Iron-catalyzed asymmetric intramolecular cyclopropanation reactions using chiral tetramethyl-1,1′-spirobiindane-based bisoxazoline (TMSI-BOX) ligands

Article abstract of DOI:10.1039/c8ob03065k

The versatile application of chiral bisoxazoline (BOX) ligands in diverse metal-catalyzed asymmetric reactions results in growing demand for novel BOX ligands containing different motifs. Herein, the successful development of a chiral spiro bisoxazoline ligand (TMSI-BOX) on the basis of the tetramethyl-1,1′-spirobiindane motif and bisoxazoline chelating units is described. The corresponding Fe complexes of TMSI-BOX proved to be excellent catalysts in the asymmetric intramolecular cyclopropanation reaction of diazo derivatives, providing synthetically versatile [3.1.0]bicycloalkane derivatives bearing two contiguous quaternary chiral centers with high enantiomeric purity.

Full text of DOI:10.1039/c8ob03065k

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Iron-catalyzed asymmetric intramolecular
cyclopropanation reactions using chiral
Cite this: DOI: 10.1039/c8ob03065k
tetramethyl-1,1’-spirobiindane-based bisoxazoline
(
TMSI-BOX) ligands†
Haorui Gu, Shaoying Huang and Xufeng Lin
*
The versatile application of chiral bisoxazoline (BOX) ligands in diverse metal-catalyzed asymmetric reac-
tions results in growing demand for novel BOX ligands containing different motifs. Herein, the successful
development of a chiral spiro bisoxazoline ligand (TMSI-BOX) on the basis of the tetramethyl-1,1’-spiro-
biindane motif and bisoxazoline chelating units is described. The corresponding Fe complexes of
TMSI-BOX proved to be excellent catalysts in the asymmetric intramolecular cyclopropanation reaction of
diazo derivatives, providing synthetically versatile [3.1.0]bicycloalkane derivatives bearing two contiguous
quaternary chiral centers with high enantiomeric purity.
Received 10th December 2018,
Accepted 9th January 2019
DOI: 10.1039/c8ob03065k
rsc.li/obc
examples for the Fe-catalyzed asymmetric cyclopropanation
reaction have been reported. Despite these elegant contri-
Introduction
6
Iron is the most abundant transition metal in the Earth’s butions, the development of new methods is still important.
crust. Also, iron is cheap, readily available and environmen- We developed a series of chiral hexamethyl-1,1′-spirobiindane-
tally benign. Due to the above reasons, iron catalysis has derived bisoxazoline ligands and successfully applied in iron-
7
attracted significant attention in organic synthesis. More and catalyzed enantioselective Si–H bond insertions. In this com-
more iron-catalyzed organic transformations have been devel- munication, we wish to report our discovery of the chiral spiro
1
oped over the past decades, such as substitutions, additions, bisoxazoline ligand (TMSI-BOX) on the basis of the tetra-
reductions, oxidations, cycloadditions and so on. Chiral iron methyl-1,1′-spirobiindane motif and bisoxazoline chelating
catalysis is quite challenging, and extensive research effort has units, and its successful application in asymmetric intra-
been devoted to the development of highly enantioselective Fe- molecular cyclopropanation reactions of diazo derivatives to
2
catalyzed reactions. Although there has been significant pro- give synthetically versatile [3.1.0]bicycloalkane derivatives
gress in the chiral iron catalysis, the development of a sustain- bearing two contiguous quaternary chiral centers with high
able chiral iron catalyst remains at the forefront and desirable. enantiomeric purity (Scheme 1). Herein, we report the prelimi-
The cyclopropanation of alkene bonds by α-diazo reagents nary results of this study.
is one of the most important transformations in organic syn-
thesis since substituted cyclopropane molecules have been
demonstrated to be versatile intermediates for syntheses of
pharmaceuticals, peptidomimetics, and natural products. In
Results and discussion
3
this context, transition metal-catalyzed asymmetric intra- The enantiopure TMSI-BOX was synthesized from the spiro
molecular cyclopropanation of diazo derivatives provides syn- dialdehyde 4 (Scheme 2). The spiro dialdehyde 4 was obtained
4
thetically versatile bicyclic molecules. Although a number of
transition metals were used and showed excellent results for
5
such asymmetric transformation,
including iridium,
rhodium, ruthenium, palladium, copper and cobalt, only a few
Laboratory of Asymmetric Catalysis and Synthesis, Department of Chemistry,
Zhejiang University, Hangzhou 310027, China. E-mail: lxfok@zju.edu.cn
†
Electronic supplementary information (ESI) available: NMR and HPLC spectra.
CCDC 1879959 for [(R ,S,S)-1d]. For ESI and crystallographic data in CIF or other
a
Scheme 1 Fe/TMSI-BOX-catalyzed
asymmetric
intramolecular
electronic format see DOI: 10.1039/c8ob03065k
cyclopropanation.
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a
Table 1 Reaction optimization: ligands
b
c
Entry
Ligand
[Fe]
Yield (%)
ee (%)
1
2
3
4
5
6
7
8
9
(R
(R
(R
(R
(R
(R
(R
(R
a
a
a
a
a
a
a
a
,S,S)-1a
,S,S)-1b
,S,S)-1c
,4S,4S′,5S,5S′)-1d
,S,S)-1e
,S,S)-1f
,S,S)-1g
,4S,4S′,5S,5S′)-1h
,S,S)-1a
,S,S)-1b
,S,S)-1c
,4S,4S′,5S,5S′)-1d
,S,S)-1e
,S,S)-1f
,S,S)-1g
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
Fe(ClO
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
)
4 2
7
20
8
45
47
86
62
84
5
23
10
27
35
64
60
72
6
59
27
83
3
88
58
68
9
37
19
30
2
66
37
51
Scheme 2 Synthesis of TMSI-BOX.
(S
a
(S
a
(S
a
(S
a
(S
a
(S
a
(S
a
(S
a
1
1
0
1
from industrially available bisphenol A or C according to the
8
literature published by our group. The spiro diacid 5 was pre- 12
1
1
1
3
4
5
pared in 97% yield by oxidation of 4 with potassium per-
manganate solution in acetone. The spiro diacid 5 was further
transformed to the corresponding hydroxyl amides 6a–h as a 16
,4S,4S′,5S,5S′)-1h
diastereomer mixture in quantitative yield by reacting with
thionyl chloride first and then a variety of enantiopure amino
alcohols. The final cyclization with methanesulfonyl chloride
and trimethylamine in the presence of N,N-dimethylamino-
pyridine (DMAP) completed the synthesis of chiral spiro-bisox-
azolines 1a–h as a diastereomer mixture. The two diastereo-
mers could be easily separated by flash chromatography to
give the target TMSI-BOX ligands in good yields. The absolute
a
Reaction conditions: 2a (0.1 mmol), 10 mol% Fe(ClO
ligand, and 12 mol% NaBAr in 2 mL CHCl
4
)
2
, 12 mol%
F
3
at 60 °C for 24 h under an
atmosphere. Isolated yields. Determined by chiral HPLC analysis.
NaBAr : sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate.
9
b
c
N
2
F
the oxazoline ring of the chiral TMSI-BOX ligand gave good
yield and significant enantioselectivity, and the ligand (R ,S,S)-
f gave the desired product in 86% yield and 88% ee. The
a
configuration of (R ,S,S)-1d was determined by X-ray crystallo-
a
1
graphic analysis of a single crystal (Fig. 1).
opposite diastereomers of the ligands 1a–h were also tested
under the same reaction conditions (Table 1, entries 9–16)
which accordingly lowered the yields and ees.
