Copper-Catalyzed Regiospecific and 1,2-Regioselective Cyclopropanation of (1 Z)-1-Amino- and (1 Z)-1-Oxy-1,3-butadienyl Derivatives

Article abstract of DOI:10.1055/s-0034-1380426

The copper-catalyzed regiospecific and 1,2-regioselective cyclopropanation of (1Z)-1-amino- and (1Z)-1-oxy-1,3-butadienyl derivatives, which could be prepared by Z-stereoselective 1,4-elimination with α-aryl diazoesters was successfully demonstrated. This successful regiospecific protocol enabled the preparation of the corresponding 1-amino- and 1-oxy-2-vinylcyclopropane derivatives as almost single stereoisomers.

Full text of DOI:10.1055/s-0034-1380426

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© Georg Thieme Verlag Stuttgart · New York
2015, 26, 1880–1884
letter
1880
E. Tayama, S. Saito
Letter
Synlett
Copper-Catalyzed Regiospecific and 1,2-Regioselective Cyclopro-
panation of (1Z)-1-Amino- and (1Z)-1-Oxy-1,3-butadienyl Deriva-
tives
Eiji Tayama*
Shun Saito
Ar
CO2Me
MeO
Ar CO2Me
4
3
base
[Cu],
N2
EDG
Department of Chemistry, Faculty of Science, Niigata
University, Niigata 950-2181, Japan
tayama@chem.sc.niigata-u.ac.jp
Z-stereoselective
1,4-elimination
1,2-regioselective
cyclopropanation
2
1
EDG
EDG
E or Z
Z
successful regiospecificity
(EDG = electron-donating group: NR2 or OR)
Received: 16.04.2015
Accepted after revision: 13.05.2015
Published online: 09.07.2015
ometry reduces the steric repulsion of the double bond, and
the rate of 1,2-addition would be improved.5 However, the
study of the 1,2-regioselective cyclopropanation of 1-sub-
stituted 1,3-butadienyl derivatives has never advanced very
far because of the difficulty of preparing (1Z)-1-substituted
1,3-butadienyl derivatives.
DOI: 10.1055/s-0034-1380426; Art ID: st-2015-u0277-l
Abstract The copper-catalyzed regiospecific and 1,2-regioselective
cyclopropanation of (1Z)-1-amino- and (1Z)-1-oxy-1,3-butadienyl de-
rivatives, which could be prepared by Z-stereoselective 1,4-elimination
with α-aryl diazoesters was successfully demonstrated. This successful
regiospecific protocol enabled the preparation of the corresponding 1-
amino- and 1-oxy-2-vinylcyclopropane derivatives as almost single ste-
reoisomers.
Recently, we reported the copper(II)/acid-catalyzed 3,4-
regioselective cyclopropanation of (E)-1-EDG (electron-
donating group) substituted 1,3-butadienyl derivatives (E)-1,
prepared by E-stereoselective 1,4-elimination7 with α-aryl
diazoesters 2 (Scheme 1).8 The cyclopropanation proceeds
at the less substituted 3,4-double bond to exclusively afford
the adduct (E)-3. In that paper, we showed one example of a
reaction of the Z counterpart (Z)-1 under the same condi-
tions. The corresponding 3,4-adduct 3 was obtained as the
major product; however, the 1,2-adduct 4 was obtained as a
minor product. This result encouraged us that further sub-
strate screening and optimization of the reaction condi-
tions might enable 1,2-regioselective cyclopropanation.
