This compound can be obtained by several related ways: 1.- The cyclization of 3-aminothiophene-2-carboxamide (I) with pentanoyl anhydride (II) by means of DCC, DMAP and pyridine in DMF and NaOH gives 2-butylthieno[3,2-d]pyrimidin-4(3H)-one (III), which by reaction with POCl3 or SOCl2 affords 2-butyl-4-chlorothieno[3,2-d]pyrimidine (IV). Finally, this compound is condensed with cyclohexylamine (V) by means of triethylamine in in THF. 2.- The intermediate 2-butylthieno[3,2-d]pyrimidin-4-(3H)-one (III) can be obtained by other ways: a.- By cyclization of amide (I) with pentanoic acid (VI) by means of DCC, DMAP and pyridine in DMF and NaOH. b.- By cyclization of 3-aminothiophene-2-carboxylic acid methyl ester (VII) with pentanoic acid (VI) by means of DCC, DMAP and ammonia in dichloromethane. c.- By cyclization of 3-aminothiophene-2-carboxylic acid methyl ester (VII) with pentanoyl chloride (VIII) by means of pyridine and ammonia. d.- By cyclization of 3-aminothiophene-2-carboxylic acid (IX) with pentanoic anhydride (II) and ammonia.