Then, a series of other iron precursors were evaluated and
all gave the desired products in moderate to high yields
With the chiral TMSI-BOX ligands in hand, we first chose
the intramolecular cyclopropanation of 2-methylallyl-2-diazo-
acetate 2a into 3-oxabicyclo-[3.1.0]hexan-2-one 3a as a bench
mark enantioselective reaction for our chiral TMSI-BOX
ligands. In initial investigation, the reaction was performed in
chloroform at 60 °C in the presence of an iron-bisoxazoline
complex catalyst, which was generated in situ from 10 mol% Fe
(
Table 2, entries 1–8). The reactions catalyzed by iron precur-
sors, such as FeCl ·4H O, Fe(BF ·6H O, FeCl and
FeCl ·6H O, resulted in the corresponding products with more
than 80% ee, and FeCl ·4H O proved to be the best catalyst
2
2
4
)
2
2
3
3
2
(
ClO ) , 12 mol% of the chiral ligand (R ,S,S)-1a, and 12 mol%
4
2
a
2
2
NaBAr . However, we obtained the cis product 3a in low yield
F
precursor with the highest ee (92%) and the best yield
93%) (Table 2, entry 2). Besides chiral TMSI-BOX ligands and
(7%) and very low ee (6%) without the formation of the trans
(
isomer (Table 1, entry 1). We screened the chiral TMSI-BOX
ligands with different substituents on the oxazoline rings and
found remarkable results for cyclopropanation reactions
iron precursors, we also screened solvents, temperature, and
additives. The reaction was carried out in a variety of solvents,
including dichloromethane, 1,2-dichloroethane, tetrahydro-
furan (THF), acetonitrile, 1,4-dioxane, and toluene (Table 2,
entries 9–14). The oxygen-containing solvents, such as THF
and 1,4-dioxane, showed low activity and only moderate
enantioselectivity. Other solvents all afforded the corres-
ponding products with high ees (87–93% ee). Chloroform still
is the best solvent in overall consideration, including the
yields. Furthermore, at room temperature, the activity of the
reaction sharply dropped although the enantioselectivity was
(Table 1, entries 2–8). To our delight, the aryl substituents on
improved a little (Table 2, entry 15). When NaBAr
used as the additive, the yield and ee were all reduced remark-
ably (Table 2, entry 16). We suggested that NaBAr could
to give the
reactive catalyst FeCl(BAr )[(R ,S,S)-1f]. When the catalyst
F
was not
F
−
provide the larger and noncoordinating ion BAr
F
7
a
Fig. 1 X-ray crystal structure of (R ,S,S)-1d.
F
a
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Table 2 Optimization of reaction: iron precursors, solvents and
a
temperature
b
c
Entry [Fe]
Solvent
T (°C)
Yield (%) ee (%)
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
Fe(ClO
FeCl ·4H
Fe(OTf)
Fe(BF
Fe(acac)
4
)
2
2
O
CHCl
CHCl
CHCl
CHCl
CHCl
CHCl
CHCl
CHCl
3
3
3
3
3
3
3
3
60
60
60
60
60
60
60
60
86
93
68
71
53
85
88
45
88
92
72
89
10
89
84
75
88
92
58
87
80
93
93
10
91
2
2
4
)
2 2
·6H O
2
FeCl
FeCl
3
3
·6H
2
O
Fe(OAc)
2
d
FeCl
FeCl
FeCl
FeCl
FeCl
FeCl
FeCl
FeCl
FeCl
2
2
2
2
2
2
2
2
2
·4H
·4H
·4H
·4H
·4H
·4H
·4H
·4H
·4H
2
2
2
2
2
2
2
2
2
O
O
O
O
O
O
O
O
O
2
CH Cl
2
CH
Reflux 77
0
1
2
3
4
5
6
7
ClCH
THF
2
2
Cl 60
80
5
64
7
42
33
57
10
60
60
60
60
25
60
60
MeCN
1,4-Dioxane
Toluene
CHCl
CHCl
CHCl
3
3
3
d
e
a
Reaction conditions: 2a (0.1 mmol), 10 mol% [Fe], 12 mol% (R
f, and 12 mol% NaBAr in 2 mL solvent for 24 h under an N
d
a
,S,S)-
atmo-
1
F
2
b
c
sphere. Isolated yields. Determined by chiral HPLC analysis. No
e
F a F
NaBAr . With 5 mol% [Fe], 6 mol% (R ,S,S)-1f and 6 mol% NaBAr .
loading was decreased from 10% to 5%, there was a significant
drop in the yield of 3a, although the enantioselectivity was not
compromised (Table 2, entry 17, 10% yield, 91% ee).
With the optimized reaction conditions in hand (Table 2,
entry 2), we next explored the substrate scope. The results are
summarized in Scheme 3. There are various substituents on
the phenyl ring of the α-diazoester substrates 2 which have a
little impact on this reaction. All the tested substrates success-
fully participated in the asymmetric reaction to provide the
corresponding products in good yields (73%–96%).
Diazoesters with an electron-withdrawing group on the phenyl Scheme 3 Substrate scope. Reactions were performed with
ring, for example, chlorine (3a–c), fluorine (3d and 3e), (0.1 mmol), 10 mol% FeCl ·4H O, 12 mol% (R ,S,S)-1f, and 12 mol%
at 60 °C for 24 h under an N atmosphere. Yields
are of the isolated products. Enantioselectivity was determined by chiral
2
2
2
a
NaBAr
F
in 2 mL CHCl
3
2
bromine (3f–h), trifluoromethyl (3i and 3j), and nitro (3k
and 3l), demonstrated excellent enantioselectivity. 2-(3-
Chlorophenyl)-2-diazoacetate 2b showed the highest enantio-
selectivity (96% ee, 2b). α-Diazoester with no substituent group
on the phenyl ring also carried out the reaction smoothly in
a
b
HPLC. With (R
a
,4S,4’S,5S,5’S)-1h as the catalyst. On a 2.0 mmol scale,
24 hours, yield of 3a = 80%, ee of 3a = 90%.
9
a a
2% yield and 91% ee with (R ,4S,4′S,5S,5′S)-1h instead of (R ,
product was obtained in good yield and moderate ee (82%
S,S)-1f (3m). Surprisingly, the enantioselectivity of the cyclo-
propanation still maintained a high standard when we tested
the substrates with an electron-donating group, such as
yield, 63% ee, 3p). The absolute configuration of the product 3
6b
can be determined according to the literature.
2
-methoxyl on the phenyl ring (91% ee, 3n). We also investi-
gated the effect of the allyl moiety in the substrate, and found
that the reaction proceeded in reasonable yield and good ee in
Conclusion
which the isopropyl took the place of the methyl (73% yield, In summary, we have developed a series of chiral bisoxazoline
7
2
4% ee, 3o). We have carried out the reaction of 2a at a (TMSI-BOX, 1) ligands based on the tetramethyl-1,1′-spirobi-
mmol scale, and 3a was obtained in 80% yield and 90% ee. indane scaffold from simple transformations of commercially
Moreover, we tested phenyl substituted alkenes in the asym- available bisphenol. Meanwhile, the cationic Fe-complex of
metric intramolecular cyclopropanation reaction, and the TMSI-BOX was successfully applied in asymmetric intra-
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molecular cyclopropanation reactions of α-diazoesters. 167.91, 154.38, 146.39, 135.27, 128.88, 126.68, 125.78, 58.28,
Notably, excellent enantioselectivity could be achieved in most 56.46, 42.28, 32.37, 29.05, 20.65; IR (film): γ = 3432, 2952,
cases, and the corresponding optically active [3.1.0]bicyclo- 2865, 1701, 1610, 1576, 1461, 1408, 1361, 1310, 1260, 1085,
alkane products with two contiguous quaternary carbon centers 872, 711 cm− ; HRMS (EI, GC-TOF): calcd for C25
were obtained with ee values of up to 96%. The excellent 392.1988, found 392.1990.
performance of chiral TMSI-BOX ligands in sustainable iron
catalysis will motivate us to further expand the new applications
to other synthetically useful enantioselective reactions.
1
28 4
H O
General procedure for synthesis of optically pure TMSI-BOX
ligand 1
A solution of diacid 5 (5 mmol) and trimethylamine (2.78 mL,
0 mmol) in freshly distilled thionyl chloride (60 mL) was
2
stirred at 60 °C for 3 hours, and then the volatiles were
removed under vacuum to give the crude diacyl chloride.
Under nitrogen, the diacylchloride was dissolved in dichloro-
methane (50 mL) at 0 °C, and then trimethylamine (2.78 mL,
Experimental
General information
NMR spectra were recorded on a Bruker DPX 400 NMR spectro-
1
13
meter at 400 MHz for H NMR, 100 MHz for C NMR, and
20 mmol) and a solution of amino alcohol (20 mmol) in di-
1
9
3
76 MHz for F. The chemical shifts were reported in CDCl3
chloromethane (10 mL) was injected into the solution succes-
sively. Then, the mixture was stirred overnight. The reaction
solution was quenched with water and extracted with dichloro-
methane three times. The organic layers were mixed and dried
over anhydrous Na SO . The solvent was removed under
or DMSO-d with tetramethylsilane (TMS) as an internal stan-
6
dard. The following abbreviations were used to describe peak
patterns where appropriate: br = broad, s = singlet, d =
doublet, t = triplet, q = quartet, and m = multiplet. Coupling
constants were reported in hertz (Hz). Infrared spectra were
recorded on an ATR-FTIR spectrometer. HRMS were obtained
using EI ionization. Optical rotations were determined using a
PerkinElmer Model 341 polarimeter at 25 °C. Enantiomeric
excesses (ee) were determined by chiral high-performance
liquid chromatography. HPLC analysis was performed using
Chiralcel columns (Chiralcel OJ-H, AS-H).
