Reduction of Bridgehead Tosylates
371
was maintained with stirring for 30 min, after which time the
reaction mixture was allowed to warm to room temperature.
Hydrolysis was e ected by the addition of saturated ammonium
chloride (6 ml). The supernatant layer was separated and the
aqueous layer extracted with ether (2 15 ml). The combined
organic layers were washed with water, then dried (MgSO4)
and evaporated. The residual oil was distilled (Kugelrohr:
1 35–2 2, 11H, m. 13C n.m.r.
41 2, 95 4.
(CDCl3) 29 8, 31 0, 32 9,
Reduction of Norborn-1-yl Nitrate (21) with Tributyltin
Hydride
A solution of norborn-1-yl nitrate (21) (0 16 g, 1 mmol)
and tributyltin hydride (0 58 g, 2 mmol) in benzene (15 ml)
was heated under re ux in a nitrogen atmosphere. A solution
of , -azobis(isobutyronitrile) (0 5 g) in benzene (5 ml) was
added to the mixture during the course of re ux. After 48
h the mixture was cooled and evaporated giving an oil which
was chromatographed on silica. The fraction that eluted with
1 : 1 ether/hexane was distilled (Kugelrohr: 50 C/0 5 mm) and
shown by g.c.–m.s. analysis to consist of a 2 : 1 mixture of
4-methylcyclohexanone (22) and 3-ethylcyclopentanone (23),
by comparison with authentic samples, together with a trace
of norbornan-1-ol (9) (3%).
60 C/0 5 mm) to give 3-ethylcyclopentanone (0 5 g, 76%),
1
b.p. 158 C (lit.22 158 C).
1740 cm
(lit.23 1741 cm 1).
max
1H n.m.r. (CDCl3) 0 95, 3H, t, J 6 0 Hz; 1 15–2 8, 9H, m.
13C n.m.r. (CDCl3) 12 0, 28 25, 28 95, 38 3, 38 7, 44 8,
219 5.
cis/trans-3-Ethylcyclopentanol (11)
3-Ethylcyclopentanone was treated with lithium aluminium
hydride under standard conditions as described.24 Distillation
(Kugelrohr: 55 C/0 5 mm) gave a mixture of cis/trans-3-
ethylcyclopentanol. 1H n.m.r. (CDCl3) 0 87, 3H, t, J 6 0
Hz; 1 1–2 35, 9H, m; 3 6, 1H, s; 4 1–4 5, 1H, m. 13C n.m.r.
(CDCl3) 12 9, 28 9 and 29 4, 29 8 and 30 1, 35 0 and 35 1,
39 2 and 40 2, 41 95 and 42 1, 73 5.
Reaction of Norbornan-1-ol (9) with Iodobenzene Diacetate
and Iodine
A solution of norbornan-1-ol (0 17 g, 1 5 mmol), iodobenzene
diacetate (0 26 g, 0 8 mmol) and iodine (0 19 g, 0 75 mmol)
in cyclohexane (20 ml) was irradiated (300-W tungsten lamp)
while being heated under re ux for 30 min. The mixture was
cooled and washed with saturated sodium hydrogen carbonate
before being dried (MgSO4) and evaporated. Distillation of the
residual oil (Kugelrohr: 90–95 C/0 2 mm) a orded an 11 : 9
mixture (0 26 g) of 4-iodomethylcyclohexanone (19), which was
identi ed by comparison of its 1H and 13C n.m.r. spectra with
those of the authentic sample below, and a product tentatively
identi ed as 3-(2-iodoethyl)cyclopentanone (20) on the basis
of g.c.–m.s. analysis and its 13C n.m.r. spectrum: (CDCl3)
4 0, 26 9, 28 6, 38 3, 39 1, 44 0, 218 0.
The product was treated with tributyltin hydride in re uxing
benzene under standard conditions and worked up in the usual
manner to give an 11 : 9 mixture of 4-methylcyclohexanone (22)
and 3-ethylcyclopentanone (23) whose identities were estab-
lished by comparison of their 13C n.m.r. spectra with those of
authentic materials.
Treatment of Norbornan-1-ol (9) with Lithium Aluminium
Hydride
The alcohol (9) (0 07 g) was added to a solution of lithium
aluminium hydride (0 3 g) in tetrahydrofuran (25 ml) and
the mixture heated under re ux for 12 days. Workup as
described above gave a product shown to be starting material
(9) exclusively.
