Org. Synth. 1968, 48, 106
[2-Norbornanone, 7,7-dimethyl-1-vinyl-, D-]
Submitted by Nikolaus Fischer1
and G. Opitz2
Checked by Hermann Ertl, Ian D. Rae, and Peter Yates.
is both explosive and poisonous, and all operations involving its preparation and use must be carried out in a hood
. Follow the directions for its handling given in earlier volumes.3,4
In a 500-ml. three-necked flask equipped with a mechanical stirrer, a dropping funnel, and a reflux condenser fitted with a potassium hydroxide drying tube are placed 7.0 g. (0.069 mole) of triethylamine (Note 1) and a solution of 3.15 g. (0.075 mole) of diazomethane in 200 ml. of ether (Note 2). The flask is cooled in an ice bath, and a solution of 13.0 g. (0.052 mole) of D-camphor-10-sulfonyl chloride (Note 3) in 75 ml. of anhydrous ether is added dropwise over a period of 1 hour. Triethylamine hydrochloride slowly precipitates. The reaction mixture is stirred for an additional 30 minutes and then concentrated to ca. 150 ml. under reduced pressure (water aspirator) with continued stirring to remove the excess of diazomethane. The mixture is filtered under reduced pressure; the precipitate is washed with 50 ml. of anhydrous ether, giving 6.7 g. (94%) of triethylamine hydrochloride. The combined filtrate and washings are freed of solvent on a rotary evaporator at room temperature to give 10.7 g. (90%) of crude episulfone, m.p. 76–85° (dec.) (Note 4). This is used without purification in the next step; it can be purified by crystallization from a little methanol at −20°. This gives colorless episulfone, m.p. 83–85° (dec.), [α]24D −6.72° (methanol, c = 3.20); infrared bands at 3070, 1300, and 1170 cm.−1 (Note 5).
The crude episulfone (3.0 g.) is placed in a 10-ml. round-bottomed flask fitted with a reflux condenser and is heated at 95° for 30 minutes, when it decomposes with loss of sulfur dioxide. The reflux condenser is replaced with a distillation head (Note 6), and the yellow residue is distilled under reduced pressure (water aspirator). D-2-Oxo-7,7-dimethyl-1-vinylbicyclo[2.2.2]heptane (1.7 g., 71% based on sulfonyl chloride), b.p. 95–96° (10 mm.), distills at a bath temperature of 110–120°. Sublimation at 60° (0.01 mm.) gives the olefin as colorless, waxy crystals, m.p. 64–65°, [α]25D +16.35° (methanol, c = 2.16); infrared band at 1650 cm.−1.
was purified by treatment with naphthyl isocyanate
and distilled; the distillate was stored over sodium wire
The ethereal diazomethane
was prepared from N-nitrosomethylurea
and aqueous potassium hydroxide
and dried over potassium hydroxide
pellets for 2–3 hours. The solid potassium hydroxide
was replaced once or twice to ensure complete dryness. The checkers used the procedure of Arndt5
for this preparation and for the estimation of the diazomethane
can be prepared from commercially available D-camphor-10-sulfonic acid
and phosphorus pentachloride6
or thionyl chloride
The checkers used the following procedure. D-Camphor-10-sulfonic acid (50.0 g.)
was added slowly to 50 g. of thionyl chloride
. The mixture was boiled under reflux until homogeneous and then for a further 2 hours. The solution was cooled and poured onto ca.
500 g. of crushed ice. The crude product (51.1 g.
) was filtered and crystallized twice from hexane
to give the sulfonyl chloride, m.p. 65–67.5°
; yield, 35.5 g.
The checkers obtained higher yields (94–97%
) of less pure material [m.p. 50–78°
The checkers observed that the episulfone
decomposed slowly at room temperature and, on one occasion, during evaporation at 15°.
The checkers found it advisable to use an apparatus with a wide-bore side arm (18 mm.) without a condenser.
The only method reported for the preparation of D-2-oxo-7,7-dimethyl-1-vinylbicyclo[2.2.1]heptane
is that of the present procedure.8,9
4. Merits of the Preparation
The method is of general applicability8,9
for the synthesis of olefins. Other sulfonyl chlorides, RCH2
Cl, have been used where R = H, C2
, and C6
; other diazoalkanes that have been used are diazoethane
. In all cases the olefins form without double-bond migration. A review9
of the method is available.
This preparation is referenced from:
Chemical Abstracts Nomenclature (Collective Index Number);
phosphorus pentachloride (10026-13-8)
thionyl chloride (7719-09-7)
sulfur dioxide (7446-09-5)
potassium hydroxide (1310-58-3)
sodium wire (13966-32-0)
Triethylamine hydrochloride (554-68-7)
naphthyl isocyanate (86-84-0)
D-camphor-10-sulfonyl chloride (6994-93-0)
2-Norbornanone, 7,7-dimethyl-1-vinyl-, D- (53585-70-9)
D-camphor-10-sulfonic acid (3144-16-9)
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