PURPOSE: To simply obtain in high yield the title compound in high concentration by reaction of each specific two kinds of compound in the presence of a base followed by reaction of the resulting product with another specific compound.

CONSTITUTION: A reaction is made in the presence of a base such as sodium hydroxide between (A) a compound of formula I (X is of formula II, OH or SH; A is divalent hydrocarbon with 2-10 in the number of chain members which may contain S, O and/or NH) and (B) another compound of formula III (L and L' are each eliminable group, where L is more reactive than L'; B is the same as A) into a compound of formula IV (X' is of formula V, O or S), which is then reacted with a compound of formula VI (Y is the same as X; A' is the same as A) similarly in the presence of a base; in the reactions where the respective compounds of the formula I and formula VI have been used, when X and/or Y is (are) of the formula II, tosyl group is eliminated, thus obtaining the objective compound of formula VII (X'' and Y'' are each NH, O or S). The solvent to be used in the above reactions is pref. dimethylformamide.