated yield; ee
value were determined by chiral HPLC analysis. b15 h. c48 h.
Scheme 2 The synthesis and the molecular structure of compound 7e.
basic additives, including 1,8-diazabicyclo[5,4,0]undec-7-ene
(DBU), Et3N, pyridine, and 2,20-bipyridine, proved that
HN(SiMe3)2 (20 mol%) is the optimal choice (Table 2, entries 2–
9).
Finally, the outcome of the model reaction on a gram scale
was satisfactory with an appropriate prolonging of the reaction
time and the absolute conguration of the epoxides was
determined by single crystal diffraction analysis, chiral HPLC
and optical rotation analysis of a representative crystal 7e
(Scheme 2).
Scheme 1 The preparation of complex 8.
standard conditions. However, neither the yield nor ee value
was comparable with results of in situ generated catalyst. The
target epoxide was obtained in 91% yield and only 70% ee
(Table 2, entry 1). Comparing described catalyst system with
complex 8, the difference is HN(SiMe3)2 generated in situ in the
former, which may have the positive effects on the asymmetric
transformation. To verify the hypothesis, complex 8 together
with 20 mol% HN(SiMe3)2 were added to the model reaction.
The outcome of 98% yield with 78% ee indicates that the
addition of HN(SiMe3)2 indeed has a positive effect on the
asymmetric catalytic process (Table 2, entry 2). Screening of
The molecular structure of 7e showing 20% probability
ꢁ
˚
ellipsoids. Selected bond lengths (A) and bond angles ( ): O(1)–
C(8) 1.4235(3), O(1)–C(9) 1.430(4), C(8)–C(9) 1.494(4), O(4)–C(24)
1.435(4), O(4)–C(25) 1.415(4), C24–C25 1.482(4), O(1)–C(8)–C(1)
116.6(2), O(1)–C(9)–C(10) 115.1(3), O(1)–O(8)–C(9) 58.37(18),
O(1)–C(9)–C(8) 58.74(18), C(9)–O(1)–C(8) 62.89(19), O(4)–C(24)–
C(23) 116.1(2), O(4)–C(25)–C(26) 113.8(3), O(4)–C(24)–C(25)
58.02(19), O(4)–C(25)–C(24) 59.33(19), C(24)–O(4)–C(25) 62.6(2).
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a faint yellow solid was obtained by centrifugal separation.
Finally, complex 8 was puried by recrystallization in the mixed
solvent of toluene and hexane.
Conclusions
In summary, the asymmetric epoxidation of a,b-unsaturated
ketones was catalyzed by a new series of lanthanide amides with
chiral salen ligands. Aer careful screening, 10 mol% of the La
amide La[N(SiMe3)2]3 together with the chiral salen ligand (S,S)-
General procedure for the synthesis of the substituted
epoxides 7a–7y
N,N0-(3,5-dimethylsalicylidene)-1,2-cyclohexanediamine
in
Under argon atmosphere, lanthanum amide La[N(SiMe3)2]3
(0.03 mmol, 18.65 mg) was added to a solution of H2L1
(0.036 mmol, 13.62 mg) in CH3CN (1 mL). Aer stirring for
30 min, unsaturated ketones (0.3 mmol) was added and stirred
for further 30 min. Aer that, oxidant TBHP (0.36 mmol) was
added to the mixture. The system was stirred for 10 h at ꢀ20 ꢁC.
Quenched by the saturated solution of Na2SO3, the crude
product was extracted by ethyl acetate, then puried by column
chromatography (ethyl acetate–petroleum ether, 1 : 10) to
obtain the target epoxide. The enantiomeric excess of epoxide
was determined by chiral HPLC analysis.
a 1 : 1.2 molar ratio were found to be the optimal catalyst in
CH3CN at ꢀ20 C. For the disubstituted chalcone derivatives,
ꢁ
the target epoxides were obtained in excellent yields (92–99%)
with moderate to good ee values (57–83%), while epoxides from
the trisubstituted a,b-unsaturated ketones were generated in
high enantioselectivities (80–87%) and relative low yields (32–
57%). Complex 8 resulting from reaction of lanthanum amide
and salen ligand was isolated and characterized, which,
together with HN(SiMe3)2 additive, gave comparable catalytic
result with that of in situ generated catalyst. The absolute
conguration of the target chiral epoxides was determined by
single crystal diffraction analysis.
Spectroscopic data for ligands
(S,S)-N,N0-Di(3,5-dimethylsalicylidene)-1,2-cyclohexanediamine
(H2L1). A yellow solid; yield: 70%; [a]D25 ꢀ255ꢁ (c1.0 in CHCl3); 1H
NMR (400 MHz, CDCl3) d 13.39 (s, 2H, OH), 8.20 (s, 2H, CH), 6.94
(s, 2H, Ar–H), 6.80 (d, J ¼ 1.5 Hz, 2H, Ar–H), 3.29 (m, 2H, CH), 2.20
(d, J ¼ 6.7 Hz, 12H, CH3), 1.88 (m, 4H, CH2CH2), 1.70 (m, 2H, CH2),
1.46 (t, J ¼ 9.6 Hz, 2H, CH2). 13C NMR (100 MHz, CDCl3) d 164.3,
156.5, 133.7, 128.6, 126.5, 124.8, 117.1, 72.2, 32.7, 23.7, 19.8,
14.9. ppm. HRMS (ESI-MS) calcd for C24H31N2O2 [M + H]+:
379.2386, found: 379.2391.
