Synthesis of 2,3-disubstituted norbornadienes

Article abstract of DOI:10.1139/v00-047

Various 2,3-disubstituted norbornadienes that can hardly be made by the traditional Diels-Alder method were synthesized by double lithium halide exchange of 2,3-dibromonorbornadiene in moderate to good yields.

Full text of DOI:10.1139/v00-047

527
Synthesis of 2,3-disubstituted norbornadienes
Geoffrey K. Tranmer, Carol Yip, Sean Handerson, Robert W. Jordan,
and William Tam
Abstract: Various 2,3-disubstituted norbornadienes that can hardly be made by the traditional Diels–Alder method were
synthesized by double lithium halide exchange of 2,3-dibromonorbornadiene in moderate to good yields.
Key words: 2,3-disubstituted norbornadienes, Diels–Alder reaction, lithium halide exchange.
Résumé: Faisant appel à un double échange de lithium/halogénure sur le 2,3-dibromonorbornadiène, on a réalisé la
synthèse, avec des rendements allant de modérés à bons, de divers norbornadiènes 2,3-disubstitués qui peuvent à peine
être fabriqués par la méthode traditionnelle de Diels–Alder.
Mots clés: norbornadiènes 2,3-disubstitués, réaction de Diels–Alder, échange lithium halogénure. Tranmer et al.
535
Introduction
Results and discussion
During our study of the effect of a C-3 substituent on
regio- and stereoselectivity in the intramolecular 1,3-dipolar
cycloaddition of norbornadiene-tethered nitrile oxides
(Scheme 1) (1), we came across a problem for the synthesis
of the 2,3-disubstituted norbornadienes (1). Most of the liter-
ature syntheses of 2,3-disubstituted norbornadienes rely on
Diels–Alder reactions between cyclopentadiene and highly
activated acetylenes (2–6). Less activated or unactivated
acetylenes are poor dienophiles in Diels–Alder reactions,
thus limiting the substituents on the norbornadiene ring sys-
tem to electron-withdrawing groups. In this paper, we report
a more general and simple procedure for the synthesis of
2,3-disubstituted norbornadienes 8 and 9 with a variety of
substituents (E1 and E2) (Scheme 2).
2,3-Disubstituted norbornadienes are important compounds,
which have found a place as key intermediates in the synthe-
sis of many natural products, such as prostaglandin endo-
peroxides PGH2 and PGG2 (7), cis-trikentrin B (8), and
β-santalol (9, 10). 2,3-Disubstituted norbornadienes also
serve in the reversible photoinduced isomerization of nor-
bornadiene derivatives into the corresponding quadricyclanes
(11–14). Extensive investigation of 2,3-disubstituted nor-
bornadienes–quadricyclanes interconversion for solar energy
storage has demonstrated the efficiency and switching poten-
tial of these reversible systems (15–17).
Schlosser and co-workers (18) and Brandsma and co-worker
(19) have shown independently that deprotonation of a vinyl
hydrogen of norbornadiene 6 can be achieved by the use of
Schlosser’s base, a mixture of n-butyllithium (nBuLi) and
t
potassium or sodium tert-butoxide (tBuOK or BuONa).
Trapping of the metalated norbornadiene 10 with electro-
philes leads to the formation of 2-substituted norbornadienes
(11) (Scheme 3). This method has been used in the synthesis
of 2,3-dibromonorbornadiene (7) (20). We have modified the
procedure to achieve a more reliable large-scale (10–20g scale)
synthesis of 2,3-dibromonorbornadiene (7) (Scheme 4). Af-
ter deprotonation of norbornadiene with Schlosser’s base,
1,2-dibromoethane (0.5 equiv) was added to the norbor-
nadienyl potassium (10) at –78°C, and the reaction mixture
was stirred at –40°C for 1.5 h. At this point, 0.5 equiv. of 2-
bromonorbornadiene (12) would have been formed together
with the remaining 0.5 equiv. of norbornadienyl potassium
(10). We found that the temperature control is very impor-
tant at this stage. If the temperature was too low or too high,
the yield of the reaction was very poor. The Br in 12 en-
hances the acidity of its adjacent vinyl hydrogen, and the
leftover norbornadienyl potassium (10) is basic enough to
remove that proton to generate 13. Trapping of 13 with ex-
cess 1,2-dibromoethane leads to the formation of 2,3-
dibromonorbornadiene (7).
Monolithium-halide exchange of the 2,3-dibromonorbor-
t
nadiene (7) with BuLi (2 equiv) produces 2-bromo-3-lithio-
norbornadiene (14). Trapping of this organolithium with water
(Table 1, entry 1) gave 8a, and trapping with alkyl halides
(entries 2–5) and benzyl bromide (entry 6) afforded the cor-
responding 2,3-disubstituted norbornadienes (8b–8f) in mod-
erate to good yields. The disubstituted analogs 8d and 8e
have been used in the synthesis of C-2, C-3-disubstituted
norbornadiene-tethered nitrile oxides 1 (Scheme 1) in our
studies of intramolecular 1,3-dipolar cycloadditions (1). We
prepared 2,3-disubstituted norbornadienes with heteroatoms
(Si, Cl, I, and Sn) by trapping the 2-bromo-3-lithionorborna-
diene (14) with silyl chlorides (entries 7 and 8), tosyl
chloride (entry 9), iodine (entry 10), and tributyltin chloride
Received December 8, 1999. Published on the NRC Research
Press website on April 19, 2000.
G.K. Tranmer, C. Yip, S. Handerson, R.W. Jordan, and
W. Tam.1 Guelph-Waterloo Centre for Graduate Work in
Chemistry and Biochemistry, Department of Chemistry and
Biochemistry, University of Guelph, Guelph, ON N1G 2W1,
Canada.
1Author to whom correspondence may be addressed.
Telephone: (519) 824-4120, ext. 2268. Fax: (519) 766-1499.
e-mail: tam@chembio.uoguelph.ca
Can. J. Chem. 78: 527–535 (2000)
© 2000 NRC Canada

528
Can. J. Chem. Vol. 78, 2000
Scheme 1.
Scheme 2.
(entry 11). In reacting with the intermediate 2-bromo-3-
lithionorbornadiene (14), ethyl chloroformate (entry 12) pro-
vided the corresponding ester 8l, aldehydes (entries 13 and
14) afforded secondary alcohols 8m and 8n, and ketones
(entries 15 and 16) gave tertiary alcohols 8o and 8p. In all
these cases, we saw no evidence for the intermediacy of
norbornenyne (15) (21) (Scheme 5).
Scheme 3.
A second lithium halide exchange of bromide 8b followed
by trapping with 1-bromohexane (Table 2, entry 1), 1,4-
dibromobutane (entry 2), trimethylsilyl chloride (entry 3),
tosyl chloride (entry 4), iodine (entry 5), ethyl chloroformate
(entry 6), and acetone (entry 7) provided in moderate to
good yields a broad range of 2,3-disubstituted norborna-
dienes (9a–9g) with various functional groups. Trapping of
bromides 8c and 8d with 1,4-dibromobutane (entry 8) and
methyl chloroformate (entry 9), respectively, led to the for-
mation of 2,3-disubstituted norbornadienes 9h and 9i, which
are precursors of the norbornadiene-tethered nitrile oxides in
our studies of 1,3-dipolar cycloadditions (1).
mesh silica gel (obtained from Silicycle) by use of flash col-
umn chromatography techniques (27). Analytical thin-layer
chromatography (TLC) was conducted on Merck precoated
silica gel 60 F254 plates. All glassware was flame dried un-
der an inert atmosphere of dry nitrogen. Infrared spectra
were taken on a Bomem MB-100 FTIR spectrophotometer.