2
4
reduced pressure to obtain the crude product 6 in quantitative
yield for the next step without further purification. The crude
amide 6 (5 mmol) was dissolved in dichloromethane (75 mL)
under nitrogen, and to this was added 4-dimethyl-
aminopyridine (DMAP, 122 mg, 1 mmol). Then the solution
was cooled to 0 °C, and trimethylamine (5.7 mL, 40 mmol)
and methanesulfonyl chloride (MsCl, 1.6 mL, 20 mmol) were
successively added slowly. The system was stirred overnight
allowing it to warm up to room temperature naturally. The
General procedure for synthesis of spiro diacid 5
A portion of the aldehyde 4 (2.5 mmol) was dissolved in reaction was quenched with water and the aqueous layer was
acetone (80 mL) and stirred at room temperature. A solution of extracted with dichloromethane three times. The combined
potassium permanganate (2.37 g, 15 mmol) in a mixture of organic layers were washed with brine, dried over anhydrous
4
water (20 mL) and acetone (80 mL) was added dropwise over a NaSO , and then concentrated under vacuum. The residue was
period of 10 min. The mixture was heated to 45 °C and stirred purified by silica gel column chromatography (ethyl acetate/
overnight. After cooling to room temperature, 4 M NaOH was petroleum ether = 1/15–1/4) to afford a pair of diastereomers 1
added to the system until the pH was 10–11. Then, the solu- as a white solid.
tion was filtered and all the volatiles were removed under
vacuum. The aqueous phase was washed with petroleum ether m.p. 24–26 °C; [α] = +58 (c 0.09, CH Cl ); H NMR (400 MHz,
a
(R ,S,S)-1a: 1.02 g, 82% yield (two steps); white solid,
2
0
1
D
2
2
3
three times. Finally, the aqueous layer was acidified using 4 M CDCl ) δ 7.50 (dd, J = 7.5, 1.3 Hz, 2H), 7.24 (dd, J = 7.6, 1.4 Hz,
HCl until the pH was around 2 and extracted with ethyl 2H), 7.18 (t, J = 7.5 Hz, 2H), 3.73 (dd, J = 9.6, 8.1 Hz, 2H), 3.40
acetate. The combined organic phase was dried over anhy- (td, J = 9.4, 7.0 Hz, 2H), 3.04–2.94 (m, 2H), 2.89 (d, J = 12.2 Hz,
drous Na
product 5 as a white solid without purification.
a: 0.87 g, 95% yield; white solid, m.p. >320 °C; H NMR 0.65 (s, 3H); C NMR (100 MHz, CDCl ) δ 164.12, 153.95,
2
SO
4
and concentrated under vacuum to give the pure 2H), 2.30 (d, J = 12.1 Hz, 2H), 1.47 (dq, J = 13.6, 6.8 Hz, 2H),
1.39 (s, 6H), 1.39 (s, 6H), 0.86 (s, 3H), 0.84 (s, 3H), 0.67 (s, 3H),
1
13
5
3
(400 MHz, DMSO) δ 12.12 (s, 2H), 7.48 (dd, J = 7.5, 0.8 Hz, 2H), 148.25, 129.32, 126.45, 124.61, 123.98, 70.59, 68.90, 59.68,
7
1
6
1
2
1
3
.34 (dd, J = 7.5, 0.9 Hz, 2H), 7.22 (t, J = 7.6 Hz, 2H), 2.76 (d, J = 57.11, 42.84, 32.52, 31.94, 29.64, 18.83, 17.24; IR (film): γ =
2.0 Hz, 2H), 2.22 (d, J = 12.1 Hz, 2H), 1.39 (s, 6H), 1.36 (s, 2954, 2866, 2359, 2341, 1660, 1644, 1353, 1315, 1098, 979, 807,
1
3
−1
42 2 2
H); C NMR (100 MHz, DMSO) δ 167.82, 154.20, 149.02, 752 cm ; HRMS (EI, GC-TOF): calcd for C33H N O 498.3246,
28.39, 126.88, 126.39, 125.23, 59.06, 56.23, 42.47, 32.36, found 498.3238.
9.07; IR (film): γ = 2954, 1703, 1608, 1463, 1410, 1359, 1307,
(S ,S,S)-1a: 0.97 g, 78% yield (two steps); colorless oil;
a
085, 880, 715 cm− ; HRMS (EI, GC-TOF): calcd for C23
1
H
O
20
1
24
4
D
2 2 3
[α] = −200 (c 0.11, CH Cl ); H NMR (400 MHz, CDCl ) δ 7.69
64.1675, found 364.1653.
(dd, J = 7.5, 1.3 Hz, 2H), 7.29 (dd, J = 7.5, 1.3 Hz, 2H), 7.21 (t,
J = 7.5 Hz, 2H), 3.68–3.56 (m, 4H), 2.90 (dd, J = 9.3, 7.8 Hz,
1
5
b: 0.95 g, 97% yield; white solid, m.p. 318–319 °C;
H
NMR (400 MHz, DMSO) δ 12.06 (s, 2H), 7.26 (s, 2H), 7.12 (s, 2H), 2.73 (d, J = 12.2 Hz, 2H), 2.33 (d, J = 12.2 Hz, 2H), 1.64
2
2
H), 2.74 (d, J = 12.1 Hz, 2H), 2.29 (s, 6H), 2.18 (d, J = 12.1 Hz, (dq, J = 13.4, 6.8 Hz, 2H), 1.41 (s, 6H), 1.38 (s, 6H), 0.82 (s, 3H),
H), 1.36 (s, 6H), 1.33 (s, 6H); C NMR (100 MHz, DMSO) δ 0.80 (s, 3H), 0.73 (s, 3H), 0.71 (s, 3H); C NMR (100 MHz,
1
3
13
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CDCl
3
) δ 164.13, 153.94, 148.24, 129.32, 126.46, 124.62, 123.96, (400 MHz, CDCl
3
) δ 7.89 (dd, J = 6.4, 2.3 Hz, 2H), 7.30–7.23 (m,
7
1
1
0.56, 68.89, 59.67, 57.10, 42.85, 32.52, 31.93, 29.64, 18.82, 6H), 7.22–7.08 (m, 18H), 4.59 (d, J = 10.5 Hz, 2H), 4.12 (d, J =
7.23; IR (film): γ = 2955, 2868, 2359, 2341, 1651, 1465, 1357, 10.5 Hz, 2H), 2.99 (d, J = 12.0 Hz, 2H), 2.31 (d, J = 12.0 Hz, 2H),
−
1
13
316, 1101, 1071, 973, 811, 752 cm ; HRMS (EI, GC-TOF): 1.33 (s, 6H), 0.91 (s, 6H); C NMR (100 MHz, CDCl
153.90, 148.31, 140.00, 138.28, 128.88, 127.35, 127.09, 126.25,
,S,S)-1b: 1.28 g, 90% yield (two steps); white solid, 126.07, 125.67, 125.39, 123.85, 122.27, 88.72, 77.96, 58.67,
3
) δ 163.09,
calcd for C H N O 498.3246, found 498.3249.
3
3
42 2 2
(R
a
2
0
1
m.p. 53–54 °C; [α]D = −24 (c 0.10, CH
2 2
Cl ); H NMR (400 MHz, 55.49, 42.00, 31.81, 28.67, 27.25; IR (film): γ = 3062, 3030,
CDCl ) δ 7.67 (dd, J = 7.6, 1.2 Hz, 2H), 7.29–7.13 (m, 14H), 4.66 2949, 2862, 2355, 2340, 1651, 1644, 1454, 1331, 1268, 1099,
3
1
(
t, J = 10.1 Hz, 2H), 4.19 (dd, J = 10.0, 8.2 Hz, 2H), 3.09 (dd, J = 973, 808, 752, 698 cm− ; HRMS (EI, GC-TOF): calcd for
1
2
1
1
2
1
0.3, 8.2 Hz, 2H), 3.02 (d, J = 12.1 Hz, 2H), 2.35 (d, J = 12.1 Hz,
C
51
H
46
N
2
O
2
718.3559, found 718.3553.
