Jiří Šibor, D. Žůrek, R. Marek
1999
Citations
0
Influential Citations
5
Citations
Journal
Collection of Czechoslovak Chemical Communications
Abstract
Synthesis of 2-(3-acylselenoureido)benzonitriles and 2-(3-acylselenoureido)thiophene- 3-carbonitriles 5a - 5f by addition of 2-aminonitriles 4a - 4c to benzoyl- or 2,2-dimethyl- propanoylisoselenocyanate and their cycloaddition reactions are described. Structures of compounds 5a - 5f were supported by CIMS, FTIR, 1 H, 13 C, 77 Se and 15 N NMR spectra. The parameters of 15 N and 77 Se nuclei were obtained from inverse 1 H-X 2D HMBC and GSQMBC correlation experiments at natural abundance. Structure of compound 5b was confirmed by X-ray analysis. The geometry of 5b was optimized by ab initio RHF/DZVP quantum chemistry calculation. A very good correlation between the calculation and experimental data was found. The geometry of 5e was optimized by ab initio DFT/VWN/DZVP quantum chemistry calculation. It was found that title compounds 5a - 5f do not undergo isomerization to acylisoselenoureas, in contrast to analogous ester derivatives. Fused 6-imino-6 H -1,3- selenazinium salts (chlorides 6a - 6f , hydrogensulfates 7a - 7f and tetrafluoroborates 8a - 8f ) were prepared by an acid cyclization of 5a - 5f . It was found that neutralization of 6a - 6f , 7a - 7f and 8a - 8f led to their retrocyclization to 5a - 5f . Selenoureas 5a - 5f with equimolar amounts of methanolic potassium hydroxide afforded potassium salts 9a - 9f . Only the salts 9b , 9c , 9e and 9f of the thiophene series were isolated. Their heating in methanol solution led to deacylation of isoselenoureas 10b and 10c . The in situ prepared compounds 9a and 9d cyclized and deacylated to 4-aminoquinazoline-2-selenole 11a under the same conditions. The compounds 5a - 5f and 10a - 10c cyclized to fused 4-aminopyrimidine-2-selenols 11a , 11b and 4-aminopyrimidine-2-selenone 12c by boiling in methanolic potassium hydroxide solution.