1H and 13C NMR spectra were recorded on a Varian Gem-
ini-200 or a Bruker-400 spectrometer. Chemical shifts for
1H NMR spectra are reported in parts per million (ppm)
from tetramethylsilane with the solvent resonance as the in-
ternal standard (deuterochloroform: δ 7.26). Chemical shifts
for 13C NMR spectra are reported in parts per million (ppm)
from tetramethylsilane with the solvent as the internal stan-
dard (deuterochloroform: δ 77.0). High resolution mass spec-
tra were done by Mass Spectrometry Laboratory Services
Division at the University of Guelph. Elemental analyses
were performed by Canadian Microanalytical Service Ltd.,
British Columbia or by Quantitative Technologies Inc., New
Jersey.
In conclusion, we have developed a simple and convenient
access to a variety of 2,3-disubstituted norbornadienes that
can hardly be prepared by traditional Diels–Alder methodol-
ogy. Analogs 8a–8p are very useful precursors for the syn-
thesis of many other 2,3-disubstituted norbornadienes.
Obviously, instead of the second lithium halide exchange as
discussed above to provide 2,3-disubstituted norbornadienes
such as 9a–9i, one could presumably couple the bromides 8
with organotin compounds (for the Stille coupling see
refs. (22) and (23)), with organoboron compounds (for the
Suzuki coupling see ref. (24)), with alkenes (for the Heck re-
action see ref. (25)), and with 1-alkynes (for the Castro–
Stephens–Sonogashira coupling see ref. (26)) to generate
broad classes of vinyl, aryl, and alkynyl norbornadienes. We
are currently investigating these coupling reactions in the
synthesis of novel conjugated norbornadiene-based poly-
mers. Studies on asymmetric lithium halide exchange of 2,3-
Reagents
Unless stated otherwise, commercial reagents were used
without purification. THF was purified by distillation from
potassium/benzophenone under dry nitrogen. 1,2-Dibro-
moethane, 1-iodohexane, 1,4-dibromobutane, chlorotrimethyl-
silane, acetone, acetaldehyde, and methyl chloroformate were
purified by distillation from 4 Å molecular sieves under dry
nitrogen.
t
2,3-Dibromonorbornadiene (7)
dibromonornadiene (7) by precomplexation of BuLi with a
chiral base are also underway in our laboratory and will be
reported in due course.
Norbornadiene 6 (35.0 mL, 324 mmol) was added to a
flame-dried 3-neck flask containing potassium tert-butoxide
(18.7 g, 167 mmol) and THF (240 mL), which was cooled at
–78°C (cryobath). n-Butyllithium (66.0 mL, 2.5M,
165 mmol) was added dropwise through a dropping funnel
over 2 h, which the temperature was maintained below
–70°C. The mixture was stirred at –65°C for 30 min. then at
–40°C for 30 min. After the mixture was cooled to –78°C,
1,2-dibromoethane (7.20 mL, 83.5 mmol) was added, and
Experimental
General Information
All reactions were carried out in an atmosphere of dry ni-
trogen at ambient temperature unless otherwise stated. Stan-
dard column chromatography was performed on 230–400
© 2000 NRC Canada

Tranmer et al.
529
Scheme 4.
Scheme 5.
the mixture was stirred at –40°C for 1.5 h. Excess 1,2-
dibromoethane (21.6 mL, 250 mmol) was then added at
–70°C. The brown mixture was stirred at –40°C for 2 h then
at room temperature for 4 h. After quenching the mixture
with saturated ammonium chloride (150 mL) and water
(300 mL), the aqueous layer was extracted with diethyl ether
(4 × 300 mL), and the combined organic layers were washed
sequentially with water (500 mL) and brine (500 mL) and
dried over magnesium sulfate. The solvent was removed by
rotary evaporation, and the crude product was purified by
vacuum distillation to give three fractions. The first fraction
(20–30 torr (1 torr = 133.322 Pa) at 40–60°C) contained
mainly the excess 1,2-dibromoethane and norbornadiene.
The second fraction (10–15 torr (1 torr = 133.322 Pa) at
50–60°C) contained 2-bromonorbornadiene and 2,3-dibro-
monorbornadiene in a ratio of 2:1 as determined by 1H
NMR. The third fraction (6–9 torr (1 torr = 133.322 Pa) at
80–100°C) contained pure 2,3-dibromonorbornadiene 7
(13.6 g, 54.4 mmol, 65%) as colorless oil. Rf : 0.67 (hex-
Rf : 0.69 (hexanes). 1H NMR (CDCl3, 400 MHz) δ: 6.89 (dd,
1H, J = 5.2, 3.2 Hz), 6.78 (dd, 1H, J = 5.2, 3.2 Hz), 6.65 (d,
1H, J = 3.2 Hz), 3.61 (br. s, 1H), 3.48 (br. s, 1H), 2.67 (dt,
1H, J = 6.0, 1.6 Hz), 2.07 (dt, 1H, J = 6.0, 1.6 Hz). 13C
NMR (CDCl3, 100 MHz) δ: 142.9, 141.8, 139.6, 136.6,
73.9, 58.2, 51.6. Spectral data were identical to those re-
ported in the literature (20).
2-Bromo-3-methylnorbornadiene (8b)
tert-Butyllithium (17.3 mL, 1.7M, 29.4 mmol) was added
to a flame-dried flask containing dibromide 7 (3.67 g,
14.7 mmol) in THF (40 mL) at –78°C. After the yellow mix-
ture was stirred for 1 h, methyl iodide (2.30 mL, 36.8 mmol)
was added at –78°C. The mixture was stirred at –78 °C for
30 min then at room temperature for 2 h. After quenching
the mixture with water (40 mL), the aqueous layer was ex-
tracted with diethyl ether (3 × 50 mL), and the combined or-
ganic layers were washed sequentially with water (100 mL)
and brine (100 mL) and dried over magnesium sulfate. The
solvent was removed by rotary evaporation and the crude
product was purified by bulb-to-bulb distillation (15–20 torr
(1 torr = 133.322 Pa) at 70–80°C) to give 8b (2.39 g,
12.9 mmol, 88%) as colorless oil. Rf : 0.74 (hexanes). IR
(neat, NaCl) cm–1: 2973 (s), 2939 (s), 2905 (w), 2869 (w),
1639 (w), 1557 (w), 1439 (m), 1376 (w), 1262 (w). 1H NMR
(CDCl3, 400 MHz) δ: 6.87 (dd, 1H, J = 5.0, 2.9 Hz), 6.78
(m, 1H), 3.47 (m, 1H), 3.36 (br. s, 1H), 2.21 (dt, 1H, J = 6.0,
1.5 Hz), 2.02 (dt, 1H, J = 6.0, 1.7 Hz), 1.76 (s, 3H). 13C
NMR (CDCl3, 100 MHz) δ: 147.6, 142.1, 141.5, 128.7,
71.4, 57.9, 55.2, 15.4. Anal. calcd. for C8H9Br: C 51.92, H
4.90; found C 51.90, H 4.84.
1
anes). H NMR (CDCl3, 400 MHz) δ: 6.88 (s, 2H), 3.61 (m,
2H), 2.45 (dd, 1H, J = 6.3, 1.1 Hz), 2.18 (dt, 1H, J = 6.3,
1.4 Hz). 13C NMR (CDCl3, 100 MHz) δ: 141.2, 133.0, 72.0,
58.6. Spectral data were identical to those reported in the lit-
erature (20).