1
3
H), 1.40 (s, 6H), 1.34 (s, 6H); C NMR (100 MHz, CDCl ) δ
(S ,4S,4′S,5S,5′S)-1d: 1.33 g, 74% yield (two steps); white
a
3
2
0
1
64.87, 154.57, 148.81, 141.93, 129.14, 128.32, 127.19, 127.10, solid, m.p. 42–43 °C; [α] = +4 (c 0.10, CH
2
Cl
) δ 7.82–7.61 (m, 2H), 7.32–7.26 (m, 6H), 7.21
9.05; IR (film): γ = 3062, 2950, 2863, 2359, 2341, 1659, 1634, (dd, J = 6.5, 3.8 Hz, 6H), 7.07 (dd, J = 6.5, 3.0 Hz, 4H), 7.00 (d, J
2
); H NMR
D
26.51, 124.59, 123.83, 74.29, 69.83, 59.52, 56.99, 43.17, 32.68, (400 MHz, CDCl
3
−
1
454, 1357, 1274, 1098, 1071, 979, 805, 755, 698 cm ; HRMS = 4.5 Hz, 4H), 6.82 (dd, J = 6.6, 2.9 Hz, 4H), 4.91 (d, J = 9.1 Hz,
566.2933, found 566.2936. 2H), 4.78 (d, J = 9.1 Hz, 2H), 2.71 (d, J = 12.5 Hz, 2H), 2.29 (d, J
S ,S,S)-1b: 1.25 g, 88% yield (two steps); white solid, = 12.5 Hz, 2H), 1.32 (s, 6H), 1.16 (s, 6H); C NMR (100 MHz,
38 2 2
(EI, GC-TOF): calcd for C39H N O
1
3
(
a
2
0
1
m.p. 40–41 °C; [α] = −140 (c 0.10, CH
2
Cl
) δ 7.77 (dd, J = 7.2, 1.7 Hz, 2H), 7.28–7.08 (m, 128.39, 128.03, 127.16, 127.02, 126.58, 126.16, 125.20, 123.57,
0H), 7.05–6.91 (m, 4H), 4.81 (dd, J = 10.2, 6.3 Hz, 2H), 3.70 87.86, 78.78, 60.83, 56.48, 42.35, 32.68, 29.43; IR (film): γ =
dd, J = 8.1, 6.3 Hz, 2H), 3.19 (dd, J = 10.2, 8.2 Hz, 2H), 2.72 (d, 3062, 3030, 2951, 2860, 2358, 2337, 1651, 1644, 1454, 1316,
2 3
); H NMR CDCl ) δ 163.95, 153.68, 148.81, 141.31, 139.95, 129.36, 128.53,
D
(
1
(
400 MHz, CDCl
3
J = 12.3 Hz, 2H), 2.31 (d, J = 12.2 Hz, 2H), 1.37 (s, 6H), 1.25 (s, 1267, 1091, 1074, 978, 751, 698 cm− ; HRMS (EI, GC-TOF):
1
1
3
6
1
1
H); C NMR (100 MHz, CDCl ) δ 164.39, 153.10, 147.25, calcd for C H N O 718.3559, found 718.3560.
3
51 46 2 2
41.54, 128.45, 127.45, 126.18, 125.59 (d, J = 3.7 Hz), 124.06,
22.53, 73.19, 67.48, 58.83, 56.03, 41.82, 31.39, 28.67; IR (film): m.p. 67–68 °C; [α] = +93 (c 0.12, CH Cl ); H NMR (400 MHz,
2 2
a
(R ,S,S)-1e: 1.10 g, 84% yield (two steps); white solid,
2
0
1
D
γ = 3065, 2951, 2862, 2358, 2340, 1651, 1644, 1454, 1316, 1158, CDCl ) δ 7.34 (s, 2H), 7.03 (d, J = 0.9 Hz, 2H), 3.76 (dd, J = 9.6,
3
−1
1
104, 979, 752, 698 cm ; HRMS (EI, GC-TOF): calcd for 8.1 Hz, 2H), 3.44 (td, J = 9.4, 7.2 Hz, 2H), 2.95–2.88 (m, 2H),
566.2933, found 566.2936. 2.84 (d, J = 12.2 Hz, 2H), 2.32 (s, 6H), 2.27 (d, J = 12.2 Hz, 2H),
R ,S,S)-1c: 1.29 g, 87% yield (two steps); white solid, 1.45 (dq, J = 13.6, 6.8 Hz, 2H), 1.36 (s, 12H), 0.88 (s, 3H), 0.86
39 38 2 2
C H N O
(
a
2
0
1
13
m.p. 30–31 °C; [α]D = +28 (c 0.10, CH
2 2 3
Cl ); H NMR (400 MHz, (s, 3H), 0.67 (s, 3H), 0.65 (s, 3H); C NMR (100 MHz, CDCl ) δ
CDCl ) δ 7.63 (dd, J = 5.9, 3.0 Hz, 2H), 7.33–7.28 (m, 4H), 163.78, 154.29, 145.71, 135.69, 129.51, 124.78, 124.26, 72.19,
3
7
.26–7.13 (m, 6H), 7.08 (d, J = 7.0 Hz, 4H), 4.05–3.90 (m, 2H), 69.49, 58.58, 57.29, 42.81, 32.64, 32.50, 29.20, 20.86, 19.64,
3
1
.82–3.69 (m, 2H), 3.03 (dd, J = 13.7, 5.0 Hz, 2H), 2.86 (dd, J = 18.07; IR (film): γ = 3453, 2955, 2868, 1652, 1463, 1383, 1356,
−
1
3.6, 4.9 Hz, 4H), 2.33 (d, J = 12.2 Hz, 2H), 2.27 (dd, J = 13.7, 1265, 1172, 1100, 1075, 982, 938, 868, 803, 733 cm ; HRMS
1
3
9
.7 Hz, 2H), 1.42 (s, 6H), 1.35 (s, 6H); C NMR (100 MHz, (EI, GC-TOF): calcd for C H N O 526.3559, found 526.3563.
35 46 2 2
2
0
CDCl
3
) δ 164.01, 154.41, 148.40, 138.65, 129.11, 128.84, 128.37,
a
(S ,S,S)-1e: 1.06 g, 81% yield (two steps); colorless oil; [α]
D
1
1
4
2
6
2 2 3
26.43, 126.17, 124.55, 124.33, 71.54, 67.56, 59.56, 56.98, = −173 (c 0.15, CH Cl ); H NMR (400 MHz, CDCl ) δ 7.51 (s,
3.00, 41.45, 32.54, 29.38; IR (film): γ = 3062, 3026, 2950, 2862, 2H), 7.07 (d, J = 0.8 Hz, 2H), 3.67 (dt, J = 9.7, 5.7 Hz, 2H), 3.60
361, 2343, 1651, 1645, 1454, 1359, 1259, 1094, 977, 808, 753, (dd, J = 7.9, 6.2 Hz, 2H), 2.89 (dd, J = 9.6, 8.1 Hz, 2H), 2.67 (d, J
98 cm− ; HRMS (EI, GC-TOF): calcd for C41
1
H
N
O
594.3246, = 12.2 Hz, 2H), 2.35 (s, 6H), 2.29 (d, J = 12.2 Hz, 2H), 1.65 (dq,
J = 13.4, 6.7 Hz, 2H), 1.39 (s, 6H), 1.35 (s, 6H), 0.82 (s, 3H),
42
2
2
found 594.3245.
13
a
(S ,S,S)-1c: 1.25 g, 84% yield (two steps); white solid, 0.80 (s, 3H), 0.74 (s, 3H), 0.72 (s, 3H); C NMR (100 MHz,
2
0
1
m.p. 49–50 °C; [α] = −105 (c 0.11, CH
2
Cl
2 3
); H NMR CDCl ) δ 164.38, 154.11, 145.74, 135.93, 129.61, 125.43, 123.45,
D
(
400 MHz, CDCl ) δ 7.60 (dd, J = 7.2, 1.6 Hz, 2H), 7.26–7.14 (m, 70.51, 68.82, 59.08, 57.42, 42.58, 32.48, 31.92, 29.75, 20.96,
3
1
8
0H), 7.08 (d, J = 7.0 Hz, 4H), 4.24–3.94 (m, 2H), 3.57 (dd, J = 18.81, 17.19; IR (film): γ = 3447, 2955, 2868, 1652, 1462, 1383,
−
1
.3, 6.2 Hz, 2H), 3.04 (t, J = 8.8 Hz, 2H), 2.86 (dd, J = 13.8, 4.1 1357, 1269, 1177, 1096, 1074, 980, 934, 869, 803, 669 cm
;
Hz, 2H), 2.79 (d, J = 12.2 Hz, 2H), 2.32 (d, J = 12.2 Hz, 2H), HRMS (EI, GC-TOF): calcd for C H N O 526.3559, found
3
5
46 2 2
1
3
2
(
1
5
3
1
.14–2.02 (m, 2H), 1.41 (s, 6H), 1.37 (s, 6H); C NMR 526.3559.
100 MHz, CDCl ) δ 164.17, 154.18, 148.17, 138.31, 129.15, (R ,S,S)-1f: 1.35 g, 91% yield (two steps); white solid,
28.90, 128.44, 126.51, 126.26, 124.77, 124.01, 70.82, 66.74, m.p. 171–172 °C; [α] = −47 (c 0.12, CH Cl ); H NMR
3
a
2
0
1
D
2
2
3
9.70, 56.80, 42.86, 40.84, 32.46, 29.59; IR (film): γ = 3065, (400 MHz, CDCl ) δ 7.48 (d, J = 0.7 Hz, 2H), 7.26 (dd, J = 8.3,
026, 2950, 2862, 2359, 2341, 1657, 1651, 1454, 1358, 1317, 6.0 Hz, 4H), 7.23–7.13 (m, 6H), 7.01 (d, J = 0.8 Hz, 2H), 4.72 (t,
271, 1092, 977, 808, 753, 702 cm− ; HRMS (EI, GC-TOF): calcd J = 10.2 Hz, 2H), 4.21 (dd, J = 10.0, 8.2 Hz, 2H), 3.06 (dd, J =
1
for C41
H
42
N
2
O
2
594.3246, found 594.3251.
