Reaction of gem-dibromocyclopropanes or iodobenzofuran with trialkylmanganate

Article abstract of DOI:10.1016/S0040-4020(99)01095-9

Treatment of gem-dibromocyclopropanes with trialkylmanganate, derived from manganese(II) chloride and three equivalents of Grignard reagent or alkyllithium, followed by an addition of electrophiles provided dialkylated cyclopropanes in good yields. It was

Full text of DOI:10.1016/S0040-4020(99)01095-9

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 2131±2137
Reaction of gem-Dibromocyclopropanes or Iodobenzofuran
with Trialkylmanganate
*
Hirotada Kakiya, Rie Inoue, Hiroshi Shinokubo and Koichiro Oshima
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
Accepted 7 December 1999
AbstractÐTreatment of gem-dibromocyclopropanes with trialkylmanganate, derived from manganese(II) chloride and three equivalents of
Grignard reagent or alkyllithium, followed by an addition of electrophiles provided dialkylated cyclopropanes in good yields. It was found
that the reaction of gem-dibromocyclopropanes with alkylmagnesium halide proceeded in the presence of a catalytic amount of manga-
nese(II) chloride. The use of iodobenzofuran in place of gem-dibromocyclopropane gave a ring opening product, 2-alkenylphenol. q 2000
Elsevier Science Ltd. All rights reserved.
Introduction
be easily prepared by the addition of dihalocarbene to
ole®ns, provides us with an effective route to a variety of
functionalized cyclopropane derivatives. The transforma-
tion of gem-dihalocyclopropanes into 1-alkyl-1-butylcyclo-
propanes has been reported to proceed by successive
treatment with dibutylcuprate2 or tributylzincate3,4 and
several electrophiles. In this paper we describe that the reac-
tion of gem-dibromocyclopropanes with trialkylmanganate
followed by treatment with electrophiles provides dialkyl-
ated cyclopropanes as in the case of the reaction with
cuprates or zincates and also that the reaction of gem-
dibromocyclopropanes with alkylmagnesium halides takes
place in the presence of a catalytic amount of manganese(II)
chloride.
Organomanganese reagents are among the less expensive
organo transition metal compounds due to the low cost of
manganese metal. However, contrary to organocopper
reagents, which have been extensively studied in organic
synthesis, organomanganese compounds have been almost
ignored until 1976. Then, Professors J. F. Normant and G.
Cahiez started studies on the preparation of organomanga-
nese reagents and subsequent synthetic applications of
these compounds.1 They introduced the procedure for
preparation of three types of organomanganese reagents,
organomanganese halide (RMnX), dialkylmanganese
(R2Mn), and organomanganate (R3MnMtl). Among them,
trialkylmanganate is the most stable reagent and it is stable
at room temperature. Meanwhile, dialkylmanganese such as
n-Bu2Mn is unstable and decomposes at 2308C. The
stability of RMnX is between dialkylmanganese and tri-
alkylmanganate. Taking account of the stability and reactivity,
we chose trialkylmanganate and examined several reactions.
Treatment of gem-dibromocyclopropane 1a with tributyl-
manganate, generated from MnCl2 and three equivalents
of butylmagnesium bromide gave a mixture of trans-1-
butyl-2-hexylcyclopropane (2a) and cis-isomer 3a in 89%
combined yield (2a/3aˆ71/29) (Scheme 1).
Dialkylation of gem-dibromocyclopropanes with
trialkylmanganate and manganese(II) chloride-
catalyzed reaction with alkylmagnesium bromide
Various gem-dibromocyclopropanes were allowed to react
®rst with trialkylmanganate, triallylmanganate or tris(di-
methylphenylsilyl)manganate5 and then with a variety of
electrophiles. The results are summarized in Table 1.
Among the solvent systems examined (THF, ether, DME),
THF gave the best results. Several comments are worth
Cyclopropane derivatives are versatile synthetic intermediates.
Double alkylation of gem-dihalocyclopropanes, which can
Scheme 1.
Keywords: gem-dibromocyclopropanes; manganese(II) chloride; 2-alkenylphenol.
