3-tert-butyl 4-methyl (2R,4R)-2-tert-butyl-4-((S)-1-isobutoxyallyl)oxazolidine-3,4-dicarboxylate

3-tert-butyl 4-methyl (2R,4R)-2-tert-butyl-4-((S)-1-(cyclohexyloxy)allyl)oxazolidine-3,4-dicarboxylate

tert-butyl (2R)-2-(tert-butyl)-1,3-oxazol-3(2H)-carboxylate