Publication details
Tautomeric equilibria of substituted pyrazolo[4,3-c]pyrazoles: Synthesis of their possible N-methyl isomers
| Authors | |
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| Year of publication | 2012 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Substituted purines and purine analogues consist a biologically important group of heterocyclic compounds. Among them a number of variously substituted pyrazolopyridines have been shown to be potent inhibitors of phosphodiesterases, matrix metalloproteinases, glycogen synthase kinase-3, and cyclin-dependent kinases. Generally, these compounds could exist in a number of tautomeric forms. The tautomerism of isolated nucleic acid bases and several purine derivatives have been investigated extensively, since tautomeric equilibria should be considered in any study of their binding modes with biological targets. We have been previously involved in the systematic study of various pyrazolopyridines, focusing in their possible tautomeric species. As a continuation of our investigation we have also prepared a series of derivatives belonging to the closely related scaffold pyrazolo[4,3-c]pyrazole. We have thus decided to study the tautomeric equilibria of this scaffold by means of NMR experiments and theoretical calculations and for this purpose we have synthesized a number of substituted pyrazolo[4,3-c]pyrazoles along with their N-methylated isomers. For the preparation of the compounds we have used suitably substituted pyrazoles as starting materials, which underwent nitration, reduction and thermal cyclization to provide the pyrazolopyrazole ring system. The compounds were fully N-methylated and the resulting isomers were separated and studied. |