(S,S)-N,N0-Di(3,5-di-butylsalicylidene)-1,2-cyclohexanediamine
(H2L2). A yellow solid; yield: 80%. [a]D25 ꢀ265ꢁ (c1.0 in CHCl3). 1H
NMR (400 MHz, CDCl3): d 13.73 (s, 2H, OH), 8.32 (s, 2H, CH), 7.33
(d, J ¼ 2.4 Hz, 2H, Ar–H), 7.01 (d, J ¼ 2.4 Hz, 2H, Ar–H), 3.34 (m,
2H, CHCH), 1.93 (dd, J ¼ 29.2, 11.5 Hz, 4H, CH2CH2), 1.76 (d, J ¼
10.0 Hz, 2H, CH2), 1.49 (d, J ¼ 9.7 Hz, 2H, CH2), 1.44 (s, 18H,
C(CH3)3), 1.26 (s, 18H, C(CH3)3). 13C NMR (100 MHz, CDCl3):
d 165.8, 158.0, 139.90, 136.4, 126.8, 126.1, 117.9, 72.4, 35.0, 34.1,
33.3, 31.4, 29.5, 24.4 ppm. HRMS (ESI-MS) calcd for C36H55N2O2
[M + H]+: 547.4264, found: 547.4261.
(S,S)-N,N0-Di(5-chlorosalicylidene)-1,2-cyclohexanediamine
(H2L3). A yellow solid; yield: 80%. [a]D25 ꢀ195ꢁ (c1.0 in CHCl3).
1H NMR (400 MHz, CDCl3): d 13.20 (s, 2H, OH), 8.18 (s, 2H,
CH), 7.19 (dd, J ¼ 8.8, 2.6 Hz, 2H, Ar–H), 7.12 (d, J ¼ 2.6 Hz, 2H,
Ar–H), 6.84 (d, J ¼ 8.8 Hz, 2H, Ar–H), 3.32 (m, 2H, CHCH), 1.91
(dd, J ¼ 18.6, 9.3 Hz, 4H, CH2CH2), 1.72 (m, 2H, CH2), 1.48 (t, J
¼ 10.0 Hz, 2H, CH2). 13C NMR (100 MHz, CDCl3): d 163.6,
159.5, 132.2, 130.6, 123.3, 119.3, 118.4, 72.7, 32.9, 24.1 ppm.
HRMS (ESI-MS) calcd for C20H21ClN2O2 [M + H]+: 391.0980,
found: 391.0987.
Experimental
General information
All manipulations and reactions involving air and water sensi-
tive components were performed with the standard Schlenk
techniques. Solvents, such as THF, toluene and hexane, were
degassed and distilled from sodium benzophenone ketyl under
argon before use. Analytical thin layer chromatography (TLC)
was performed using F254 pre-coated silica gel plate (0.2 mm
thickness). Aer elution, plates were detected using UV radia-
tion (254 nm) on a UV lamp. Flash chromatography was per-
formed using 200–300 mesh silica gel with freshly distilled
solvents. Nuclear magnetic resonance spectra were obtained on
a Bruker AV-400 apparatus (CDCl3 as solvent). High Resolution
Mass (HRMS) spectra were obtained using Bruker ESI-TOF.
Rare-earth metal analysis was performed by EDTA titration
with a xylenol orange indicator and a hexamine buffer. Carbon,
hydrogen and nitrogen analyses were performed by direct
combustion with a Carlo-Erba EA-1110 instrument. The ee
values determination was carried out using HPLC (Agilent
Technologies 1200 Series) with Daicel chiralcel columns at
room temperature. Optical rotation was measured using an
Autopol IV polarimeter equipped with a sodium vapor lamp at
589 nm. The absolute conguration of 7e was determined by the
detection of single crystal diffraction. Intensity data were
collected with a Rigaku Mercury CCD area detector in u scan
˚
mode using Cu–Ka radiation (l ¼ 1.54178 A). Hence, the
absolute congurations of 7a–7y were assigned by analogy,
assuming the same reaction pathway and the same analysis.
(S,S)-N,N0-Di(5-tert-butylsalicylidene)-1,2-cyclohexanediamine
(H2L4). A yellow solid; yield: 72%. [a]D25 ꢀ175ꢁ (c1.0 in CHCl3). 1H
NMR (400 MHz, CDCl3): d 13.13 (s, 2H), 8.25 (s, 2H, OH), 7.29 (m,
Synthesis of lanthanum complex 8
Under a standard Schlenk vacuum line, to a THF solution of 2H, Ar–H), 7.12 (d, J ¼ 2.5 Hz, 2H, Ar–H), 6.83 (d, J ¼ 8.6 Hz, 2H,
4 mmol La[N(SiMe3)2]3, 6 mmol H2L1 in 4 mL THF was added Ar–H), 3.31 (m, 2H, CHCH), 1.89 (dd, J ¼ 18.0, 9.9 Hz, 4H,
dropwise at room temperature. The mixture was continued to CH2CH2), 1.72 (dd, J ¼ 20.6, 9.8 Hz, 2H, CH2), 1.47 (t, J ¼ 10.1 Hz,
stir overnight. Then, removing the THF solvent in vacuo, the 2H, CH2), 1.24 (s, 18H, C(CH3)3). 13C NMR (100 MHz, CDCl3):
crude product was washed with hexane for three times and d 165.0, 158.6, 141.2, 129.5, 127.9, 118.0, 116.3, 72.8, 33.9, 33.2,
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31.4, 24.2 ppm. HRMS (ESI-MS) calcd for C28H39N2O2 [M + H]+: CH). HPLC: OD-H column, 90% hexanes, 10% iPrOH, 1.0
435.3021, found: 435.3028.
mL minꢀ1, tr (minor) ¼ 7.6 min, tr (major) ¼ 8.4 min. HRMS
(S,S)-N,N0-Di(3-tert-butylsalicylidene)-1,2-cyclohexanediamine (ESI, m/z) calcd for C15H14O2Na [M + Na]+: 247.0735, found:
(H2L5). A yellow solid; yield: 72%. [a]D25 ꢀ398ꢁ (c1.0 in CHCl3). H 247.0738. Mp: 74–76 C.