Herein, we wish to report the copper-catalyzed regio-
specific and 1,2-regioselective cyclopropanation of (1Z)-1-
amino- and (1Z)-1-oxy-1,3-butadienyl derivatives (Z)-1
with 2. The method affords the corresponding 1-amino- or
1-oxy-2-vinyl (alkenyl) cyclopropane derivatives 4,9–11
which could act as an interesting building block for the syn-
thesis of biologically active compounds.12
First, we examined the copper(II)/acid-catalyzed cyclo-
propanation of (E)- and (Z)-1 with methyl p-bro-
mophenyldiazoacetate (2a) to clarify the effects of the dou-
ble-bond geometry and the 1-EDG for 3,4- vs. 1,2-regiose-
lectivity (Table 1). A CH2Cl2 solution of 1 mol% Cu(acac)2
and 1 mol% BF3·OEt2 was added to a CH2Cl2 solution of (E)-
tert-butyl buta-1,3-dien-1-yl(phenyl)carbamate [(E)-1a, E/Z
= >98:2, 1.1 equiv] and 2a (1.0 equiv) at room temperature
under an argon atmosphere. The reaction proceeded at the
Key words cycloaddition, diastereoselectivity, diazo compounds, re-
gioselectivity, stereoselective synthesis
The transition-metal-catalyzed cyclopropanation of
alkenes with α-diazoesters is a powerful and efficient syn-
thetic method that enables the preparation of valuable
building blocks for the synthesis of natural products.1 The
reactivity of alkenes is determined by the electronic and
steric effects of substituents at the double bond and the E/Z
geometry.1d,2 Cyclopropanation with an electron-deficient
intermediate generated from the α-diazoester preferential-
ly occurs at the less substituted Z double bond with elec-
tron-donating substituents. Studies have been applied for
the regioselective cyclopropanation of 1,3-dienyl deriva-
tives.3–5 In the cases of 1-substituted 1,3-butadienyl deriva-
tives, the reaction preferentially proceeded at the 3,4-dou-
ble bond because the terminal double bond has an elec-
tron-donating substituent and is the less substituted double
bond.4 Therefore, successful examples of 1,2-regioselective
cyclopropanation of 1-substituted 1,3-butadienyl deriva-
tives are quite limited because the 1,2-double bond is a ste-
rically unfavorable internal double bond. Gareev et al. re-
ported one example of the 1,2-regioselective cyclopropana-
tion of (Z)-1-methyl-1,3-butadiene (1,3-pentadiene) to give
the corresponding vinylcyclopropane derivative.6 The Z ge-
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 1880–1884

1881
E. Tayama, S. Saito
Letter
Synlett
(Table 2, entries 1 and 2). The use of (MeCN)4CuPF6 im-
proved the yield of 4ea to 77% (Table 2, entry 3).15 It is
worth noting that the reaction in the presence of Rh2(OAc)4,
which is one of the standard catalysts in α-diazocarbonyl
reactions, did not give 3ea and 4ea at all (Table 2, entry 4).
Various side products were observed on TLC and (Z)-1e was
recovered in 29% yield. The higher catalytic activity of
Rh2(OAc)4 would be mismatched. Thus, we selected
(MeCN)4CuPF6 as the standard catalyst for the reactions
with various types of α-aryl diazoesters 2 to define the
scope and limitations of the reactions. Similar results were
obtained using 2-, 3-, and 4-chlorophenyl diazoesters 2b–d
(Table 2, entries 5–7). When the reaction of phenyl di-
azoester 2e was carried out under the same conditions, the
yields of the products (Z)-3ee and 4ee were lower (Table 2,
entry 8), even if a slight excess of 2e was present (Table 2,
entry 9). The use of 4-methyl derivative 2f also afforded ad-
ducts 3ef and 4ef in lower yields (Table 2, entry 10). Fur-
thermore, the reaction of the 4-methoxy derivative 2g re-
sulted in an unsuccessful yield with the recovery of (Z)-1e
in 77% yield (Table 2, entry 11).
previous work (ref. 8)
Ar
CO2R
Ar CO2R
4
3
E-stereoselective
1,4-elimination
Cu(II),
N2 (2)
3,4-regioselective
cyclopropanation
EDG
(E)-1
EDG
MeO
(E)-3
regiospecific reactions
EDG
Ar
CO2R
N2 (2)
E or Z
Ar CO2R
cat.,
EDG
Z-stereoselective
1,4-elimination
1,2-regioselective
cyclopropanation
2
1
EDG
(Z)-1
4
this work
Scheme 1 Regiospecific and regioselective cyclopropanation of 1
3,4-double bond, and the corresponding β-cyclopropyl
enamide (E)-3aa was obtained in 85% yield with good dia-
stereoselectivity (Table 1, entry 1, 9:1 dr). When the same
reaction of the geometric isomer (Z)-1a (E/Z = 3:97) was
carried out under the same conditions, the 3,4-adduct (Z)-
3aa was obtained along with the 1,2-adduct 4aa in a com-
bined yield of 75% [(E)-3aa/(Z)-3aa/4aa = 0:72:28] (Table 1,
entry 2).13,14 Both (Z)-3aa and 4aa were obtained as almost
single diastereomers (>20:1 dr). The use of 1-(tert-butyldi-
methylsilyloxy)-1,3-butadienes (E)-1b and (Z)-1b as analo-
gous substrates afforded similar results (Table 1, entries 3
and 4).
