Mou-Yung Yeh

Two heterocyclic 1,2,4,5-tetrazines

The title compounds, 6-bromo-1,4-dihydro-1,4-di(otolyl)-1,2,4,5-tetrazin-3(2H)-one, C 16 H 15 BrN 4 O, and 3,6-dibromo-1,4-dihydro-1,4-bis(p-methoxyphenyl)1,2,4,5-tetrazine, C 16 H 14 Br 2 N 4 O 2 , were prepared from 4-bromo-3-(o-tolyl)sydnone and 4-bromo-3-(pmethoxyphenyl)sydnone, respectively, in thf under ultrasonic irradiation, and identified with IR, 1 H NMR, mass spectrum and elemental analyses. The heterocyclic rings of both title compounds appear to lack aromatic character, as judged from the bond lengths

13C NMR Studies on 3-Aryl-4-Cyanosydnones (II). NMR Spectroscopy and the Chain-Conjugated Structure of Sydnones

Abstract Carbon-13 NMR spectra of 3-aryl-4-cyanosydnones have been analyzed to serve as an electronic structure probe of sydnones. 2-Dimensional INADEQUATE experiments and spin-lattice relaxation time measurements were employed to ascertain exact assignments. Deshielding of the phenyl carbon para to the sydnone ring manifests that N(3) bears positive charge. The electronic-rich property of C(4) is confirmed by shift data of cyano carbons, which have been found by far the most shielded cyano carbons in nitrile-containing compounds yet reported. Shift variations of C(5) resulting from the substitution at C(4) and supplementary oxygen-17 chemical shift data provide evidence in favor of the chain-conjugated structure.