N2-Isobutyryl-O6-[2-(p-Nitrophenyl)Ethyl]Guanine: A New Building Block for the Efficient Synthesis of Carbocyclic Guanosine Analogs

Abstract
N2-Isobutyryl-O6-[2-(p-nitrophenyl)ethyl]guanine (4) allows the synthesis of different types of carbocyclic analogs of guanosine in high yield under Mitsunobu conditions. Only the desired N9-substituted derivatives of guanine are formed.