* Corresponding author. Tel.: 181-75753-4868; fax: 181-75761-8846; e-mail: oshima@fm1.kuic.kyoto-u.ac.jp
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(99)01095-9

2132
H. Kakiya et al. / Tetrahedron 56 (2000) 2131±2137
Table 1. Stereoselective dialkylation of gem-dibromocyclopropanes (the reactions were performed at 08C unless otherwise stated)
Entry
Substrate 1
R1 MnMtl
Electrophile
Yield (%)
Isomeric ratio of 2/3
3
1
2
3
4
5
6
7
8
9
10
n-Bu3MnLi
EtOHa
H2O
CH2yCHCH2Br
MeI
53
89
77
65
72
54
58
61
69
84
68/32
71/29
89/11
94/6
83/17
72/28
99/1
86/14
88/12
58/42
n-Bu3MnMgBr
n-Bu3MnMgBr
n-Bu3MnMgBr
n-Bu3MnMgBr
n-Bu3MnMgBr
n-Bu3MnMgBr
n-Bu3MnMgBr
n-Bu3MnMgBr
(PhMe2Si)3MnLi
PhCOCl
I2
CH2yCHBrb
H2O
CH2yCHCH2Br
H2O
11
12
13
n-Bu3MnLi
n-Bu3MnMgBr
n-Bu3MnMgBr
H2O
H2O
CH2yCHCH2Br
56
82
88
87/13
97/3
97/3
14
15
16
n-Bu3MnMgBr
n-Bu3MnMgBr
(CH2yCHCH2)3MnMgBr
H2O
PhCOCl
H2O
64
75
64
87/13
84/16
83/17
17
18
n-Bu3MnMgBrc
n-Bu3MnMgBrc
H2O
CH2yCHCH2Br
78
50
87/13
92/8
19
20
n-Bu3MnMgBr
n-Bu3MnMgBr
H2O
CH2yCHCH2Br
75
66
88/12
88/12
21
(PhMe2Si)3MnLi
H2O
62
±
a Quenching the reaction with EtOH or H2O gave the same results (yield and isomeric ratio of 2/3).
b Pd(PPh3)4 (10 mol%) was added.
c The reaction was performed at 2488C.
noting. (1) In contrast to the reaction with cuprate or zincate
which has been performed at 248 or 2858C, the reaction
with manganate could be performed conveniently at 08C.
The reaction of 1a with n-Bu3MnLi at 2788C for 30 min
provided 1-bromo-2-hexylcyclopropane6 (cis/transˆ1/2) in
65% yield in addition to an isomeric mixture of 1-butyl-2-
hexylcyclopropane (2a/3aˆ76/24, 30% yield). Moreover,
treatment of 1a with n-Bu3MnMgBr at 2788C for 30 min
resulted in almost complete recovery of 1a. (2) Tributyl-
manganesemagnesium bromide, derived from MnCl2 and
three equivalents of butylmagnesium bromide, afforded
better yields of butylated cyclopropanes 2 and 3 than
tributylmanganeselithium generated from butyllithium
(Entry 1 vs. 2, 11 vs. 12). (3) Triphenylmanganate Ph3Mn-
MgBr or Ph3MnLi gave phenylated cyclopropane in 34% or
30% yield, respectively, upon treatment of 1a. (4)
(CH2vCH)3MnMgBr and (Me3Si±CuC)3MnMgBr gave
a minimal amount of the corresponding alkenyl- or alkynyl-
cyclopropanes (,5%). Manganates having secondary and
tertiary alkyl ligands such as i-Pr3MnMgBr and
t-Bu3MnMgCl gave 1-bromo-2-hexylcyclopropane in 50±
55% yield along with an unidenti®ed complex mixture
which did not contain the desired isopropylcyclopropane
or tert-butylcyclopropane. (5) The intermediary cyclo-
propylmanganese reagents 5 could be trapped by acid
chloride,7 iodine, and vinyl bromide (in the presence of
Pd(PPh3)4 (10 mol%))8 as well as methyl iodide and allyl
bromide. (6) 1,1-Dichlorocyclopropane such as 9,9-
dichlorobicyclo[6.1.0]nonane was found to be unreactive.
We are tempted to assume a similar reaction mechanism
to the reaction with cuprate and zincates: (1) the initial
halogen±manganese exchange at the less hindered bromine
to afford 4; (2) alkyl migration under Br2 elimination
producing 5 (inversion on the cyclopropane carbon); (3)
the second alkylation by R2X with retention of the con-
®guration. The stereoselective formation of 2 might be
attributed to the bulkiness of the manganese reagents
which attack the less hindered halogen selectively
(Scheme 2).
Scheme 2.

H. Kakiya et al. / Tetrahedron 56 (2000) 2131±2137
2133
Table 2. Manganese(II) chloride-catalyzed reaction of gem-dibromocyclopropanes (the reactions were performed in the presence of 0.1 mmol of MnCl2)
Entry
Substrate 1 (1.0 mmol)
RMtl (3.0 mmol)
Electrophile (3.0 mmol)
Yield (%)
Isomeric ratio of 2/3
1
2
3
4
5
6
n-BuLi
n-BuMgBr
n-BuMgBr
CH2yCHCH2MgBr
CH2yCHCH2MgBr
PhMe2SiLi
H2O
H2O
CH2yCHCH2Br
H2O
CH2yCHCH2Br
EtOH
68
75
57
79
47
43
66/34
79/21
81/19
58/42
±
79/21
7
8
n-BuLi
n-BuMgBr
H2O
EtOH
62
51
85/15
93/7
9
n-BuMgBr
H2O
51
77/23
Moreover, the reaction proceeded in the presence of a
catalytic amount of manganese(II) chloride. For instance,
an addition of a solution of dibromocyclopropane 1a to a
THF solution of butylmagnesium bromide and manganese(II)
chloride (10 mol%) at 08C gave 1-butyl-2-hexylcyclo-
propane 2a and 3a in 75% combined yield after aqueous
workup. In contrast, the reaction of 1a with butylmagnesium
bromide without manganese provided 1,2-nonadiene in 95%
yield. The representative results of the catalytic reactions
are shown in Table 2.
