Thienooxazolopyrimidinium salts. Reaction of 1-bromomethyl-5-oxo-4-phenyl-1,2,4,5,6,7,8,9-octahydro[1]benzothieno-[3,2-<Emphasis Type="Italic">e</Emphasis>][1,3]oxazolo[3,2-<Emphasis Type="Italic">a</Emphasis>]pyrimidin-11-ium bromide with oxygen-centered nucleophiles

Reactions of 1]benzothieno3,2-e]1,3]oxazolo3,2-a]pyrimidin-11-ium bromide with oxygen-containing nucleophiles involve opening of the dihydrooxazole ring and lead to the formation of new functionally substituted thieno2,3]-d]pyrimidine derivatives.