To clarify the effect of the bulkiness of the EDG substitu-
ent, we examined the reactions of the 1-triisopropylsilyl-
oxy derivative (Z)-1c (Table 1, entry 5) and the 1-benzyloxy
derivative (Z)-1d (Table 1, entry 6); however, no remarkable
improvement in the 1,2-regioselectivity was observed.
Next, we prepared 1-(N,N-diisopropycarbamoyloxy) deriva-
tives 1e as substrates and carried out their reactions. Treat-
ment of an E/Z = 95:5 mixture of 1e under the same condi-
tions afforded a mixture of (E)-3ea and 4ea in a combined
yield of 62% with the same level of 3,4-regioselectivity [(E)-
3ea/(Z)-3ea/4ea = 95:0:5, Table 1, entry 7]. Interestingly,
however, the reaction of an E/Z = 5:95 mixture of 1e afford-
ed the 1,2-adduct 4ea exclusively with a small amount of
(E)-3ea in a combined yield of 63% (Table 1, entry 8). The
double-bond geometry of the minor product 3ea obtained
in entry 8 was E, which would have been derived from the
5% of (E)-1e included in the substrate. In entry 7, the minor
product 4ea would also be derived from the 5% of (Z)-1e in-
cluded in the substrate. Therefore, each of the reactions of
(E/Z)-1e was found to proceed with perfect regiospecificity
to afford (E)-3ea and 4ea.
Table 1 Regiospecific Cyclopropanation of 1-EDG-Substituted 1,3-Bu-
tadienes 1 with 2aa
4
3
Cu(acac)2 (1 mol%)
CO2Me
BF3•OEt2 (1 mol%)
4-BrC6H4
2
1
+
CH2Cl2
r.t., 2 h
N2
2a
EDG
(E)- or (Z)-1
4-BrC6H4 CO2Me
4-BrC6H4 CO2Me
+
EDG
EDG
(E)- or (Z)-3
3,4-adduct
(9:1 to >20:1 dr)
4
1,2-adduct
(>20:1 dr)
Entry
1
EDG
E/Zb
3 + 4 (%)c (E)-3/(Z)-3/4b
1
2
3
4
5
6
7
8
1a
1a
1b
1b
1c
1d
1e
1e
NPhBoc
>98:2
3:97
aa 85
aa 75
ba 85
ba 80
ca 53
da 70
ea 62
ea 63
100:0:0
0:72:28
100:0:0
0:77:23
0:91:9
NPhBoc
OSiMe2t-Bu
OSiMe2t-Bu
OSii-Pr3
98:2
2:>98
2:>98
2:>98
95:5
OBn
0:65:35
95:0:5
OCONi-Pr2
OCONi-Pr2
5:95
5:0:95
a Reaction conditions: 1 (1.1 equiv) and 2a (1.0 equiv) in CH2Cl2 (0.1 M).
b The ratios were determined by 1H NMR spectroscopy.
c Isolated yield of a mixture of 3 and 4.
We tested various catalysts to improve the yield of the
1,2-adduct 4ea (Table 2). Reactions in the presence of
Cu(OTf)2 or (CuOTf)2·C6H6 did not show any improvement
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 1880–1884

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E. Tayama, S. Saito
Letter
Synlett
Table 2 Effects of Catalysts in the Regioselective Cyclopropanation of
(Z)-1e with Various 2a
we successfully developed a Z-regioselective preparation of
the N–H derivative [(Z)-1g]. When the reaction of (Z)-1g
was examined under the same conditions, the desired 1,2-
adduct 4ga was preferentially obtained (Table 3, entry 3).
We also attempted the reaction of the more electron-defi-
cient and sterically bulky bis-Boc derivative (Z)-1h; howev-
er, this reaction was unsuccessful (Table 3, entry 4). This cy-
clopropanation was found to preferentially occur at the 3,4-
double bond without a sufficient EDG at the 1-position (Ta-
ble 3, entry 5). When cis-1,3-pentadiene (1i) was used in
the reaction, the cyclopropanation occurred at the less sub-
stituted double bond to preferentially produce the 3,4-ad-
duct (Z)-3ia.
