Regio- and stereoselectivity of ene eeactions: The dimerization of bicyclic 1,3-fused 2-(trimethylsilyl)cycloprop-1-enes

Article abstract of DOI:10.1002/ejoc.200600771

Cycloalkenes proceed through bromination, dehydrobromination and dibromocarbene addition reactions to give tribromocyclopropanes 10 and 11. The treatment of tribromocyclopropanes 10 and 11 with 3 equiv. of methyllithium in diethyl ether at -78°C followed by treatment with trimethylsilyl chloride produce 8-(trimethylsilyl)bicyclo[5.1.0]oct-1(8)-ene (4) and 9-(trimethylsilyl)bicyclo[6.1.0]non-1(9)-ene (5). Both 4 and 5 undergo ene dimerization via the same steric isomer and an endo transition state to generate the stable adducts 6 and 7, respectively, as the sole isomers. Compound 6, containing an unstable bicyclo[5.1.0]oct-1(8)-enyl group and produced in high yields, has been reported to be an unstable species. Both of the ene dimers, (trimethylsilyl)cyclopropenes 6 and 7, can be converted into cyclopropenes 8 and 9 by treatment with a fluoride salt followed by protonation. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejoc.200600771

FULL PAPER
DOI: 10.1002/ejoc.200600771
Regio- and Stereoselectivity of Ene Reactions: The Dimerization of Bicyclic
1,3-Fused 2-(Trimethylsilyl)cycloprop-1-enes
Ko Chou Chen,[a] Wen Chieh Wang,[a] Mei-Yun Chen,[a] Wei-Cheng Chen,[a]
Ming-Chieh Her,[a] and Gon-Ann Lee*[a]
Keywords: Cyclopropene / Regioselectivity / Stereoselectivity / Ene reaction / Dimerization
Cycloalkenes proceed through bromination, dehydrobromi- and 7, respectively, as the sole isomers. Compound 6, con-
nation and dibromocarbene addition reactions to give tribro- taining an unstable bicyclo[5.1.0]oct-1(8)-enyl group and
mocyclopropanes 10 and 11. The treatment of tribromocyclo-
propanes 10 and 11 with 3 equiv. of methyllithium in diethyl
ether at –78 °C followed by treatment with trimethylsilyl
chloride produce 8-(trimethylsilyl)bicyclo[5.1.0]oct-1(8)-ene
(4) and 9-(trimethylsilyl)bicyclo[6.1.0]non-1(9)-ene (5). Both
4 and 5 undergo ene dimerization via the same steric isomer
and an endo transition state to generate the stable adducts 6
produced in high yields, has been reported to be an unstable
species. Both of the ene dimers, (trimethylsilyl)cyclopropenes
6 and 7, can be converted into cyclopropenes 8 and 9 by
treatment with a fluoride salt followed by protonation.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
pene,[8] they undergo ene reactions to give high yields of
ene dimers. Bicyclic 1,3-fused cyclopropenes, bicyclo[n.1.0]-
alk-1(n+3)-enes, are unstable compounds when nϽ6.[9] Al-
though the synthesis and chemistry of 1,3-fused bicyclic cy-
clopropenes are well known,[9,10] only three cyclopropenes,
bicyclo[4.1.0]hept-1(7)-ene (1), 8-chlorobicycloct[5.1.0]oct-
1(8)-ene (2) and bicyclo[5.1.0]oct-1(8)-ene (3), are reported
to undergo ene reactions to give ene dimers (Figure 1).
Compound 1 undergoes an ene reaction to give an unstable
ene dimer (n = 4) which then dimerizes through [2+2] cycli-
zation and/or a coupling reaction to give tetramers. The
regio- and stereochemistry of this ene reaction have been
confirmed by single-crystal X-ray analysis of the tetramers
formed from [2+2] dimerization of an ene dimer.[11] The
regiochemistry of the ene reactions of compound 2 (n = 5)
was assigned based on NMR spectroscopic data, but the
stereochemistry of these reactions remains unknown.[12]
Both of the ene dimers were unstable (n = 5) and isomerized
Introduction
Although the first derivative of cyclopropane was ob-
tained as early as 1881,[1] cyclopropenes continue to fasci-
nate both theoretical and experimental chemists because of
their unique structures, high degree of ring strain and the
difficulties associated with their synthesis.[2] Cyclopropenes
are usually unstable as a result of their high ring-strain en-
ergy and isomerize, dimerize and/or react with other rea-
gents to form a variety of products.[3,4] Therefore, it is very
important to develop methods to control the reactions of
cyclopropenes, to generate high yields of a single product
and to synthesize versatile, stable cyclopropenes to expand
their applications.