Norborn-1-yl Mesylate (17)
Methanesulfonyl chloride (0 63 g, 5 5 mmol) was added
dropwise to a solution of norbornan-1-ol (9) (0 50 g, 4 5 mmol)
in dichloromethane (15 ml) at 0 C. The mixture was stirred
at 0 C for 30 min, and then at ambient temperature for 1
h. Workup as outlined above for the tosylate (8) gave an oil
which, upon distillation (Kugelrohr: 120 C/0 05 mm), yielded
norborn-1-yl mesylate (17) (0 7 g, 82%) (Found: C, 50 9; H,
7 2. C8H14O3S requires C, 50 5; H, 7 4%). 1H n.m.r.
(CDCl3) 1 35–2 2, 11H, m; 3 0, 3H, s. 13C n.m.r. (CDCl3)
29 6, C 3,5; 32 7, C 4; 33 1, C 2,6; 41 95, C 7; 94 4, C 1.
4-Iodomethylcyclohexanone (19)
4-Tosyloxymethylcyclohexanone (5 6 g, 20 mmol) was added
to
a solution of sodium iodide (12 g, 20 mmol) in 1,2-
Reduction of Norborn-1-yl Mesylate (17)
dimethoxyethane (60 ml) and the mixture stirred at 65 C for
3 h and for a further 16 h at room temperature. Hexane
(300 ml) was added and the solution washed with water and
saturated sodium sulfate before being dried (MgSO4) and
evaporated. The solid residue was recrystallized from hexane
to give 4-iodomethylcyclohexanone (19) (4 3 g, 90%), m.p.
85 C (Found: C, 35 5; H, 4 7. C7H11IO requires C, 35 2; H,
4 7%). 1H n.m.r. (CDCl3) 1 2–2 5, 9H, m; 3 2, 2H, d, J 6
Hz. 13C n.m.r. (CDCl3) 12 3, 32 6, 38 2, 39 9, 210 7.
(A) With lithium aluminium hydride. Norborn-1-yl mesylate
(17) (0 14 g, 0 7 mmol) was added to a solution of lithium
aluminium hydride (0 3 g, 8 mmol) in dry tetrahydrofuran
(25 ml) and the mixture heated under re ux and monitored
by gas chromatography as before. The reaction was found to
be complete within 36 h. Workup in the usual manner gave a
product which was found by g.c.–m.s. analysis to consist solely
of norbornan-1-ol (9).
(B) With lithium aluminium hydride containing p-thiocresol.
The reaction in (A) was performed with added p-thiocresol
(0 18 g, 1 8 mmol). Analysis of the product so obtained
showed it to consist of norbornan-1-ol (9) exclusively.
Acknowledgment
We thank the Australian Research Council for
nancial support.
Norborn-1-yl Nitrate (21)
References
Norbornan-1-ol (0 4 g, 3 5 mmol) was added in small
portions to a solution of fuming nitric acid (3 ml) in acetic
anhydride (5 ml) cooled in ice and the mixture stirred for
1 h. The mixture was then added to cold (0 C) saturated
sodium hydrogen carbonate and extracted with ether, and the
combined ether extracts were dried (MgSO4) and evaporated.
The residue was chromatographed on silica; elution with hex-
ane a orded the nitrate as a colourless liquid. Distillation
(Kugelrohr: 25 C/0 5 mm) yielded norborn-1-yl nitrate (21)
(0 5 g, 89%) (Found: C, 53 2; H, 7 4; N, 9 1. C7H11NO3
1
Krishnamurthy, S., and Brown, H. C., J. Org. Chem., 1976,
41, 3064.
Dolby, L. J., and Rosencrantz, D. R., J. Org. Chem., 1963,
28, 1888.
Wang, S. S., and Sukenik, C. N., J. Org. Chem., 1985, 50,
653.
Gonzalez-Sierra, M., de los Angeles Laborde, M., and
Ruveda, E. A., Synth. Commun., 1987, 17, 431.
Seyden-Penne, J., Habert-Somny, A., and Cohen, A.-M.,
Bull. Soc. Chim. Fr., 1965, 32, 700.
2
3
4
5
requires C, 53 5; H, 7 1; N, 8 9%). 1H n.m.r.
(CDCl3)