A 12 L, round bottom flask was inerted and charged with Lawesson's reagent (211.5 g, 0.52 mol, 1.2 equiv), a solution of (S)-tert-butyl 2,2,4-trimethyl-4-(2-(4-(octyloxy)-3-(trifluoromethyl)benzoyl)-hydrazinecarbonyl)oxazolidine-3-carboxylate (D8A) (250 g—based on theoretical output, 0.43 mol) in toluene (2.5 L), and the resulting slurry was heated to 80° C. and held for 3 hours. TLC indicated the reaction was complete. The mixture was cooled to 18-23° C., charged with saturated NaHCO3 solution (2 L), which was slightly exothermic. The aqueous was extracted twice with ethyl acetate (2 L, 1.5 L), the organic phases were combined, concentrated, dissolved in dichloromethane (500 mL), charged with silica-gel (500 g), concentrated to remove dichloromethane, and purified using a silica-gel (2.5 kg) column which was eluted with 5% ethyl acetate: 95% heptane to afford the title product (185 g, 74% yield, 95% AUC by HPLC) as a yellow color oil.
