Studies directed toward the design of orally active renin inhibitors. 2. Development of the efficacious, bioavailable renin inhibitor (2S)-2-benzyl-3-[(1-methylpiperazin-4-yl)sulfonylpropionyl]-3-thiazol-4-yl-L-alanine amide of (2S,3R,4S)-2-amino-1-cyclohexyl-3,4-dihydroxy-6-methylheptane (A-72517)