¹H and ¹³C NMR study of novel fused 1,2,4‐triazole heterocycles

Abstract

The 1H and 13C NMR spectra of some novel 1,2,4‐triazolo [1,3] thiazinoquinoline isomeric pairs are interpreted in terms of structural assignments. The structure of most compounds has been confirmed by NOE difference spectroscopy. Characteristic differences have been observed in both 1H and 13C NMR spectra of these isomeric Pairs: some of the 1H and 13C chemical shifts, and also the one bond 13C1H couplings of triazole protons, differ consistently in the NMR spectra of the isomers. The coupling constants have been determined using a combination of INEPT and chemical shift selective filtering.

Fused 1,2,4-Triazole Heterocycles. Iii. Syntheses and Structures of Novel [1,2,4]triazolo[1,3]thiazinoquinolines.

“…Under these conditions the reaction led to the formation of the mixture of 5 and 6 immediately, however, the presence of an intermediate was monitored by tic. (5). The ratio of the isomers ( Table 2) was totally different from that was observed in the cyclisation of 3, but was very similar (R=H) to that was observed in cyclisation of 12.…”

“…These rules have been drawn from the 1 H-and 13 C-nmr study of a large number of [1,2,4]triazolo [5,1]-and [1,2,4]triazolo [3,4] 3-Chloromethyl-2-(1,2,4-triazol-5-yl)thioquinoline 12 , the regioisomer of 3a was prepared by an unequivocal route starting from 1 via 9, 10, and H (Scheme 4). These rules have been drawn from the 1 H-and 13 C-nmr study of a large number of [1,2,4]triazolo [5,1]-and [1,2,4]triazolo [3,4] 3-Chloromethyl-2-(1,2,4-triazol-5-yl)thioquinoline 12 , the regioisomer of 3a was prepared by an unequivocal route starting from 1 via 9, 10, and H (Scheme 4).…”