When cyclopropenes undergo ene dimerization, the inter-
mediate exo and endo transition states generate different
stereoadducts.[4] Asymmetric cyclopropenes usually un-
dergo ene reactions to form several regio- and stereodi-
mers.[4,5] Therefore, control of the regio- and stereochemis-
try of ene reactions of cyclopropenes is an important issue
in the synthesis of functionalized 3-cyclopropylcycloprope-
nes. The regio- and stereochemistry of ene reactions of sev-
eral substituted cyclopropenes have been reported. When
cyclopropenes contain a trimethylsilyl group, such as 1-
chloro-3-(trimethylsilyl)cyclopropene,[6] 1,2-bis(trimethyl-
silyl)cyclopropene[7] or 1-phenyl-2-(trimethylsilyl)cyclopro-
1
or treated with oxygen at room temperature. Based on H
NMR and mass spectra, Billups and co-worker reported
that compound 3 (n = 5) underwent ene dimerization and
trimerzation, but the regio- and stereochemistry were not
clear.[11]
We wish to report herein that two bicyclic 1,3-fused 2-
(trimethylsilyl)cycloprop-1-enes, 8-(trimethylsilyl)bicyclo-
[5.1.0]oct-1(8)-ene (n = 5) (4) and 9-(trimethylsilyl)bicy-
clo[6.1.0]non-1(9)-ene (n = 6) (5) undergo ene reactions to
form stable 1,3-fused cyclopropenes, (n+3)-trimethylsilyl-
(n+2)-[(n+3)-(trimethylsilyl)bicyclo[n.1.0]alkyl]bicyclo-
[n.1.0]alk-1(n+3)-enes [n = 5 (6) and 6 (7)] as the sole prod-
ucts. The regio- and stereochemistry of these ene reactions
have been confirmed by single-crystal X-ray analysis of (tri-
[a] Department of Chemistry, Fu Jen Catholic University,
Hsinchuang, Taipei 24205, Taiwan, Republic of China
E-mail: chem1010@mails.fju.edu.tw
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
Eur. J. Org. Chem. 2007, 953–958
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
953

G.-A. Lee et al.
FULL PAPER
methylsilyl)cyclopropenes 6 and 7 and these two (trimethyl-
silyl)cyclopropenes can be converted into cyclopropenes 8
and 9.
Figure 1. Ene dimerizations of bicyclo[4.1.0]hept-1(7)-ene (1), 8-
chlorobicyclo[5.1.0]oct-1(8)-ene (2), and bicyclo[5.1.0]oct-1(8)-ene
(3).
Results and Discussion
We previously reported an easier synthesis of the 2-sub-
stituted bicyclic 1,3-fused cyclopropenes, 8-substituted bicy-
clo[5.1.0]oct-1(8)-ene, using 1,8,8-tribromobicyclo[5.1.0]-
octane (10).[13] Compound 10 was generated from cyclohep-
tene. The cycloalkene reacted by bromination, dehydrobro-
Scheme 1.
After compound 4 had been synthesized and purified at
mination and dibromocarbene addition to give tribromocy- low temperature, it was kept neat at room temperature for
clopropane 10 (Scheme 1). Treatment of tribromocyclopro- 1 day and a sole stable product 6 (Scheme 1) was isolated
pane 10 with 3 equiv. of methyllithium in diethyl ether at in 92% yield. According to spectral analysis (MS: m/z =
–78 °C generated cyclopropenyl anion 12, which was treated 360; 13C NMR: δ = 145.4 and 114.4 ppm; IR: ν =
˜
with trimethylsilyl chloride to produce 4.[13] Cyclopropene 4 1772 cm–1), compound 6, with a dimeric mass and a cyclo-
was trapped with cyclopentadiene to give the corresponding propenyl group, is an ene dimer of 4.
[4+2] cycloadduct 14.[13] The higher analogue, compound
In principle, four regioisomers, two 1,3- and two 1,2-
5, was synthesized by the same procedure and also trapped fused cyclopropenes, can be generated when compounds 4
with cyclopentadiene (Scheme 1).
and 5 undergo ene dimerizaton (Figure 2).
Figure 2. Regiochemistry of ene dimerization reactions of 4 and 5.