2-Bromonorbornadiene (8a)
tert-Butyllithium (1.04 mL, 1.7M, 1.77 mmol) was added
to a flame-dried flask containing dibromide 7 (222 mg,
0.887 mmol) in THF (4 mL) at –78°C. After the yellow mix-
ture was stirred for 15 min, distilled water (0.50 mL,
28.0 mmol) was added at –78°C. The mixture was stirred at
–78°C for 30 min. then at room temperature for 1 h. After
quenching the mixture with water (5 mL), the aqueous layer
was extracted with diethyl ether (3 × 10 mL), and the com-
bined organic layers were washed sequentially with water
(10 mL) and brine (10 mL) and dried over magnesium
sulfate. The solvent was removed by rotary evaporation and
the crude product was purified by column chromatography
(hexanes) to give 8a (93.2 mg, 0.545 mmol, 61%) as color-
less oil. Note: 8a is not very stable and it turned to black-
ened oil upon standing at room temperature for a few days.
2-Bromo-3-hexylnorbornadiene (8c)
tert-Butyllithium (9.70 mL, 1.7M, 16.5 mmol) was added
to a flame-dried flask containing dibromide 7 (1.87 g, 7.48 mmol)
in THF (25 mL) at –78°C. After the yellow mixture was
© 2000 NRC Canada

530
Can. J. Chem. Vol. 78, 2000
Table 1.
Table 2.
100 MHz) δ: 151.3, 141.90, 141.87, 129.0, 71.5, 57.9, 53.5,
31.6, 29.2, 28.8, 26.4, 22.6, 14.1. HRMS m/z for C13H19Br:
calcd. 254.0671; found 254.0677.
2-Bromo-3-(4-tetrahydropyranyloxybutyl)norbornadiene
(8d)
tert-Butyllithium (24.0 mL, 1.7M, 40.8 mmol) was added
to a flame-dried flask containing dibromide 7 (5.10 g,
20.4 mmol) in THF (41 mL) at –78°C. After the yellow mix-
ture was stirred for 30 min, 1-iodo-4-tetrahydropyranyloxy-
butane (4.43 g, 15.6 mmol) was added at –78°C. The
mixture was stirred at –78°C for 1 h then at room tempera-
ture for 20 h. After quenching the mixture with water (80 mL),
the aqueous layer was extracted with diethyl ether (3 ×
80 mL), and the combined organic layers were washed se-
quentially with water (100 mL) and brine (100 mL) and
dried over magnesium sulfate. The solvent was removed by
rotary evaporation and the crude product was purified by
column chromatography (EtOAc:hexanes = 1:19) to give 8d
(6.01 g, 18.4 mmol, 90%) as colorless oil. Rf : 0.35
(EtOAc:hexanes = 1:19). IR (neat, NaCl) cm–1: 3067 (w),
2939 (s), 2867 (s), 1633 (w), 1558 (m), 1440 (m), 1352 (m),
1323 (w), 1297 (m), 1260 (m), 1224 (w), 1201 (m), 1137
(m), 1120 (m), 1077 (m), 1033 (m). H NMR (CDCl3,
400 MHz) δ: 6.84 (dd, 1H, J = 4.9, 2.9 Hz), 6.73 (dd, 1H,
J = 4.9, 2.9 Hz), 4.55 (m, 1H), 3.85 (m, 1H), 3.71 (m, 1H),
3.51–3.42 (m, 3H), 3.37 (m, 1H), 2.27–2.10 (m, 3H), 2.01
(dm, 1H, J = 5.9 Hz), 1.80 (m, 1H), 1.70 (m, 1H), 1.59–1.42
(m, 8H). 13C NMR (CDCl3, 100 MHz) δ: 150.9, 141.8 (2),
129.3, 98.8, 98.7, 71.5, 67.2, 62.24, 62.22, 57.9, 53.3, 30.7,
29.1, 28.9, 25.4, 23.13, 23.11, 19.61, 19.59. HRMS m/z for
C16H23BrO2: calcd. 326.0882; found 326.0886.
stirred for 1 h, 1-iodohexane (2.00 mL, 13.6 mmol) was
added at –78°C. The mixture was stirred at –78 °C for
90 min then at room temperature for 2 h. After quenching
the mixture with water (50 mL), the aqueous layer was ex-
tracted with diethyl ether (4 × 50 mL), and the combined or-
ganic layers were washed sequentially with water (100 mL)
and brine (100 mL) and dried over magnesium sulfate. The
solvent was removed by rotary evaporation and the crude
product was purified by bulb-to-bulb distillation (1–2 torr
(1 torr = 133.322 Pa) at 60°C for 1 h) to remove excess 1-
iodohexane, then 0.3 torr (1 torr = 133.322 Pa) at 100°C) to
give 8c (1.66 g, 6.50 mmol, 87%) as colorless oil. Rf : 0.85
(hexanes). IR (neat, NaCl) cm–1: 3068 (w), 2958 (s), 2929
(s), 2857 (s), 1633 (w), 1557 (w), 1466 (m), 1378 (w), 1297
1
(m), 1263 (w), 1224 (w); H NMR (CDCl3, 400 MHz) δ:
6.86 (m, 1H), 6.75 (m, 1H), 3.47 (m, 1H), 3.43 (m, 1H),
2.24–2.08 (m, 3H), 2.03 (dt, 1H, J = 5.9, 1.7 Hz), 1.44–1.24
(m, 8H), 0.89 (t, 3H, J = 6.8 Hz). 13C NMR (CDCl3,
© 2000 NRC Canada

Tranmer et al.
531
2-Bromo-3-(4-bromobutyl)norbornadiene (8e)
ture was stirred for 30 min, chlorotrimethylsilane (0.27 mL,
2.10 mmol) was added at –78°C. The mixture was stirred at
–78°C for 1 h then at room temperature for 1 h. After
quenching the mixture with water (5 mL), the aqueous layer
was extracted with diethyl ether (3 × 10 mL), and the com-
bined organic layers were washed sequentially with water
(10 mL) and brine (10 mL) and dried over magnesium sul-
fate. The solvent was removed by rotary evaporation and the
crude product was purified by column chromatography (hex-
anes) to give 8g (185 mg, 0.762 mmol, 88%) as colorless
oil. Rf : 0.88 (EtOAc:hexanes = 1:19). IR (neat, NaCl) cm–1:
2957 (s), 2938 (s), 1571 (s), 1549 (s), 1296 (s), 1248 (s),
tert-Butyllithium (8.20 mL, 1.7M, 13.9 mmol) was added
to a flame-dried flask containing dibromide 7 (1.60 g,
6.40 mmol) in THF (30 mL) at –78°C. After stirring the re-
action mixture for 1 h, the resulting yellow reaction mixture
was added to a flame-dried flask containing 1,4-dibromo-
butane (5.50 mL, 46.1 mmol) in THF (30 mL) at –78°C. The
mixture was stirred at –78°C for 1 h then at room tempera-
ture for 12 h. After quenching the mixture with water
(100 mL), the aqueous layer was extracted with diethyl ether
(4 × 50 mL), and the combined organic layers were washed
sequentially with water (100 mL) and brine (100 mL) and
dried over magnesium sulfate. The solvent was removed by
rotary evaporation and the excess 1,4-dibromobutane was re-
moved by bulb-to-bulb distillation (4 torr (1 torr = 133.322
Pa) at 70°C for 4 h) and the crude product was purified by
column chromatography (hexanes) to give 8e (1.04 g,
3.40 mmol, 53%) as colorless oil. Rf : 0.50 (EtOAc:hexanes
= 1:9). IR (neat, NaCl) cm–1: 3066 (w), 2973 (m), 2937 (s),
2866 (w), 1632 (w), 1557 (w), 1451 (w), 1296 (s), 1249 (w).
