(3S,7R,8R,8aR)-7,8-dihydroxy-3-isobutylhexahydropyrrolo-[1,2-a]pyrazin-4(1H)-one

1-(3-((3S,7R,8R,8aR)-7,8-dihydroxy-4-oxooctahydropyrrolo-[1,2-a]pyrazin-3-yl)propyl)guanidine

(1R,2R,5aS,10aR)-1,2-dihydroxyoctahydrodipyrrolo[1,2-a:1′,2′-d]pyrazin-5(1H)-one

(S)-2-((((2R,3R,4R)-3,4-dihydroxypyrrolidin-2-yl)methyl)amino)-3-methylbutanamide

(2R,3R,4R)-2-(((S)-aspartic(β-tert-butyl)amidyl)methyl)-3,4-dihydroxypyrrolidine