954
www.eurjoc.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 953–958

Regio- and Stereoselectivity of Ene Reactions
FULL PAPER
Furthermore, theoretical calculations have shown that (5.8 kcal/mol) and 9-(trimethylsilyl)bicyclo[6.1.0]non-1(8)-
the heats of formation of the bicyclic 1,3-fused cyclo- ene (–1.4 kcal/mol).[14] These results suggest that only com-
propenes, 8-trimethylbicyclo[5.1.0]oct-1(8)-ene (4) (1.9 kcal/ pound 4 can form 1,3-fused ene dimers when they undergo
mol) and 9-(trimethylsilyl)bicyclo[6.1.0]non-1(9)-ene (5) ene dimerization reactions. There are four stereoisomers,
(–5.6 kcal/mol), are lower than those of the bicyclic 1,2- RR exo, RR endo, SR exo and SR endo adducts, that can
fused cyclopropenes, 1-trimethylbicyclo[5.1.0]oct-1(7)-ene be produced for each dimerization reaction (Figure 3).
Figure 3. Transition states of ene dimerization reactions of 4 in the formation of the 1,3-fused bicyclic cyclopropenes and the heats of
formation of these adducts.
Eur. J. Org. Chem. 2007, 953–958
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
955

G.-A. Lee et al.
FULL PAPER
According to the PM3 theoretical calculations, the heats
of formation of the 1,3-fused ene dimers of compound 4,
type-A RR endo, SR endo, RR exo, SR exo and type-B RR
endo, SR endo, RR exo, SR exo, are –33.9, –21.6, –10.7,
–29.6 and –24.3, –29.2, –24.3, –24.0 kcal/mol, respec-
tively.[14] Based on these results, compound 6 may be a type-
A RR endo adduct. Although compound 6 contains a 1,3-
fused bicyclo[5.1.0]oct-1(8)-enyl group, which is reported to
be an unstable species, it is stable at room temperature and
its structure was determined by single-crystal X-ray analysis
(Figure 4). Thus, compound 6 is formed from the same ste-
ric compound 4 via an endo transition state. Compound 4
dimerizes within one day at room temperature, but the 7-
substituted derivative 6 is stable as a result of the bulky
group that protects the active cyclopropenyl site.
Figure 5. The X-ray crystal structure of 7.
Figure 4. The X-ray crystal structure of 6.
Scheme 2.
The higher analogue, compound 5, was also synthesized
and isolated at room temperature and was then stirred at
50 °C for two weeks: product 7 was isolated as the sole
stable product in 90% yield. According to its spectra (MS:
stable sole adducts in which one of the two adducts con-
tains an unstable bicyclo[5.1.0]oct-1(8)-enyl group. Both of
the ene dimers, (trimethylsilyl)cyclopropenes 6 and 7, can
be converted into cyclopropenes 8 and 9 by treatment with
a fluoride salt and subsequent protonation gives 8 and 9.
m/z = 388; 13C NMR: δ = 145.9 and 118.1 ppm; IR: ν =
˜
1758 cm–1), compound 7, with a dimeric mass and cyclo-
propenyl group, is an ene dimer of 5. The structure of 7
was determined by single-crystal X-ray analysis (Figure 5).
Compound 7 was also formed from the same steric isomer
of 5 via an endo transition state.
Experimental Section
Treatment of ene dimers 6 and 7 with a fluoride salt gen-
erated the cyclopropenyl anions 16 and 17, which reacted
further with water to produce (n+2)-[(n+3)-(trimethylsilyl)-
bicyclo[n.1.0]alkyl]bicyclo[n.1.0]alk-1(n+3)-enes [n = 5 (8)
and 6 (9)] (Scheme 2). The selectivity of the desilylation re-
action of the ene dimers is based on the stability of the
carbanion. Because a carbanion at an sp2 carbon atom is
more stable than at an sp3 carbon atom, F– only reacts with
the trimethylsilyl group of the cyclopropenyl moiety to gen-
erate sp2 carbanions 16 and 17.
General: All solvents were dried using standard methods. Deuter-
iated solvents were used to collect 1H and 13C NMR spectra.
HRMS data were obtained with a JEOL JEM-200CX instrument.
Infrared spectra were obtained with a Perkin–Elmer 1600 instru-
ment. X-ray data for compounds were recorded with a Kappa CCD
diffractometer. Calculations were performed with the HyperChem
Molecular Modeling System for Windows, Version 6.03 (geometry
optimization, semi-empirical, PM3). Silica gel for column
chromatography (70–230 mesh) and flash chromatography
(230 mesh) was obtained from E. Merck. Purity of solvents: reagent
grade.