1H NMR (CDCl3, 400 MHz) δ: 6.85 (dd, 1H, J = 5.1,
2.9 Hz), 6.76 (dd, 1H, J = 4.6, 3.0 Hz), 3.47 (m, 1H), 3.44
(m, 1H), 3.40 (t, 2H, J = 6.6 Hz), 2.28–2.12 (m, 3H), 2.04
(dt, 1H, J = 6.0, 1.7 Hz), 1.78 (m, 2H), 1.57 (m, 2H). 13C
NMR (CDCl3, 100 MHz) δ: 150.3, 141.9, 141.8, 129.9,
71.6, 57.9, 53.3, 33.7, 31.8, 28.1, 24.8. HRMS m/z for
C11H14Br2: calcd. 303.9463; found 303.9460.
1
1022 (m), 836 (s). H NMR (CDCl3, 400 MHz) δ: 6.83 (dd,
1H, J = 5.0, 3.2 Hz), 6.70 (dd, 1H, J = 5.0, 3.2 Hz), 3.73
(br. s, 1H), 3.54 (br. s, 1H), 2.14 (dt, 1H, J = 6.1, 1.5 Hz),
1.94 (dt, 1H, J = 6.1, 1.5 Hz), 0.15 (s, 9H). 13C NMR
(CDCl3, 100 MHz) δ: 147.6, 147.2, 142.7, 141.0, 72.3, 61.4,
55.7, –1.7. HRMS m/z for C10H15SiBr: calcd. 242.0127;
found 242.0124.
2-Bromo-3-tert-Butyldimethylsilylnorbornadiene (8h)
tert-Butyllithium (1.00 mL, 1.7M, 1.70 mmol) was added
to a flame-dried flask containing dibromide 7 (212 mg,
0.847 mmol) in THF (4 mL) at –78°C. After the yellow mix-
ture was stirred for 30 min, tert-butyldimethylsilyl chloride
(338 mg, 2.24 mmol) was added at –78°C. The mixture was
stirred at –78°C for 1 h then at room temperature for 1 h.
After quenching the mixture with water (5 mL), the aqueous
layer was extracted with diethyl ether (3 × 10 mL), and the
combined organic layers were washed sequentially with wa-
ter (10 mL) and brine (10 mL) and dried over magnesium
sulfate. The solvent was removed by rotary evaporation and
the crude product was purified by column chromatography
(hexanes) to give 8h (187 mg, 0.655 mmol, 77%) as color-
less oil. Rf : 0.88 (EtOAc:hexanes = 1:19). IR (neat,
NaCl) cm–1: 2953 (s), 2928 (s), 2855 (s), 1570 (s), 1548 (s),
2-Benzyl-3-bromonorbornadiene (8f)
tert-Butyllithium (19.0 mL, 1.7M, 32.3 mmol) was added
to a flame-dried flask containing dibromide 7 (4.0 g, 16 mmol)
in THF (48 mL) at –78°C. After the yellow mixture was
stirred for 1.2 h, benzyl bromide (2.85 mL, 24.0 mmol) was
added at –78°C. The mixture was stirred at –78 °C for 2 h
then at room temperature for 22 h. After quenching the mix-
ture with water (25 mL), the aqueous layer was extracted
with diethyl ether (4 × 25 mL), and the combined organic
layers were washed sequentially with water (25 mL) and
brine (25 mL) and dried over magnesium sulfate. The sol-
vent was removed by rotary evaporation and the excess
benzyl bromide was by vacuum bulb-to-bulb distillation (5
torr (1 torr = 133.322 Pa) at 120°C for 3 h). The crude prod-
uct was purified by column chromatography (hexanes) to
give 8f (2.62 g, 10.0 mmol, 63%) as yellow oil. Rf : 0.85
(EtOAc:hexanes = 1:9). IR (neat, NaCl) cm–1: 3064 (m),
3027 (s), 2976 (s), 2938 (s), 2867 (s), 1630 (m), 1601 (m),
1557 (m), 1494 (s), 1453 (s), 1428 (w), 1297 (s), 1264 (m),
1224 (m), 1168 (w), 1087 (w), 1074 (m), 1029 (s), 1010
1
1470 (m), 1296 (s), 1249 (s), 1019 (s), 835 (s). H NMR
(CDCl3, 400 MHz) δ: 6.85 (dd, 1H, J = 4.9, 3.1 Hz), 6.72
(dd, 1H, J = 4.9, 2.9 Hz), 3.77 (br. s, 1H), 3.55 (br. s, 1H),
2.18 (d, 1H, J = 6.1 Hz), 1.94 (dm, 1H, J = 6.1 Hz), 0.88 (s,
9H), 0.18 (s, 3H), 0.15 (s, 3H). 13C NMR (CDCl3,
100 MHz) δ: 148.8, 146.1, 142.9, 140.9, 72.4, 61.7, 56.7,
26.7, 18.4, –5.4, –5.8. HRMS m/z for C13H21SiBr: calcd.
284.0596; found 284.0597.
2-Bromo-3-chloronorbornadiene (8i)
tert-Butyllithium (1.00 mL, 1.7M, 1.70 mmol) was added
to a flame-dried flask containing dibromide 7 (213 mg,
0.852 mmol) in THF (4 mL) at –78°C. After the yellow mix-
ture was stirred for 30 min, p-toluenesulfonyl chloride
(345 mg, 1.81 mmol) was added at –78°C. The mixture was
stirred at –78°C for 45 min then at room temperature for 1 h.
After quenching the mixture with water (5 mL), the aqueous
layer was extracted with diethyl ether (3 × 10 mL), and the
combined organic layers were washed sequentially with wa-
ter (10 mL) and brine (10 mL) and dried over magnesium
sulfate. The solvent was removed by rotary evaporation and
the crude product was purified by column chromatography
(hexanes) to give 8i (130 mg, 0.635 mmol, 75%) as colorless
1
(m). H NMR (CDCl3, 400 MHz) δ: 7.31–7.20 (m, 3H),
7.12 (dm, 2H, J = 7.2 Hz), 6.81 (dd, 1H, J = 4.9, 3.0 Hz),
6.55 (dd, 1H, J = 4.9, 2.9 Hz), 3.57 (dAB, 1H, J = 14.9 Hz),
3.55 (br. s, 1H), 3.48 (dAB, 1H, J = 14.9 Hz), 3.30 (m, 1H),
2.21 (dt, 1H, J = 6.0, 1.5 Hz), 2.00 (dt, 1H, J = 6.0, 1.6 Hz).
13C NMR (CDCl3, 100 MHz) δ: 149.7, 142.0, 140.9, 137.5,
129.9, 128.8, 128.3, 126.2, 71.4, 57.9, 53.4, 35.7.
HRMS m/z for C14H13Br: calcd. 260.0201; found 260.0189.
2-Bromo-3-trimethylsilylnorbornadiene (8g)
tert-Butyllithium (1.01 mL, 1.7M, 1.72 mmol) was added
to a flame-dried flask containing dibromide 7 (215 mg,
0.862 mmol) in THF (4 mL) at –78°C. After the yellow mix-
1
oil. Rf : 0.76 (hexanes). H NMR (CDCl3, 400 MHz) δ: 6.89
(m, 2H), 3.60 (m, 1H), 3.52 (m, 1H), 2.43 (dtd, 1H, J = 6.3,
© 2000 NRC Canada

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Can. J. Chem. Vol. 78, 2000
1.6, 0.3 Hz), 2.19 (dt, 1H, J = 6.3, 1.9 Hz). 13C NMR
(CDCl3, 100 MHz) δ: 144.0, 141.6, 141.1, 128.3, 71.5, 57.8,
56.8. Spectral data were identical to those reported in the lit-
erature (20).
