Organic Syntheses, CV 5, 863
NORTRICYCLANOL
Submitted by J. Meinwald, J. Crandall, and W. E. Hymans
1.
Checked by J. R. Roland and B. C. McKusick.
1. Procedure
A.
Nortricyclyl acetate. A mixture of
156 g. (1.70 moles) of bicyclo[2.2.1]hepta-2,5-diene (Note
1),
105 g. (100 ml., 1.75 moles) of glacial acetic acid, and
3 ml. of boron trifluoride etherate (Note
2) is placed in a
500-ml. flask attached to a
condenser equipped with a drying tube. The mixture is heated on a
steam bath for 6 hours, cooled to room temperature, and diluted with
250 ml. of ether. The ethereal solution is washed successively with two
50-ml. portions of 3N ammonia and 50 ml. of water and dried over
magnesium sulfate. The
ether is removed by distillation through a
short column of glass helices, and the dark residue is distilled under reduced pressure to give about
200 g. of a mixture of
nortricyclyl acetate and bicyclo[2.2.1]hepta-5-en-2-yl acetate as a colorless liquid, b.p.
85–95° (15 mm.) (Note
3).
The acetate mixture is dissolved in
500 ml. of chloroform (analytical reagent grade) in a
2-l. Erlenmeyer flask equipped with a
thermometer and a
gas-inlet tube and located in a good
hood.
Caution! All operations using nitrosyl chloride should be performed in a good hood. The solution is cooled to −10° in an
ice-salt bath, and
nitrosyl chloride (Note
4) is bubbled into the solution with swirling at −10° ± 3° until the color of the solution changes through bright green to a brownish green that indicates excess
nitrosyl chloride. A white precipitate begins to form at this point. There is added
500 ml. of 30–60° petroleum ether, and the mixture is cooled at −10° ± 3° for an additional 15 minutes. The precipitated
nitrosyl chloride adduct (Note
5) is collected by suction filtration
(Caution! Hood). The filtrate is washed successively with two
200-ml. portions of saturated sodium carbonate solution and
500 ml. of saturated sodium chloride and dried over
magnesium sulfate. The solvent is removed through a short column of glass helices, and the dark residue is distilled under reduced pressure
(Caution! (Note 6)) to give
132–167 g. (
52–66%) of
nortricyclyl acetate as a faintly green liquid, b.p.
83–85° (13 mm.),
n25D 1.4673–1.4681 (Note
7).
B.
Nortricyclanol. The
nortricyclyl acetate obtained above is added to a solution of
0.5 g. of sodium in
500 ml. of anhydrous methanol (analytical grade reagent). The solution is heated on a steam bath, and the
methanol is slowly distilled through a short column packed with glass helices (Note
8). The residue is cooled, diluted with
250 ml. of 30–60° petroleum ether, and the solution is washed with two 50-ml. portions of water and dried over
magnesium sulfate. The solvent is removed by distillation through a short column packed with glass helices, finally at 25° and water-pump pressure. The crude product, which solidifies on cooling, is sublimed at 80° (2 mm.) to yield
84–107 g. (
45–57% based on
bicycloheptadiene; (Note
9)) of
nortricyclanol, m.p.
108–110°. It is pure enough for most purposes. A slightly purer product is obtained by resublimation (Note
10).
2. Notes
1.
Bicycloheptadiene supplied by Shell Chemical Corporation can usually be used without purification. If the material is cloudy or contains a precipitate, it should be distilled before being used.
2. The purified grade of Eastman Organic Chemicals is satisfactory. After the procedure had been checked, the submitters found that the use of only 1 ml. of this reagent gave the specified yield more consistently.
3. The exact proportion of unsaturated acetate varies slightly but is typically 10–15% as determined by vapor-phase chromatography.
5. The adduct may be recrystallized from
chloroform to give a white crystalline product, m.p.
152–153°.
6. The hot residue decomposes vigorously with the evolution of irritating gases when opened to the atmosphere. Consequently, the distillation flask should be cooled to room temperature before breaking the vacuum.
7. Vapor-phase chromatographic analysis of this product showed less than 1% of isomeric material.
8. The checkers used a
1.3-cm. × 25-cm. column of helices and removed the solvent over a period of about 5 hours.
9. The yield of
nortricyclanol from
nortricyclyl acetate is
82–95%.
10. Vapor-phase chromatography shows no detectable impurities under conditions where <1% of isomeric material would be easily visible. A melting point of
108–109° has been reported.
2
3. Discussion
The addition of carboxylic acids to
bicyclo[2.2.1]hepta-2,5-diene has been described by several authors;
3 4 5 6 the method described here is a modification of these procedures.
Nortricyclanol has been prepared by the hydration of
bicyclo[2.2.1]hepta-2,5-diene7 and the solvolysis of nortricyclyl
2 and bicyclo[2.2.1]hept-2-en-5-yl
8 halides, as well as by the saponification
3,
9 and transesterification
5 of the corresponding esters. The described conversion of the acetate to the alcohol is patterned after a similar procedure of Hall.
5
4. Merits of the Preparation
The present preparation affords high-purity
nortricyclanol in good yield without the necessity of tedious purification. It illustrates a convenient way to convert olefins to alcohols and to remove olefinic impurities from alcohols.
Nortricyclanol is of current interest in studies of highly strained ring systems. It is readily oxidized to
nortricyclanone.
10
This preparation is referenced from:
Copyright © 1921-2002, Organic Syntheses, Inc. All Rights Reserved