A synthetic approach towards the synthesis of asmarine analogues

Asmarines are marine alkaloids with the unique N(10)-hydroxytetrahydro[1,4] diazepino[1,2,3-g,h]purine system and interesting biological activity. The heterotricyclic system was prepared from substituted purines. CH-correlations were found to be an easy way to determine the mode of cyclisation in those cases where more than one is possible, that is, obtaining the tetrahydrodiazepinopurine or tetrahydropyrimidopurine system.