stirred at –78°C for 3 h. After quenching the mixture with
water (15 mL), the aqueous layer was extracted with diethyl
ether (4 × 15 mL), and the combined organic layers were
washed sequentially with water (20 mL) and brine (20 mL)
and dried over magnesium sulfate. The solvent was removed
by rotary evaporation and the crude product was purified by
column chromatography (EtOAc:hexanes = 1:19) to give 8l
(130 mg, 0.535 mmol, 61%) as colorless oil. Rf : 0.70
(EtOAc:hexanes = 1:4). IR (neat, NaCl) cm–1: 2980 (m),
2943 (m), 2872 (w), 1718 (s), 1717 (s), 1704 (s), 1699 (s),
1695 (s), 1559 (m), 1368 (m), 1310 (s), 1290 (s), 1277 (s),
1249 (s), 1235 (s), 1203 (w), 1150 (m), 1101 (s), 1086 (s),
2-Bromo-3-iodonorbornadiene (8j)
tert-Butyllithium (1.00 mL, 1.7M, 1.70 mmol) was added
to a flame-dried flask containing dibromide 7 (213 mg,
0.854 mmol) in THF (3 mL) at –78°C. After the yellow mix-
ture was stirred for 30 min, iodine (456 mg, 1.80 mmol), in
a separate flame-dried flask containing 4Å molecular sieves
(550 mg) and THF (1 mL), was added via a cannula at
–78°C. The mixture was stirred at –78°C for 45 min then at
room temperature for 1 h. After quenching the mixture with
saturated sodium thiosulfate (5 mL), the aqueous layer was
extracted with diethyl ether (3 × 10 mL), and the combined
organic layers were washed sequentially with water (10 mL)
and brine (10 mL) and dried over magnesium sulfate. The
solvent was removed by rotary evaporation and the crude
product was purified by column chromatography (hexanes)
to give 8j (207 mg, 0.699 mmol, 82%) as pale-yellow oil.
Rf : 0.77 (hexanes). IR (neat, NaCl) cm–1: 2993 (s), 2940 (s),
2867 (w), 1573 (s), 1551 (w), 1291 (s), 1220 (w), 711 (s).
1H NMR (CDCl3, 400 MHz) δ: 6.87 (m, 2H), 3.71 (m, 1H),
3.62 (m, 1H), 2.44 (dm, 1H, J = 6.4 Hz), 2.14 (dm, 1H, J =
6.4 Hz). 13C NMR (CDCl3, 100 MHz) δ: 141.9, 141.4,
140.8, 105.0, 72.5, 61.9, 59.0. HRMS m/z for C7H6BrI:
calcd. 295.8700; found 295.8697.
1
1024 (w). H NMR (CDCl3, 400 MHz) δ: 6.90 (dd, 1H, J =
4.9, 3.0 Hz), 6.84 (m, 1H), 4.21 (m, 2H), 3.99 (m, 1H), 3.67
(m, 1H), 2.30 (dt, 1H, J = 6.6, 1.5 Hz), 2.11 (dt, 1H, J = 6.7,
1.6 Hz), 1.30 (t, 3H, J = 7.1 Hz). 13C NMR (CDCl3,
100 MHz) δ: 163.7, 148.4, 143.0, 142.0, 140.4, 71.7, 61.6,
60.4, 52.0, 14.2. Anal. calcd. for C10H11BrO2: C 49.41, H
4.56; found C 49.23, H 4.58.
2-Bromo-3-(1-hydroxyethyl)norbornadiene (8m)
tert-Butyllithium (0.50 mL, 1.7M, 0.850 mmol) was added
to a flame-dried flask containing dibromide 7 (106 mg,
0.424 mmol) in THF (2 mL) at –78°C. After the yellow mix-
ture was stirred for 45 min, acetaldehyde (0.10 mL,
2.88 mmol) was added at –78°C. The mixture was stirred at
–78°C for 1 h. After quenching the mixture with water
(5 mL), the aqueous layer was extracted with diethyl ether
(3 × 10 mL), and the combined organic layers were washed
sequentially with water (10 mL) and brine (10 mL) and
dried over magnesium sulfate. The solvent was removed by
rotary evaporation and the crude product was purified by
column chromatography (EtOAc:hexanes = 1:4) to give 8m
(75.9 mg, 0.353 mmol, 83%, 1:1 inseparable mixture of
diastereomers) as colorless oil. Rf : 0.33 (EtOAc:hexanes =
1:4); IR (neat, NaCl) cm–1: 3354 (br. s), 3069 (w), 2973 (s),
2939 (s), 2869 (s), 1628 (m), 1558 (m), 1449 (m), 1368 (m),
1327 (m), 1296 (s), 1268 (m), 1224 (m), 1209 (m), 1091 (s),
2-Bromo-3-tributylstannylnorbornadiene (8k)
tert-Butyllithium (1.05 mL, 1.7M, 1.79 mmol) was added
to a flame-dried flask containing dibromide 7 (233 mg,
0.894 mmol) in THF (4 mL) at –78°C. After the yellow mix-
ture was stirred for 30 min, tributyltin chloride (0.61 mL,
2.25 mmol) was added at –78°C. The mixture was stirred at
–78°C for 45 min then at room temperature for 1 h. After
quenching the mixture with water (5 mL), the aqueous layer
was extracted with diethyl ether (3 × 10 mL), and the com-
bined organic layers were washed sequentially with water
(10 mL) and brine (10 mL) and dried over magnesium sul-
fate. The solvent was removed by rotary evaporation and the
crude product was purified by column chromatography (hex-
anes) to give 8k (299 mg, 0.649 mmol, 73%) a$s colorless
oil. Rf : 0.89 (hexanes). IR (neat, NaCl) cm–1: 2956 (s), 2930
(s), 2870 (m), 2853 (m), 1566 (m), 1541 (s), 1463 (m), 1294
1
1062 (s), 1030 (m), 1009 (m). H NMR (CDCl3, 400 MHz)
δ: 6.86–6.76 (m, 2H), 4.70 (q, 0.5H, J = 6.2 Hz), 4.69 (q,
0.5H, J = 6.2 Hz), 3.72 (br. s, 0.5H), 3.68 (br. s, 0.5H), 3.50
(br. s, 1H), 2.16 (m, 1H), 2.04 (m, 1H), 1.87 (br. s, 1H), 1.62
(br. s, 1H), 1.33 (d, 1.5H, J = 6.4 Hz), 1.11 (d, 1.5H, J =
6.5 Hz). 13C NMR (CDCl3, 100 MHz) δ: 152.6, 152.4,
142.9, 142.5, 141.4, 141.2, 130.4, 130.2, 71.8, 71.3, 64.6,
64.5, 58.2, 58.1, 50.0, 49.5, 20.8, 18.9. Anal. calcd. for
C9H11BrO: C 50.26, H 5.15; found C 50.09, H 5.16.
1
(s), 1009 (s), 874 (w). H NMR (CDCl3, 400 MHz) δ: 6.85
(dd, 1H, J = 5.1, 3.0 Hz), 6.65 (dd, 1H, J = 5.1, 2.9 Hz),
3.74 (br. s, 1H), 3.51 (br. s, 1H), 2.19 (dm, 1H, J = 6.0 Hz),
1.98 (dm, 1H J = 6.0 Hz), 1.49 (m, 6H), 1.29 (m, 6H), 1.00
(t, 6H, J = 8.0 Hz), 0.88 (t, 9H, J = 7.2 Hz). 13C NMR
(CDCl3, 100 MHz) δ: 151.2, 148.9, 142.6, 141.3, 73.1, 60.3,
57.5, 29.1, 27.2, 13.7, 9.7. HRMS m/z for C19H33SnBr:
calcd. 460.0788; found 460.0792.
