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 secondary, tertiary, and phenols is reported. The reactions were carried out under neat conditions with trimethylsilyl azide (TMSN3) and, when necessary, in the presence of a catalytic amount (20 mol %) of tetrabutylammonium bromide (TBABr) at 30 or 70 degreesC. Under catalytic conditions, the yields of the corresponding trimethylsilyl ethers were greater than 91%. This procedure also allows the selective protection of primary and secondary alcohols in the presence of tertiary ones.