Org. Synth. 1968, 48, 25
DOI: 10.15227/orgsyn.048.0025
BICYCLO[2.2.1]HEPTEN-7-ONE
[2-Norbornen-7-one]
Submitted by P. G. Gassman and J. L. Marshall
1.
Checked by William G. Dauben and James L. Chitwood.
1. Procedure
Into a 250-ml. Erlenmeyer flask are placed 45.9 g. (0.298 mole) of 7,7-dimethoxybicyclo[2.2.1]heptene (Note 1), 75 ml. of 5% aqueous sulfuric acid, and a Teflon-coated magnetic stirring bar. The flask is stoppered, and the mixture is stirred vigorously with a magnetic stirrer for 20 hours. The mixture is extracted with three 40-ml. portions of pentane, and the combined extracts are dried over anhydrous magnesium sulfate. The drying agent is removed by filtration, and the solvent is distilled through a 12-in. Vigreux column. Fractional distillation of the residual oil yields 28.9 g. (90%) of colorless bicyclo[2.2.1]hepten-7-one, b.p. 96–100° (115 mm.), n25D 1.4786 (Note 2) and (Note 3).
2. Notes
1.
The preparation of
7,7-dimethoxybicyclo[2.2.1]heptene is described on
p. 424.
2.
The checkers, working at half-scale, obtained an
85% yield of product, b.p.
93–97° (118 mm.).
3.
This material is extremely volatile and should be handled with care.
3. Discussion
Bicyclo[2.2.1]hepten-7-one has been prepared by the oxidation of
anti-7-hydroxybicyclo[2.2.1]heptene with
chromic acid in
acetone2 and with
aluminum t-butoxide in
benzene with
benzoquinone as the
hydrogen acceptor.
3 The procedure described here is essentially that of Gassman and Pape.
4
4. Merits of the Preparation
Bicyclo[2.2.1]hepten-7-one is a useful intermediate in the synthesis of a variety of norbornane derivatives. The present procedure involves a four-step synthesis from
hexachlorocyclopentadiene with a 39% overall yield. The next best method
3 involves a four-step synthesis from
norbornadiene with a 15% overall yield.
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
sulfuric acid (7664-93-9)
Benzene (71-43-2)
hydrogen (1333-74-0)
acetone (67-64-1)
chromic acid (7738-94-5)
Pentane (109-66-0)
benzoquinone (106-51-4)
magnesium sulfate (7487-88-9)
Bicyclo[2.2.1]hepten-7-one,
2-Norbornen-7-one (694-71-3)
7,7-Dimethoxybicyclo[2.2.1]heptene (875-04-7)
hexachlorocyclopentadiene
norbornadiene
anti-7-hydroxybicyclo[2.2.1]heptene
aluminum t-butoxide
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