1
ꢁ
NMR (400 MHz, CDCl3): d 13.82 (s, 2H, OH), 8.22 (s, 2H, CH), 7.17
((2R,3S)-3-(4-Methphenyl)oxiran-2-yl)-(phenyl)methanone 7b.14a
(dd, J ¼ 7.9, 1.5 Hz, 2H, Ar–H), 6.92 (dd, J ¼ 7.6, 1.4 Hz, 2H, Ar–H), A white powder; yield 93%, ee 73%; [a]2D5 ꢀ110ꢁ (c0.3 in acetone).
6.64 (t, J ¼ 7.6 Hz, 2H, Ar–H), 3.25 (m, 2H, CHCH), 1.91 (d, J ¼ 1H NMR (400 MHz, CDCl3) d 7.94 (m, 2H, Ar–H), 7.55 (m, 1H, Ar–
13.9 Hz, 2H, CH2), 1.81 (m, 2H, CH2), 1.68 (dd, J ¼ 22.0, 11.4 Hz, H), 7.42 (m, 2H, Ar–H), 7.17 (q, J ¼ 7.8 Hz, 5H, Ar–H), 4.22 (d, J ¼
2H, CH2), 1.40 (m, 2H, CH2), 1.33 (s, 18H, C(CH3)3). 13C NMR (100 1.9 Hz, 1H, CH), 3.97 (d, J ¼ 1.8 Hz, 1H, CH), 2.31 (s, 3H, CH3).
MHz, CDCl3): d 164.9, 159.3, 133.2, 129.2, 125.7, 118.0, 72.6, 33.2, HPLC: OD-H column, 90% hexanes, 10% iPrOH, 1.0 mL minꢀ1, tr
24.2, 15.5 ppm. HRMS (ESI-MS) calcd for C28H39N2O2 [M + H]+: (minor) ¼ 6.5 min, tr (major) ¼ 7.3 min. HRMS (ESI, m/z) calcd for
435.3021, found: 435.30323.
C16H14O2Na [M + Na]+: 261.2758, found: 261.2753. Mp: 76 ꢁC.
(S,S)-N,N0-Di(5-methylsalicylidene)-1,2-cyclohexanediamine
((2R,3S)-3-(4-Methoxyphenyl)oxiran-2-yl)-(phenyl)methanone
(H2L6). A yellow solid; yield: 71%. [a]D25 ꢀ495ꢁ (c1.0 in CHCl3). 7c.14a A white powder; yield 95%, ee 79%; [a]2D5 ꢀ102ꢁ (c0.3in
1
1H NMR (400 MHz, CDCl3): d 13.63 (s, 2H, OH), 8.27 (s, 2H, acetone). H NMR (400 MHz, CDCl3) d 8.01 (m, 2H, Ar–H), 7.62
CH), 7.12 (d, J ¼ 7.3 Hz, 2H, Ar–H), 7.01 (d, J ¼ 7.6 Hz, 2H, Ar– (m, 1H, Ar–H), 7.49 (m, 2H, Ar–H), 7.30 (m, 2H, Ar–H), 6.93 (m,
H), 6.72 (t, J ¼ 7.5 Hz, 2H, Ar–H), 3.31 (m, 2H, CH), 2.24 (s, 6H, 2H, Ar–H), 4.29 (d, J ¼ 1.9 Hz, 1H, CH), 4.03 (d, J ¼ 1.8 Hz, 1H,
H3), 1.91 (m, 4H, CH2CH2), 1.71 (d, J ¼ 10.1 Hz, 2H, CH2), 1.48 CH), 3.83 (s, 3H, CH3). HPLC: OD-H column, 90% hexanes, 10%
(dd, J ¼ 12.7, 6.1 Hz, 2H, CH2). 13C NMR (100 MHz, CDCl3): iPrOH, 1.0 mL minꢀ1, tr (minor) ¼ 9.4 min, tr (major) ¼ 10.4 min.
d 164.4, 158.8, 132.7, 128.7, 125.2, 117.5, 72.1, 32.7, 23.7, HRMS (ESI, m/z) calcd for C16H14O2Na [M + Na]+: 277.0841,
15.0 ppm. HRMS (ESI-MS) calcd for C22H27N2O2 [M + H]+: found: 277.0846. Mp: 81–82 ꢁC.
351.2073, found: 351.2077.
