[C:1](=[O:8])([S:6][CH3:7])[O:2][CH:3](Cl)[CH3:4].[C:9]([OH:14])(=[O:13])[CH:10]([CH3:12])[CH3:11].C(N(C(C)C)CC)(C)C>CCOCC>[C:1](=[O:8])([S:6][CH3:7])[O:2][CH:3]([O:14][C:9](=[O:13])[CH:10]([CH3:12])[CH3:11])[CH3:4]Compound (3) (308 g, 2 mol) was dissolved in isobutyric acid (264 g, 3 mol). This mixture was slowly added to a pre-mixed solution of isobutyric acid (264 g, 3 mol) and diisopropylethylamine (387 g, 3 mol), and the reaction mixture heated to 55° C. for 16 h, diluted with ether (10 L), washed with water (4×5 L), saturated bicarbonate solution (2×5 L) and brine (5 L), then dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo to give the title compound (2) as colorless liquid (400 g, 97% yield). The product was optionally further purified by vacuum distillation (135° C./20 Torr). 1H NMR (CDCl3, 400 MHz): δ 1.17 (d, J=6.8 Hz, 6H), 1.49 (d, J=5.6 Hz, 3H), 2.33 (s, 3H), 2.54 (m, 1H), 6.91 (q, J=5.2 Hz, 1H).
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