抄録
The reaction of 1, 1, 3, 3-tetraethoxypropane with guanosine under strongly acidic conditions resulted in the formation of diastereomeric oxadiazabicyclononene residues linked to guanine base. The diastereomers were decomposed by heat, giving changed pyrimido[1, 2-a]purin-10(3H)-one nucleoside (3) in a good yield. A convenient method for the preparation of 3, which includes the thermal decomposition process of the diastereomers, was developed.