Ambrisentan for the treatment of pulmonary arterial hypertension was synthesized from 2-hydroxy-3-methoxy-3,3-diphenylpropionic acid via resolution to give the crude (S)-2-hydroxy-3-methoxy-3,3-diphenylpropionic acid, which was subjected to condensation with 4,6-dimethyl-2-methylsulfonyl pyrimidine in the presence of lithium hydroxide monohydrate and purification by salt formation with ammonia with an overall yield about 32%.