((2R,3S)-3-(4-Isopropylphenyl)oxiran-2-yl)-(phenyl)methanone
(S,S)-N,N0-Di(5-methyl-3-adamantylsalicylidene)-1,2-cyclohexa- 7d.14a A white powder; yield 95%, ee 63%; [a]2D5 ꢀ88ꢁ (c0.3 in
nediamine (H2L7). A yellow solid; yield: 45%. [a]D25 ꢀ235ꢁ (c1.0 in acetone). H NMR (400 MHz, CDCl3) d 8.00 (m, 2H, Ar–H), 7.60
1
CHCl3). 1H NMR (400 MHz, CDCl3): d 13.66 (s, 2H, OH), 8.30 (s, (m, 1H, Ar–H), 7.47 (m, 2H, Ar–H), 7.28 (m, 4H, Ar–H), 4.31 (d, J ¼
2H, CH), 7.24 (d, J ¼ 2.4 Hz, 2H, Ar–H), 6.97 (d, J ¼ 2.4 Hz, 2H, Ar– 1.9 Hz, 1H, CH), 4.05 (d, J ¼ 1.8 Hz, 1H, CH), 2.93 (m, 1H, CH),
H), 3.31 (m, 2H, CH), 2.15 (s, 12H, CH2), 2.07 (s, 6H, CH), 1.90 (m, 1.26 (d, J ¼ 6.9 Hz, 6H, CH3). HPLC: OD-H column, 90% hexanes,
4H, CH2CH2), 1.79 (s, 12H, CH2), 1.45 (m, 2H, CH2), 1.30 (m, 2H, 10% PrOH, 1.0 mL minꢀ1, tr (minor) ¼ 5.7 min, tr (major) ¼
i
CH2), 1.24 (s, 18H, CH3). 13C NMR (100 MHz, CDCl3): d 165.0, 6.4 min. HRMS (ESI, m/z) calcd for C18H18O2Na [M + Na]+:
158.6, 141.2, 129.5, 127.9, 118.0, 116.2, 72.8, 33.9, 33.2, 31.40, 289.1204, found: 289.1205. Mp: 74–76 ꢁC.
24.2 ppm. HRMS (ESI-MS) calcd for C48H67N2O2 [M + H]+:
703.5203, found: 703.5204.
((2R,3S)-3-(2-Methoxyphenyl)oxiran-2-yl)-(phenyl)methanone
7e.14a A white powder; yield 97%, ee 83%; [a]2D5 ꢀ94ꢁ (c0.3 in
(S,S)-N,N0-Di(3,5-dimethylsalicylidene)-1,2-diphenyl-1,2-ethane- acetone). 1H NMR (400 MHz, CDCl3) d 8.05 (m, 2H, Ar–H), 7.62 (t,
diamine (H2L8). A yellow solid; yield: 72%. [a]2D5 189ꢁ (c1.0 in J ¼ 7.4 Hz, 1H, Ar–H), 7.49 (t, J ¼ 7.7 Hz, 2H, Ar–H), 7.31 (m, 2H,
CHCl3). 1H NMR (400 MHz, CDCl3): d 13.25 (s, 2H, OH), 8.27 (s, 2H, Ar–H), 7.00 (t, J ¼ 7.5 Hz, 1H, Ar–H), 6.92 (d, J ¼ 8.2 Hz, 1H, Ar–H),
CH), 7.16 (m, 10H, Ar–H), 6.94 (s, 2H, Ar–H), 6.77 (s, 2H, Ar–H), 4.39 (d, J ¼ 1.8 Hz, 1H, CH), 4.20 (d, J ¼ 1.9 Hz, 1H, CH), 3.83 (s,
4.68 (s, 2H, CHCH), 2.24 (s, 6H, CH3), 2.17 (s, 6H, CH3). 13C NMR 3H, CH3). HPLC: OD-H column, 90% hexanes, 10% PrOH, 1.0
i
(100 MHz, CDCl3): d 166.3, 156.9, 139.7, 134.6, 129.5, 128.3, 128.0, mL minꢀ1, 8.3 min (minor), 10.1 (major). tr (minor) ¼ 8.3 min, tr
127.5, 127.2, 125.4, 117.6, 80.5, 20.3, 15.5 ppm. HRMS (ESI-MS) (major) ¼ 10.1 min. HRMS (ESI, m/z) calcd for C16H14O3Na [M +
calcd for C32H33N2O2 [M + H]+: 477.2542, found: 477.2549.
Na]+: 277.0841, found: 277.08443. Mp: 89–90 ꢁC.
(S,S)-N,N0-Di(3,5-di-tert-butylsalicylidene)-1,2-diphenyl-1,2-
((2R,3S)-3-(2-Methphenyl)oxiran-2-yl)-(phenyl)methanone 7f.14a
ethanediamine (H2L9). A yellow solid; yield: 81%. [a]D25 203ꢁ A white powder; yield 96%, ee 73%; [a]2D5 ꢀ77ꢁ (c0.3 in acetone). 1H
(c1.0 in CHCl3). 1H NMR (400 MHz, CDCl3): d 13.60 (s, 2H, OH), NMR (400 MHz, CDCl3) d 8.05 (m, 2H, Ar–H), 7.63 (m, 1H, Ar–H),
8.40 (s, 2H, CH), 7.31 (s, 2H, Ar–H), 7.16 (m, 10H, Ar–H), 6.98 (s, 7.50 (t, J ¼ 7.7 Hz, 2H, Ar–H), 7.34 (dd, J ¼ 6.8, 2.3 Hz, 1H, Ar–H),
2H, Ar–H), 4.72 (s, 2H, CHCH), 1.42 (s, 18H, CH3), 1.22 (s, 18H, 7.26 (m, 2H, Ar–H), 7.19 (m, 1H, Ar–H), 4.21 (t, J ¼ 1.8 Hz, 2H, CH),
CH3). 13C NMR (100 MHz, CDCl3): d 167.1, 158.0, 140.1, 139.9, 2.36 (s, 3H, CH3). HPLC: OD-H column, 90% hexanes, 10% iPrOH,
136.4, 128.3, 128.1, 127.5, 127.2, 126.4, 117.9, 80.2, 35.1, 34.1, 1.0 mL minꢀ1, tr (minor) ¼ 6.8 min, tr (major) ¼ 7.7 min. HRMS
31.5, 29.5 ppm. HRMS (ESI-MS) calcd for C44H57N2O2 [M + H]+: (ESI, m/z) calcd for C16H14O2Na [M + Na]+: 261.2758, found:
645.4420, found: 645.4426.
