Calcium Carbonate → (E)-methyl 4-methoxybut-2-enoate

Participants

Reaction Steps

A mixture of 54 g of methyl 4-bromocrotonate and 30.2 g of calcium carbonate in 200 mL of methanol was refluxed for 5 days. The mixture was filtered and the solvent was removed from the filtrate. The residue was dissolved in ether and washed with water containing a trace of hydrochloric acid. The ether solution was dried over magnesium sulfate. The solvent was removed and the residue was distilled to give 30.6 g of methyl 4-methoxycrotonate. This material was stirred in 170 mL of 1N sodium hydroxide for 3 min. The solution was washed with ether and the aqueous layer was acidified with sulfuric acid. The mixture was extracted several times with ether. The combined extracts were washed with brine and dried over magnesium sulfate. The solvent was removed to give 4-methoxycrotonic acid as a crystalline solid. A 10 g portion of this acid was stirred in 50 mL of benzene at 0° C. and 8.3 mL of oxalyl chloride was added. The mixture was stirred at room temperature for 6 hr. The solvent was removed and the residue was distilled to give 4-methoxycrotonyl chloride as a colorless liquid.

Provenance & Evidence