Synthesis, Reactions, and Properties of 2,8-Didehydronoradamantane Derivatives
FULL PAPER
vacuo and filtered through a short column of alumina (activity I),
with pentane as the eluant, to give 11 mg (21%) of hydrocarbon 9
as a very volatile substance. An analytical sample (waxy solid) was
obtained by sublimation at atmospheric pressure and at room tem-
1.5 mL of dry ether was then added dropwise. The dry-ice/acetone
bath was replaced with an ice/water bath and the reaction mixture
was stirred for 8 h. After evaporation of the NH3, solid NH4Cl was
added to destroy the excess Li and then 20 mL of water was added.
perature using a dry-ice finger-trap. Ϫ IR (KBr): ν˜ ϭ 3030 cmϪ1 The mixture was extracted with ether (3ϫ 10 mL) and the com-
1
(w), 2930 (s), 2850 (m). Ϫ H NMR (CDCl3): δ ϭ 1.20Ϫ1.80 (m, bined extracts were dried with anhydrous MgSO4. After evapor-
5 H), 2.45Ϫ2.74 (m, 4 H), 3.00 (m, 1 H), 5.88 (dd, J ϭ 8.8 and 6.2
ation of the solvent the residue was chromatographed on silica gel,
with 0Ϫ10% of ether in pentane as the eluant, to give 16 mg (26%)
Hz, 1 H), 6.32 (dd, J ϭ 8.8 and 8.4 Hz, 1 H). Ϫ 13C NMR (CDCl3):
δ ϭ 34.3 (d), 35.9 (t, 2 C), 37.3 (d), 37.9 (d), 38.5 (d), 40.2 (t), 131.9 of tricyclo[4.2.1.03,8]nonan-5-one (7) as a waxy solid and 9 mg of
(d), 137.4 (d). Ϫ HRMS: calcd. for C9H12 120.093900; found
starting ketone 2.
120.093831.
Tricyclo[4.2.1.03,8]nonan-5-ols (8): A solution of 135 mg (1.0 mmol)
of ketone 7 in 10 mL of dry ether was added to a stirred suspension
of 38 mg (1.0 mmol) of LiAlH4 in 10 mL of dry ether. The reaction
mixture was refluxed for 5 h, cooled to room temp., and diluted
with 7 mL of ether. The excess LiAlH4 was destroyed by careful
addition of water (30 mL). The ether layer was separated and the
aqueous layer was extracted with ether (3ϫ 20 mL). The ether ex-
tracts were combined and dried with anhydrous MgSO4. The sol-
vent was evaporated and the residue sublimed (60°C, 14 mbar) to
afford 90 mg (70%) of a mixture of endo- and exo-alcohols 8 in a
92:8 ratio[16]. The ratio of isomers was determined by integration
Reduction of Tosylhydrazone 4 with NaBH3CN/pTsOH/HMPA: A
solution of 300 mg (1.0 mmol) of tosylhydrazone 4, 315 mg (5
mmol) of NaBH3CN, 50 mg of pTsOH and 5 mL of HMPA was
heated at 180°C for 5 h. During this time the product sublimed.
The sublimate was washed off with CDCl3 directly into an NMR
tube and identified, by comparison of its H- and 13C-NMR spec-
1
tra with the spectra of an authentic sample, as tricy-
clo[4.2.1.03,8]non-4-ene (9).