261.2759. Mp: 70–72 ꢁC.
(4-Methylphenyl)-[(2R,3S)-3-(4-isopropylphenyl)-2-oxiran]-
methanone 7g.14a A white powder; yield 95%, ee 57%;
[a]2D5 ꢀ97ꢁ (c0.3 in acetone).1H NMR (400 MHz, CDCl3) d 7.83
(d, J ¼ 8.2 Hz, 2H, Ar–H), 7.20 (m, 6H, Ar–H), 4.20 (d, J ¼ 1.9 Hz,
Spectroscopic data for saymmetric epoxidation products
((2R,3S)-3-Phenyloxiran-2-yl)-phenylmethanone 7a.14a
A
white powder; yield 99%, ee 80%; [a]2D5 ꢀ112ꢁ (c0.3 in acetone). 1H, CH), 3.95 (d, J ¼ 1.8 Hz, 1H, CH), 2.84 (m, 1H, CH), 2.33 (s,
1H NMR (400 MHz, CDCl3) d 8.00 (d, J ¼ 7.3 Hz, 2H, Ar–H), 7.61 3H, CH3), 1.18 (d, J ¼ 6.9 Hz, 6H, CH3). HPLC: OD-H column,
(t, J ¼ 7.4 Hz, 1H, Ar–H), 7.47 (t, J ¼ 7.7 Hz, 2H, Ar–H), 7.38 (m, 90% hexanes, 10% iPrOH, 1.0 mL minꢀ1, 7.8 min (minor), 8.2
5H, Ar–H), 4.29 (d, J ¼ 1.7 Hz, 1H, CH), 4.07 (d, J ¼ 1.6 Hz, 1H, (major). tr (minor) ¼ 7.8 min, tr (major) ¼ 8.2 min. HRMS (ESI,
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m/z) calcd for C19H20O2Na [M + Na]+: 303.1361, found: 1H NMR (400 MHz, CDCl3) d 7.97 (dd, J ¼ 3.9, 1.0 Hz, 1H, CH),
ꢁ
303.1367. Mp: 64–67 C.
7.72 (dd, J ¼ 4.9, 1.0 Hz, 1H, CH), 7.34 (m, 5H, Ar–H), 7.15 (dd, J
¼ 4.9, 3.9 Hz, 1H, CH), 4.15 (d, J ¼ 1.7 Hz, 1H, CH), 4.08 (d, J ¼
(3-Methoxyphenyl)-[(2R,3S)-3-phenyloxiran-2-yl]-methanone
7h.14a A white powder; yield 93%, ee 37%; [a]2D5 ꢀ49ꢁ (c0.3 in 1.8 Hz, 1H, CH). HPLC: OD-H column, 90% hexanes, 10%
acetone). 1H NMR (400 MHz, CDCl3) d 7.57 (dd, J ¼ 4.9, 3.6 Hz, iPrOH, 1.0 mL minꢀ1, tr (minor) ¼ 10.8 min, tr (major) ¼
1H, Ar–H), 7.52 (m, 1H, Ar–H), 7.38 (m, 6H, Ar–H), 7.16 (m, 1H, 10.1 min. HRMS (ESI, m/z) calcd for C13H10O2SNa [M + Na]+:
ꢁ
Ar–H), 4.29 (d, J ¼ 1.9 Hz, 1H, CH), 4.07 (d, J ¼ 1.8 Hz, 1H, CH), 253.0229, found: 253.0233. Mp: 54–56 C.
3.84 (s, 3H, CH3). HPLC: OD-H column, 90% hexanes, 10%
[(2R,3S)-3-Phenyloxiran-2-yl](furan-2-yl)-methanone 7o.15a
A
iPrOH, 1.0 mL minꢀ1, tr (minor) ¼ 7.5 min, tr (major) ¼ 8.7 min. white powder; yield 95%, ee 71%; [a]2D5 ꢀ57ꢁ (c0.3 in acetone).
HRMS (ESI, m/z) calcd for C16H14O3Na [M + Na]+: 277.0841, 1H NMR (400 MHz, CDCl3) d 7.66 (d, J ¼ 1.0 Hz, 1H, CH), 7.45 (d,
ꢁ
found: 277.0849. Mp: 74–76 C.
J ¼ 3.6 Hz, 1H, CH), 7.35 (m, 5H, Ar–H), 6.59 (dd, J ¼ 3.6, 1.7 Hz,
((2R,3S)-3-(4-Fluorophenyl)oxiran-2-yl)-(phenyl)methanone
1H, CH), 4.14 (s, 2H, CH). HPLC: OD-H column, 90% hexanes,
7i.14a A white powder; yield 93%, ee 77%; [a]2D5 ꢀ98ꢁ (c0.3 in 10% PrOH, 1.0 mL minꢀ1, tr (minor) ¼ 10.8 min, tr (major) ¼
acetone). 1H NMR (400 MHz, CDCl3) d 7.93 (m, 2H, Ar–H), 7.56 11.3 min. HRMS (ESI, m/z) calcd for ꢁC13H10O3Na [M + Na]+:
(m, 1H, Ar–H), 7.44 (m, 4H, Ar–H), 7.17 (dd, J ¼ 6.2, 4.5 Hz, 2H, 237.0528, found: 237.0533. Mp: 44–47 C.
i
Ar–H), 4.17 (d, J ¼ 1.8 Hz, 1H, CH), 3.98 (d, J ¼ 1.7 Hz, 1H, CH).
