NEW-GAMMA-HYDROXYCARBOXYLIC ACID DERIVATIVE

PROBLEM TO BE SOLVED: To obtain a new compound useful as a synthetic intermediate for medicines. SOLUTION: This compound is shown by formula I (R is amino or p- cyanobenzoylamino; R is H or a 1-4C lower alkyl) such as 6-amino-4- hydroxychroman-3-acetic acid methyl ester. The compound of formula I is obtained by hydrogenating a compound of formula II in the presence of a hydrogenating catalyst (e.g. Pd/C) in a solvent (e.g. methanol) under 1-150kg/cm hydrogen pressure at 0-100 deg.C for 1-24 hours in the case in which R is amino. The amount of the catalyst used is the metal weight of 1/10-1/10,000 as much as the compound of formula II. When R is p-cyanobenzoylamino, the compound of formula I is obtained by reacting a compound of formula III with a p- cyanobenzoic acid chloride of an equivalent to 1.5 times as much as the compound of formula III in the presence of a base. When R is a 1-4C alkyl, the compound of formula I is treated with a base such as aqueous or an alcoholic sodium hydroxide and the ester group is hydrolyzed or treated with an acid (e.g. hydrochloric acid) to give a carboxylic acid derivative.