(S)-spiro[(1,3-diazacyclopent-1-ene)-5,2'-(7'-methyl-1',2',3',4'- tetrahydronaphthalene)]: resolution, stereospecific synthesis, and preliminary pharmacological characterization as a partial alpha-adrenergic agonist

Recently, we reported on the design, synthesis, and structure-activity relationships of a series of spiroimidazolines endowed with alpha-adrenergic agonist activities. Among the compounds described, (R,S)-spiro(1,3-diazacyclopent-1-ene)-[5,2'](7'-methyl-1'2',3', 4',-tetrahydronaphthalene) fumarate (5RS) was chosen for further development as a venotonic agent. The resolution of this compound, as well as the pharmacological characterization of the enantiomers, stereospecific synthesis of eutomer (5S, S 18149), and determination of absolute configuration by single-crystal X-ray diffraction analysis, are described.