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

Article abstract of DOI:10.1080/15257779408013222

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.

Full text of DOI:10.1080/15257779408013222

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Nucleosides and Nucleotides
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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
L. Wang a , A. Bhan a , R. S. Hosmane a & R. D. Guiles b
a Laboratory for Drug Design and Synthesis Department of Chemistry
and Biochemistry , University of Maryland Baltimore County ,
Baltimore, Maryland, 21228
b Division of Biomedicinal Chemistry School of Pharmacy University
of Maryland at Baltimore , Baltimore, Maryland, 21201
Published online: 24 Sep 2006.
To cite this article: L. Wang , A. Bhan , R. S. Hosmane & R. D. Guiles (1994) 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, Nucleosides and
Nucleotides, 13:10, 2307-2320, DOI: 10.1080/15257779408013222
To link to this article: http://dx.doi.org/10.1080/15257779408013222
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