10.3, 8.2 Hz, 2H), 2.99 (d, J = 12.1 Hz, 2H), 2.32 (d, J = 12.1 Hz,
1
3
(R
a
,4S,4′S,5S,5′S)-1d: 1.35 g, 75% yield (two steps); white 2H), 2.21 (s, 6H), 1.38 (s, 6H), 1.32 (s, 6H); C NMR (100 MHz,
2
0
1
solid, m.p. 204–205 °C; [α] = −64 (c 0.09, CH Cl ); H NMR CDCl ) δ 165.19, 154.71, 146.21, 142.06, 135.97, 129.86, 128.27,
D
2
2
3
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1
7
27.07 (d, J = 7.4 Hz), 125.16, 123.61, 77.37, 77.05, 76.74,
4.27, 69.74, 58.61, 57.33, 43.05, 32.72, 28.92, 20.88; IR (film): solid, m.p. 52–53 °C; [α] = +8 (c 0.12, CH Cl ); H NMR
D
2 2
(S
a
,4S,4′S,5S,5′S)-1h: 1.38 g, 74% yield (two steps); white
2
0
1
3
γ = 2950, 2895, 1640, 1493, 1454, 1382, 1357, 1268, 1173, 1105, (400 MHz, CDCl ) δ 7.51 (d, J = 1.0 Hz, 2H), 7.31–7.27 (m, 6H),
−
1
9
81, 910, 870, 733, 700 cm ; HRMS (EI, GC-TOF): calcd for 7.25–7.19 (m, 6H), 7.10–6.99 (m, 4H), 6.94–6.87 (m, 4H), 6.80
C H N O 594.3246, found 594.3241. (d, J = 1.1 Hz, 2H), 4.90 (d, J = 9.0 Hz, 2H), 4.75 (d, J = 9.0 Hz,
,S,S)-1f: 1.29 g, 87% yield (two steps); white solid, 2H), 2.64 (d, J = 12.6 Hz, 2H), 2.29 (d, J = 12.5 Hz, 2H), 2.15 (s,
4
1
42 2 2
(S
a
2
0
1
13
2 2 3
m.p. 101–102 °C; [α] = −94 (c 0.13, CH Cl ); H NMR 6H), 1.31 (s, 6H), 1.17 (s, 6H); C NMR (100 MHz, CDCl ) δ
D
(
400 MHz, CDCl ) δ 7.58 (s, 2H), 7.16 (dt, J = 14.3, 7.8 Hz, 6H), 164.45, 153.77, 146.62, 141.55, 139.94, 135.77, 130.23, 128.45,
3
7
.02 (d, J = 8.7 Hz, 6H), 4.82 (dd, J = 10.1, 6.1 Hz, 2H), 3.71 (dd, 128.33, 128.01, 127.18, 126.94, 126.11, 126.02, 123.07, 88.24,
J = 7.9, 6.3 Hz, 2H), 3.18 (dd, J = 10.0, 8.3 Hz, 2H), 2.67 (d, J = 78.67, 60.22, 57.02, 42.13, 32.73, 29.57, 21.08; IR (film): γ =
1
6
1
1
2.3 Hz, 2H), 2.32 (s, 6H), 2.28 (d, J = 12.3 Hz, 2H), 1.35 (s, 3030, 2951, 2861, 1647, 1605, 1495, 1454, 1344, 1260, 1177,
H), 1.23 (s, 6H); C NMR (100 MHz, CDCl ) δ 165.67, 154.33, 1070, 978, 910, 869, 759, 733, 698 cm ; HRMS (EI, GC-TOF):
3
1
3
−1
45.81, 142.68, 136.16, 129.84, 128.47, 127.23, 126.66, 125.87, calcd for C53
23.15, 74.25, 68.54, 59.21, 57.43, 42.64, 32.42, 29.78, 21.01; IR
50 2 2
H N O 746.3872, found 746.3865.
General procedure for Fe-catalyzed asymmetric intramolecular
cyclopropanation
(
film): γ = 2950, 2863, 1644, 1493, 1454, 1382, 1357, 1269,
1
163, 1106, 981, 910, 870, 733, 699 cm−1; HRMS (EI, GC-TOF):
calcd for C H N O 594.3246, found 594.3242.
Under
a
nitrogen atmosphere, FeCl ·4H O (2.0 mg,
2 2
4
1
42
2
2
(
R
a
,S,S)-1g: 1.31 g, 84% yield (two steps); white solid, 0.01 mmol), (R
a
,S,S)-1f (7.1 mg, 0.012 mmol) and NaBAr
); H NMR (400 MHz, (10.6 mg, 0.012 mmol) were dissolved in CHCl (1.5 mL) in a
CDCl ) δ 7.50 (s, 2H), 7.25 (dd, J = 9.0, 5.5 Hz, 4H), 7.18 (t, J = dry Schlenk tube (10 mL). The mixture was stirred at room
F
2
0
1
m.p. 57–58 °C; [α]D = +51 (c 0.15, CH
2
Cl
2
3
3
7
.3 Hz, 2H), 7.08 (dd, J = 10.7, 4.0 Hz, 6H), 4.04 (qd, J = 9.2, 4.8 temperature for 4 hours. Then, the solution of α-diazoester 2
Hz, 2H), 3.76 (t, J = 8.7 Hz, 2H), 3.10 (dd, J = 13.6, 4.7 Hz, 2H), (0.1 mmol) in CHCl (0.5 mL) was injected into the reaction
.79 (dd, J = 14.2, 5.5 Hz, 4H), 2.42 (s, 6H), 2.28 (dd, J = 14.3, mixture. Then, the reaction mixture was stirred at 60 °C for
3
2
1
1
3
1.1 Hz, 4H), 1.40 (s, 6H), 1.32 (s, 6H); C NMR (100 MHz, 24 hours. The mixture was cooled to room temperature and
) δ 164.40, 154.58, 145.95, 138.67, 135.87, 129.36, 129.11, concentrated under reduced pressure, and then it was purified
28.37, 126.16, 125.41, 123.81, 71.59, 67.47, 58.93, 57.33, by flash chromatography on silica gel (ethyl acetate/petroleum
CDCl
1
3
4
2.76, 41.59, 32.53, 29.50, 21.05; IR (film): γ = 3026, 2950, ether = 1/10) to afford the product 3.
2
7
863, 1645, 1605, 1454, 1359, 1266, 1176, 980, 910, 869, 733,
02 cm− ; HRMS (EI, GC-TOF): calcd for C H N O 622.3559,
1
Characterization of compounds
4
3
46 2 2
found 622.3567.
(1S,5S)-1-(4-Chlorophenyl)-5-methyl-3-oxabicyclo[3.1.0]
a
(S ,S,S)-1g: 1.26 g, 81% yield (two steps); white solid, hexan-2-one (3a). 21 mg, 93% yield; white solid;
2
0
1
m.p. 43–44 °C; [α]D = −24 (c 0.19, CH Cl ); H NMR (400 MHz, m.p. 122–123 °C; 92% ee; HPLC analysis: Chiralpak OJ-H
2
2
−
1
CDCl
3
) δ 7.43 (s, 2H), 7.29–7.22 (m, 6H), 7.18 (t, J = 7.3 Hz, (hexane/i-PrOH = 80/20, 1.0 mL min , 210 nm), t
H), 7.09 (d, J = 7.0 Hz, 4H), 7.03 (d, J = 0.9 Hz, 2H), 4.28–3.96 18.115 min, t
m, 2H), 3.57 (dd, J = 8.2, 6.2 Hz, 2H), 3.02 (t, J = 8.8 Hz, 2H),
R
(major)
(minor) 21.659 min; [α] = +49 (c 0.04, CH Cl );
H NMR (400 MHz, CDCl ) δ 7.39–7.32 (m, 2H), 7.23–7.16 (m,
2
0
2
(
R
2
2
D
1
3
2
6
1
1
1
2
1
.91 (dd, J = 13.8, 4.0 Hz, 2H), 2.75 (d, J = 12.2 Hz, 2H), 2.33 (s, 2H), 4.36 (d, J = 9.2 Hz, 1H), 4.19 (d, J = 9.2 Hz, 1H), 1.58 (d, J =
13
H), 2.29 (d, J = 12.2 Hz, 2H), 2.08 (dd, J = 13.7, 10.5 Hz, 2H), 5.0 Hz, 1H), 1.41 (d, J = 5.0 Hz, 1H), 1.17 (s, 3H); C NMR
1
3
.38 (s, 6H), 1.34 (s, 6H); C NMR (100 MHz, CDCl ) δ 164.55, (100 MHz, CDCl ) δ 176.91, 134.11, 131.05 (d, J = 91.0 Hz),
3
3
54.73, 146.11, 138.83, 136.02, 129.52, 129.27, 128.53, 126.32, 130.60, 128.96, 73.14, 36.38, 31.38, 22.77, 15.14; IR (film): γ =
25.57, 123.96, 71.75, 67.63, 59.08, 57.48, 42.91, 41.76, 32.68, 2963, 2900, 1771, 1497, 1449, 1384, 1328, 1211, 1162, 1093,
9.66, 21.21; IR (film): γ = 3026, 2949, 2863, 1645, 1605, 1454, 1079, 1011, 868, 821, 734, 563 cm− ; HRMS (EI, GC-TOF): calcd
1
−
1
358, 1266, 1175, 980, 910, 869, 733, 702 cm ; HRMS (EI, for C12
11 2
H O Cl 222.0448, found 222.0452.
