o‐(α‐Benzotriazolylalkyl)phenols: Versatile Intermediates for the Synthesis of Substituted Phenols

Phenols and naphthols are benzotriazolylmethylated by 1‐(hydroxymethyl)‐1H‐benzotriazole (13) (a formaldehyde derivative) in the o‐ or (if both o‐positions are occupied) in the p‐position. The reaction can be extended to other aldehydes in the case of the naphthols. The methylene group in the o‐(benzotriazolylmethyl)phenols can be lithiated (but only after trimethylsilyl protection of the hydroxy group) and then substituted by various electrophiles. The benzotriazole residues in both the primary products and in their substituted derivatives can be displaced by the alkyl anions of Grignard reagents or by hydride ions allowing the elaboration of many new types of substituted phenols.