Wolff؊Kishner Reduction of 2,8-Didehydronoradamantan-9-one (2):
A solution of 200 mg (1.5 mmol) of ketone 2, 10 mL of diethylene
glycol, 0.4 mL (8.0 mmol) of 98Ϫ100% hydrazine hydrate and 280
mg (5.0 mmol) of KOH was heated at 100°C for 2 h and then at
210°C for 5 h. During this time the product sublimed. The subli-
mate was dissolved in pentane (20 mL) and dried with anhydrous
MgSO4. The pentane was evaporated to give 120 mg (67%) of 2,8-
didehydronoradamantane (10) as a white waxy solid. Ϫ IR (KBr):
ν˜ ϭ 3040 cmϪ1 (w), 3010 (w), 2960 (s), 2920 (s), 2850 (s), 1435 (m),
1290 (m), 1255 (m), 875 (s), 770 (s), 720 (m). Ϫ 1H NMR (CDCl3):
δ ϭ 0.72 (br.s, 1 H, 1-H), 0.93Ϫ1.01 (m, 2 H, 4-Hexo and 6-Hexo),
1.39 (d, 2 H, J ϭ 11.7 Hz, 4-Hendo and 6-Hendo), 1.55Ϫ1.59 (m, 2
H, 2-H and 8-H), 1.88 (br.s, 2 H, 9-H), 2.20 (br.s, 1 H, 5-H), 2.64
(br.s, 2 H, 3-H and 7-H). Ϫ 13C NMR (CDCl3): δ ϭ 12.9 (d, 1 C,
C-1), 18.0 (d, 2 C, C-2 and C-8), 29.2 (t, 1 C, C-9), 33.2 (t, 2 C, C-
4 and C-6), 33.7 (d, 2 C, C-3 and C-7), 35.0 (d, 1 C, C-5). Ϫ C9H12
(120.2): calcd. C 89.93, H 10.07; found C 89.73, H 10.12.
1
of the signals at δ ϭ 4.38 and δ ϭ 4.06 in the H-NMR spectrum
1
of the mixture of isomers. The isomers were not separated. Ϫ H
NMR (CDCl3) of the mixture of isomers: δ ϭ 1.20Ϫ1.55 (m),
1.82Ϫ1.92 (m), 1.98 (d, J ϭ 13.5 Hz), 2.16Ϫ2.20 (m), 2.35Ϫ2.47
(m), 2.50Ϫ2.60 (m), 2.71Ϫ2.77 (m), 4.06 (dd, J ϭ 8.1 and 7.9 Hz,
H-COH of exo-8), 4.38 (dd, J ϭ 7.8 and 7.6 Hz, H-COH of endo-
8). Ϫ 13C NMR (CDCl3) of endo-8: δ ϭ 30.6 (t), 31.1 (t), 31.2 (d),
31.7 (t), 32.4 (t), 34.4 (d), 36.3 (d), 41.4 (d), 70.2 (d). Ϫ 13C NMR
(CDCl3) of exo-8: δ ϭ 28.1 (t), 28.6 (d), 30.9 (t), 32.0 (t), 34.8 (d),
37.0 (d), 38.4 (t), 45.3 (d), 73.2 (d).
Dehydration of Tricyclo[4.2.1.03,8]nonan-5-ols (8): A solution of 75
mg (0.55 mmol) of alcohols 8 in 2 mL of HMPA was heated at
230°C for 20 h, cooled to room temp., diluted with 50 mL of pen-
tane, and washed with water (3ϫ 25 mL). The pentane layer was
dried with anhydrous MgSO4. Evaporation of the solvent afforded
16 mg (24%) of tricyclo[4.2.1.03,8]non-4-ene (9).
