Ritonavir EP Impurity B

[4-[(2-Amino-3-methyl-1-oxobutyl)amino]-2-hydroxy-5-phenyl-1-(phenylmethyl)pentyl]-carbamic Acid 5-Thiazolylmethyl Ester, is an intermediate that can be used for the synthesis of Ritonavir (R535000), which is a selective HIV protease inhibitor.