Imidazo-fused pyrimidines, tautomerism

The tautomeric equilibrium in variously substituted imidazo- 53 (93KGS1353) and triazolo-fused pyrimidines 54 (88KGS1489 91KGS1539 93KGS1353 93KGS1357) has been comprehensively studied by Desenko and colleagues, whose results were summarized in a special review (95KGS147). 

For historical reasons, the numbering of purine (imidazo[4,5-d]pyrimidine) does not comply with lUPAC rules. The X-ray structure of purine shows that the imidazole part is planar and the fused pyrimidine ring deviates from a coplanar arrangement (see Fig. 6.20). Purine exists in two tautomeric forms, namely 7i/-purine 1 and 9//-purine 2, which are in equal concentration in solution (annular tautomerism). In the solid state, the 7//-form is dominant ... 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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