[C:1]([OH:6])(=[O:5])[C@H:2]([CH3:4])[OH:3].[CH:7](=O)[C:8]([CH3:11])([CH3:10])[CH3:9].O.C1(C)C=CC(S(O)(=O)=O)=CC=1.O>OS(O)(=O)=O.CCCCC>[C:8]([C@@H:11]1[O:5][C:1](=[O:6])[C@H:2]([CH3:4])[O:3]1)([CH3:10])([CH3:9])[CH3:7]
A mixture of L-Lactic acid (106 g of 85% in H2O), pivalaldehyde (220 mL), p-toluene sulfonic acid mono hydrate (2.0 g) and H2SO4 conc. (8 drops) in pentane (800 mL) was refluxed with azeotropic removal of the water formed using a Dean-Stark trap. The supernatant was decanted, washed with water, dried over MgSO4 and concentrated. The resulting residue was dissolved in hexane (800 mL) and cooled to -80° C. for 20 h. Crystals were collected by filtration in a cold room (5° C.) and washed with cold hexane (-78° C.). The crystals were dissolved in Et2O, dried over MgSO4 and concentred to give the title compound as a colorless oil. 1H NMR(CD3COCD3): δ0.95 (9H, s), 1.38 (3H,d), 4.47 (1H, m), 5.24 (1H, s).
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