R
catalyst (2 mol%)
OCONi-Pr2
CO2Me
+
CH2Cl2
r.t., 2 h
N2
(Z)-1e
(E/Z = 5:95)
2
R
R
CO2Me
CO2Me
+
OCONi-Pr2
OCONi-Pr2
3
4
Table 3 Effect of the 1-EDG on the Cyclopropanation of (Z)-1a
Entry
2 R
Catalyst
Cu(OTf)2
3 (%)b,c
4 (%)b
4-BrC6H4
+
CO2Me
(MeCN)4CuPF6 (2 mol%)
R1
1
2
2a 4-Br
2a 4-Br
2a 4-Br
2a 4-Br
2b 4-Cl
2c 3-Cl
2d 2-Cl
2e H
3ea 5
3ea 5
3ea 4
3ea 0
3eb 4
3ec 3
3ed 5
3ee 3
3ee 3
3ef 3
3eg 5f
4ea 55
4ea 45
4ea 77
4ea 0
CH2Cl2
r.t., 2 h
N2
2a
d
(CuOTf)2·C6H6
(MeCN)4CuPF6
Rh2(OAc)4
(Z)-1
(E/Z = 2:>98)
3
4-BrC6H4 CO2Me
4-BrC6H4 CO2Me
4
+
R1
5
(MeCN)4CuPF6
(MeCN)4CuPF6
(MeCN)4CuPF6
(MeCN)4CuPF6
(MeCN)4CuPF6
(MeCN)4CuPF6
(MeCN)4CuPF6
4eb 71
4ec 69
4ed 72
4ee 43
4ee 46
4ef 41
4eg 14
R1
6
(Z)-3
4
7
Entry
(Z)-1
R1
NPhBoc
(Z)-3 (%)b
4 (%)b
8
9e
10
11
2e H
1
2
3
4
5
1a
1f
3aa 42
3fa 35
3ga 15
3ha 8
4aa 47
4fa 57
4ga 65
4ha 2
4ia 8
2f 4-Me
2g 4-MeO
N-(4-MeOC6H4)Boc
NHBoc
1g
1h
1i
a Reaction conditions: 1 (1.1 equiv) and 2a (1.0 equiv), and catalyst (2
mol%) in CH2Cl2 (0.1 M) unless otherwise noted.
b Compounds 3 and 4 were isolated as a mixture. The yields were calculat-
ed by the ratio determined by 1H NMR spectroscopy.
c Unless otherwise noted, (E)-3 was obtained as a minor product.
d 1 mol%.
N(Boc)2
Me
3ia 45
a Reaction conditions: 1 (1.1 equiv), 2a (1.0 equiv), and catalyst (2 mol%) in
CH2Cl2 (0.1 M).
b Compounds 3 and 4 were isolated as a mixture. The yields were calculat-
ed by the ratio determined by 1H NMR spectroscopy.
e 1 (1.0 equiv) and 2e (1.5 equiv) were used.
f E/Z = 4:6 mixture.
Though its exact origin is unclear at present, the high
1,2-regioselectivity of the cyclopropanation of (Z)-1e may
be rationalized as a result of the precoordination of copper
carbenoid to the carbamoyl carbonyl to form complex A
(Scheme 2). The complex A is in resonance with copper-sta-
bilized carbocation complex B which leads to 4e. Without
carbonyl [(Z)-1b–d], the 3,4- vs. 1,2-regioselectivity is de-
termined by steric repulsion. Large O-substituents (Sii-Pr3 >
SiMe2t-Bu > Bn) would inhibit the formation of 4. The N-Boc
carbonyl [(Z)-1a,f–h] also coordinates to copper carbenoid;
however, the 1,2-regioselectivities were lower. Both sides of
the 1,2-double bond might be blocked by N-substituents.
The 1,2-regioselective cyclopropanation of (Z)-1 could
be achieved by introducing a substituent at the 4-position
(Table 4). The cyclopropanation of 4-butyl (1j,k, Table 4, en-
tries 1 and 2) and 4,4-dimethyl derivatives (1l,m, Table 4,
entries 3 and 4) exclusively proceeded at the (Z)-1,2-double
bond. With these results in hand, the competition between
An electron-donating substituent on the aromatic ring
would enhance the rate of decomposition of 2g16 and the
corresponding coupling product, dimethyl 2,3-bis(4-me-
thoxyphenyl)but-2-enedioate was obtained in 70% yield.
