合成路线1

The condensation of diethyl (2-methoxyphenoxy)malonate (I) with pyrimidine-2-carboxamidine (II) by means of NaOMe (Na in MeOH), followed by treatment with NaOH, provides the dihydroxy pyrimidine derivative (III), which is converted into the dichloro derivative (IV) by treatment with refluxing PCl5 and DIEA. Compound (IV) can also be obtained from the pyrimidinedione (V) by reaction with phosphorus oxychloride at 90 C. Reaction of compound (IV) with 4-tert-butylbenzenesulfonamide (VI), performed either directly in DMSO or by means of benzyltriethylammonium chloride (BTEAC) or tetrabutylammonium bromide (TBAB) and K2CO3 in refluxing toluene, gives compound (VII). Finally, this compound is converted into bosentan by reaction with sodium and ethylene glycol (VIII).