46 2 2
GC-TOF): calcd for C43H N O
622.3559, found 622.3564. (1S,5S)-1-(3-Chlorophenyl)-5-methyl-3-oxabicyclo[3.1.0]hexan-
(
R ,4S,4′S,5S,5′S)-1h: 1.42 g, 76% yield (two steps); white 2-one (3b). 21 mg, 93% yield; white solid; m.p. 67–68 °C; 96%
a
2
0
1
solid, m.p. 196–197 °C; [α] = −97 (c 0.10, CH
400 MHz, CDCl
.24–7.08 (m, 14H), 6.95 (s, 2H), 4.64 (d, J = 10.3 Hz, 2H), 4.08 19.715 min; [α] = +75 (c 0.07, CH Cl ); H NMR (400 MHz,
D
2 2
2
Cl
2
); H NMR ee; HPLC analysis: Chiralpak AS-H (hexane/i-PrOH = 80/20,
D
1
(
7
3
) δ 7.69 (s, 2H), 7.30 (dd, J = 10.8, 5.1 Hz, 6H), 1.0 mL min− , 210 nm), t
R
(major) 12.981 min, t
R
(minor)
2
0
1
(
d, J = 10.3 Hz, 2H), 2.97 (d, J = 12.0 Hz, 2H), 2.27 (d, J = 12.0 CDCl
3
) δ 7.24 (dd, J = 3.9, 1.3 Hz, 2H), 7.19 (dd, J = 3.3, 1.8 Hz,
13
Hz, 2H), 2.18 (s, 6H), 1.30 (s, 6H), 0.91 (s, 6H); C NMR 1H), 7.13–7.03 (m, 1H), 4.29 (d, J = 9.2 Hz, 1H), 4.12 (d, J = 9.2
(
100 MHz, CDCl ) δ 164.51, 155.14, 146.77, 141.30, 139.62, Hz, 1H), 1.54 (d, J = 5.0 Hz, 1H), 1.35 (d, J = 5.0 Hz, 1H), 1.11
35.88, 130.69, 128.44, 128.15, 128.08, 127.17, 127.06, 126.56, (s, 3H); C NMR (100 MHz, CDCl ) δ 175.65, 133.51, 133.04,
3
25.40, 123.22, 89.70, 78.87, 58.73, 56.99, 42.99, 32.90, 28.17, 129.22, 128.94, 127.38, 127.30, 72.08, 35.55, 30.51, 21.65,
3
1
3
1
1
2
1
0.82; IR (film): γ = 3030, 2949, 2863, 1644, 1605, 1495, 1454, 14.09; IR (film): γ = 2964, 2900, 1770, 1599, 1569, 1479, 1448,
341, 1265, 1197, 1073, 976, 909, 871, 761, 733, 699 cm−
1
;
1383, 1328, 1261, 1163, 1077, 1019, 808, 754, 692 cm ;
−1
HRMS (EI, GC-TOF): calcd for C53
46.3875.
H
50
N
2
O
2
746.3872, found HRMS (EI, GC-TOF): calcd for C12
222.0450.
11 2
H O Cl 222.0448, found
7
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Paper
(
1R,5S)-1-(2-Chlorophenyl)-5-methyl-3-oxabicyclo[3.1.0]hexan- ee; HPLC analysis: Chiralpak AS-H (hexane/i-PrOH = 80/20,
-one (3c). 22 mg, 96% yield; white solid; m.p. 120–121 °C; 1.0 mL min− , 210 nm), t (major) 13.796 min, t (minor)
1
2
9
8
1
R R
2
0
1
5% ee; HPLC analysis: Chiralpak AS-H (hexane/i-PrOH = 20.390 min; [α] = +69 (c 0.01, CH
2
Cl
) δ 7.56–7.35 (m, 2H), 7.32–7.14 (m, 2H), 4.36 (d, J = 9.2
6.589 min; [α]D = +3 (c 0.05, CH Cl ); H NMR (400 MHz, Hz, 1H), 4.19 (d, J = 9.2 Hz, 1H), 1.61 (d, J = 5.0 Hz, 1H), 1.41
2
); H NMR (400 MHz,
D
−1
R R 3
0/20, 1.0 mL min , 210 nm), t (major) 13.977 min, t (minor) CDCl
2
0
1
2
2
1
3
3 3
CDCl ) δ 7.42–7.31 (m, 1H), 7.28–7.18 (m, 3H), 4.31 (dd, J = (d, J = 5.0 Hz, 1H), 1.19 (s, 3H); C NMR (100 MHz, CDCl ) δ
2
1
1
2
1
7.4, 9.0 Hz, 2H), 1.45 (d, J = 5.0 Hz, 1H), 1.36 (d, J = 5.0 Hz, 176.68, 134.37, 133.16, 131.26, 130.25, 128.91, 122.71, 73.13,
1
3
H), 1.08 (s, 3H); C NMR (100 MHz, CDCl ) δ 174.87, 135.18, 36.56, 31.57, 22.71, 15.14; IR (film): γ = 2965, 2899, 1770, 1596,
3
31.53, 130.14, 128.84, 128.51, 126.19, 72.09, 35.74, 29.81, 1564, 1478, 1449, 1382, 1328, 1163, 1074, 1016, 781, 732,
0.38, 13.55; IR (film): γ = 2965, 2898, 1770, 1483, 1442, 1383, 692 cm− ; HRMS (EI, GC-TOF): calcd for C12
1
H
O
Br 265.9942,
11
2
−1
327, 1165, 1130, 1068, 1015, 808, 757, 710, 657 cm ; HRMS found 265.9938.
Cl 222.0448, found 222.0450. (1R,5S)-1-(2-Bromophenyl)-5-methyl-3-oxabicyclo[3.1.0]hexan-
1S,5S)-1-(4-Fluorophenyl)-5-methyl-3-oxabicyclo[3.1.0]hexan- 2-one (3h). 24 mg, 90% yield; white solid; m.p. 86–87 °C; 91%
-one (3d). 19 mg, 92% yield; white solid; m.p. 110–111 °C; ee; HPLC analysis: Chiralpak AS-H (hexane/i-PrOH = 90/10,
11 2
(EI, GC-TOF): calcd for C12H O
(
2
9
8
1% ee; HPLC analysis: Chiralpak AS-H (hexane/i-PrOH = 0.8 mL min− , 210 nm), t
1
(major) 39.312 min, t
(minor)
R
R
0/20, 1.0 mL min− , 210 nm), t
1
(major) 11.978 min, 42.360 min; [α]D = −2 (c 0.05, CH Cl ); H NMR (400 MHz,
20
1
R
2 2
2
0
1
tR (minor) 15.280 min; [α] = +63 (c 0.05, CH Cl ); H NMR CDCl ) δ 7.62 (d, J = 7.9 Hz, 1H), 7.41–7.16 (m, 3H), 4.46–4.35
D
2
2
3
(
3
400 MHz, CDCl ) δ 7.24 (ddd, J = 7.5, 6.7, 4.1 Hz, 2H), (m, 2H), 1.51 (d, J = 5.0 Hz, 1H), 1.44 (d, J = 5.0 Hz, 1H), 1.18
1
3
7
1
3
.14–7.00 (m, 2H), 4.36 (d, J = 9.2 Hz, 1H), 4.19 (d, J = 9.2 Hz, (s, 3H); C NMR (100 MHz, CDCl
3
) δ 175.71, 133.12, 132.93,
H), 1.57 (d, J = 4.9 Hz, 1H), 1.41 (d, J = 4.9 Hz, 1H), 1.17 (s, 132.87, 130.09, 127.81, 126.67, 73.13, 38.70, 31.00, 21.47,
1
3
3
H); C NMR (100 MHz, CDCl ) δ 177.19, 162.53 (d, J = 247.2 14.59; IR (film): γ = 2959, 2926, 1770, 1471, 1436, 1382, 1325,
−
1
Hz), 131.95 (d, J = 8.2 Hz), 127.90 (d, J = 3.4 Hz), 115.76 (d, J = 1275, 1210, 1159, 1125, 1079, 1013, 754, 727, 648 cm ; HRMS
2
1
9
1.5 Hz), 73.16, 36.29, 31.09, 22.93, 15.19; F NMR (376 MHz, (EI, GC-TOF): calcd for C H O Br 265.9942, found 265.9945.
12 11 2
CDCl
3
) δ −113.87; IR (film): γ = 2968, 2901, 1766, 1516, 1452,
(1S,5S)-5-Methyl-1-(4-(trifluoromethyl)phenyl)-3-oxabicyclo
1
5
384, 1329, 1224, 1164, 1079, 1029, 1012, 869, 828, 812, [3.1.0]hexan-2-one (3i). 23 mg, 90% yield; white solid;
71 cm− ; HRMS (EI, GC-TOF): calcd for C H O F 206.0743, m.p. 58–59 °C; 90% ee; HPLC analysis: Chiralpak AS-H
1
12 11 2
−
1
found 206.0741.