2-Bromo-3-(1-hydroxybenzyl)norbornadiene (8n)
tert-Butyllithium (1.10 mL, 1.7M, 1.87 mmol) was added
to a flame-dried flask containing dibromide 7 (212 mg,
0.849 mmol) in THF (4.2 mL) at –78°C. After the yellow
mixture was stirred for 1 h, benzaldehyde (0.10 mL,
0.98 mmol) was added at –78°C. The mixture was stirred at
–78°C for 2 h. After quenching the mixture with water
(15 mL), the aqueous layer was extracted with diethyl ether
(4 × 15 mL), and the combined organic layers were washed
sequentially with water (15 mL) and brine (15 mL) and
dried over magnesium sulfate. The solvent was removed by
rotary evaporation and the crude product was purified by
column chromatography (EtOAc:hexanes = 1:9) to give 8n
2-Bromo-3-ethoxycarbonylnorbornadiene (8l)
tert-Butyllithium (1.20 mL, 1.7M, 2.04 mmol) was added
to a flame-dried flask containing dibromide 7 (219 mg,
0.876 mmol) in THF (2.4 mL) at –78°C. After stirring the
mixture for 1 h, the resulting yellow mixture was added to a
flame-dried flask containing ethyl chloroformate (0.40 mL,
4.18 mmol) in THF (2 mL) at –78°C. The mixture was
© 2000 NRC Canada

Tranmer et al.
533
(164 mg, 0.592 mmol, 70%, 1:1 inseparable mixture of
diastereomers) as colorless oil. Rf : 0.55 (EtOAc:hexanes =
1:4). IR (neat, NaCl) cm–1: 3395 (s), 3064 (m), 3028 (m),
2992 (s), 2939 (s), 2869 (m), 1626 (m), 1602 (w), 1557 (w),
1494 (m), 1449 (s), 1299 (s), 1266 (m), 1224 (m), 1127 (w),
3061 (m), 2938 (m), 2868 (m), 1557 (w), 1492 (s), 1448 (s),
1329 (m), 1295 (s), 1259 (w), 1210 (w), 1163 (m), 1032 (s),
1017 (s). 1H NMR (CDCl3, 400 MHz) δ: 7.34–7.25 (m,
10H), 6.79 (dd, 1H, J = 4.7, 3.0 Hz), 6.48 (dd, 1H, J = 4.8,
2.9 Hz), 3.58 (m, 1H), 3.41 (m, 1H), 2.98 (s, 1H), 2.36 (dt,
1H, J = 6.2, 1.5 Hz), 1.95 (dt, 1H, J = 6.3, 1.7 Hz). 13C
NMR (CDCl3, 100 MHz) δ: 153.0, 143.81, 143.77, 142.5,
140.2, 129.7, 128.1, 128.0, 127.6, 127.5, 80.7, 70.3, 60.7,
54.5. HRMS m/z for C20H17BrO: calcd. 352.0463; found
352.0461.
1
1037 (s), 1021 (s), 1002 (s). H NMR (CDCl3, 400 MHz) δ:
7.42–7.22 (m, 5H), 6.88 (dd, 0.5H, J = 5.0, 3.0 Hz), 6.82
(dd, 0.5H, J = 5.0, 3.0 Hz), 6.58 (dd, 0.5H, J = 4.9, 3.0 Hz),
6.22 (dd, 0.5H, J = 4.9, 2.9 Hz), 5.70 (br. s, 0.5H), 5.68 (d,
0.5H, J = 2.7 Hz), 3.58 (br. s, 0.5H), 3.55 (br. s, 1H), 3.47
(br. s, 0.5H), 2.26 (dm, 0.5H, J = 2.0 Hz), 2.19 (dm, 0.5H, J
= 6.2 Hz), 2.09 (dm, 0.5H, J = 6.2 Hz), 2.03 (d, 0.5H, J =
3.4 Hz), 1.98 (dd, 1H, J = 6.2, 1.3 Hz). 13C NMR (CDCl3,
100 MHz) δ: 151.3, 151.1, 142.7, 142.5, 141.5, 141.1,
139.2, 139.0, 132.0, 130.9, 128.4, 128.2, 127.4, 127.3,
125.6, 125.5, 72.1, 70.4, 70.3, 70.0, 58.2, 58.1, 50.8, 49.6.
Anal. calcd. for C14H13BrO: C 60.67, H 4.73; found C
60.83, H 4.71.
2-Hexyl-3-methylnorbornadiene (9a)
tert-Butyllithium (0.96 mL, 1.7M, 1.63 mmol) was added
to a flame-dried flask containing bromide 8b (151 mg,
0.817 mmol) in THF (4 mL) at –78°C. After the yellow mix-
ture was stirred for 20 min, 1-bromohexane (0.25 mL,
1.78 mmol) was added at –78°C. The mixture was stirred at
–78°C for 45 min then at room temperature for 1 h. After
quenching the mixture with water (5 mL), the aqueous layer
was extracted with diethyl ether (3 × 10 mL), and the com-
bined organic layers were washed sequentially with water
(10 mL) and brine (10 mL) and dried over magnesium sul-
fate. The solvent was removed by rotary evaporation and the
crude product was purified by column chromatography (hex-
anes) to give 9a (124 mg, 0.652 mmol, 80%) as colorless
oil. Rf : 0.83 (hexanes). IR (neat, NaCl) cm–1: 2970 (s), 2938
(s), 2870 (s), 1558 (w), 1440 (m), 1378 (w), 1295 (m), 715
(s). 1H NMR (CDCl3, 400 MHz) δ: 6.74 (m, 2H), 3.29 (br. s,
1H), 3.20 (br. s, 1H), 2.13 (m, 1H), 2.02 (m, 1H), 1.88 (dt,
1H, J = 5.6, 1.5 Hz), 1.82 (dm, 1H, J = 5.6 Hz), 1.69 (s,
3H), 1.40–1.17 (m, 8H), 0.87 (t, 3H, J = 6.8 Hz). 13C NMR
(CDCl3, 100 MHz) δ: 146.3, 142.8, 142.6, 142.1, 70.9, 55.2,
53.2, 31.8, 28.9, 28.0, 27.4, 22.6, 14.2, 14.1. Anal. calcd. for
C14H22: C 88.35, H 11.65; found C 88.04, H 11.69.
