New photolabile protecting groups in nucleoside and nucleotide chemistry - Synthesis, cleavage mechanisms and applications
New photolabile protecting groups have been found in the 2-(2- nitrophenyl)ethoxycarbonyl and the 2-(2-nitrophenyl)ethylsulfonyl group, respectively. The influence of substituents at the phenyl ring as well as the side-chain has been investigated regarding the photolysis rates on irradiation at 365 mn. β-Branching in the side-chain leads to highly increased rates of photodeprotection. A new type of photocleavage mechanism consisting of a photoinduced β-elimination process is proposed.