(2R,30S)-30-Phenyl-3,4-dihydro-1H-spiro[naphthalene-2,20-
HPLC: OD-H column, 90% hexanes, 10% iPrOH, 1.0 mL minꢀ1
,
oxiran]-1-one 7p.14b A white powder; yield 43%, ee 83%;
tr (minor) ¼ 8.4 min, tr (major) ¼ 9.4 min. HRMS (ESI, m/z) calcd [a]2D5 ꢀ96ꢁ (c0.3 in acetone). H NMR (400 MHz, CDCl3) d 8.10
1
for C15H11FO2Na [M + Na]+: 265.0641, found: 265.0647. Mp: (dd, J ¼ 7.8, 0.9 Hz, 1H, Ar–H), 7.51 (m, 1H, Ar–H), 7.37 (m, 6H,
ꢁ
91.5–94.2 C.
Ar–H), 7.22 (d, J ¼ 7.6 Hz, 1H, Ar–H), 4.35 (s, 1H, CH), 2.82 (dd, J
¼ 8.5, 4.1 Hz, 2H, CH2), 2.43 (m, 1H, CH2), 1.85 (m, 1H, CH2).
((2R,3S)-3-(4-Chlorophenyl)oxiran-2-yl)-(phenyl)methanone
7j.14a A white powder; yield 95%, ee 71%; [a]2D5 ꢀ80ꢁ (c0.3 in HPLC: OD-H column, 97% hexanes, 3% iPrOH, 1.0 mL minꢀ1, tr
acetone). 1H NMR (400 MHz, CDCl3) d 8.01 (m, 2H, Ar–H), 7.63 (minor) ¼ 19.5 min, tr (major) ¼ 21.1 min. HRMS (ESI, m/z)
(m, 1H, Ar–H), 7.49 (m, 2H, Ar–H), 7.35 (m, 2H, Ar–H), 7.10 (m, calcd for C17H14O2Na [M + Na]+: 273.0891, found: 273.0897. Mp:
ꢁ
2H, Ar–H), 4.26 (s, 1H, CH), 4.07 (d, J ¼ 1.8 Hz, 1H, CH). HPLC: 73.5–75.5 C.
OD-H column, 90% hexanes, 10% PrOH, 1.0 mL minꢀ1, tr
(2R,30S)-30-(4-Methoxyphenyl)-3,4-dihydro-1H-spiro[naph-
i
(minor) ¼ 8.0 min, tr (major) ¼ 8.8 min. HRMS (ESI, m/z) calcd thalene-2,20-oxiran]-1-one 7q.14b A white powder; yield 43%, ee
for C15H11ClO2Na [M + Na]+: 281.0345, found: 281.0349. Mp: 114 87%; [a]D25 ꢀ111ꢁ (c0.3 in acetone). H NMR (400 MHz, CDCl3)
1
ꢁC.
d 8.10 (d, J ¼ 7.8 Hz, 1H, Ar–H), 7.51 (m, 1H, Ar–H), 7.35 (t, J ¼
7.5 Hz, 1H, Ar–H), 7.29 (d, J ¼ 8.6 Hz, 2H, Ar–H), 7.22 (d, J ¼
((2R,3S)-3-(4-Bromophenyl)oxiran-2-yl)-(phenyl)methanone
7k.14a A white powder; yield 92%, ee 67%; [a]2D5 ꢀ78ꢁ (c0.3 in 7.6 Hz, 1H, Ar–H), 6.93 (dd, J ¼ 6.6, 4.8 Hz, 2H, Ar–H), 4.30 (s,
acetone). 1H NMR (400 MHz, CDCl3) d 8.00 (m, 2H, Ar–H), 7.63 1H, CH), 3.83 (s, 3H, CH3), 2.83 (dd, J ¼ 8.5, 4.0 Hz, 2H, CH2),
(m, 1H, Ar–H), 7.49 (dd, J ¼ 10.7, 4.8 Hz, 2H, Ar–H), 7.38 (m, 2H, 2.44 (m, 1H, CH2), 1.86 (m, 1H, CH2). HPLC: OD-H column, 97%
Ar–H), 7.31 (m, 2H, Ar–H), 4.25 (d, J ¼ 1.8 Hz, 1H, CH), 4.06 (d, J hexanes, 3% PrOH, 1.0 mL minꢀ1, tr (minor) ¼ 30.0 min, tr
i
¼ 1.8 Hz, 1H, CH). HPLC: OD-H column, 90% hexanes, 10% (major) ¼ 28.7 min. HRMS (ESI, m/z) calcd for C18H16O3Na [M +
iPrOH, 1.0 mL minꢀ1, tr (minor) ¼ 7.7 min, tr (major) ¼ 8.2 min. Na] : 303.0997, found: 303.0999. Mp: 76–79 C.
+
ꢁ
HRMS (ESI, m/z) calcd for C15H11BrO2Na [M + Na]+: 324.9840,
(2R,30S)-30-(4-Methphenyl)-3,4-dihydro-1H-spiro[naphtha-
lene-2,20-oxiran]-1-one 7r.14b A white powder; yield 41%, ee 81%;
ꢁ
found: 324.9843. Mp: 89–90 C.