2-Bromo-3-(2-hydroxypropyl)norbornadiene (8o)
tert-Butyllithium (1.05 mL, 1.7M, 1.79 mmol) was added
to a flame-dried flask containing dibromide 7 (199 mg,
0.797 mmol) in THF (4.0 mL) at –78°C. After the yellow
mixture was stirred for 1 h, acetone (0.40 mL, 5.4 mmol)
was added at –78°C. The mixture was stirred at –78 °C for
2 h. After quenching the mixture with water (15 mL), the
aqueous layer was extracted with diethyl ether (4 × 15 mL),
and the combined organic layers were washed sequentially
with water (15 mL) and brine (15 mL) and dried over mag-
nesium sulfate. The solvent was removed by rotary evapora-
tion and the crude product was purified by column
chromatography (EtOAc:hexanes
= 1:9) to give 8o
(0.133 mg, 0.580 mmol, 73%) as colorless oil. Rf : 0.45
(EtOAc:hexanes = 1:4). IR (neat, NaCl) cm–1: 3400 (s),
3122 (w), 3069 (w), 2975 (s), 2937 (s), 2869 (m), 1614 (m),
1557 (m), 1463 (m), 1363 (s), 1296 (s), 1269 (m), 1249 (m),
1-Bromo-4-(3-methyl-2-norbornadienyl)butane (9b)
1
1232 (m), 1170 (s), 1141 (s), 1058 (m). H NMR (CDCl3,
tert-Butyllithium (30.0 mL, 1.7M, 51.0 mmol) was added
to a flame-dried flask containing bromide 8b (4.40 g,
23.8 mmol) in THF (120 mL) at –78°C. After stirring the
mixture for 1 h, the resulting yellow mixture was added to a
flame-dried flask containing 1,4-dibromobutane (18.0 mL,
151 mmol) in THF (120 mL) at –78°C. The mixture was
stirred at –78°C for 30 min then at room temperature for
12 h. After quenching the mixture with water (300 mL), the
aqueous layer was extracted with diethyl ether (4 × 150 mL),
and the combined organic layers were washed sequentially
with water (150 mL) and brine (150 mL) and dried over
magnesium sulfate. The solvent was removed by rotary
evaporation and the crude product was purified by vacuum
distillation to give two fractions. The first fraction (4–6 torr
(1 torr = 133.322 Pa) at 70–80°C) contained mainly the ex-
cess 1,4-dibromobutane. The second fraction (0.4–1 torr (1
torr = 133.322 Pa) at 60–80°C) contained 9b (2.35 g,
9.74 mmol, 41%) as colorless oil. Rf : 0.54 (hexanes). IR
(neat, NaCl) cm–1: 3066 (w), 2963 (s), 2932 (s), 2862 (m),
1557 (w), 1438 (m), 1376 (w), 1301 (m), 1249 (w), 1230
(w), 1202 (w). 1H NMR (CDCl3, 400 MHz) δ: 6.74 (m, 2H),
3.38 (t, 2H, J = 7.0 Hz), 3.29 (br. s, 1H), 3.22 (m, 1H), 2.17
(m, 1H), 2.06 (m, 1H), 1.89 (dt, 1H, J = 5.7, 1.5 Hz), 1.84
(m, 1H), 1.74 (m, 2H), 1.69 (br. s, 3H), 1.52 (m, 2H). 13C
NMR (CDCl3, 100 MHz) δ: 145.3, 143.5, 142.7, 142.1,
400 MHz) δ: 6.87(dd, 1H, J = 5,0, 3.3 Hz), 6.80 (dd, 1H, J
= 5.0, 2.9 Hz), 3.67 (m, 1H), 3.47 (m, 1H), 2.17 (dt, 1H, J =
6.1, 1.5 Hz), 2.13 (br. s, 1H), 1.94 (dt, 1H, J = 6.1, 1.7 Hz),
1.38 (s, 3H), 1.37 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ:
154.1, 142.2, 141.6, 126.0, 71.9, 70.7, 60.2, 53.0, 28.1, 28.0.
Anal. calcd. for C10H13BrO: C 52.42, H 5.72; found C
52.61, H 5.70.
2-Bromo-3-(1,1-diphenyl-1-hydroxymethyl)norbornadiene
(8p)
tert-Butyllithium (1.20 mL, 1.7M, 2.04 mmol) was added
to a flame-dried flask containing dibromide 7 (225 mg,
0.902 mmol) in THF (4.5 mL) at –78°C. After the yellow
mixture was stirred for 1 h, benzophenone (204 mg,
1.12 mmol) was added at –78°C. The mixture was stirred at
–78°C for 3 h. After quenching the mixture with water
(15 mL), the aqueous layer was extracted with diethyl ether
(4 × 15 mL), and the combined organic layers were washed
sequentially with water (20 mL) and brine (20 mL) and
dried over magnesium sulfate. The solvent was removed by
rotary evaporation and the crude product was purified by
column chromatography (EtOAc:hexanes = 1:19) to give 8p
(210 mg, 0.594 mmol, 66%) as colorless oil. Rf : 0.40
(EtOAc:hexanes = 1:9). IR (neat, NaCl) cm–1: 3560 (m),
© 2000 NRC Canada

534
Can. J. Chem. Vol. 78, 2000
70.9, 55.3, 53.1, 33.9, 32.1, 27.0, 25.9, 14.2. HRMS m/z for
C12H17Br: calcd. 240.0514; found 240.0516.
tion and the crude product was purified by column chroma-
tography (hexanes) to give 9e (115 mg, 0.496 mmol, 60%)
as colorless oil. Rf : 0.79 (hexanes). IR (neat, NaCl) cm–1:
2970 (s), 2938 (s), 2870 (m), 1646 (w), 1558 (w), 1440 (m),
2-Methyl-3-trimethylsilylnorbornadiene (9c)
1
1295 (s), 1163 (m), 715 (s). H NMR (CDCl3, 400 MHz) δ:
tert-Butyllithium (0.99 mL, 1.7M, 1.68 mmol) was added
to a flame-dried flask containing bromide 8b (156 mg,
0.845 mmol) in THF (4 mL) at –78°C. After the yellow mix-
ture was stirred for 20 min, chlorotrimethylsilane (0.27 mL,
2.13 mmol) was added at –78°C. The mixture was stirred at
–78°C for 45 min then at room temperature for 1 h. After
quenching the mixture with water (5 mL), the aqueous layer
was extracted with diethyl ether (3 × 10 mL), and the com-
bined organic layers were washed sequentially with water
(10 mL) and brine (10 mL) and dried over magnesium sul-
fate. The solvent was removed by rotary evaporation and the
crude product was purified by column chromatography (hex-
anes) to give 9c (106 mg, 596 mmol, 71%) as colorless oil.
Rf : 0.79 (hexanes). IR (neat, NaCl) cm–1: 2965 (s), 2933 (s),
2864 (s), 1608 (m), 1556 (m), 1439 (w), 1299 (s), 1247 (s),
6.86 (dd, 1H, J = 4.9, 2.9 Hz), 6.75 (dd, 1H, J = 4.9,
3.0 Hz), 3.58 (br. s, 1H), 3.37 (br. s, 1H), 2.19 (dt, 1H, J =
6.0, 1.6 Hz), 1.99 (dt, 1H, J = 6.0, 1.6 Hz), 1.80 (s, 3H). 13C
NMR (CDCl3, 100 MHz) δ: 155.4, 142.3, 141.1, 100.2,
72.0, 61.0, 55.2, 18.5. HRMS m/z for C8H9I: calcd.
231.9751; found 231.9760.
2-ethoxycarbonyl-3-methylnorbornadiene (9f)
tert-Butyllithium (1.10 mL, 1.7M, 1.87 mmol) was added
to a flame-dried flask containing bromide 8b (158 mg,
0.852 mmol) in THF (2.0 mL) at –78°C. After stirring the
mixture for 1 h, the resulting yellow mixture was added to a
flame-dried flask containing ethyl chloroformate (0.38 mL,
4.0 mmol) in THF (2.5 mL) at –78°C. The mixture was
stirred at –78°C for 3 h. After quenching the mixture with
water (15 mL), the aqueous layer was extracted with diethyl
ether (4 × 15 mL), and the combined organic layers were
washed sequentially with water (20 mL) and brine (20 mL)
and dried over magnesium sulfate. The solvent was removed
by rotary evaporation and the crude product was purified by
column chromatography (EtOAc:hexanes = 1:9) to give 9f
(109 mg, 0.655 mmol, 77%) as colorless oil. Rf : 0.50
(EtOAc:hexanes = 1:4). IR (neat, NaCl) cm–1: 2978 (m),
2939 (m), 2870 (w), 1702 (s), 1632 (m), 1558 (w), 1370
(m), 1331 (m), 1314 (m), 1295 (s), 1249 (m), 1237 (s), 1189
1
835 (s), 709 (s). H NMR (CDCl3, 400 MHz) δ: 6.72 (dd,
1H, J = 5.2, 3.1 Hz), 6.67 (dd, 1H, J = 5.2, 2.9 Hz), 3.63
(br. s, 1H), 3.27 (br. s, 1H), 1.93 (s, 3H), 1.83 (dm, 1H, J =
6.0 Hz), 1.77 (dm, 1H, J = 6.0 Hz), 0.08 (m, 9H). 13C NMR
(CDCl3, 100 MHz) δ: 164.4, 143.6, 141.5, 140.9, 71.6, 57.9,
54.5, 18.1, –0.9. Anal. calcd. for C11H18Si: C 74.08, H
10.17; found C 74.38, H 10.13.