In summary, the trimethylsilyl group has been used to
control the cyclopropene ene dimerization reaction via the
1,8,8-Tribromobicyclo[5.1.0]octane (10): 1-Bromocycloheptene was
same steric isomer and an endo transition state to generate synthesized from cycloheptanol, essentially by the procedure re-
956 Eur. J. Org. Chem. 2007, 953–958
www.eurjoc.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Regio- and Stereoselectivity of Ene Reactions
FULL PAPER
ported by HaltonЈs group but with minor modifications.[15] A sus-
pension of 1-bromocycloheptene (10.0 g, 57.1 mmol) and bromo-
form (15 mL), 50% sodium hydroxide (15 mL) and tetra-n-butyl-
ammonium bromide (0.1 g) were placed in a 100 mL flask. The
mixture was stirred for 24 h at room temperature and dichloro-
methane (25 mL) and water (30 mL) were then added. The water
layer was extracted with dichloromethane (3ϫ25 mL). The com-
bined organic phases were washed with water and brine and dried
with anhydrous magnesium sulfate. Filtration and distillation gave
10 as a yellow liquid (81 °C, 1.5 Torr, 13.9 g, 70%). All spectro-
scopic data for compound 10 are in agreement with literature val-
ues.[13]
(CH), 37.7 (CH), 34.2 (C), 29.9 (CH2), 28.9 (CH2), 28.1 (CH2),
26.7 (CH2), 26.5 (CH2), 25.9 (CH2), 14.6 (C), 0.9 (CH3) ppm. MS:
m/z (%) = 260 (34) [M]+. HRMS: calcd. for C17H28Si 260.1960;
found 260.1956. C17H28Si (260.49): calcd. C 78.38, H 10.83; found
C 78.25, H 10.14.
Compound 5: 1H NMR (300 MHz, CDCl3): δ = 2.77–2.69 (m, 1 H,
CH2), 2.43–2.30 (m, 1 H, CH2), 1.95–1.82 (m, 1 H, CH2), 1.73–
1.03 (m, 10 H, CH2, CH), 0.15 (s, 9 H, CH3) ppm. 13C NMR
(75 MHz, CDCl3): δ = 141.4 (C), 110.3 (C), 33.4 (CH2), 30.1 (CH2),
28.4 (CH2), 26.0 (CH2), 25.6 (CH2), 20.6 (CH2), 18.4 (CH), –0.8
(CH3) ppm.
8-(Trimethylsilyl)-1-[8-(trimethylsilyl)bicyclo[5.1.0]octan-1-yl]bicy-
clo[5.1.0]oct-7-ene (6): Methyllithium (58 mL, 1.5 ) in diethyl
ether was added to a solution of 1,8,8-tribromobicyclo[5.1.0]octane
(10)[15] (10.0 g, 28.82 mmol) in dry diethyl ether (20.0 mL) at
–78 °C over 30 min and trimethylsilyl chloride (5.5 mL,
43.23 mmol) was then added. The mixture was stirred for 1 h and
then warmed to room temperature and stirred for 8 h. Water was
added and the solution was extracted with diethyl ether
(3ϫ25 mL). The ether phase was dried, concentrated and purified
by chromatography (hexanes) to give 8-(trimethylsilyl)bicyclo-
[5.1.0]oct-1(8)-ene (4). Compound 4 was degassed and kept at room
temperature. After 1 d, the mixture was purified by chromatog-
raphy (hexanes) and recrystallization to give compound 6 as a
1,9,9-Tribromobicyclo[6.1.0]nonane (11): A modification of a pre-
viously reported procedure was used.[16] A mixture of 1-bromocy-
clononene (18.9 g, 100 mmol) and bromoform (26 mL), 50% so-
dium hydroxide (26 mL) and tetra-n-butylammonium bromide
(0.1 g) were placed in a 100 mL flask. The mixture was stirred un-
der reflux for 12 h and dichloromethane (25 mL) and water
(30 mL) were then added. The aqueous phase was extracted with
dichloromethane (3ϫ25 mL). The combined organic phases were
washed with water and brine and dried with anhydrous magnesium
sulfate. Filtration and distillation gave compound 11 as a yellow
liquid (70 °C, 0.2 Torr, 19.0 g, 53%). IR (neat): ν = 2924, 2854,
˜
1461, 1445, 1139, 899, 833, 773, 719, 563 cm–1. 1H NMR
1
(300 MHz, CDCl3): δ = 2.31–2.18 (m, 1 H, CH), 2.14–2.03 (dq, J
white solid (4.8 g, 92%). M.p. 53–54 °C. IR (neat): ν = 2958, 2916,
˜
= 4, 14 Hz, 1 H, CH2), 1.86–1.50 (m, 9 H, CH2), 1.39–1.14 (m, 2
H, CH2) ppm. 13C NMR (75 MHz, CDCl3): δ = 49.6 (C), 43.7
(CH), 41.5 (C), 35.1 (CH2), 28.2 (CH2), 27.2 (CH2), 27.1 (CH2),
25.8 (CH2), 25.5 (CH2) ppm. MS: m/z (%) = 364 (0.2) [M + 6]+,
358 (0.2) [M]+, 119 (100). HRMS: calcd. for C9H13Br3 357.8567;
found 357.8570. C9H13Br3 (360.91): calcd. C 29.95, H 3.63; found
C 30.05, H 3.63.
