Bosentan Related Compound 4 BenzenesulfonaMide, N-[1,6-dihydro-5-(2-Methoxyphenoxy)-6-oxo[2,2'-bipyriMidin]-4-yl]-4-(1,1-diMethylethyl)- 4-tert-Butyl-N-(6-chloro-5-(2-methoxyphenoxy)-2,2'-bipyrimidin-4-yl)benzenesulfonamide BenzenesulfonaMide, N,N'-[1,2-ethanediylbis[oxy[5-(2-Methoxyphenoxy)[2,2'-bipyriMidine]-6,4-diyl]]]bis[4-(1,1-diMethylethyl)- 4-tert-Butylbenzenesulfonamide Bosentan Impurity 15 HCl 4,6-Dichloro-5-(2-methoxyphenoxy)-2,2'-bipyrimidine