Ethyl 2,3-Butadienoate

Typical procedure: To a solution of ethyl 2,3-butadinenoate (123 mg) in dry THF (8 mL) is added 1.59 M butyl lithium in hexane (0.69 mL) at -92°C. After 1 h, a solution of heptanal (114 mg) is added, and the mixture is stirred for 5 h at -92°C. Aqueous THF is added, and the mixture is poured into ice-water and neutralized with 10% HCl. Organic materials are extracted with ethyl acetate, and the combined extracts are washed with water and dried over MgSO4. After evaporation of the solvent, the products are separated by column chromatography (eluent: hexane / ethyl acetate = 10/1－1/1) on silica gel to give 136 mg (60% yield) of the desired product as the first fraction.