PURPOSE: To prepare the titled compound, in high yield, by the ester-exchange of N,N'-bis(3-hydroxypropyl)homopiperazine with a 3,4,5-trimethoxybenzoic acid ester under basic condition while removing the produced lower alcohol.

CONSTITUTION: The homopiperazine derivative of formula III {e.g. N,N'-bis[3- (3',4',5'-trimethoxybenzoyloxy)propyl]homopiperazine} is prepared by the ester- exchange reaction of the N,N'-bis(3-hydroxypropyl)-homopiperazine of formula I with the 3,4,5-trimethoxybenzoic acid ester of formula II (R is lower alkyl) in the presence of a base (e.g. sodium ethoxide) while absorbing and removing the by-produced lower alcohol from the system with a molecular sieve.

USE: A drug having coronary vessel dilating activity.