with D2O provided 2-[(E)-2-deuterio-1-hexenyl]phenol.
(E)-Alkene was obtained exclusively (Scheme 4).
The reaction might proceed as follows: (1) iodine±manga-
nese exchange to provide a manganate 7; (2) migration of
butyl group from manganese to an adjacent carbon under
cleavage of C±O bond producing 8; and (3) protonation of
alkenylmanganese species upon aqueous workup.
The reaction also proceeded in a catalytic manner. For
instance, treatment of 6 with butylmagnesium bromide in
THF in the presence of a catalytic amount of MnCl2
(10 mol%) at 258C for 10 h gave 2-alkenylphenol 9a in
21% yield. The change of the solvent from THF to ether
dramatically increased the yield up to 85% after 1 h at
258C. Various Grignard reagents were examined in the
MnCl2-catalyzed ring-opening reaction of 6. Ethyl-
magnesium bromide or allylmagnesium bromide gave
the corresponding (E)-2-alkenylphenol 9b or 9c in 88% or
46% yield, respectively after stirring the reaction mixture
for 1 or 1.5 h at 258C. In contrast, the reaction with phenyl-
magnesium bromide or methylmagnesium iodide
proceeded very slowly at 258C and afforded the corre-
sponding ring-opened product 9d or 9e in 62 or 46%
yield, respectively after heating the reaction mixture at
re¯ux for 16 or 28 h. In the case of methylmagnesium
iodide, dimethylated product, 2-(2-methyl-1-propenyl)-
phenol (10) was obtained in 18% yield in addition to the
desired 9e (Scheme 5).
Ring opening of iodobenzofuran with trialkylmanganate
The reaction of 1,1-dibromo-1-octene with tributylmanga-
nate took place very easily even at 2788C. However, the
expected product based on 1,2-migration reaction could not
be detected and unidenti®ed complex mixture was obtained
(Scheme 3).
Then, we turned our attention to heteroatom substituted
alkenyl halides such as 2-iodobenzofuran,9,10 2,6-dibromo-
pyridine,11 and 2-iodobenzothiophene. Among them, 2-
iodobenzofuran proved to be a good substrate and afforded
the desired ring-opening product upon treatment with tri-
alkylmanganate. Thus, an addition of tributylmanganate to
a solution of 2-iodobenzofuran (6) in THF followed by
heating a mixture at 508C for 2.5 h gave 2-[(E)-1-hexenyl]-
phenol (9a) in 49% yield. Quenching the reaction mixture
Scheme 3.
Scheme 4.

2134
H. Kakiya et al. / Tetrahedron 56 (2000) 2131±2137
Scheme 5.
Scheme 6.
The intermediary alkenylmagnesium in the MnCl2-
catalyzed reaction of 6 could be trapped by various electro-
philes. An addition of D2O, allyl bromide or benzaldehyde
gave the corresponding adducts (11a, 11b or 11c) in 77, 63
or 86%, respectively. Furthermore, quenching the reaction
mixture with CO2 produced 3-butyl-2H-benzopyran-2-one
12 in 53% yield.12 (Scheme 6).
1 M HCl and extracted with hexane (3£20 ml). Puri®cation
of the products by silica-gel column chromatography gave
a mixture of 2a and 3a (162 mg) in 89% combined yield
(2a/3aˆ71/29).
Physical data for 2a, 3a, 7-butylnorcarane, 9-butylbicyclo-
[6.1.0]nonane, 1-butyl-2-phenylcyclopropane and 1-butyl-
2-[(phenylmethoxy)methyl]cyclopropane were identical
with those reported in literature.2,3,13
Financial support by grant-in-aid for Scienti®c Research on
Priority Area (B) (No. 10208208) and grant-in-aid for
Scienti®c Research (No. 09450341) from the Ministry of
Education, Science, Sports and Culture, Japan, is acknowl-
edged. We also thank Prof. Tamejiro Hiyama for helpful
discussions.