2848, 1772, 1461, 1444, 1414, 1245, 1049, 989, 835, 757, 627 cm–1.
1H NMR (300 MHz, CDCl3): δ = 2.78–2.73 (m, 1 H, CH2), 2.32–
2.22 (dt, 1J = 6, 18 Hz, 2 H, CH2), 1.97–1.89 (m, 2 H, CH2), 1.86–
1.70 (m, 5 H, CH2), 1.65–1.60 (m, 2 H, CH2, CH), 1.25–1.16 (m,
1
1 H, CH2), 1.11–0.98 (m, 4 H, CH2), 0.95–0.81 (d, J = 10 Hz, 2
H, CH2), 0.72–0.56 (m, 2 H, CH2), 0.16 (s, 9 H, CH3), 0.09 (s, 9
H, CH3), –0.45 (d, 1J = 10 Hz, 1 H, CH) ppm. 13C NMR (75 MHz,
CDCl3): δ = 145.4 (C), 114.4 (C), 39.3 (C), 37.2 (CH2), 34.6 (CH2),
32.6 (CH2), 31.2 (CH2), 29.9 (CH2), 29.6 (CH), 29.5 (CH2), 29.4
(CH2), 27.2 (CH2), 26.7 (CH2), 26.6 (CH2), 23.1 (CH), 1.9 (CH3),
–0.2 (CH3) ppm. MS: m/z (%) = 360 (23) [M]+. HRMS: calcd. for
C22H40Si2 360.2669; found 360.2677. C22H40Si2 (360.72): calcd. C
73.25, H 11.18; found C 72.97, H 11.16.
Trapping of 8-(Trimethylsilyl)bicyclo[5.1.0]oct-1(8)-ene (4) with Cy-
clopentadiene: Methyllithium (6.1 mL, 1.5 ) in diethyl ether was
added to a solution of compound 10 (1.06 g, 3.05 mmol) in dry
diethyl ether (5 mL) at –78 °C over 30 min and trimethylsilyl chlo-
ride (0.58 mL, 4.58 mmol) was then added. The mixture was stirred
for 1 h and cyclopentadiene (10 mL) was added. The mixture was
then warmed to –40 °C and stirred for 6 h. Water was added and
mixture was extracted with diethyl ether (3ϫ25 mL). The ether
phase was dried, concentrated and the residue purified by
chromatography to give 14 as a yellow liquid (0.51 g, 68%). All
spectroscopic data for compound 14 are in agreement with litera-
ture values.[13]
9-(Trimethylsilyl)-1-[9-(trimethylsilyl)bicyclo[6.1.0]nonan-1-yl]bicy-
clo[6.1.0]non-8-ene (7): Methyllithium (100.0 mL, 1.5 ) in diethyl
ether was added to a solution of 1,9,9-tribromobicyclo[6.1.0]
nonane (11) (18.0 g, 50 mmol) in dry diethyl ether (100.0 mL) at
–78 °C over 1 h and trimethylsilyl chloride (9.6 mL, 75 mmol) was
then added. The mixture was stirred at –40 °C for 1 h, then warmed
to room temperature. Water was added and the solution was ex-
tracted with diethyl ether (3ϫ25 mL). The ethereal solution was
dried, concentrated and purified by chromatography (hexanes) to
give 9-(trimethylsilyl)bicyclo[6.1.0]non-1(9)-ene (5). Compound 5
was degassed and kept at 50 °C. After 14 d, the mixture was puri-
fied by chromatography (hexanes) and recrystallization to give 7 as
Trapping of 9-(Trimethylsilyl)bicyclo[6.1.0]non-1(9)-ene (5) with Cy-
clopentadiene: Methyllithium (100.0 mL, 1.5 ) in diethyl ether was
added to a solution of compound 11 (18.0 g, 50 mmol) in dry di-
ethyl ether (100.0 mL) at –78 °C over 1 h and trimethylsilyl chloride
(9.6 mL, 75 mmol) was then added. The mixture was stirred for
