Efficient synthesis of fused isothiazolo C-nucleosides. III. Synthesis of substituted isothiazol.

The Divakar-Reese procedure has been successfully applied for transforming 7-oxo-isothiazolo[4,5-d]pyrimidine C-nucleosides (4a,b, 5a,b, 6a) via 1,2,4-triazol-1-yl intermediates (7a,b, 8a,b) into various 7-substituted C-nucleosides 15a,b, 16a,b, 17a, 18a, 19a,b, 20a,b; their subsequent deprotection provides novel types of unusual C-glycosides 22b, 23a, 24a,b, 25b, 26b. C-Nucleosides, possessing on its heterocyclic base other than naturally occuring oxo- or amino substituents, are important model compounds for biological or medicinal studies (2,3). We want to report on the synthesis of novel 7-substituted isothiazolo = [4,5-d]pyrimidine C-nucleosides.

An efficient synthesis of thioisomunchnones derived from uracils and uridine: novel type of mesoionic nucleosides.

[reaction: see text] Synthetic approaches to a variety of thioisomunchnones derived from uracils and uridine are described, as well as their properties and cycloaddition tendencies. The anhydro-3-hydrocy-2-phenyl-6-(2',3',5'-tri-O-benzoyl-beta-D-ribofuranosyl)thiazolo[3,2-c]pyrimidine-5(6H)-on-4-ium hydroxide represents a novel class of mesoionic nucleosides.

Photodegradation of imidacloprid.

The photolytic decomposition of the insecticide imidacloprid (1) in HPLC grade water and of imidacloprid as the formulated product Confidor insecticide in tap water was studied using HPLC methodology. The structures of several degradates have been determined in aquatic medium, and the DT(50) values of imidacloprid and Confidor have been measured. In addition, the influence of TiO(2) on the photodegradation of Confidor was studied.