Organic Syntheses, Coll. Vol. 5, p.755 (1973); Vol. 49, p.78 (1969).
A. Dimethyloxosulfonium methylide (Note 1)
. In a 500-ml., three-necked, round-bottomed flask with a magnetic stirrer (Note 2)
are placed 8.8 g. (0.22 mole) of sodium hydride (60% oil dispersion) (Note 3)
and 150 ml. of petroleum ether
(30–60°). The suspension is stirred, the hydride allowed to settle, the petroleum ether
decanted (Note 4)
, and 250 ml. of dry dimethyl sulfoxide (Note 5)
is added. The flask is immediately fitted with an inlet and outlet for nitrogen
and a piece of Gooch tubing connected to a 125-ml. Erlenmeyer flask
containing 50.6 g. (0.23 mole) of trimethyloxosulfonium iodide (Note 6)
. A gentle stream of dry nitrogen
is then continuously passed through the system. With stirring, the oxosulfonium iodide is added, in portions, over a period of 15 minutes (Note 7)
and stirring is then continued for an additional 30 minutes (Note 8)
B. Methylenecyclohexane oxide
. The Gooch tubing is removed from the reaction flask and immediately replaced with a sealed, pressure-compensated dropping funnel
containing 19.6 g. (0.2 mole) of cyclohexanone (Note 9)
, which is then added to the reaction mixture over a 5-minute period. After stirring for 15 minutes, the reaction mixture is heated to 55–60° for 30 minutes with an oil bath
and then poured into 500 ml. of cold water and extracted with three 100-ml. portions of ether
. The combined ether
extracts are washed with 100 ml. of water, then with 50 ml. of saturated aqueous salt solution, dried over anhydrous sodium sulfate
, and the ether
is distilled at atmospheric pressure through a 20-cm. Vigreux column
. The almost colorless residue is transferred to a 50-ml. round-bottomed flask
and distilled under reduced pressure through a 5-cm. Vigreux column
to yield 15–17 g.
) of the oxide as a colorless liquid, b.p. 61–62° (39 mm.)
1.4485 (Note 10)
. The n.m.r. spectrum (CDCl3
Si internal standard) showed a band at δ 1.58 (10H) and a sharp singlet at δ 2.53 (2H).
The reaction should be carried out in a well-ventilated hood
The submitters used a mechanical stirrer, but the checkers found that the more convenient magnetic stirrer works as well.
The submitters used Alfa Inorganics Inc. sodium hydride
The petroleum ether
removes most of the oil from the hydride dispersion.
Matheson, Coleman and Bell anhydrous dimethyl sulfoxide
was stirred over powdered calcium hydride
overnight and then distilled under reduced pressure, b.p. 64–65° (4 mm.)
. Dimethyl sulfoxide
should not be distilled at temperatures above 90° since at these higher temperatures appreciable disproportionation occurs producing dimethyl sulfone
and dimethyl sulfide
, the latter of which contaminates the distilled solvent.
The reaction is only mildly exothermic. No cooling is necessary.
After this time the evolution of hydrogen
is essentially complete.
Eastman Kodak white label cyclohexanone
was used without further purification.
Reported physical constants are b.p. 62–63° (37 mm.)
b.p. 66–68° (50 mm.) n20D
This reaction illustrates a general method for the conversion of ketones and aldehydes8
into oxiranes using the methylene-transfer reagent dimethyloxosulfonium methylide
. The yields of oxiranes are usually high, and the crude products, in most cases, are of sufficient purity to be used in subsequent reactions (e.g.
, rearrangement to aldehydes) without further purification.
This preparation is referenced from:
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