Halo substituent, as in 2a–d, acts as a weakly electron-
withdrawing group and the undesirable coupling reaction
may be minimized.
To achieve the 1,2-regioselective cyclopropanation giv-
ing vinylcyclopropylamine derivatives, we investigated the
reactions of N-Boc-1-amino-1,3-butadienes under various
conditions. The use of (MeCN)4CuPF6 itself gained 1,2-regi-
oselectivity (Table 3, entry 1). Substitution on the N-aro-
matic ring by an EDG substituent such as a 4-methoxy
slightly improved the yield and 1,2-regioselectivity of the
reaction (Table 3, entry 2). We tested other commercially
available copper(I) catalysts and various types of N-Boc-N-
substituted 1-amino-1,3-butadienes; however, the 1,2-re-
gioselectivity did not show any improvements. Meanwhile,
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 1880–1884

1883
E. Tayama, S. Saito
Letter
Synlett
(Z)-1e + 2
4e
oxy-bearing double bond to afford the cyclopropyl silyl
ether 4oa as the main product in 69% yield (Table 4, entry
6).
CuLn
CuLn
Ni-Pr2
Ni-Pr2
In summary, we demonstrated the copper-catalyzed re-
giospecific and 1,2-regioselective cyclopropanation of (1Z)-
1-amino- and (1Z)-1-oxy-1,3-dienes (Z)-1 with α-aryl di-
azoesters 2. The 1,2-addition at the internal Z-double bond
in (Z)-1 proceeded with minimal competition from the 3,4-
addition at the terminal double bond. The substrate (Z)-1
could be prepared by the stereoselective 1,4-elimination
developed by our group. This successful regiospecific proto-
col enabled the preparation of the corresponding 1-amino-
and 1-oxy-2-vinyl (alkenyl) cyclopropane derivatives 4 as
nearly single stereoisomers, which could act as useful
building blocks for biologically active and natural com-
pounds.
O
O
O
O
Ar
Ar
CuLn
O
CuLn
O
OMe
OMe
A
B
R
N
3 + 4
Ot-Bu
O
(Z)-1a,f–h
Scheme 2 Proposed mechanism for 1,2-regioselectivity
Acknowledgment
the E- and Z-double bonds with electron-donating substitu-
ents were investigated. When N-Boc-1-amino-4-ethoxy de-
rivative 1n (1Z,3E/1Z,3Z = 80:20) was used in the reaction
under the same conditions, the cyclopropanation occurred
at the Z-double bond, and the cyclopropylamine derivative
4na was obtained as the main product in 64% yield (Table 4,
entry 5). Similarly, a reaction of the 4-ethoxy-1-siloxy de-
rivative 1o (1Z,3E/1Z,3Z = >95:5) proceeded at the (Z)-sil-
This work was supported by the JGC-S Scholarship Foundation
(No.1307).
Supporting Information
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0034-1380426.
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References and Notes
Table 4 Effect of Substituents at the 4-Positiona
(1) Reviews: (a) Lebel, H.; Marcoux, J.-F.; Molinaro, C.; Charette, A.
B. Chem. Rev. 2003, 103, 977. (b) Kirmse, W. Angew. Chem. Int.
Ed. 2003, 42, 1088. (c) Davies, H. M. L.; Antoulinakis, E. G. In
Organic Reactions; John Wiley and Sons: New York, 2001, Chap.
1. (d) Doyle, M. P.; Mckervey, M. A.; Ye, T. Modern Catalytic
Methods for Organic Synthesis with Diazo Compounds: From
Cyclopropanes to Ylides; John Wiley and Sons: New York, 1998.
(2) (a) Maxwell, J. L.; O’Malley, S.; Brown, K. C.; Kodadek, T. Organo-
metallics 1992, 11, 645. (b) Doyle, M. P.; Griffin, J. H.; Bagheri,
V.; Dorow, R. L. Organometallics 1984, 3, 53.
(3) Representative examples of cyclopropanation of dienyl deriva-
tives: (a) Guzmán, P. E.; Lian, Y.; Davies, H. M. L. Angew. Chem.