1
((2R,3S)-3-(3-Chlorophenyl)oxiran-2-yl)-(phenyl)methanone
[a]2D5 ꢀ41ꢁ (c0.3 in acetone). H NMR (400 MHz, CDCl3) d 8.11
7l.14a A white powder; yield 98%, ee 61%; [a]2D5 ꢀ78ꢁ (c0.3 in (dd, J ¼ 7.9, 1.0 Hz, 1H, Ar–H), 7.51 (m, 1H, Ar–H), 7.36 (t, J ¼
acetone). 1H NMR (400 MHz, CDCl3) d 8.00 (m, 2H, Ar–H), 7.63 7.5 Hz, 1H, Ar–H), 7.25 (m, 6H, Ar–H), 4.32 (s, 1H, CH), 2.83 (dd,
(m, 1H, Ar–H), 7.49 (m, 2H, Ar–H), 7.38 (m, 2H, Ar–H), 7.30 (m, J ¼ 8.5, 4.1 Hz, 2H, CH2), 2.44 (m, 1H, CH2), 2.38 (s, 3H, CH3),
2H, Ar–H), 4.25 (d, J ¼ 1.9 Hz, 1H, CH), 4.06 (d, J ¼ 1.8 Hz, 1H, 1.86 (m, 1H, CH2). HPLC: OD-H column, 90% hexanes, 10%
CH). HPLC: OD-H column, 90% hexanes, 10% iPrOH, 1.0 iPrOH, 1.0 mL minꢀ1, tr (minor) ¼ 14.9 min, tr (major) ¼
mL minꢀ1, tr (minor) ¼ 8.0 min, tr (major) ¼ 8.8 min. HRMS 20.9 min. HRMS (ESI, m/z) calcd for C18H16O2Na [M + Na]+:
(ESI, m/z) calcd for Cꢁ15H11ClO2Na [M + Na]+: 281.0345, found: 287.1048, found: 287.1051. Mp: 165–169 C.
ꢁ
281.0346. Mp: 74–75 C.
(2R,30S)-30-(3-Methphenyl)-3,4-dihydro-1H-spiro[naphtha-
lene-2,20-oxiran]-1-one 7s.17 A white powder; yield 99%, ee 80%;
(3-Chlorophenyl)-[(2R,3S)-3-phenyloxiran-2-yl]-methanone
7m.14a A white powder; yield 97%, ee 61%; [a]2D5 ꢀ89ꢁ (c0.3 in [a]D25 ꢀ78ꢁ (c0.3 in acetone). 1H NMR (400 MHz, CDCl3) d 8.11
acetone). 1H NMR (400 MHz, CDCl3) d 8.03 (m, 2H, Ar–H), 7.48 (m, 1H, Ar–H), 7.51 (m, 1H, Ar–H), 7.36 (t, J ¼ 7.6 Hz, 1H, Ar–H),
(m, 2H, Ar–H), 7.38 (m, 5H, Ar–H), 4.23 (d, J ¼ 1.9 Hz, 1H, CH), 7.25 (m, 2H, Ar–H), 7.17 (m, 3H, Ar–H), 4.32 (s, 1H, CH), 2.83
4.08 (d, J ¼ 1.8 Hz, 1H, CH). HPLC: OD-H column, 97% hexanes, (dd, J ¼ 8.4, 4.1 Hz, 2H, CH2), 2.44 (m, 1H, CH2), 2.37 (s, 3H,
i
3% PrOH, 1.0 mL minꢀ1, tr (minor) ¼ 21.1 min, tr (major) ¼ CH3), 1.87 m, 1H, CH2). HPLC: OD-H column, 90% hexanes,
i
22.0 min. HRMS (ESI, m/z) calcd for C15H11ClO2Na [M + Na]+: 10% PrOH, 1.0 mL minꢀ1, tr (minor) ¼ 7.8 min, tr (major) ¼
ꢁ
281.0345, found: 281.0354. Mp: 67–68 C.
6.9 min. HRMS (ESI, m/z) calcd for C18H16O2Na [M + Na]+:
287.1048, found: 287.1052. Mp: 96–98 C.
[(2R,3S)-3-Phenyloxiran-2-yl](thien-2-yl)-methanone 7n.14a
A
ꢁ
white powder; yield 99%, ee 65%; [a]2D5 ꢀ43ꢁ (c0.3 in acetone).
13754 | RSC Adv., 2019, 9, 13749–13756
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(2R,30S)-30-(2-Methphenyl)-3,4-dihydro-1H-spiro[naphtha-
1H, CH2), 2.39 (m, 1H, CH2), 1.64 (m, 1H, CH2). HPLC: OD-H
i
column, 97% hexanes, 3% PrOH, 1.0 mL minꢀ1, tr (minor) ¼
lene-2,20-oxiran]-1-one 7t.17 A white powder; yield 99%, ee 87%;
1
[a]2D5 ꢀ88ꢁ (c0.3 in acetone). H NMR (400 MHz, CDCl3) d 8.13
21.1 min, tr (major) ¼ 19.5 min. HRMS (ESI, m/z) calcd for
C
17H13ClO2Na [M + Na]+: 307.0502, found: 307.0506. Mp: 132–
(dd, J ¼ 7.9, 1.0 Hz, 1H, Ar–H), 7.53 (m, 1H, Ar–H), 7.36 (dd, J ¼
12.4, 5.4 Hz, 2H, Ar–H), 7.25 (m, 3H, Ar–H), 7.18 (dd, J ¼ 6.4,
2.2 Hz, 1H, Ar–H), 4.36 (s, 1H, CH), 2.83 (m, 2H, CH2), 2.37 (m,
1H, CH2), 2.25 (s, 3H, CH3), 1.74 (m, 1H, CH2). HPLC: OD-H
ꢁ
134 C.
Conflicts of interest
i
column, 90% hexanes, 10% PrOH, 1.0 mL minꢀ1, tr (minor)
¼ 6.6 min, tr (major) ¼ 6.9 min. HRMS (ESI, m/z) calcd for
The authors declare no competing nancial interest.
