A Novel Heterocyclic Compound. Synthesis and Reactivities of an Oxazolo[3, 2-a]thieno[3, 2-d]pyrimidine Derivative

A practical preparation of 2, 3-dihydro-5H-oxazolo[3, 2-a]thieno[3, 2-d]pyrimidin-5-oen (2) from methyl 3-aminothiophene-2-carboxylate in two steps was developed. The addition reactions of various nucleophiles to 2 were investigated and oxazole-ring-opened compounds were produced (5, 6, 12, 13 and 14). Desulfurization reaction of 2 with Raney Ni gave an oxazolo[3, 2-a]pyrimidine derivative (15). It was found that 2 showed potent anti-gastric secretion activity.