1 h and cyclopentadiene (30 mL) was added. The mixture was then
warmed to room temperature and stirred for 12 h. Water was added
and the mixture was extracted with diethyl ether (3ϫ25 mL). The
ether phase was dried, concentrated and the residue purified by
chromatography to give 15 as a yellow liquid (11.07 g, 85%). Com-
a white solid (8.74 g, 90%). M.p. 70–71 °C. IR (neat): ν = 2924,
˜
2851, 1758, 1455, 1245, 874, 836, 753 cm–1. 1H NMR (CDCl3): δ
1
1
= 2.74–2.64 (ddd, J = 4, 5, 10 Hz, 1 H, CH2), 2.42–2.30 (ddd, J
= 5, 11, 14 Hz, 1 H, CH2), 2.25–2.15 (m, 1 H, CH2), 2.10–2.00 (dd,
1J = 8, 14 Hz, 1 H, CH2), 1.85–1.67 (m, 2 H, CH2, CH), 1.47–1.31
pound 15: IR (neat): ν = 3056, 2953, 2917, 2856, 1644, 1565, 1449,
˜
1246, 886, 843, 738 cm–1. H NMR (300 MHz, CDCl3): δ = 5.87– (m, 9 H, CH2), 1.29–1.21 (m, 3 H, CH2), 1.20–1.05 (m, 5 H, CH2),
1
5.83 (dd, 1J = 3, 6 Hz, 1 H, CH), 5.67–5.64 (dd, J = 3, 6 Hz, 1 H, 0.78–0.63 (m, 1 H, CH2), 0.50–0.39 (m, 1 H, CH2), 0.18 (s, 9 H,
1
CH), 2.74–2.70 (m, 1 H, CH), 2.62–2.58 (m, 1 H, CH), 1.87–1.79 CH3), 0.08 (s, 9 H, CH3), –0.43 (d, 1J = 10 Hz, 1 H, CH) ppm. 13
C
(dt, 1J = 4, 14 Hz, 1 H, CH2), 1.74–1.64 (m, 2 H, CH2, CH), 1.61–
NMR (CDCl3): δ = 145.9 (C), 118.1 (C), 37.2 (C), 35.0 (C), 34.4
1.39 (m, 6 H, CH2), 1.35–1.15 (m, 5 H, CH2), 0.44–0.36 (d, J = (CH2), 31.0 (CH2), 29.5 (CH2), 28.8 (CH2), 28.7 (CH2), 27.7 (CH2),
1
11 Hz, 1 H, CH), 0.10 (s, 9 H, CH3) ppm. 13C NMR (75 MHz,
27.4 (CH), 26.6 (CH2), 26.4 (CH2), 26.2 (CH2), 25.5 (CH2), 20.4
CDCl3): δ = 131.2 (CH), 130.8 (CH), 59.4 (CH2), 48.3 (CH), 46.8
(CH2), 18.0 (CH), 1.9 (CH3), 0.3 (CH3) ppm. MS: m/z (%) = 388
Eur. J. Org. Chem. 2007, 953–958
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
957

G.-A. Lee et al.
FULL PAPER
(8) [M]+, 73 (100). HRMS: calcd. for C24H44Si2 388.2982; found
388.2978. C24H44Si2 (388.78): calcd. C 74.14, H 11.41; found C
74.11, H 11.30.
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
[1-(Bicyclo[5.1.0]oct-7-en-1-yl)bicyclo[5.1.0]octan-8-yl]trimethyl-
silane (8): nBu4NF (8.3 mL, 1.0 ) in tetrahydrofuran was added
to solution of 8-(trimethylsilyl)-1-[8-(trimethylsilyl)bicyclo[5.1.0]-
octan-1-yl]bicyclo[5.1.0]oct-7-ene (6) (1.0 g, 2.77 mmol) in tetra-
hydrofuran (5 mL). The mixture was stirred for 4 d at room tem-
perature. Water was added and the solution was extracted with di-
ethyl ether (3ϫ25 mL). The ether phase was dried, concentrated
and purified by chromatography (hexanes) to give compound 8 as
Financial support from the National Science Council of the Repub-
lic of China (NSC 94-2113-M-030-006) is gratefully acknowledged.
[1] W. Markownikoff, A. Krestownikoff, Justus Liebigs Ann.
Chem. 1881, 208, 334.
