Design, synthesis, X-ray analysis, and dopamine receptor-modulating activity of mimics of the "C5" hydrogen-bonded conformation in the peptidomimetic 2-oxo-3(R)-[(2(S)-pyrrolidinylcarbonyl)amino]-1- pyrrolidineacetamide.

3(R)-(7a(S)-Hexahydro-1-oxo-3,3-dimethyl-1H-pyrrolo[1,2-c]imidazol-2-yl) - oxo-1-pyrrolidine-acetamide (2) and 3(R)-[1-(2,5-dioxopyrrolidino[3,4-c]piperazino)]-2-oxo-1- pyrrolidineacetamide (3) were designed and prepared as mimics of the "C5" hydrogen-bonded structure found in the crystal structure of 2-oxo-3(R)-[(2(S)-pyrrolidinylcarbonyl)amino]-1- pyrrolidineacetamide (1). Both compounds effectively restrict the psi 1 torsional angle to very …