Efficient O-trimethylsilylation of alcohols and phenols with trimethylsilyl azide catalyzed by tetrabutylammonium bromide under neat conditions

A very efficient procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered second ary, tertiary, and phenols is reported. The reactions were carried out unde r neat conditions with trimethylsilyl azide (TMSN3) and, when necessary, in the presence of a catalytic amount (20 mol %) of tetrabutylammonium bromid e (TBABr) at 30 or 70 degreesC. Under catalytic conditions, the yields of t he corresponding trimethylsilyl ethers were greater than 91%. This procedur e also allows the selective protection of primary and secondary alcohols in the presence of tertiary ones.