[2] B. Halton, M. B. Banwell, “Cyclopropenes” in The Chemistry
of the Cyclopropyl Group (Ed.: Z. Rappoport), Wiley, New
York, 1987, chapter 21.
a yellow liquid (0.73 g, 91%). IR (neat): ν = 2958, 2916, 2848, 1772,
˜
1461, 1444, 1414, 1245, 1049, 989, 757, 627 cm–1 1H NMR
.
[3] a) A. E. Sheshenev, M. S. Baird, A. K. Corft, I. G. Bolesov,
Mendeleev Commun. 2004, 6, 299; b) W. R. Dolbier Jr, M. A.
Battiste, Chem. Rev. 2003, 103, 1071; c) G.-A. Lee, C.-H.
Cherng, A. N. Huang, Y.-H. Lin, Tetrahedron 2003, 59, 1539;
d) A. D. Meijere, D. Feber, U. Heinecke, R. Walsh, T. Muller,
Y. Apleoig, Eur. J. Org. Chem. 2001, 4, 663; e) W. E. Billups,
W. Luo, G.-A. Lee, J. Chee, B. E. Arney Jr, K. B. Wiberg, D. R.
Artis, J. Org. Chem. 1996, 61, 764; f) G.-A. Lee, P.-K. Chen,
M.-Y. Chen, J. Chin. Chem. Soc. 1996, 43, 297; g) M. G.
Banwell, M. Corbett, J. Gulbis, M. F. Mackay, M. E. Reum, J.
Chem. Soc., Perkin Trans. 1 1993, 945; h) A. Padwa, M. W.
Wannamaker, Tetrahedron 1991, 47, 6139; i) A. Padwa, D. M.
Cordova, M. J. Pulwer, J. Org. Chem. 1991, 56, 4747; j) K. B.
Wiberg, D. R. Artis, G. Bonneville, J. Am. Chem. Soc. 1991,
113, 7969; k) H. R. Parker, W. M. Jones, Tetrahedron Lett.
1984, 25, 1245; l) K. B. Wiberg, G. Bonneville, Tetrahedron
Lett. 1982, 23, 5385.
[4] a) G.-A. Lee, C.-Y. Chang, J. Org. Chem. 2004, 69, 8949; b) Q.
Deng, B. E. Thomas IV, K. N. Houk, P. Dowd, J. Am. Chem.
Soc. 1997, 119, 6902.
[5] a) A. E. Sheshenev, M. S. Baird, A. K. Croft, Z. A. Starikova,
A. S. Shashkov, A. L. Zhuze, I. G. Bolesov, Tetrahedron Lett.
2006, 47, 2839; b) P. J. Garratt, A. Tostinis, J. Org. Chem. 1990,
55, 84; c) M. S. Baird, H. H. Hussein, W. Clegg, J. Chem. Res.
(M) 1988, 4, 1101; d) K. Komatsu, T. Niwa, H. Akari, K.
Okamoto, J. Chem. Res. (M) 1985, 8, 2847.
(300 MHz, CDCl3): δ = 6.41 (s, 1 H, CH), 2.75–2.65 (m, 1 H, CH2),
2.36–2.15 (m, 2 H, CH2), 2.02–1.89 (m, 2 H, CH2), 1.87–1.73 (m,
3 H, CH2), 1.71–1.52 (m, 5 H, CH2, CH), 1.29–1.03 (m, 5 H, CH2),
1.00–0.87 (m, 1 H, CH2), 0.86–0.65 (m, 2 H, CH2), 0.12 (s, 9 H,
1
CH3), –0.40 (d, J = 10 Hz, 1 H, CH) ppm. 13C NMR (75 MHz,
CDCl3): δ = 128.1 (C), 104.7 (CH), 39.3 (CH), 37.1 (C), 32.7 (C),
31.8 (CH2), 31.0 (CH2), 29.9 (CH2), 29.8 (CH2), 29.6 (CH2), 29.6
(CH2), 29.4 (CH3), 27.1 (CH2), 25.3 (CH2), 23.0 (CH3), 1.9
(CH) ppm. MS: m/z (%) = 288 (9) [M]+. HRMS: calcd. for
C
19H32Si 288.2273; found 288.2279. C19H32Si (288.54): calcd. C
79.09, H 11.18; found C 78.87, H 11.05.
