Diethyl methylmalonate → Diethyl 2-methyl-2-(pent-4-ynyl)malonate

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Reaction Steps

A solution of diethyl methylmalonate (Aldrich Chemical Company, 35.6 ml) in dry tetrahydrofuran (200 ml) was added, dropwise, to a stirred suspension of sodium hydride (60% dispersion in mineral oil, 9.1 g) in tetrahydrofuran (50 ml) under nitrogen. After the addition was complete, the mixture was heated to gentle reflux for 1 hour and then allowed to cool before a solution of pent-4-ynyl methanesulphonate (35.2 g) in tetrahydrofuran (50 ml) was added. The resulting mixture was heated to gentle reflux for a further 2 hours. The bulk of the solvent was then removed in vacuo and the residue was partitioned between diethyl ether and water. The organic phase was separated and washed with water and brine before drying over anhydrous magnesium sulphate and evaporation under reduced pressure. Distillation gave diethyl 2-methyl-2-(pent-4-ynyl)malonate (45.8 g) as a colourless oil (b.p. 92°-97°, 0.5 mm Hg).

Provenance & Evidence