Differentiation between [1,2,4]triazolo[1,5-a] pyrimidine and [1,2,4]triazolo[4,3-a]- Pyrimidine regioisomers by ¹H-¹⁵N HMBC experiments

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.Wealso observed that these two structural surrogates could be unambiguously differentiated by indirectly measuring their 15N chemical shifts by 1H-15N 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 15N NMR data. Copyright © 2010 John Wiley & Sons, Ltd.

Año de publicación:

2010

Keywords:

• 13 C
• 15 N
• NMR
• 1 H
• Regioisomerism
• HMBC
• Isomerisation
• [1,2,4]triazolo[4,3-a]pyrimidines
• [1,2,4]triazolo[1,5-a] pyrimidines

Fuente:

scopus