Synthesis of Ring-Expanded Xanthines and Xanthosines Containing the Imidazo[4,5-<u>d</u>][1,3]diazepine Ring System

Abstract

Abstract Syntheses of 4, 5, 6, 8-tetrahydro-1H, 7H-imidazo[4, 5-d] [1, 3]-diazepine-5, 8-dione (9), its 3-benzyl derivative (8), and 3- and 1-ribosyl derivatives, (12) and (13), respectively, are reported. Single-crystal x-ray analyses of 8 and 9 are also presented.