1,2-Dihexycyclopropane (2/3ˆ86/14). IR (neat) 3056,
2986, 2952, 2920, 2850, 1467, 1458, 1378, 1020,
1
721 cm21; H NMR (CDCl3) d 20.28±20.23 (m, 0.14H),
0.11 (t, Jˆ6.6 Hz, 1.72H), 0.28±0.40 (m, 1.72H), 0.49±0.57
(m, 0.14H), 0.58±0.68 (m, 0.28H), 0.86 (t, Jˆ6.9 Hz, 6H),
1.01±1.40 (m, 20H); 13C NMR (CDCl3) d 10.78, 11.64,
14.00, 15.67, 18.68, 22.60, 28.55, 29.13, 29.28, 29.58,
30.11, 31.88, 34.31. Found: C, 85.34; H, 14.15%. Calcd
for C15H30: C, 85.63; H, 14.37%.
Experimental
Distillation of the products was performed using Kugelrohr
(BuÈchi); the boiling points are indicated by the air-bath
temperature values without any correction. The NMR
spectra (1H and 13C) were recorded on a Varian GEMINI
300 spectrometer in CDCl3; tetramethylsilane (TMS) was
used as an internal standard. The IR spectra were deter-
mined on a JASCO IR-810 spectrometer. The analyses
were carried out at the Elemental Analysis Center of
Kyoto University.
9-Allylbicyclo[6.1.0]nonane (2/3ˆ83/17). IR (neat) 3350,
2974, 2918, 2848, 2684, 1640, 1466, 1446, 1354, 1300,
1277, 1150, 1025, 993, 961, 908, 736 cm21 1H NMR
;
(CDCl3) d 0.12±0.22 (m, 0.83H), 0.32±0.44 (m, 1.66H),
0.60±0.69 (m, 0.17H), 0.70±0.83 (m, 0.17H), 0.84±1.02
(m, 1.83H), 1.03±1.16 (m, 0.34H), 1.25±1.42 (m, 4H),
1.44±1.82 (m, 4H), 1.93±2.10 (m, 4H), 4.89±5.12 (m,
2H), 5.84±5.98 (m, 0.17H), 5.87 (ddt, Jˆ17.1, 10.2,
6.0 Hz, 0.83H); 13C NMR (CDCl3) d 17.71, 21.51, 22.33,
22.60, 26.45, 26.52, 26.70, 29.59, 29.71, 37.69, 113.86,
138.65. Found: C, 87.68; H, 12.52%. Calcd for C12H20: C,
87.73; H, 12.27%.
General procedure for the reaction of gem-dibromocyclo-
propane with trialkylmanganate
The reaction of 1,1-dibromo-2-hexylcyclopropane (1a) with
tributylmanganate is representative (Entry 2, Table 1).
Manganese(II) chloride (151 mg, 1.2 mmol) was sonicated
in tetrahydrofuran (THF, 10 ml) under argon atmosphere for
20 min. Butylmagnesium bromide (1.0 M ether solution,
3.6 ml, 3.6 mmol) was added to the suspension of MnCl2
in THF at 08C. The mixture turned into a clear brown solu-
tion and then was stirred for 20 min at 08C. A solution of
dibromocyclopropane 1a (0.28 g, 1.0 mmol) in THF (2 ml)
was added at 08C and the whole was stirred at 08C for 1 h
and then at 258C for 20 min. The mixture was poured into
3-Dimethylphenylsilyl-1,1,2,2-tetramethylcyclopropane.
IR (neat) 3066, 3046, 2936, 2866, 1470, 1455, 1428, 1378,
1248, 1139, 1111, 914, 880, 833, 811, 779, 726, 698 cm21
;
1H NMR (CDCl3) d 20.54 (s, 1H), 0.29 (s, 6H), 1.09
(s, 6H), 1.17 (s, 6H), 7.30±7.39 (m, 3H), 7.50±7.57
(m, 2H); 13C NMR (CDCl3) d 0.04, 20.64, 24.34,
25.10, 25.34, 127.71, 128.57, 133.69, 141.58. Found:
C, 77.30; H, 10.66%. Calcd for C15H24Si: C, 77.51; H,
10.41%.

H. Kakiya et al. / Tetrahedron 56 (2000) 2131±2137
2135
General procedure for the reaction of gem-dibromo-
cyclopropane with trialkylmanganate followed by
addition of electrophile
0.88H), 0.31±0.40 (m, 1H), 0.43±0.54 (m, 1H), 0.81±0.99
(m, 6H), 1.14±1.42 (m, 20H), 1.76 (dd, Jˆ14.7, 6.6 Hz,
0.12H), 1.90 (dd, Jˆ14.7, 6.6 Hz, 0.88H), 2.00±2.16 (m,
1H), 4.92±5.06 (m, 2H), 5.68±5.88 (m, 1H); 13C NMR
(CDCl3) d 13.91, 17.68, 18.01, 22.55, 23.05, 23.77,
24.11, 26.65, 29.19, 29.37, 29.48, 29.68, 30.06, 30.71,
31.83, 35.24, 37.80, 115.33, 115.49, 137.18, 137.80.
