Characterization of Orally Active Nonpeptide Vasopressin V 2 Receptor Agonist. Synthesis and Biological Evaluation of Both the (5 R )- and (5 S )-Enantioisomers of 2-[1-(2-Chloro-4-pyrrolidin-1-yl-benzoyl)-2,3,4,5-tetrahydro-1 H -1-benzazepin- 5-yl]- N -isopropylacetamide