Synthesis of New 5-(1,4-Benzodioxan-2-yl)thieno[2,3-d]pyrimidine Derivatives

Cyclization of previously synthesized ethyl 2-amino-4-(1,4-benzodioxan-2-yl)thiophene-3-carbox­ylate with formamide gave 5-(1,4-benzodioxan-2-yl)thieno[2,3- d ]pyrimidin-4(3 H )-one which was treated with phosphoryl chloride in pyridine to obtain the corresponding 4-chloro derivative. The latter reacted with various primary and secondary amines to produce a series of new thieno[2,3- d ]pyrimidines containing a pharmacophoric fragment at the 4-position. The reaction of 5-(1,4-benzodioxan-2-yl)-4-chlorothieno[2,3- d ]pyrimidine with hydrazine hydrate afforded the corresponding 4-hydrazinyl derivative which was cyclized with formic acid to thieno[3,2- e ][1,2,4]triazolo[1,5- c ]pyrimidine derivative. Antihypoxic properties of the synthesized compounds were studied.