Found: C, 86.04; H, 13.76%. Calcd for C18H34: C, 86.32;
H, 13.68%.
Preparation of 1-butyl-2-hexyl-1-iodocyclopropane is
representative (Entry 6, Table 1). A solution of 1a (0.28 g,
1.0 mmol) in THF (2 ml) was added to a solution of
tributylmanganate generated from MnCl2 (151 mg,
1.2 mmol) and butylmagnesium bromide (3.6 mmol). The
resulting mixture was stirred at 08C for 1 h and then at 258C
for 20 min. The mixture was cooled to 2788C and iodine
(0.46 g, 3.6 mmol) was added. The whole was warmed to
room temperature over 1 h and stirred for another 30 min.
The mixture was poured into aq. Na2S2O3 and extracted with
hexane (3£20 ml). Puri®cation by silica-gel column
chromatography gave a mixture of cis- and trans-1-butyl-
2-hexyl-1-iodocyclopropane (cis/transˆ72/28): Bp 130±
1408C (bath temp, 0.5 Torr); IR (neat) 3058, 2954, 2924,
2852, 1466, 1379, 1294, 1261, 1211, 1164, 1116, 1031, 942,
7-Allyl-7-butylnorcarane (2/3ˆ97/3). IR (neat) 3072,
1
2924, 2854, 1639, 1467, 1449, 1377, 991, 909 cm21; H
NMR (CDCl3) d 0.56±0.66 (m, 2H), 0.86 (t, Jˆ6.9 Hz,
2.91H), 0.91 (t, Jˆ7.2 Hz, 0.09H), 1.06±1.46 (m, 12H),
1.79±1.93 (m, 2.06H), 2.09 (d, Jˆ6.6 Hz, 1.94 H), 4.97
(d, Jˆ10.2 Hz, 0.03H), 4.98 (d, Jˆ17.1 Hz, 0.03H), 5.03
(d, Jˆ10.2 Hz, 0.97H), 5.08 (d, Jˆ17.1 Hz, 0.97H), 5.83
(ddt, Jˆ17.1, 10.2, 6.6 Hz, 1H); 13C NMR (CDCl3) d
14.02, 18.54, 19.11, 22.15, 22.84, 24.46, 28.26, 30.85,
38.95, 115.36, 137.32.
914, 800, 724 cm21 1H NMR (CDCl3) d 20.05±0.10
;
(m, 0.72H), 0.32 (t, Jˆ6.3 Hz, 0.28H), 0.68 (t, Jˆ6.0 Hz,
0.72H), 0.80±0.98 (m, 6H), 1.02±1.75 (m, 17.28H);
13C NMR (CDCl3) d 13.98, 14.01, 21.81, 22.00, 22.51,
22.56, 22.80, 23.67, 24.02, 24.67, 28.63, 28.70, 29.01,
29.17, 30.17, 31.68, 31.77, 32.50, 36.95, 39.15, 46.00.
Found: C, 50.79; H, 8.40%. Calcd for C13H25I: C, 50.66;
H, 8.17%.
9-Benzoyl-9-butylbicyclo[6.1.0]nonane (2/3ˆ84/16). IR
(neat) 3056, 3022, 2954, 2920, 2852, 1672, 1598, 1581,
1467, 1449, 1349, 1280, 1250, 1210, 1196, 1174, 1073,
1053, 1020, 976, 960, 935, 806, 782, 741, 715, 691 cm21
;
1H NMR (CDCl3) d 0.76 (t, Jˆ6.9 Hz, 2.52H), 0.86 (t,
Jˆ7.2 Hz, 0.48H), 0.90±1.08 (m, 4H), 1.10±1.42 (m, 8H),
1.48±1.69 (m, 6H), 1.97±2.06 (m, 2H), 7.39±7.55 (m, 3H),
7.94±8.00 (m, 2H); 13C NMR (CDCl3) major product d
13.76, 22.33, 24.43, 26.22, 28.47, 29.55, 29.65, 35.87,
39.95, 128.37, 129.57, 132.55, 137.32, 200.61. Found:
C, 84.28; H, 10.01%. Calcd for C20H28O: C, 84.45; H,
9.92%.
