Solid-phase synthesis of N-9-substituted 2,8-diaminopurines

A general and efficient solid-phase synthesis of N-9-substituted 2,8-diaminopurines from 5-nitrouracil is described. The key synthetic transformation employs a carbodiimide-mediated cyclization of a thiourea. Thiourea formation on solid phase is performed using both thermal and microwave reaction conditions. Regiospecific solution-phase synthesis of key building blocks allows the incorporation of desired substituents at N-9 of the purine nucleus.

A general and efficient solid-phase synthesis of N-9-substituted 2,8-diaminopurines from 5-nitrouracil employing a carbodiimide-mediated cyclization of a thiourea is described.