(hexane/i-PrOH = 80/20, 1.0 mL min , 210 nm), t
R
(major)
(minor) 9.760 min; [α] = +26 (c 0.02, CH Cl );
H NMR (400 MHz, CDCl ) δ 7.64 (d, J = 8.1 Hz, 2H), 7.39 (d,
2
0
(
1S,5S)-1-(3-Fluorophenyl)-5-methyl-3-oxabicyclo[3.1.0]hexan- 7.970 min, t
-one (3e). 19 mg, 94% yield; white solid; m.p. 57–58 °C;
R
2
2
D
1
2
9
8
3
4% ee; HPLC analysis: Chiralpak AS-H (hexane/i-PrOH = J = 8.0 Hz, 2H), 4.39 (d, J = 9.2 Hz, 1H), 4.22 (d, J = 9.2 Hz, 1H),
0/20, 1.0 mL min , 210 nm), t
tR (minor) 17.355 min; [α]2 = +58 (c 0.04, CH Cl ); H NMR
−1
R
(major) 11.952 min, 1.67 (d, J = 5.1 Hz, 1H), 1.47 (d, J = 5.1 Hz, 1H), 1.19 (s, 3H);
0
1
13
C NMR (100 MHz, CDCl ) δ 176.56, 136.16, 130.48, 130.22 (d,
3
D
2
2
(
3
5
3
400 MHz, CDCl ) δ 7.35 (td, J = 8.0, 6.1 Hz, 1H), 7.10–6.90 (m, J = 32.7 Hz), 125.69 (q, J = 3.8 Hz), 123.99 (d, J = 271.8 Hz),
1
9
3
H), 4.37 (d, J = 9.2 Hz, 1H), 4.19 (d, J = 9.2 Hz, 1H), 1.61 (d, J = 73.13, 36.68, 31.88, 22.72, 15.08; F NMR (376 MHz, CDCl )
1
3
.0 Hz, 1H), 1.42 (d, J = 5.0 Hz, 1H), 1.18 (s, 3H); C NMR δ −62.67; IR (film): γ = 2968, 2904, 1770, 1620, 1452, 1411,
−
1
(100 MHz, CDCl
3
) δ 176.75, 162.80 (d, J = 246.9 Hz), 134.47 (d, 1385, 1327, 1164, 1123, 1068, 1015, 873, 829, 610 cm ; HRMS
J = 8.0 Hz), 130.27 (d, J = 8.3 Hz), 125.85 (d, J = 2.8 Hz), 117.14 (EI, GC-TOF): calcd for C13
11 2 3
H O F
256.0711, found 256.0711.
(
d, J = 22.1 Hz), 115.13 (d, J = 21.0 Hz), 73.12, 36.62 (d, J = 1.8
(1S,5S)-5-Methyl-1-(3-(trifluoromethyl)phenyl)-3-oxabicyclo
1
9
Hz), 31.64, 22.76, 15.07; F NMR (376 MHz, CDCl
3
) δ −112.59; [3.1.0]hexan-2-one (3j). 21 mg, 84% yield; white solid;
IR (film): γ = 2967, 2902, 1771, 1616, 1588, 1492, 1444, 1383, m.p. 55–56 °C; 91% ee; HPLC analysis: Chiralpak AS-H
−
1
−1
1
329, 1205, 1088, 1018, 829, 784, 693 cm ; HRMS (EI, (hexane/i-PrOH = 80/20, 1.0 mL min , 210 nm), tR (major)
2
0
GC-TOF): calcd for C12
H
11
O
2
F 206.0743, found 206.0746.
8.111 min, t
H NMR (400 MHz, CDCl
3
R
(minor) 10.910 min; [α] = +66 (c 0.02, CH
2
Cl
) δ 7.61 (d, J = 7.7 Hz, 1H), 7.57–7.41
-one (3f). 24 mg, 91% yield; white solid; m.p. 109–110 °C; (m, 3H), 4.39 (d, J = 9.2 Hz, 1H), 4.23 (d, J = 9.2 Hz, 1H), 1.66
2
);
D
1
(
1S,5S)-1-(4-Bromophenyl)-5-methyl-3-oxabicyclo[3.1.0]hexan-
2
9
1
3
1% ee; HPLC analysis: Chiralpak AS-H (hexane/i-PrOH = (d, J = 4.9 Hz, 1H), 1.47 (d, J = 5.1 Hz, 1H), 1.19 (s, 3H);
C
−1
8
0/20, 1.0 mL min , 210 nm), t
R
(major) 12.398 min, t
R
(minor) NMR (100 MHz, CDCl
3
) δ 176.58, 133.72, 133.19, 131.15 (d, J =
2
0
1
1
5.673 min; [α]D = +61 (c 0.04, CH Cl ); H NMR (400 MHz, 32.6 Hz), 129.30, 126.77 (q, J = 3.7 Hz), 125.00 (q, J = 3.8 Hz),
2
2
1
9
CDCl
3
) δ 7.63–7.45 (m, 2H), 7.20–7.00 (m, 2H), 4.36 (d, J = 9.2 123.89 (d, J = 271 Hz), 73.13, 36.70, 31.62, 22.75, 15.12;
) δ −62.61; IR (film): γ = 2969, 2904,
J = 5.0 Hz, 1H), 1.17 (s, 3H); C NMR (100 MHz, CDCl ) δ 1770, 1452, 1385, 1366, 1325, 1254, 1162, 1127, 1075, 1018,
F
Hz, 1H), 4.19 (d, J = 9.2 Hz, 1H), 1.58 (d, J = 5.0 Hz, 1H), 1.41 (d, NMR (376 MHz, CDCl
3
1
3
3
76.81, 131.91, 131.82, 131.13, 122.30, 73.14, 36.46, 31.40, 961, 813, 797, 703 cm− ; HRMS (EI, GC-TOF): calcd for
2.73, 15.14; IR (film): γ = 2964, 2899, 1770, 1492, 1448, 1382, 256.0711, found 256.0712.
(1S,5S)-5-Methyl-1-(4-nitrophenyl)-3-oxabicyclo[3.1.0]hexan-
2-one (3k). 19 mg, 80% yield; yellow solid; m.p. 128–129 °C;
1S,5S)-1-(3-Bromophenyl)-5-methyl-3-oxabicyclo[3.1.0]hexan- 85% ee; HPLC analysis: Chiralpak OJ-H (hexane/i-PrOH =
1
1
2
1
13 11 2 3
C H O F
−1
328, 1210, 1162, 1072, 1008, 867, 818, 717, 561 cm ; HRMS
Br 265.9942, found 265.9939.
(EI, GC-TOF): calcd for C12
H O
11 2
(
-one (3g). 24 mg, 90% yield; white solid; m.p. 61–62 °C; 80% 70/30, 1.0 mL min− , 210 nm), tR (major) 35.710 min, tR
1
2
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minor) 93.335 min; [α]2 = +3 (c 0.01, CH
0
Cl
); H NMR (100 MHz, CDCl
1
) δ 177.19, 133.88, 131.28, 130.39, 128.76,
(
2
2
3
D
(
400 MHz, CDCl ) δ 8.25–8.11 (m, 2H), 7.44–7.30 (m, 2H), 4.34 68.63, 41.44, 37.26, 28.66, 21.44, 20.33, 18.32; IR (film): γ =
3
(
1
d, J = 9.3 Hz, 1H), 4.16 (d, J = 9.3 Hz, 1H), 1.66 (d, J = 5.2 Hz, 2965, 2905, 1770, 1498, 1466, 1370, 1345, 1242, 1142, 1094,
H), 1.47 (d, J = 5.2 Hz, 1H), 1.13 (s, 3H); C NMR (100 MHz, 1083, 1031, 1010, 821, 737 cm ; HRMS (EI, GC-TOF): calcd for
1
3
−1
CDCl ) δ 175.95, 147.54, 139.60, 130.90, 123.86, 73.07, 36.67, C H O Cl 250.0761, found 250.0764.
