C-NUCLEOSIDES .19. SYNTHESIS OF 7-SUBSTITUTED AND 8-SUBSTITUTED 4-[1-(BETA-D-RIBOFURANOSYL)OXO]-1,3-DIHYDRO-2H-1,5-BENZODIAZEPIN-2-ONE

The synthesis of 7- and 8-substituted 4-[1-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)oxo]-1,3-dihydro-2H-1,5-benzodiazepin-2-one from furanone glycoside (1) is described. Treatment of 1,2-diamino-4-substituted benzenes (2a-c) with 1 gave a mixture of 7- and 8-substituted 4-[1-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)oxo]-1,3,4,5-tetrahydro-2H-1,5-benzodiazepin-2-one (3a-d). Dehydrogenation of 3a-d with DDQ and a trace of PTSA afforded 7- and 8-substituted 4-[1-(2,3,5-tri-O-benzoyl-beta-D-ribo-furanosyl)oxo]-1,3-dihydro-2H-1,5-benzodiazepin-2-ones (4a-f). The position of the substituent in compounds (4a-f) was confirmed by H-1-C-13 long-range COSY and NOE experiments with the corresponding N1-methyl derivatives (5a-c). Deprotection of compounds (4a-e) with methanolic sodium hydroxide afforded 4g-k.