Physical data for 1-butyl-1-methyl-2-hexylcyclopropane
and 1-benzoyl-1-butyl-2-hexylcyclopropane were identical
with those reported in literature.3,13
1-Allyl-1-butyl-2-hexylcyclopropane (2/3ˆ89/11). IR
(neat) 3072, 3050, 2954, 2920, 2852, 1640, 1467, 1459,
1
1415, 1379, 1020, 993, 909, 723 cm21; H NMR (CDCl3)
1-Allyl-1-butyl-2-phenylcyclopropane (2/3ˆ92/8). IR
(neat) 3058, 3022, 2992, 2952, 2922, 2854, 1639, 1605,
1498, 1457, 1440, 1416, 1378, 1085, 1070, 1028, 996,
d 20.14 (dd, Jˆ5.1, 4.5 Hz, 0.11H), 20.09 (dd, Jˆ5.4,
4.5 Hz, 0.89H), 0.30±0.39 (m, 1H), 0.43±0.55 (m, 1H),
0.80±0.90 (m, 6H), 1.11±1.44 (m, 16H), 1.76 (dd,
Jˆ15.0, 6.6 Hz, 0.11H), 1.92 (dd, Jˆ15.0, 6.6 Hz, 0.89H),
2.01±2.16 (m, 1H), 4.93±5.02 (m, 0.22H), 4.98 (d,
Jˆ10.2 Hz, 0.89H), 5.02 (d, Jˆ17.1 Hz, 0.89H), 5.69±
5.83 (m, 0.11H), 5.81 (ddt, Jˆ17.1, 10.2, 6.9 Hz, 0.89H);
13C NMR (CDCl3) d 14.00, 14.06, 18.00, 22.59, 22.86,
22.98, 24.06, 28.50, 29.22, 29.38, 30.07, 31.84, 35.16,
37.44, 115.34, 115.45, 137.75. Found: C, 86.03; H,
13.70%. Calcd for C16H30: C, 86.41; H, 13.59%.
1
910, 775, 728, 696 cm21; H NMR (CDCl3) d 0.69±0.80
(m, 1.24 H), 0.81±0.87 (m, 0.08H), 0.87±0.96 (m, 3.68H),
1.10±1.66 (m, 6.92H), 1.87±1.99 (m, 2H), 2.34 (dd,
Jˆ14.1, 7.5 Hz, 0.08H), 4.89 (d, Jˆ17.4 Hz, 0.92H), 4.91
(d, Jˆ10.2 Hz, 0.92H), 5.07 (d, Jˆ9.9 Hz, 0.08H), 5.08 (d,
Jˆ16.8 Hz, 0.08H), 5.67 (ddt, Jˆ17.4, 10.2, 6.9 Hz, 0.92H),
5.91 (ddt, Jˆ16.8, 9.9, 7.2 Hz, 0.08H), 7.12±7.26 (m, 3H),
7.27±7.35 (m, 2H); 13C NMR (CDCl3) d 13.87, 14.01,
16.06, 16.37, 22.67, 22.87, 26.67, 28.40, 28.50, 28.69,
28.85, 30.10, 35.18, 37.18, 41.70, 115.61, 116.21, 125.57,
125.68, 127.86, 127.96, 129.09, 136.58, 136.92, 139.79.
Found: C, 89.59; H, 10.62%. Calcd for C16H22: C, 89.66;
H, 10.34%.
1-Butyl-2-hexyl-1-vinylcyclopropane (2/3ˆ99/1). IR
(neat) 3080, 3058, 2954, 2920, 2852, 1634, 1460, 1378,
1
1261, 1026, 993, 908, 894, 723 cm21; H NMR (CDCl3) d
0.33±0.40 (m, 1H), 0.52±0.58 (m, 1H), 0.62±0.75 (m, 1H),
0.86 (t, Jˆ6.9 Hz, 6H), 1.14±1.48 (m, 16H), 4.93
(dd, Jˆ17.1, 1.8 Hz, 1H), 5.01 (dd, Jˆ10.5, 1.8 Hz, 1H),
5.69 (dd, Jˆ17.1, 10.5 Hz, 1H); 13C NMR (CDCl3) d
14.01, 18.15, 22.58, 22.90, 26.54, 27.43, 29.03, 29.10,
29.13, 29.75, 31.81, 37.99, 113.32, 140.33. Found:
C, 86.21; H, 13.54%. Calcd for C15H28: C, 86.46; H,
13.54%.
