General method of synthesis of N-benzylamides of 4-oxo-5-methylthieno[2,3-d]pyrimidine-6-carboxylic acid (5.1-5.5)

N-Benzyl-5-methyl-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidine-6-carboxamide 5.1

5-Methyl-N-(4-methylbenzyl)-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidine-6-carboxamide 5.2

N-(4-methoxybenzyl)-5-methyl-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidine-6-carboxamide 5.3

5-Methyl-4-oxo-N-(4-fluorobenzyl)-3,4-dihydrothieno[2,3-d]pyrimidine-6-carboxamide 5.4

5-Methyl-4-oxo-N-(3,4-dichlorobenzyl)-3,4-dihydrothieno[2,3-d]pyrimidine-6-carboxamide 5.5