Isopropyl Acetate → (R)-3-(4-Methoxybenzyl)-2-oxothiazolidine-4-carboxylic Acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A 22 L three-necked round bottom flask fitted with an internal temperature probe and a mechanical stirrer was charged with the title compound from Example 2 (400.0 g, 1.66 mol), K2CO3 (480.0 g, 3.47 mol) and water (2.8 L). The mixture was heated at 40° C. while stirring until it became homogeneous and was then cooled to room temperature. A solution of N,N-carbonyldiimidazole (400.0 g, 222.47 mol) in acetonitrile (2.8 L) was added dropwise at a rate that maintained an internal reaction temperature less than 30° C. The reaction was monitored by HPLC and was complete upon the disappearance of the starting material (about 15 minutes). The acetonitrile was removed by heating at 40° C. and 80-100 torr. Isopropyl acetate (200 mL) was added and the pH of the mixture was adjusted to 2 with 3 M H2SO4. The biphasic mixture was filtered, and the organic phase was isolated. Additional isopropyl acetate was added and the solution was dried by azeotropic distillation. The reaction volume was reduced further until a precipitate began to form. The yellow precipitate was isolated by filtration and dried at 50° C. overnight to afford the title compound (310 g, 70%).

Herkunft & Nachweise