Methyl iodide → Ethyl (4E)-2,4-dimethyl-5-(4-methylphenyl)-4-pentenoate

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Reaction Conditions

Reaction Steps

n-Butyl lithium (1.6 M in hexanes from Fluka, 70 ml, 0.111 mol) was added rapidly to a solution of diisopropylamine (11.7 g, 0.116 mol) in dry THF (200 ml) under nitrogen, maintaining the temperature below −20° C. by cooling in a dry ice-acetone bath. After cooling to −78° C., dry DMPU (14.9 g, 0.116 mol) was added drop-wise for 5 minutes. Then, ethyl (4E)-4-methyl-5-(4-methylphenyl)-4-pentenoate (21.5 g, 0.092 mol) was added in 10 minutes. The reaction was warmed up to 0° C. and kept for 20 minutes at this temperature before cooling back to −78° C. Methyl iodide (66 g, 0.46 mol) was added drop-wise. The reaction was warmed up to room temperature and stirred overnight. It was then poured onto water and extracted twice with diethyl ether. Each organic fraction was washed with water and brine. Combined extracts are dried over solid anhydrous sodium sulfate. The solid was filtered off, rinsed with diethyl ether. Solvents are removed under vacuum and the product was purified by bulb-to-bulb distillation (125° C./0.04 mbar). 18.5 g of colorless liquid were obtained (yield=81%).

Provenance & Evidence