The synthesis of several analogues of (8R)-3-(2-deoxy-~-~-erythro-pentofuranosyl)-3, 6, 7, 8- tetrahydroimidazo [4, 5-d][1, 31diazepin-8-01 (pentostatin, la) is described. Ring closure of 2- amino-l-(5-amino-1H-imidazol-4-yl) ethanone dihydrochloride (3) with triethyl orthoacetate or triethyl orthopropionate gave the C-5 methyl and ethyl ketoaglycons, 6, 7-dihydro-5- methylimidazo [4, 5-d][1, 3] diazepin-8 (3H)-one (4b) and 5-ethyl-6, 7-dihydroimidazo [4, 5 ...
![4,7-Dihydro-imidazole[4,5-d]1,3-diazepine-8(1H)-one hydrochloride Structure](https://image.chemsrc.com/caspic/013/71222-44-1.png)