(1-(Bicyclo[6.1.0]non-8-en-1-yl)bicyclo[6.1.0]nonan-9-yl)trimethyl-
silane (9): nBu4NF (4.6 mL, 1.0 ) in tetrahydrofuran was added
to a solution of 9-(trimethylsilyl)-1-[9-(trimethylsilyl)bicyclo[6.1.0]-
nonan-1-yl]bicyclo[6.1.0]non-8-ene (7) (0.6 g, 1.54 mmol) in tetra-
hydrofuran (5 mL). The mixture was stirred for 2 d at room tem-
perature. Water was added and the solution was extracted with di-
ethyl ether (3ϫ25 mL). The solution was dried, concentrated and
purified by chromatography (hexanes) to give 9 as a white powder
(0.41 g, 84%). M.p. 47.2–48.3 °C. IR (neat): ν = 2919, 2847, 2689,
˜
1926, 1760, 1468, 1453, 1245, 1033, 965, 885, 833, 754, 723,
1
686 cm–1. H NMR (CDCl3): δ = 6.55 (s, 1 H, CH), 2.67–2.58 (m,
1J = 5, 14 Hz, 1 H, CH2), 2.31–2.21 (m, 1 H, CH2), 2.19–2.11 (dt,
1J = 4, 14 Hz,1 H, CH2), 2.03–1.95 (dd, 1J = 9, 14 Hz, 1 H, CH2),
1.85–1.80 (m, 1 H, CH2), 1.74–1.60 (m, 3 H, CH2, CH), 1.55–1.51
[6] G.-A. Lee, C.-S. Chen, Tetrahedron Lett. 1997, 38, 8717.
[7] J. G. Peter, A. Tsotinis, J. Org. Chem. 1990, 55, 84.
[8] G.-A. Lee, C.-Y. Chang, Tetrahedron Lett. 1998, 39, 3013.
[9] W. E. Billups, M. M. Haley, G.-A. Lee, Chem. Rev. 1989, 89,
1147.
[10] a) G.-A. Lee, C.-Y. Chang, C.-H. Cherng, C.-S. Chen, M. Liu,
J. Chin. Chem. Soc. 2004, 51, 839; b) T. J. Stierman, R. P. John-
son, J. Am. Chem. Soc. 1985, 107, 3971; c) M. S. Baird, W.
Nethercott, Tetrahedron Lett. 1983, 24, 605.
1
(d, J = 11 Hz,1 H, CH2), 1.50–1.38 (m, 5 H, CH2), 1.36–1.24 (m,
3 H, CH2), 1.24–1.16 (m, 1 H, CH2), 1.15–1.07 (m, 2 H, CH2),
1.04–0.97 (m, 2 H, CH2), 0.96–0.81 (m, 2 H, CH2), 0.53–0.42 (dd,
1
1J = 4, 10 Hz, 1 H, CH2), 0.10 (s, 9 H, CH3), –0.4 (d, J = 10 Hz,
1 H, CH) ppm. 13C NMR (CDCl3): δ = 125.9 (C), 107.8 (CH), 36.8
(C), 33.6 (CH2), 31.1 (CH2), 30.9 (C), 30.0 (C), 28.2 (CH2), 27.4
(CH2), 27.3 (CH2), 27.2 (CH), 26.8 (CH2), 26.5 (CH2), 26.5 (CH2),
25.2 (CH2), 20.1 (CH2), 17.5 (CH), 1.9 (CH3) ppm. MS: m/z (%) =
316.6 (4) [M]+. HRMS: calcd. for C21H36Si 316.2586; found
316.2581. C21H36Si (316.6): calcd. C 79.67, H 11.46; found C 79.65,
H 11.40.
[11] W. E. Billups, G.-A. Lee, B. E. Arney Jr, K. H. Whitmire, J.
Am. Chem. Soc. 1991, 113, 7980.
[12] G.-A. Lee, C.-S. Shiau, C.-S. Chen, J. Chen, J. Org. Chem.
1995, 60, 3565.
[13] G.-A. Lee, P.-K. Chen, M.-Y. Chen, J. Chin. Chem. Soc. 1998,
45, 381.
[14] Using HyperChem, Single Point, SemiEmpirical, molecule,
PM3, convergence limit: 0.001, RHF calculation: singlet state
calculation.
Supporting Information (see also the footnote on the first page of
this article): X-ray crystallographic data for compounds 6 and 7
and NMR spectra of compounds 5–9, 11 and 15.
[15] B. R. Dent, B. Halton, A. M. F. Smith, Aust. J. Chem. 1986,
39, 1621.
[16] G. E. Gream, M. Mular, Aust. J. Chem. 1975, 28, 2227.
Received: September 4, 2006
CCDC-249717 (for 6) and -249716 (for 7) contain the supplemen-
tary crystallographic data for this paper. These data can be ob-
Published Online: December 19, 2006
958
www.eurjoc.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 953–958