Thioxopyrimidine in heterocyclic synthesis II: Novel synthesis of some triazoles and triazepine derivatives with a pyrimido[3,2:4,5]thieno[2,3- d ]pyrimidine skeleton

Condensation of ethoxymethyleneamino-thieno[2,3-d]pyrimidines 4 with appropriate amino compounds afforded the corresponding 7-substituted-8-imino- pyrimido[3,2:4,5]thieno[2,3-d]pyrimidines 6a,6b,and 7 and 2-substituted- pyrimido[3′,2′:4,5]thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines 9a,9b,respectively. also,hydrazinolysis of compound 4 in ethanol which yielded the key intermediate 7-amino-8-imino-pyrimido[3,2:4,5]thieno[2,3-d] pyrimidine (10),which can be cyclized with appropriate isothiocyanates 14a-14g in refluxing pyridine,afforded the corresponding 2-(substituted-amino)- pyrimido[3′,2′:4,5]thieno[3,2-e][1,2,4]triazolo[1,5-c]pyramidines 15a-15g. furthermore,intramolecular cyclization of compound (10) with appropriate 1,3-dibromopropane and mannich bases 18a-18c under the basic condition afforded the corresponding (tri)dihydropyrimido[3′,2′:4,5] thieno[3,2:4,5]pyrimido[1,6-b][1,2,4]triazepines 16 and 18a-18c,respectively. on the other hand,the 11-substituted-pyrimido[3′,2′:4,5]thieno[3,2: 4,5]pyrimido[1,6-b][1,2,4]triazepines 21a-21e were also obtained by the intramolecular cyclization of compound (10) with appropriate enaminone derivatives 19a-19e under the acidic condition. © 2013 yuh wen ho and se long chou.