[摘要]:The synthesis of acyclic N(4)-substituted cytosine nucleoside phosphonates using a microwave-assisted N(4)-silylation-amination and olefin cross-metathesis as key steps is described. The microwave-assisted silylation-amination is compared to a conventional heating protocol. While yields and purities of the coupling products were comparable under both conditions, microwave heating allows a significant acceleration of the reaction (from 48 to 5 h).