Visible-Light-Promoted Site-Selective N¹-Alkylation of Benzotriazoles with α-Diazoacetates

A visible-light-promoted highly site-selective N 1 -alkylation of benzotriazoles with diazo compounds has been achieved under mild and metal-free conditions. Using cheap, readily available p -benzoquinone (PBQ) as a catalyst, a wide range of benzotriazoles and diazo compounds are reacted, providing N 1 -alkylated benzotriazoles in moderate to excellent yields with excellent N 1 -selectivities. Preliminary mechanistic studies suggest that a radical process accounts for the exclusive site-selectivity of this transformation.