Photochemically Induced Electron Transfer Reduction of Ketone 2:
A solution of 83 mg (0.61 mmol) of 2,8-didehydronoradamantan-
9-one (2), 0.88 mL (6.1 mmol) of Et3N and 67 mg (0.61 mmol) of
LiClO4 in 22.5 mL of dry CH3CN was irradiated during 24 h in a
Rayonet reactor equipped with sixteen 254 nm lamps. The solvent
was evaporated and the residue was chromatographed on silica gel
using 0Ϫ10% of diethyl ether in pentane as the eluant. The first
chromatography fractions afforded 46 mg (56%) of tricy-
clo[4.2.1.03,8]nonan-5-one (7) as a waxy solid. Subsequent elution
afforded 22 mg of the starting ketone 2. Spectral data for tricy-
clo[4.2.1.03,8]nonan-5-one (7): Ϫ IR (KBr): ν˜ ϭ 2940 cmϪ1 (s), 2850
(m), 1720 (s, CϭO). Ϫ 1H NMR (CDCl3): δ ϭ 1.05 (m, 1 H), 1.56
(ddd, J ϭ 12.9, 4.3 and 4.2 Hz, 1 H), 1.69 (d, J ϭ 13.2 Hz, 1 H),
1.92Ϫ1.98 (m, 2 H with distinguishable doublet at 1.94, J ϭ 12.9
Hz), 2.18 (d, J ϭ 17.0 Hz, 1 H), 2.47 (dd, J ϭ 17.0 and 5.0 Hz, 1
H), 2.53Ϫ2.69 (m, 3 H), 2.87 (m, 1 H), 3.11 (m, 1 H). Ϫ 13C NMR
(CDCl3): δ ϭ 26.8 (d), 30.7 (t), 33.4 (t), 34.7 (d), 36.5 (d), 38.1 (t),
40.4 (t), 52.4 (d), 217.2 (s). Ϫ HRMS: calcd. for C9H12O
136.088815; found 136.089139.
2,2-Dichlorobrend-4-ene (16): To a cooled (ice/water) solution of 50
mg (0.37 mmol) of brend-4-en-2-one (1) in 2 mL of CCl4 was added
120 mg (0.58 mmol) of PCl5. The reaction mixture was stirred over-
night at room temp., and then poured into 30 mL of cold water.
The mixture was extracted with ether (3ϫ 15 mL) and the com-
bined extracts were dried with anhydrous MgSO4. After evapo-
ration of the solvent the residue was filtered through a column of
silica gel, with pentane as the eluant, to give 30 mg (43%) of 2,2-
dichlorobrend-4-ene (16) as a waxy solid. Ϫ IR (KBr): ν˜ ϭ 3060
(w) cmϪ1, 2970 (s), 2880 (w), 2860 (w), 1470 (m), 1445 (m), 950
(m), 850 (s), 770 (s), 750 (s), 720 (s). Ϫ 1H NMR (CDCl3): δ ϭ
1.57 (m, 1 H), 1.64 (d, J ϭ 11.0 Hz, 1 H), 1.77 (d, J ϭ 12.9 Hz, 1
H), 2.32 (d, J ϭ 11.0 Hz, 1 H), 2.48 (m, 1 H), 2.84 (br.s, 1 H), 3.09
(br.s, 2 H), 5.90 (dd, J ϭ 5.4 and 3.0 Hz, 1 H), 6.18 (dd, J ϭ 5.4
and 3.1 Hz, 1 H). Ϫ 13C NMR (CDCl3): δ ϭ 32.8 (t), 35.4 (t), 41.4
(d), 53.8 (d), 59.0 (d), 61.2 (d), 95.8 (s), 134.2 (d) 141.3 (d). Ϫ
HRMS: calcd. for C9H10Cl2 188.015956; found 188.015777.
Electron Transfer Reduction of Ketone 2 with Li/NH3: A two-necked
flask was fitted with a dry-ice reflux condenser and the flask was
Acknowledgements
immersed into a dry-ice/acetone bath. A gentle stream of NH3 gas We gratefully acknowledge the support of the project by the Minis-
was passed through the apparatus until 7 mL of liquid NH3 was
collected. To the liquid ammonia was added 42 mg of Li metal, in
small pieces, until an intense blue color was obtained. A solution
try of Science and Technology of the Republic of Croatia and, in
a part, by U. S.ϪCroatia Joint Fund, JF 141, in cooperation with
the National Science Foundation and the Ministry of Science and
of 70 mg (0.52 mmol) of 2,8-didehydronoradamantan-9-one (2) in Technology.
Eur. J. Org. Chem. 1999, 1401Ϫ1406
1405