(3R)-3-tert-butyl-4-phenyl-2-((S)-1-phenyl-ethyl)-[1,2,4]oxadiazolidin-5-one
(3S)-3-tert-butyl-4-phenyl-2-((S)-1-phenyl-ethyl)-[1,2,4]oxadiazolidin-5-one
(3R)-3r-tert-butyl-5t-phenyl-2-((S)-1-phenyl-ethyl)-isoxazolidine
(3R)-3r-tert-butyl-5c-phenyl-2-((S)-1-phenyl-ethyl)-isoxazolidine
(3S)-3r-tert-butyl-5c-phenyl-2-((S)-1-phenyl-ethyl)-isoxazolidine