1-Allyl-1-butyl-2-[(phenylmethoxy)methyl]cyclopropane
(2/3ˆ88/12). IR (neat) 3060, 3026, 2988, 2952, 2922, 2852,
1640, 1497, 1455, 1415, 1380, 1363, 1204, 1165, 1093,
1
1076, 1028, 995, 910, 733, 696 cm21; H NMR (CDCl3) d
0.13 (dd, Jˆ5.1, 5.1 Hz, 0.12H), 0.18 (dd, Jˆ5.1, 5.1 Hz,
0.88H), 0.50±0.59 (m, 1H), 0.87 (t, Jˆ6.9 Hz, 3H),
0.92±1.03 (m, 1H), 1.15±1.39 (m, 6H), 1.98±2.16
(m, 2H), 3.41±3.60 (m, 2H), 4.51 (d, Jˆ12.0 Hz, 1H),
4.55 (d, Jˆ12.0 Hz, 1H), 4.98±5.09 (m, 2H), 5.74±5.93
(m, 1H), 7.27±7.37 (m, 5H); 13C NMR (CDCl3) major
product d 13.95, 16.43, 22.75, 23.17, 23.53, 28.33,
35.40, 37.05, 70.74, 72.59, 115.67, 127.57, 127.78,
1-Allyl-1,2-dihexylcyclopropane (2/3ˆ88/12). IR (neat)
3072, 3050, 2954, 2920, 2850, 1640, 1460, 1415, 1379,
1
1018, 993, 909, 721 cm21; H NMR (CDCl3) d 20.14
(dd, Jˆ5.4, 5.4 Hz, 0.12H), 20.09 (dd, Jˆ5.4, 5.4 Hz,

2136
H. Kakiya et al. / Tetrahedron 56 (2000) 2131±2137
128.44, 137.31. Found: C, 83.69; H, 10.34%. Calcd for
C18H26O: C, 83.67; H, 10.14%.
2-[(E)-1-hexenyl]phenol (9a): IR (neat) 3032, 2954, 2924,
2854, 1606, 1586, 1499, 1486, 1455, 1378, 1330, 1294,
1239, 1177, 1089, 971, 848, 800, 748 cm21 1H NMR
;
(CDCl3) d 0.93 (t, Jˆ6.9 Hz, 3H), 1.31±1.53 (m, 4H),
4.24 (dt, Jˆ6.9, 6.9 Hz, 2H), 4.94 (s, 1H), 6.19 (dt,
Jˆ15.9, 6.9 Hz, 1H), 6.55 (d, Jˆ15.9 Hz, 1H), 6.79 (dd,
Jˆ7.8, 1.2 Hz, 1H), 6.88 (ddd, Jˆ7.8, 7.8, 1.2 Hz, 1H),
7.10 (ddd, Jˆ7.8, 7.8, 1.8 Hz, 1H), 7.31 (dd, Jˆ7.8,
1.8 Hz, 1H); 13C NMR (CDCl3) d 13.83, 22.17, 31.42,
33.04, 115.70, 120.91, 123.63, 125.10, 127.43, 128.02,
133.84, 152.48. Found: C, 81.50; H, 8.94%. Calcd for
C12H16O: C, 81.77; H, 9.15%.
General procedure for manganese(II) chloride-catalyzed
reaction of gem-dibromocyclopropane
A solution of dibromocyclopropane 1a (0.28 g, 1.0 mmol)
in THF (2 ml) was added to a THF solution of butylmagne-
sium bromide (3.0 mmol) and manganese(II) chloride
(12 mg, 10 mol%) at 2788C. The mixture was stirred for
30 min at 08C. Extractive workup (AcOEt, brine) followed
by silica-gel column puri®cation provided a mixture of 2a
and 3a (2a/3aˆ79/21, 136 mg) in 75% combined yield.
General procedure for the reaction of 2-iodobenzofuran
with Grignard reagent in the presence of a catalytic
amount of MnCl2
1-Allyl-2-hexylcyclopropane (2/3ˆ58/42). IR (neat) 3058,
2990, 2954, 2920, 2850, 1641, 1459, 1438, 1379, 1022, 992,
1
909, 719 cm21; H NMR (CDCl3) d 20.30±20.23 (m,
0.42H), 0.14±0.23 (m, 1.16H), 0.36±0.50 (m, 1.16H),
0.56±0.65 (m, 0.42H), 0.67±0.80 (m, 0.84H), 0.86 (t,
Jˆ6.9 Hz, 3H), 1.13±1.44 (m, 10H), 1.87±2.15 (m, 2H),
4.93 (d, Jˆ9.9 Hz, 0.58H), 4.95 (d, Jˆ10.2 Hz, 0.42H),
5.02 (d, Jˆ17.1 Hz, 0.58H), 5.07 (d, Jˆ17.1 Hz, 0.42H),
5.85 (ddt, Jˆ17.1, 9.9, 6.6 Hz, 0.58H), 5.90 (ddt, Jˆ17.1,
10.2, 6.9 Hz, 0.42H); 13C NMR (CDCl3) d 10.56, 11.37,
13.99, 14.65, 15.71, 17.61, 18.40, 22.59, 28.62, 29.08,
29.24, 29.47, 30.03, 31.85, 32.75, 34.09, 38.09, 114.05,
114.20, 138.40, 139.06. Found: C, 86.43; H, 13.61%.
Calcd for C12H22: C, 86.67; H, 13.33%.
