Acetic Acid → Diethyl 2-methylidenecyclopropane-1,1-dicarboxylate

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Reaction Steps

Compound 5 (43.4 g, 0.156 mol) from Example 1 was added to a vigorously stirred refluxing solution of potassium tert-butoxide (17.5 g, 0.156 mol) in tert-butyl alcohol (500 mL) under nitrogen. The stirring was continued for 15 min. and the mixture was immediately cooled in an ice bath. Acetic acid was then added, the solid portion was filtered off and thoroughly washed with ether. The filtrate was concentrated in vacuo, diluted with ether and the organic layer was washed several times with water. After drying with magnesium sulfate, the solution was evaporated in vacuo and the residue was distilled, bp. 99-93° C./0.3 torr, yield 14.8 g (47%) of a 1:1 mixture of 4+6. This mixture was chromatographed on a silica gel column using first hexanes-ether (40:1) and then (20:1) to give product 6 (7.3 g, 23%) as a colorless liquid.

Provenance & Evidence