Manufacturing method null of val professional

摘要

PURPOSE:To advantageously obtain the titled compound useful as medicines, etc., without forming by-products and causing problems in post-treatment, by deacetylating a reaction product of an acetoacetic acid ester with propyl halide which are readily available raw materials and hydrolyzing the deacetylation product. CONSTITUTION:An acetoacetic acid ester and propyl halide which are raw materials are used and reacted in the presence of a base catalyst, preferably in the coexistence of a phase-transfer catalyst to provide a 2,2- dipropylacetoacetic acid ester. The amounts of the raw materials used are preferably 2-10mol propyl halide based on 1mol acetoacetic acid ester. In the second step, the resultant product is then deacetylated with an alcohol to provide a valproic acid ester. The amount of the alcohol used is within the range of 3-50mol based on 1mol product. Sodium alcoholate is preferred as the catalyst. As the third step, the resultant valproic acid ester is then hydro lyzed while heating to afford the aimed compound.