Abstract
The synthesis of two regioisomeric nucleosides, 4,5,7,8-tetrahydro-6H-3-(β-D-ribofuranosyl)imidazo[4,5-e][1,4]diazepin-5,8-dione (2) and its 1-glycosyl analogue (3) is reported. They were prepared by ribosydation of the heterocyclic aglycon 4 which in turn was synthesized in three steps from 4(5)-nitroimidazole-5(4)-carboxylic acid (5). Distinction between the two isomers was achieved by an unequivocal synthesis of 2.