3
14 15 2
3
1
2.70, 23.03, 14.99; IR (film): γ = 2965, 2895, 1770, 1603, 1520,
(1S,5R)-1-(4-Chlorophenyl)-5-phenyl-3-oxabicyclo[3.1.0]hexan-
2-one (3p). 23 mg, 82% yield; white solid; m.p. 140–141 °C;
450, 1385, 1350, 1164, 1081, 1031, 1012, 852, 751, 695 cm−
1
;
HRMS (EI, GC-TOF): calcd for C H NO 233.0688, found 63% ee; HPLC analysis: Chiralpak AS-H (hexane/i-PrOH =
1
2
11
4
80/20, 1.0 mL min− , 210 nm), t
1
(major) 13.977 min, t
2
33.0685.
2 2
1S,5S)-5-Methyl-1-(3-nitrophenyl)-3-oxabicyclo[3.1.0]hexan- (minor) 17.221 min; [α] = +78 (c 0.05, CH Cl ); H NMR
R R
2
0
1
(
D
2
9
7
-one (3l). 18 mg, 76% yield; white solid; m.p. 133–134 °C; (400 MHz, CDCl ) δ 7.30–7.23 (m, 3H), 7.18 (t, J = 6.4 Hz, 4H),
3
2% ee; HPLC analysis: Chiralpak OJ-H (hexane/i-PrOH = 7.09 (d, J = 8.5 Hz, 2H), 4.57 (dd, J = 21.8, 9.5 Hz, 2H), 2.33 (d,
0/30, 1.0 mL min− , 210 nm), t
1
(major) 26.890 min, J = 5.3 Hz, 1H), 1.75 (d, J = 5.3 Hz, 1H); C NMR (100 MHz,
13
R
2
0
1
tR (minor) 33.628 min; [α] = +55 (c 0.01, CH Cl ); H NMR CDCl ) δ 175.82, 133.71, 133.60, 130.65, 129.93, 129.31, 128.90,
D
2
2
3
(
400 MHz, CDCl
3
) δ 8.22 (ddd, J = 8.0, 2.1, 1.2 Hz, 1H), 8.14 (t, 128.65, 128.37, 73.47, 41.28, 38.06, 21.56; IR (film): γ = 2903,
−
1
J = 1.9 Hz, 1H), 7.79–7.47 (m, 2H), 4.42 (d, J = 9.3 Hz, 1H), 4.26 2360, 1766, 1497, 1349, 1091, 1021, 823, 699 cm ; HRMS
+
(d, J = 9.3 Hz, 1H), 1.72 (d, J = 5.2 Hz, 1H), 1.53 (d, J = 5.2 Hz, (ESI): calcd for C H O ClNa ([M + Na] ) 307.0502, found
17 13 2
1
3
1
1
2
1
H), 1.22 (s, 3H); C NMR (100 MHz, CDCl
36.46, 134.38, 129.83, 124.90, 123.15, 73.13, 36.55, 32.08,
2.91, 15.08; IR (film): γ = 2966, 2902, 1770, 1531, 1451, 1384, tion on a scale of 2.0 mmol. Under a nitrogen atmosphere,
351, 1164, 1090, 1035, 1016, 810, 739, 686 cm−1; HRMS FeCl
·4H (40.0 mg, 0.2 mmol), (R ,S,S)-1f (142 mg,
233.0688, found 233.0684. 0.24 mmol) and NaBAr (212 mg, 0.24 mmol) were dissolved
1S,5S)-5-Methyl-1-phenyl-3-oxabicyclo[3.1.0]hexan-2-one (3m). in CHCl3 (30 mL) in a dry three-neck flask (100 mL). The
7 mg, 92% yield; white solid; m.p. 58–59 °C; 91% ee; HPLC mixture was stirred at room temperature for 4 hours. Then, the
(10 mL) was
min , 210 nm), t (major) 12.708 min, t (minor) 19.252 min; injected into the reaction mixture. Then, the reaction mixture
3
) δ 176.17, 148.41, 307.0495.
For Fe-catalyzed asymmetric intramolecular cyclopropana-
2
2
O
a
(
EI, GC-TOF): calcd for C12
(
H
11NO
4
F
1
analysis: Chiralpak AS-H (hexane/i-PrOH = 80/20, 1.0 mL solution of α-diazoester 2a (2 mmol) in CHCl
3
−
1
R
R
2
0
1
[α] = −5 (c 0.03, CH
2
Cl
.42–7.30 (m, 3H), 7.29–7.23 (m, 2H), 4.36 (d, J = 9.1 Hz, 1H), room temperature and concentrated under reduced pressure,
.19 (d, J = 9.1 Hz, 1H), 1.62 (d, J = 4.9 Hz, 1H), 1.39 (d, J = and then it was purified by flash chromatography on silica gel
2 3
); H NMR (400 MHz, CDCl ) δ was stirred at 60 °C for 24 hours. The mixture was cooled to
D
7
4
4
1
1
1
1
3
3
.9 Hz, 1H), 1.16 (s, 3H); C NMR (100 MHz, CDCl ) δ 177.40, (ethyl acetate/petroleum ether = 1/10) to afford the product 3a
31.99, 130.18, 128.72, 128.04, 73.20, 36.92, 31.21, 22.62, (355 mg) in 80% yield with 90% ee.
5.19; IR (film): γ = 2963, 2929, 2895, 1767, 1503, 1447, 1383,
328, 1210, 1162, 1086, 1013, 808, 755, 699, 669 cm−1; HRMS
(
EI, GC-TOF): calcd for C12
1S,5S)-1-(3-Methoxyphenyl)-5-methyl-3-oxabicyclo[3.1.0]hexan-
-one (3n). 18 mg, 85% yield; colorless oil; 91% ee; HPLC ana-
H
12
O
2
188.0837, found 188.0833.
Conflicts of interest
(
There are no conflicts to declare.
2
−
1
lysis: Chiralpak AS-H (hexane/i-PrOH = 90/10, 0.8 mL min
,
=
2
0
2
+
1
4
1
10 nm), t (major) 44.522 min, t (minor) 59.034 min; [α]
R
R
D
1
Acknowledgements
93 (c 0.03, CH
2
Cl
2
); H NMR (400 MHz, CDCl
3
) δ 7.28 (dd, J =
2.5, 4.6 Hz, 1H), 6.91–6.76 (m, 3H), 4.36 (d, J = 9.1 Hz, 1H),
.19 (d, J = 9.1 Hz, 1H), 3.81 (s, 3H), 1.61 (d, J = 4.9 Hz, 1H),
We thank the National Natural Science Foundation of China
(
21572200) and the Fundamental Research Funds for the
1
3
.38 (d, J = 4.9 Hz, 1H), 1.18 (s, 3H); C NMR (100 MHz,
) δ 177.46, 159.73, 133.40, 129.74, 122.48, 116.08, 113.43,
3.27, 55.29, 36.98, 31.33, 22.73, 15.16; IR (film): γ = 2963,
Central Universities for financial support.
CDCl
3
7
2
1
895, 1766, 1603, 1583, 1493, 1452, 1383, 1328, 1288, 1226,
155, 1079, 1018, 818, 781, 697 cm− ; HRMS (EI, GC-TOF):
Notes and references
1
calcd for C H O 218.0943, found 218.0942.
1 (a) C. Bolm, J. Legros, J. L. Paih and L. Zani, Chem. Rev.,
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3
14 3
(1S,5R)-1-(4-Chlorophenyl)-5-isopropyl-3-oxabicyclo[3.1.0]hexan-
2
7
8
-one (3o). 18 mg, 73% yield; white solid; m.p. 104–105 °C;
5% ee; HPLC analysis: Chiralpak AS-H (hexane/i-PrOH =
0/20, 1.0 mL min− , 210 nm), t
1
(major) 10.823 min, t
R
R
2
0
1
(
(
(
D
2 2
minor) 13.117 min; [α] = +20 (c 0.03, CH Cl ); H NMR 2 For reviews, see: (a) S.-F. Zhu and Q.-L. Zhou, Natl. Sci. Rev.,
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3
1
1
H), 1.35 (d, J = 5.1 Hz, 1H), 1.29 (dd, J = 13.9, 7.0 Hz, 1H),
.00 (d, J = 7.1 Hz, 3H), 0.86 (d, J = 6.9 Hz, 3H); C NMR
13
Org. Biomol. Chem.
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Paper
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3
4
(
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