Preparation of 9b is representative. Ethylmagnesium bromide
(0.93 M, ether solution, 3.2 ml, 3.0 mmol) was added to a
suspension of MnCl2 (12 mg, 10 mol%) in Et2O (10 ml) at
08C under argon atmosphere. After being stirred for 20 min
at 08C, a solution of 6 (0.24 g, 1.0 mmol) in Et2O (2 ml) was
added. The mixture was stirred for 30 min at 08C then for
1 h for 258C. Extractive workup followed by silica-gel
column puri®cation provided 9b. Physical data for 9b
were identical with those reported in literature.15
General procedure for the trapping of an intermediary
alkenylmagnesium
1,1-Diallyl-2-hexylcyclopropane. 1H NMR (CDCl3) d
20.04 (dd, Jˆ4.5, 4.5 Hz, 1H), 0.43 (dd, Jˆ8.7, 4.5 Hz,
1H), 0.53±0.63 (m, 1H), 0.86 (t, Jˆ6.9 Hz, 3H), 1.14±
1.62 (m, 10H), 0.80 (dd, Jˆ13.8, 6.6 Hz, 1H), 0.94 (dd,
Jˆ13.8, 6.6 Hz, 1H), 2.00±2.15 (m, 2H), 4.92±5.06 (m,
4H), 5.66±5.87 (m, 2H). HRMS calcd for C15H26
206.2035, found 206.2036.
Preparation of 11b is representative. A solution of 6 (0.24 g,
1.0 mmol) in Et2O (2 ml) was added to a Et2O solution of
butylmagnesium bromide (3.0 mmol) and MnCl2 (12 mg,
10 mol%) at 08C under argon atmosphere. The resulting
mixture was stirred for 30 min at 08C and then for 1 h at
258C. The mixture was cooled to 08C and allyl bromide
(8.0 mmol) was added. After being stirred for 30 min at
08C, the whole mixture was stirred for 1 h at 258C. Extrac-
tive workup followed by silica-gel column puri®cation
provided 11b in 63% yield.
1-Dimethylphenylsilyl-2-hexylcyclopropane (2/3ˆ79/21).
IR (neat) 3064, 3048, 2952, 2920, 2850, 1458, 1428,
1248, 1113, 1037, 943, 861, 831, 812, 770, 727,
1
698 cm21; H NMR (CDCl3) d 20.54±20.45 (m, 0.79H),
3-Butyl-2H-benzopyran-2-one.16 A suspension of manga-
nese(II) chloride (12 mg, 10 mol%) in Et2O was sonicated
for 10 min under argon atmosphere. Butylmagnesium
bromide (0.91 M, Et2O solution, 3.3 ml, 3.0 mmol) was
added to the resulting suspension of MnCl2 at 08C. The
mixture was stirred for 20 min. A Et2O solution of 6
(1.0 mmol) was added and stirred for 30 min at 08C. The
whole mixture was warmed to 258C and stirred for 1 h. The
mixture was cooled to 2788C and a piece of dry ice was
added at 2788C. The reaction mixture was warmed to 258C
over 30 min. Usual workup and puri®cation by silica-gel
column chromatography afforded 3-butyl-2H-benzopyran-
2-one in 53% yield.
20.26±20.15 (m, 0.21H), 0.14 (s, 2.37H), 0.16 (s, 2.37H),
0.24 (s, 0.63H), 0.27 (s, 0.63H), 0.31±0.44 (m, 2H), 0.58±
0.68 (m, 1H), 0.82±0.91 (m, 3H), 1.10±1.42 (m, 10H),
7.30±7.36 (m, 3H), 7.50±7.59 (m, 2H); 13C NMR
(CDCl3) d 24.04, 23.78, 3.12, 8.91, 14.01, 15.66, 22.57,
29.10, 29.74, 31.86, 35.84, 127.70, 128.84, 133.86, 139.68.
Found: C, 78.20; H, 10.92%. Calcd for C17H28Si: C, 78.38;
H, 10.83%.
The reaction of 2-iodobenzofuran with tributyl-
manganate
A THF (2 ml) solution of 2-iodobenzofuran (6, 0.24 g,
1.0 mmol)14 was added at 08C to a solution of tributyl-
manganate generated from MnCl2 (163 mg, 1.3 mmol) and
butylmagnesium bromide (3.9 mmol). The resulting
mixture was stirred at 08C for 30 min and then at 508C for
2.5 h. The mixture was poured into 1 M HCl and extracted
with ethyl acetate (20 ml£3). The combined organic
layer was dried over Na2SO4 and concentrated in vacuo.
The crude products were puri®ed by silica-gel column
chromatography (hexane/ethyl acetateˆ5/1) to give
References
1. Normant, J. F.; Cahiez, G. In Organomanganous Reagents in
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2. Kitatani, K.; Hiyama, T.; Nozaki, H. J. Am. Chem. Soc. 1976,
98, 2362±2364; Kitatani, K.; Hiyama, T.; Nozaki, H. Bull. Chem.

H. Kakiya et al. / Tetrahedron 56 (2000) 2131±2137
2137
Scheme 7.
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