3-[[(2R)-2-hydroxy-3,3-dimethyl-4-phosphonatooxybutanoyl]amino]propanoate
3-[[(2R)-2-hydroxy-3,3-dimethyl-4-phosphonatooxy-butanoyl]amino]propanoate
3-[[(2R)-2-hydroxy-3,3-dimethyl-1-oxo-4-phosphonatooxybutyl]amino]propanoate
3-[[(2R)-2-hydroxy-3,3-dimethyl-4-phosphato-butanoyl]amino]propionate