PURPOSE: To obtain the subject compd. as an intermediate for the synthesis of a biologically active silane compd. with easy handling property in high yield by using a specified compd. which is easily available as the source material, allowing the compd. to react with an alkali phenolate, oxidizing the product, and pyrolyzing the oxidized product.

CONSTITUTION: A compd. expressed by formula I (X is halogen) is used as the source material and is allowed to react with an alkali or alkaline earth phenolate expressed by formula II (M is an alkali or alkaline earth metal; R is H, halogen, 1-4C alkyl or 1-4C alkoxy) by preferably using a polyethyleneglycol dialkylether at 100 to 255°C, preferably 130 to 190°C to obtain a compd. expressed by formula III. Then the compd. of formula III is oxidized to produce an amine oxide, which is then pyrolyzed to obtain a compd. expressed by formula IV. The compd. of formula II is preferably used by 1 to 1.4 mol. per 1 mol. of the compd. of formula I.