Int. Ed. 2014, 53, 13083. (b) Werle, T.; Maas, G. Adv. Synth. Catal.
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(4) Representative examples of cyclopropanation of 1-substituted
1,3-butadienyl derivatives: (a) Davies, H. M. L.; Lee, G. H. Org.
Lett. 2004, 6, 2117. (b) Hahn, N. D.; Nieger, M.; Dötz, K. H. Eur. J.
Org. Chem. 2004, 1049; see also ref. 1c.
(5) Z-Regioselective cyclopropanation of E,Z-dienyl derivatives:
(a) Davies, H. M. L.; Doan, B. D. J. Org. Chem. 1998, 63, 657.
(b) Anciaux, A. J.; Demonceau, A.; Noels, A. F.; Warin, R.;
Hubert, A. J.; Teyssié, P. Tetrahedron 1983, 39, 2169.
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Tomilov, Y. V. Russ. Chem. Bull., Int. Ed. 2008, 57, 1784.
(7) (a) Our previous studies on the 1,4-elimination: Tayama, E.;
Toma, Y. Tetrahedron 2015, 71, 554. (b) Tayama, E.; Horikawa,
K.; Iwamoto, H.; Hasegawa, E. Tetrahedron 2013, 69, 2745.
(c) Tayama, E.; Otoyama, S.; Isaka, W. Chem. Commun. 2008,
4216. (d) Tayama, E.; Hashimoto, R. Tetrahedron Lett. 2007, 48,
4-BrC6H4 CO2Me
R2
(MeCN)4CuPF6 (2 mol%)
4
3
R1
+ 2a
CH2Cl2
r.t., 2 h
R3
R2
R1
2
1
R3
1
4
(1Z major)
Entry
1
R1
R2
n-Bu
R3
4 (%)b
1c
2d
3e
4f
1j
NPhBoc
H
4ja 93
1k
1l
OSiMe2t-Bu
NPhBoc
n-Bu
Me
H
4ka 83
4la 97
Me
Me
H
1m
1n
1o
OSiMe2t-Bu
NPhBoc
Me
4ma 84g
4na 64
4oa 69
5h
6i
OEt
OEt
OSiMe2t-Bu
H
a Reaction conditions: 1 (1.1 equiv), 2a (1.0 equiv), and catalyst (2 mol%) in
CH2Cl2 (0.1 M).
b Isolated yield.
c 1j: 1Z,3E/1Z,3Z = 87:13, 4ja: E/Z = 93:7.
d 1k: 1Z,3E only.
e 1l: 1Z only.
f 1m: 1E/1Z = 5:95.
g The 3,4-adduct (Z)-3ma was observed in 3% yield in the isolated 4ma.
The yields were calculated by 1H NMR assay.
h 1n: 1Z,3E/1Z,3Z = 80:20, 4na: E/Z = 90:10.
i 1o: 1Z,3E/other isomers = >95:5, 4oa: almost a single stereoisomer.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 1880–1884

1884
E. Tayama, S. Saito
Letter
Synlett
7950. (e) Tayama, E.; Sugai, S. Tetrahedron Lett. 2007, 48, 6163.
(f) Tayama, E.; Sugai, S.; Hara, M. Tetrahedron Lett. 2006, 47,
7533. (g) Tayama, E.; Sugai, S. Synlett 2006, 849.
(14) When the reaction was carried out at 0 °C, (Z)-3aa and 4aa
were obtained in 7% combined yield [(E)-3aa/(Z)-3aa/4aa =
0:51:49] with the recovery of the substrates [(Z)-1a, 84%; 2a,
86%].
(8) Tayama, E.; Horikawa, K.; Iwamoto, H.; Hasegawa, E. Tetrahe-
dron Lett. 2014, 55, 3041.
(15) Representative Procedure
(9) Preparation of 1-amino-2-vinyl (alkenyl) cyclopropanes: (a) de
Meijere, A.; Chaplinski, V.; Winsel, H.; Kordes, M.; Stecker, B.;
Gazizova, V.; Savchenko, A. I.; Boese, R.; Schill, F. Chem. Eur. J.
2010, 16, 13862. (b) Wiedemann, S.; Rauch, K.; Savchenko, A.;
Marek, I.; de Meijere, A. Eur. J. Org. Chem. 2004, 631.
