Hydroxylamine → 1-Hydroxy-(3R,4R)-2,5-Dioxo-3,4-dibenzoyloxypyrrolidine

Participants

Reaction Conditions

Reaction Steps

In a second step (Step B), to a 3-neck 5 L round bottom flask fitted with a mechanical stirrer and a Teflon-coated temperature probe was added compound (29) (2.79 mol) followed by acetonitrile (2 L). The suspension was cooled in an ice bath to 4° C., followed by the addition of 50% aqueous hydroxylamine (180 mL, 2.93 mol) over 1 h. The starting material gradually dissolved during the addition and the reaction mixture was warmed to 20° C. and stirred for 1 h. The reaction mixture was concentrated in vacuo, diluted with EtOAc (1 L) and washed with 1 N HCl (2×1 L). The organic phase was separated and concentrated in vacuo to afford a viscous, red syrup. The syrup was then heated for two hours in toluene (2.5 L) at 100° C. with azeotropic removal of water. The syrup gradually dissolved and then the product crystallized. After cooling to room temperature the solid was collected by filtration, washed with 10% acetone in hexane (2×1 L) and dried in a vacuum oven to afford 1-hydroxy-(3R,4R)-2,5-dioxo-3,4-dibenzoyloxypyrrolidine (30) (862 g, 2.43 mol, 87% yield) as a white solid. 1H NMR (CDCl3, 400 MHz): δ 5.85 (s, 2H), 7.45 (app. t, 4H), 7.65 (app t, 2H), 8.05 (m, 4H).

Provenance & Evidence