General and efficient method for the synthesis of alkoxymethylsilanes

Although alkoxymethylsilanes serve as useful building blocks, various efforts to synthesize them by substitution reaction with an alkoxide ion at the carbon adjacent to the silicon failed. To solve this synthetic problem a new route which is very simple to perform was developed. Bromination of (methoxymethyl)trimethylsilane by using N-bromosuccinimide/2,2′-azobisisobutyronitrile (NBS/AIBN) was followed by a substitution by alcohols in the presence of triethylamine to give the corresponding [alkoxy-(methoxy)methyl]trimethylsilanes. These acetals can be used directly for the next reduction with di-isobutylaluminium hydride (DIBAL-H) or Et₃SiH/BF₃·OEt₂ to give alkoxymethylsilanes in good to moderate yields. The success of the substitution reaction with the alcohols suggests that the mechanism is of somewhat S_N1 by nature and formation of the cationic intermediate seems to release the steric hindrance around the carbon, allowing the attack of alcohols.