PURPOSE: The reaction of γ-formylbutyric ester with a grignard reagent followed by lactonization under acidic conditions gives title compound useful as a flavor for dairy products from readily available starting materials in high yield.
CONSTITUTION: The reaction of γ-formylbutyric ester (A) with a grignard reagent of formula: RMgX (R is 3W9C straight chain alkyl; X is Cl, Br, I) is followed by hydrolysis and lactonization under acidic conditions to give the objective compound of the formula. The starting material A is obtained by conducting the Michael reaction between acrolein and malonic ester to form γ,γ-dicarboalkoxybutyraldehyde, which is heated together with a nonprotonic solvent (e.g., DMSO) containing water. In the reaction between the starting material A and the grignard reagent, the amount of A employed is a little in excess and ethyl ether is used as a solvent. The temperature is -30W30°C.
EFFECT: The operations are simple.
KAMOGAWA KOUICHI
SHIOZAKI SHIYOUZOU