2-Chloro-3-methylnorbornadiene (9d)
tert-Butyllithium (1.00 mL, 1.7M, 1.70 mmol) was added
to a flame-dried flask containing bromide 8b (159 mg,
0.860 mmol) in THF (4 mL) at –78°C. After the yellow mix-
ture was stirred for 20 min, p-toluenesulfonyl chloride
(259 mg, 1.36 mmol) was added at –78°C. The mixture was
stirred at –78°C for 45 min then at room temperature for 1 h.
After quenching the mixture with water (5 mL), the aqueous
layer was extracted with diethyl ether (3 × 10 mL), and the
combined organic layers were washed sequentially with wa-
ter (10 mL) and brine (10 mL) and dried over magnesium
sulfate. The solvent was removed by rotary evaporation and
the crude product was purified by column chromatography
(hexanes) to give 9d (88.3 mg, 0.628 mmol, 73%) as color-
less oil. Rf : 0.78 (hexanes). IR (neat, NaCl) cm–1: 2970 (s),
2938 (s), 2870 (m), 1670 (w), 1646 (m), 1440 (m), 1295 (s),
1
(m), 1146 (m), 1101 (m), 1066 (m), 1047 (m), 1019 (w). H
NMR (CDCl3, 400 MHz) δ: 6.86 (dd, 1H, J = 5.0, 3.0 Hz),
6.70 (dd, 1H, J = 4.9, 3.2 Hz), 4.14 (m, 2H), 3.86 (br. s, 1H),
3.37 (br. s, 1H), 2.19 (s, 3H), 2.02 (dm, 1H, J = 6.4 Hz),
1.92 (dm, 1H, J = 6.4 Hz), 1.26 (t, 3H, J = 7.1 Hz). 13C
NMR (CDCl3, 100 MHz) δ: 169.4, 165.9, 144.0, 140.3,
138.3, 70.8, 59.6, 58.0, 50.9, 17.1, 14.3. Anal. calcd. for
C11H14O2: C 74.13, H 7.92; found C 73.99, H 7.95.
2-(2-Methyl-3-norbornadienyl)-2-propanol (9g)
tert-Butyllithium (0.80 mL, 1.7M, 1.4 mmol) was added
to a flame-dried flask containing bromide 8b (116 mg,
0.627 mmol) in THF (3.0 mL) at –78°C. After the yellow
mixture was stirred for 1 h, acetone (0.35 mL, 4.8 mmol)
was added at –78°C. The mixture was stirred at –78 °C for
3 h. After quenching the mixture with water (15 mL), the
aqueous layer was extracted with diethyl ether (4 × 15 mL),
and the combined organic layers were washed sequentially
with water (20 mL) and brine (20 mL) and dried over mag-
nesium sulfate. The solvent was removed by rotary evaporation
and the crude product was purified by column chromatogra-
phy (EtOAc:hexanes = 1:4) to give 9g (82 mg, 0.50 mmol,
80%) as colorless oil. Rf : 0.45 (EtOAc:hexanes = 1:4). IR
(neat, NaCl) cm–1: 3384 (s), 3063 (m), 2971 (s), 2932 (s),
2864 (s), 1557 (w), 1448 (m), 1372 (m), 1299 (s), 1250 (m),
1236 (m), 1174 (m), 1132 (m), 1112 (m), 1023 (w). 1H
NMR (CDCl3, 400 MHz) δ: 6.76 (m, 2H), 3.48 (m, 1H),
3.16 (m, 1H), 1.92 (s, 3H), 1.89 (dm, 1H, J = 5.7 Hz), 1.75
(dm, 1H, J = 5.7 Hz), 1.53 (br. s, 1H), 1.34 (s, 3H), 1.32
(s, 3H). 13C NMR (CDCl3, 100 MHz) δ: 150.3, 143.0, 142.9,
1
1015 (s). H NMR (CDCl3, 400 MHz) δ: 6.87 (dd, 1H, J =
4.9, 2.9 Hz), 6.79 (dd, 1H, J = 4.9, 2.9 Hz), 3.37 (br. s, 1H),
3.35 (br. s, 1H), 2.19 (dt, 1H, J = 6.0, 1.6 Hz), 2.01 (dt, 1H,
J = 5.6, 2.0 Hz), 1.75 (s, 3H). 13C NMR (CDCl3, 100 MHz)
δ: 143.6, 142.0(2), 139.6, 71.0, 56.3, 54.8, 13.7.
2-Iodo-3-methylnorbornadiene (9e)
tert-Butyllithium (0.97 mL, 1.7M, 1.65 mmol) was added
to a flame-dried flask containing bromide 8b (152 mg,
0.822 mmol) in THF (4 mL) at –78°C. After the yellow mix-
ture was stirred for 20 min, iodine (437 mg, 1.72 mmol) was
added at –78°C. The mixture was stirred at –78°C for
30 min then at room temperature for 1 h. After quenching
the mixture with saturated sodium thiosulfate (5 mL), the
aqueous layer was extracted with diethyl ether (3 × 10 mL),
and the combined organic layers were washed sequentially
with water (10 mL) and brine (10 mL) and dried over mag-
nesium sulfate. The solvent was removed by rotary evapora-
© 2000 NRC Canada

Tranmer et al.
535
141.9, 72.4, 70.0, 57.6, 52.5, 29.2, 28.8, 15.9. HRMS m/z
for C11H16O: calcd. 164.1201; found 164.1206.
Acknowledgements
We thank the Natural Sciences and Engineering Research
Council of Canada (NSERC) and the University of Guelph
for generous financial support of our program. GKT thanks
the Ontario government for a graduate scholarship.
2-(4-bromobutyl)-3-hexylnorbornadiene (9h)
tert-Butyllithium (7.50 mL, 1.7M, 12.8 mmol) was added
to a flame-dried flask containing bromide 8c (1.48 g,
5.80 mmol) in THF (30 mL) at –78°C. After stirring the
mixture for 1 h, the resulting yellow mixture was added to a
flame-dried flask containing 1,4-dibromobutane (4.50 mL,
37.7 mmol) in THF (30 mL) at –78°C. The mixture was
stirred at –78°C for 1 h then at room temperature for 12 h.
After quenching the mixture with water (100 mL), the aque-
ous layer was extracted with diethyl ether (4 × 50 mL), and
the combined organic layers were washed sequentially with
water (100 mL) and brine (100 mL) and dried over magne-
sium sulfate. The solvent was removed by rotary evaporation
and the excess 1,4-dibromobutane was removed by bulb-to-
bulb distillation (2.5 torr (1 torr = 133.322 Pa) at 65°C for
2 h) and the crude product was purified by column chroma-
tography (hexanes) to give 9h (980 mg, 3.15 mmol, 54%) as
colorless oil. Rf : 0.50 (EtOAc:hexanes = 1:9). IR (neat,
NaCl) cm–1: 3063 (w), 2960 (s), 2928 (s), 2857 (s), 1557
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2-methoxycarbonyl-3-(4-
tetrahydropyranyloxybutyl)norbornadiene (9i)
tert-Butyllithium (14.0 mL, 1.7M, 23.8 mmol) was added
to a flame-dried flask containing bromide 8d (3.00 g,
9.17 mmol) in THF (17.0 mL) at –78°C. After stirring the
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flame-dried flask containing methyl chloroformate (3.0 mL,
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1103 (m), 1074 (s), 1034 (s), 1022 (m). H NMR (CDCl3,
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1H), 3.69 (s, 3H), 3.50–3.48 (m, 2H), 3.37 (m, 1H), 2.76–
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© 2000 NRC Canada