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Differentiation between [1,2,4]triazolo[1,5-a] pyrimidine and [1,2,4]triazolo[4,3-a]- pyrimidine regioisomers by 1H15N HMBC experiments

✍ Scribed by Antonio Salgado; Carmen Varela; Ana María García Collazo; Paolo Pevarello

Publisher
John Wiley and Sons
Year
2010
Tongue
English
Weight
228 KB
Volume
48
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

The condensation of malonoaldehyde derivatives with either a 3‐amino‐[1,2,4]‐triazole or a 3,5‐diamino‐[1,2,4]‐triazole precursor was studied. In agreement with previous reports, two different bicycles, namely, bearing the regioisomeric [1,2,4]triazolo[1,5‐a]pyrimidine (1) or[1,2,4] triazolo [4,3‐a]pyrimidine (2) structural surrogates, could be obtained. We found that, depending on the triazole precursor, only one regioisomer resulted, either of the 1 or 2 series. We also observed that these two structural surrogates could be unambiguously differentiated by indirectly measuring their ^15^N chemical shifts by ^1^H^15^N HMBC experiments. The occasional conversion of [1,2,4]triazolo[4,3‐a]pyrimidines to the [1,2,4]triazolo[1,5‐a]pyrimidine counterparts could be unequivocally determined by ^15^N NMR data. Copyright © 2010 John Wiley & Sons, Ltd.

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