PURPOSE: To obtain the titled compound useful as a coronary vasodilator, etc. in high yield in one stage, by condensing a partially novel specific propionic acid ester derivative with a halide of a tertiary amine in the presence of a metal hydride in an aprotic polar solvent.

CONSTITUTION: A partially novel substance of formula I (Ar is phenyl substituted by a lower alkoxyl; R is H or lower acyl; R1 is lower alkyl) which is novel when R is lower acyl is condensed with a compound of formula II (R2 and R3 are lower alkyl; Y is lower alkylene; Z is halogen) in the presence of a metal hydride, e.g. sodium hydride, in an aprotic polar solvent, preferably dimethyl sulfoxide at 5W70°C, preferably 10W40°C to afford industrially and advantageously the aimed compound of formula III useful as medicines such as a psychotropic agent in addition to those described above or an intermediate thereof, etc.