Org. Synth. 1961, 41, 72
DOI: 10.15227/orgsyn.041.0072
NORCARANE
[Bicyclo[4.1.0]heptane]
Submitted by R. D. Smith and H. E. Simmons
1.
Checked by William E. Parham and M. D. Bhavsar.
1. Procedure
A. Zinc-copper couple. In a 500-ml. Erlenmeyer flask fitted with a magnetic stirrer are placed 49.2 g. (0.75 g. atom) of zinc powder (Note 1) and 40 ml. of 3% hydrochloric acid. The mixture is stirred rapidly for 1 minute, then the supernatant liquid is decanted. In a similar manner, the zinc powder is washed successively with three additional 40-ml. portions of 3% hydrochloric acid, five 100-ml. portions of distilled water, two 75-ml. portions of 2% aqueous copper sulfate solution, five 100-ml. portions of distilled water, four 100-ml. portions of absolute ethanol, and five 100-ml. portions of absolute ether (Note 2). The couple is finally transferred to a Büchner funnel, washed with additional anhydrous ether, covered tightly with a rubber dam, and suction-dried until it reaches room temperature. The zinc-copper couple is stored overnight in a vacuum desiccator over phosphorus pentoxide and is then ready for use in the preparation of norcarane (Note 3).
B.
Norcarane. In a
500-ml. round-bottomed flask fitted with a magnetic stirrer and a
reflux condenser protected by a
drying tube filled with Drierite are placed
46.8 g. (0.72 g. atom) of zinc-copper couple and
250 ml. of anhydrous ether. A crystal of
iodine is added, and the mixture is stirred until the brown color has disappeared
(Note 4). A mixture of
53.3 g. (0.65 mole) of cyclohexene and
190 g. (0.71 mole) of methylene iodide is added in one portion
(Note 5). The reaction mixture is then heated under gentle reflux with stirring. After 30–45 minutes, a mildly exothermic reaction occurs which may require cessation of external heating. After the exothermic reaction has subsided (approximately 30 minutes), the mixture is stirred under reflux for 15 hours. At the end of this time, most of the gray couple has been converted to finely divided
copper. The
ether solution is decanted
(Note 6) from the
copper and unreacted couple, which are then washed with two
30-ml. portions of ether. The washes are combined with the bulk of the solution and shaken with two
100-ml. portions of saturated ammonium chloride solution
(Note 7),
100 ml. of saturated sodium bicarbonate solution, and 100 ml. of water. The
ether solution is dried over anhydrous
magnesium sulfate and filtered. The
ether is distilled through a
20 × 2-cm. column packed with glass helices. The residue is distilled through a
45-cm. spinning-band column2 to give
35–36 g. (
56–58%) of
norcarane, b.p.
116–117°,
nD25 1.4546
(Note 8).
2. Notes
1.
Mallinckrodt A. R. zinc dust was found satisfactory for this preparation. The checkers used
Merck zinc dust but found it necessary to start with
51 g. of zinc in order to obtain sufficient couple for the next step.
2.
The washings with
hydrochloric acid should be done rapidly to avoid adsorption of bubbles of
hydrogen on the
zinc which make subsequent washings more difficult. The use of a magnetic stirrer greatly facilitates the washings. The absolute
ethanol and absolute
ether washings are decanted directly on a Büchner funnel to prevent loss of the couple.
3.
This method of preparing
zinc-copper couple is essentially that of Shank and Shechter.
3 An equally active couple can be prepared by reduction of
cupric oxide in the presence of
zinc powder.
4 Mallinckrodt A. R. wire-form cupric oxide (30 g.) is ground to a powder in a
mortar and mixed with
240 g. of Mallinckrodt A. R. zinc dust. The mixture is placed in a Vycor combustion boat lined with copper foil, and a
thermocouple is imbedded in the powder. The boat is placed in a
Vycor tube heated by a muffle furnace. A mixed gas (
hydrogen, 65 l. per hour;
nitrogen, 25 l. per hour) is passed through the tube while the temperature is raised to 500° during 4 hours. The mixture is kept at 500° for 30 minutes, and the tube is then allowed to cool to room temperature in a
hydrogen atmosphere. The
zinc-copper couple is obtained as dark gray lumps, which are ground to a fine powder in a mortar before use. In some instances, there is also found in the mixture a small amount of material which has apparently melted and agglomerated during heating. This shiny, metallic material is easily separated from the powdered couple and is not used in the preparation of
norcarane.
4.
The addition of
iodine appears to promote the subsequent reaction of the
zinc-copper couple with
methylene iodide.
5.
Commercial
cyclohexene (Eastman Kodak) was distilled and passed over a
column of activated alumina just before use.
Methylene iodide (Matheson, Coleman and Bell) was distilled under reduced pressure, b.p.
50–51°/7 mm., and was stored in a
brown bottle over iron wire.
6.
The checkers filtered the solution because the finely divided
copper and unreacted couple did not settle completely.
7.
Care must be taken when adding the
ammonium chloride solution to the
ether solution since considerable heat is generated.
8.
About
10–12 g. of
cyclohexene, b.p.
82–84°, is recovered. The intermediate fraction, b.p. 84–116°, amounts to 1.5–2.5 g., and 10–12 g. of a dark residue remains in the still pot.
3. Discussion
This method is generally applicable to the stereospecific synthesis of
cyclopropane derivatives from a large variety of substituted olefins.
4Three methods have been employed to generate
iodomethylzinc iodide, the intermediate active in cyclopropanation: (1)reaction of
methylene iodide with a
zinc-copper couple in an
ether solvent;
4 (2) reaction of
diazomethane with
zinc iodide in an
ether solvent;
5 (3) reaction of
methylene iodide with
diethylzinc in
ether or hydrocarbon solvents.
6 Method (1) has been used more extensively to prepare cyclopropanes from olefins because it is generally the simplest, most convenient, and most economical variation when applicable.
7 An active
zinc-copper couple has been reported that is easily prepared and is recommended for the cyclopropanation reaction.
8Norcarane has been prepared by the reduction of
7,7-dichloronorcarane with
sodium and alcohol,
9 and by the light-catalyzed reaction of
diazomethane with
cyclohexene.
9 The reaction of
cyclohexene with
methylene iodide and
zinc-copper couple represents the most convenient preparation of
norcarane which is of high purity.
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
zinc-copper couple
ethanol (64-17-5)
hydrochloric acid (7647-01-0)
ether (60-29-7)
ammonium chloride (12125-02-9)
hydrogen (1333-74-0)
sodium bicarbonate (144-55-8)
Cyclohexene (110-83-8)
nitrogen (7727-37-9)
copper sulfate (7758-98-7)
copper (7440-50-8)
iodine (7553-56-2)
zinc,
zinc powder (7440-66-6)
sodium (13966-32-0)
cupric oxide (1317-38-0)
Methylene iodide (75-11-6)
diethylzinc (557-20-0)
cyclopropane (75-19-4)
magnesium sulfate (7487-88-9)
Diazomethane (334-88-3)
zinc iodide
Norcarane,
Bicyclo[4.1.0]heptane (286-08-8)
iodomethylzinc iodide
7,7-dichloronorcarane (823-69-8)
phosphorus pentoxide (1314-56-3)
Copyright © 1921-, Organic Syntheses, Inc. All Rights Reserved