Reductive dehalogenation of 1,3-dibromoadamantane by sodium methoxide in methanol

Full text of DOI:10.1134/S1070363211090325

ISSN 1070-3632, Russian Journal of General Chemistry, 2011, Vol. 81, No. 9, pp. 1913–1914. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © M.Yu. Skomorokhov, Yu.N. Klimochkin, 2011, published in Zhurnal Obshchei Khimii, 2011, Vol. 81, No. 9, pp. 1576–1577.
LETTERS
TO THE EDITOR
Reductive Dehalogenation of 1,3-Dibromoadamantane
by Sodium Methoxide in Methanol
M. Yu. Skomorokhov and Yu. N. Klimochkin
Samara State Technical University, ul. Molodogvardeiskaya 244, Samara, 443010 Russia
e-mail: orgchem@samgtu.ru
Received April 18, 2011
DOI: 10.1134/S1070363211090325
The reaction of 1,3-dihaloadamantanes with glycols
in the presence of a strong base have been found to
give vinyl ethers and spirodioxolanes of bicycle-
[3.3.1]nonane series [1]. Aiming to synthesize new 3-
The reaction of 1,3-dibromadamantane with 30%
solution of sodium methoxide in methanol at 175°C
affords a mixture of 1-methoxyadamantane II and
adamantane III (88 and 12%, respectively, according
to GLC). The target 3-methoxy-7-methylenebicyclo
[3.3.1]non-2-ene IV was not found in the reaction
products.
alkoxy-7-methylenebicyclo[3.3.1]non-2-ene,
we
studied the reaction of 1,3-dibromadamantane I with
the primary alcohols in the presence of a strong base.
OCH3
Br
CH3OH
OCH3
CH3OH
+
Br
CH3ONa
CH3ONa
I
III
II
IV
The formation of 1-methoxyadamantane proceeds
probably via the stage of 3-bromadamant-1-
ylcarbenium ion A formation. This ion is highly
reactive due to the negative inductive effect of the
bromine atom and is able to detach a hydride ion from
the methoxy anion to form the 1-bromoadamantane .
The latter is converted into the methoxyadamantane II
by the SN1 reaction. Adamantane III formation is
probably due to the elimination of the hydride ion from
the methoxide anion formed at the solvolysis of 1-
bromoadamantane with adamant-1-ylcarbenium ion.
The relative ease of the elimination of the hydride ion
from the methoxide anion may be due to the fact that
the latter forms a stable neutral molecule of formal-
dehyde. The intermolecular hydride transfer in a basic
media is very rare. Only one example of such
transformation of adamantane derivatives was reported
[2].
Br
Br
Br
CH3O−
CH3O−
CH3OH
CH3OH
+
+
Br
−CH2O
−CH2O
−Br−
III
А
I
CH3OH
OCH3
II
1913

1914
SKOMOROKHOV, KLIMOCHKIN
spectrum, m/z (Irel, %): 166 [M+] (24), 135 (10), 109
Dibromide I does not react with ethanol, 1-butanol,
and benzyl alcohol at 175°C in the presence of sodium
alkoxide.
(100), 40 (20).
The NMR spectra were recorded on a Bruker AC-
200 spectrometer operating at 200 MHz (CDCl3). The
mass spectra (EI, 70 eV) were registered on a Finnigan
MAN JNCOS50 spectrometer. The GLC analysis was
carried out on a Tsvet-100 chromatograph with a flame
ionization detector and 25 m quartz capillary column
using a stationary phase SE-30, carrier gas – helium.
To a solution of 28 g (1.22 mol) of sodium in 200 ml
of methanol was added 84 g (0.28 mol) of 1,3-di-
bromoadamantane I. The mixture was heated in a
pressure reactor at 175°C for 24 h, poured into water,
and extracted with chloroform. The organic layer was
washed with water, dried over anhydrous sodium
sulfate, and concentrated. The residue was purified by
the column chromatography on silica gel eluting with
petroleum ether to give compounds II and III.
REFERENCES
1. Skomorokhov, M.Yu. and Klimochkin, Yu.N., Zh. Org.
Khim., 2001, vol. 37, p. 1096.
2. Yurchenko, A.G., Isaev, S.D., Murzinova, Z.R., and
Chernyakhovskaya, E.E., Zh. Org. Khim., 1972, vol. 8,
p. 2617.
3. Alper, P., J. Org. Chem., 1977, no. 42, p. 3522.
4. Baklan, V.F., Hil’chevskii, A.N., and Kukhar’, V.P., Zh.
Org. Khim., 1984, vol. 20, p. 2238.
Adamantane (III). Yield 3.6 g (9%), mp 265–267°C
(mp 266–268°C [3]).
1-Methoxyadamantane (II). Yield 5.28 g (61%),
bp 90–92°C (5 mm Hg), nD20 1.4990 (nD20 1.4971 [4]).
1H NMR spectrum, δ, ppm: 1.62 s (6H, Ad), 1.73 s
(6H, Ad), 2.13 s (3H, Ad), 3.32 s (3H, OCH3). Mass
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 9 2011