162009-81-6Relevant articles and documents
A short synthesis of a novel ring-expanded purine and its nucleoside analogue containing the imidazo[4,5-e][1,3]diazepine ring skeleton with multiple amino substituents attached to the 7-membered ring
Wang,Bhan,Hosmane
, p. 2307 - 2320 (1994)
The synthesis of 4,6,8-triaminoimidazo[4,5-e][1,3]diazepine (1) and its nucleoside analogue (6) are reported. The heterocycle was prepared in a single step by condensation of 4,5-dicyanoimidazole with guanidine. The 5,7- fused ring structure of 1 was distinguished from the other possible 5:5- fused isomer 2 by preparing the 15N-labeled heterocycle (1*) and exploring its 15N-1H coupling patterns in both 1H and 15N NMR spectra. These spectral patterns also enabled establishment of the triamino tautomeric form of 1 as assigned. Compound 1, a novel ring-expanded ('fat') analogue of purine, is anticipated to be planar and aromatic as predicted by molecular modeling. The 1-benzyl analogue (4), a protocol for the ribosyl analogue 6, was similarly prepared from 1-benzyl-4,5-dicyanoimidazole. The nucleoside 6 was prepared by the modified Vorbruggen ribosylation of 1. The position of ribosylation was unequivocally established by an unambiguous synthesis of 6 from condensation of 1-(2',3',5'-tri-O-benzoyl-β-D-ribofuranosyl)-4,5- dicyanoimidazole (7) with guanidine in a solution of sodium methoxide in methanol. The nucleoside 7 was prepared by the Vorbruggen ribosylation of 4,5-dicyanoimidazole.