(2R,3S)-3-isopropylmalate = (2S)-2-isopropylmalate
(2r,3s)-3-isopropylmalate = (2s)-2-isopropylmalate
(2R,3S)-3-isopropylmalate = (2S)-2-isopropylmalate
(2r,3s)-3-isopropylmalate = (2s)-2-isopropylmalate