PURPOSE: To advantageously obtain the title compound useful as a synthetic intermediate for methyl ether derivatives suitable as chemical sensitizer by using a specific compound prepared from a alkylsulfonic acid and a lower fatty acid anhydride and a reaction product between trioxane and a lower fatty acid anhydride as raw materials.

CONSTITUTION: An alkylsulfonic acid or arylsulfonic acid shown by formula I (R1 is 1-8C alkyl, 6-10C substituted or nonsubstituted aryl) is reacted with a lower fatty acid anhydride shown by formula II (R2 is 1-4C alkyl) in a substantially anhydrous atmosphere under reduced pressure while selectively distilling away a lower fatty acid shown by formula III to give a compound shown by formula IV, which is used as a raw material and reacted with a compound shown by formula V in a substantially anhydrous state under reduced pressure to give the objective compound shown by formula VI. In order to obtain various methyl ether derivatives, the compound shown by formula VI is reacted with an active hydrogen-containing organic compound or a basic organic compound.