C
18H16O2Na [M + Na]+: 287.1048, found: 287.1051. Mp: 114–
ꢁ
116 C.
(2R,30S)-30-(4-Fluorophenyl)-3,4-dihydro-1H-spiro[naphtha-
Acknowledgements
lene-2,20-oxiran]-1-one 7u.17 A yellow powder; yield 38%, ee 81%;
[a]2D5 ꢀ54ꢁ (c0.3 in acetone). 1H NMR (400 MHz, CDCl3) d 8.10 (d,
J ¼ 7.9 Hz, 1H, Ar–H), 7.53 (t, J ¼ 7.5 Hz, 1H, Ar–H), 7.36 (m, 3H,
Ar–H), 7.23 (d, J ¼ 7.7 Hz, 1H, Ar–H), 7.09 (t, J ¼ 8.4 Hz, 2H, Ar–
H), 4.34 (s, 1H, CH), 2.85 (m, 2H, CH2), 2.43 (m, 1H, CH2), 1.82
We gratefully acknowledge nancial support from the National
Natural Science Foundation of China (Grant No. 21572151), the
project of Scientic and Technologic Infrastructure of Suzhou
(SZS201708), and PAPD.
i
(m, 1H, CH2). HPLC: OD-H column, 90% hexanes, 10% PrOH,
1.0 mL minꢀ1, tr (minor) ¼ 8.6 min, tr (major) ¼ 8.1 min. HRMS
(ESI, m/z) calcd for C17H13FO2Na [M + Na]+: 291.0907, found:
291.0913. Mp: 99.5–101.5 ꢁC.
Notes and references
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(2S,30R)-30-(4-Chlorophenyl)-3,4-dihydro-1H-spiro[naphtha-
lene-2,20-oxiran]-1-one 7v.14b A white powder; yield 32%, ee 83%;
[a]2D5 ꢀ102ꢁ (c0.3 in acetone). 1H NMR (400 MHz, CDCl3) d 8.10
(dd, J ¼ 7.9, 1.0 Hz, 1H, Ar–H), 7.53 (m, 1H, Ar–H), 7.34 (m, 5H,
Ar–H), 7.24 (d, J ¼ 7.6 Hz, 1H, Ar–H), 4.33 (s, 1H, CH), 2.83 (m,
2H, CH2), 2.44 (m, 1H, CH2), 1.81 (m, 1H, CH2).HPLC: OD-H
column, 90% hexanes, 10% iPrOH, 1.0 mL minꢀ1, tr (minor)
¼ 9.1 min, tr (major) ¼ 8.5 min. HRMS (ESI, m/z) calcd for
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C
17H13ClO2Na [M + Na]+: 307.0502, found: 307.0509. Mp: 138–
ꢁ
142 C.
(2R,30S)-30-(4-Bromophenyl)-3,4-dihydro-1H-spiro[naphtha-
lene-2,20-oxiran]-1-one 7w.14b A white powder; yield 49%, ee
1
80%; [a]2D5 ꢀ113ꢁ (c0.3 in acetone). H NMR (400 MHz, CDCl3)
d 8.10 (d, J ¼ 7.8 Hz, 1H, Ar–H), 7.53 (dd, J ¼ 6.6, 4.4 Hz, 3H, Ar–
H), 7.37 (t, J ¼ 7.5 Hz, 1H, Ar–H), 7.25 (m, 3H, Ar–H), 4.31 (s, 1H,
CH), 2.83 (m, 2H, CH2), 2.44 (m, 1H, CH2), 1.81 (m, 1H, CH2).
HPLC: OD-H column, 90% hexanes, 10% iPrOH, 1.0 mL minꢀ1
,
tr (minor) ¼ 9.5 min, tr (major) ¼ 8.9 min. HRMS (ESI, m/z) calcd
for C17H13BrO2Na [M + Na]+: 350.9997, found: 351.0002. Mp:
122–125 ꢁC.
(2R,30S)-30-(3-Chlorophenyl)-3,4-dihydro-1H-spiro[naphtha-
lene-2,20-oxiran]-1-one 7x.17 A white powder; yield 99%, ee 80%;
1
[a]2D5 ꢀ99ꢁ (c0.3 in acetone). H NMR (400 MHz, CDCl3) d 8.10
(dd, J ¼ 7.9, 1.1 Hz, 1H, Ar–H), 7.53 (m, 1H, Ar–H), 7.35 (m, 4H,
Ar–H), 7.26 (m, 2H, Ar–H), 4.34 (s, 1H, CH), 2.35 (m, 2H, CH2),
2.44 (m, 1H, CH2), 1.84 (m, 1H, CH2). HPLC: OD-H column, 90%
i
hexanes, 10% PrOH, 1.0 mL minꢀ1, tr (minor) ¼ 8.1 min, tr
(major) ¼ 7.6 min. HRMS (ESI, m/z) calcd for C17H13ClO2Na [M +
+
ꢁ
Na] : 307.0502, found: 307.0506. Mp: 94–97 C.
(2R,30S)-30-(2-Chlorophenyl)-3,4-dihydro-1H-spiro[naphtha-
lene-2,20-oxiran]-1-one 7y.17 A white powder; yield 99%, ee 80%;
[a]2D5 ꢀ110ꢁ (c0.3 in acetone). 1H NMR (400 MHz, CDCl3) d 8.14
(dd, J ¼ 7.9, 1.2 Hz, 1H, Ar–H), 7.53 (m, 1H, Ar–H), 7.44 (m, 1H,
Ar–H), 7.39 (m, 2Hm, Ar–H), 7.34 (m, 2H, Ar–H), 7.25 (d, J ¼
7.7 Hz, 1H, Ar]H), 4.44 (s, 1H, CH), 3.02 (m, 1H, CH2), 2.85 (m,
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