(c) Williams, C. M.; Chaplinski, V.; Schreiner, P. R.; de Meijere, A.
Tetrahedron Lett. 1998, 39, 7695.
(10) Representative examples of preparation of 1-amino-2-vinylcy-
clopropane-1-carboxylic acid derivatives: (a) Lou, S.; Cuniere,
N.; Su, B.-N.; Hobson, L. A. Org. Biomol. Chem. 2013, 11, 6796.
(b) Tang, W.; Wei, X.; Yee, N. K.; Patel, N.; Lee, H.; Savoie, J.;
Senanayake, C. H. Org. Process Res. Dev. 2011, 15, 1207.
(c) Crane, Z. D.; Nichols, P. J.; Sammakia, T.; Stengel, P. J. J. Org.
Chem. 2011, 76, 277.
(11) Preparation of 1-oxy-2-vinyl (alkenyl) cyclopropanes:
(a) McGaffin, G.; Grimm, B.; Heinecke, U.; Michaelsen, H.; de
Meijere, A.; Walsh, R. Eur. J. Org. Chem. 2001, 3559. (b) Militzer,
H.-C.; Schömenauer, S.; Otte, C.; Puls, C.; Hain, J.; Bräse, S.; de
Meijere, A. Synthesis 1993, 998. (c) Davies, H. M. L.; Hu, B. J. Org.
Chem. 1992, 57, 4309. (d) de Meijere, A.; Schulz, T.-J.; Kostikov,
R. R.; Graupner, F.; Murr, T.; Bielfeldt, T. Synthesis 1991, 547.
(12) A representative review: Hudlicky, T.; Reed, J. W. Angew. Chem.
Int. Ed. 2010, 49, 4864.
A solution of (Z)-1e (65 mg, 0.33 mmol) and 2a (77 mg, 0.30
mmol) in CH2Cl2 (3.0 mL) was added to (MeCN)4CuPF6 (2 mg,
0.005 mmol) in a flask at r.t. and stirred for 2 h under an argon
atmosphere. Extractive workup and purification of the residue
by chromatography on silica gel (CH2Cl2–MeOH = 200:1 to 40:1
as the eluent) afforded a mixture of (E)-3ea and 4ea [103 mg,
(E)-3ea/4ea = 5:95; (E)-3ea, 4% yield; 4ea, 77% yield] as a white
solid.
Analytical Data of 4ea
IR (KBr): 2982, 2935, 2873, 1728, 1711, 1693, 1490, 1479, 1447,
1369, 1317, 1294, 1250, 1209, 1188, 1156, 1128, 1077, 1066,
1011, 974, 920, 900, 827, 772, 762, 732 cm–1 1H NMR (400
.
MHz, CDCl3): δ = 7.43 (2 H, ddd, J = 8.4, 2.2, 2.2 Hz, ArH), 7.15 (2
H, ddd, J = 8.4, 2.2, 2.2 Hz, ArH), 5.50–5.40 (1 H, m, CH=CH2),
5.31–5.18 (2 H, m, CH=CH2), 4.95 (1 H, d, J = 7.2 Hz, 2-H), 3.90 [1
H, br, CH(CH3)2], 3.61 (3 H, s, OCH3), 3.59–3.47 [1 H, m,
CH(CH3)2], 2.89–2.77 (1 H, m, 3-H), 1.40–1.10 [6 H, m,
CH(CH3)2], 0.89 [3 H, d, J = 6.4 Hz, CH(CH3)2], 0.82 [3 H, d, J = 6.4
Hz, CH(CH3)2]. 13C NMR (100 MHz, CDCl3): δ = 171.9, 154.1,
134.2, 131.11, 131.08, 130.7, 121.7, 119.0, 60.6, 60.5, 52.7, 46.4,
46.0, 36.6, 33.9, 20.7, 20.6, 20.5, 20.3. ESI-HRMS: m/z [M + H]+
calcd for C20H27BrNO4: 424.1118; found: 424.1111.
(16) A study on decomposition of α-aryl diazoesters with rho-
dium(II) catalysts: Qu, Z.; Shi, W.; Wang, J. J. Org. Chem. 2001,
66, 8139.
(13) A study on cyclopropanation of (E)- and (Z)-enamides: Lu, T.;
Song, Z.; Hsung, R. P. Org. Lett. 2008, 10, 541.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 1880–1884