Peracetic Acid → (1R)-1-[((3S,4S)-2,5-Dioxo-3,4-dibenzoyloxypyrrolidinyl)-oxycarbonyloxy]-2-methylpropyl 2-methylpropanoate

Participants

Reaction Steps

In a third step (Step C), to a stirred solution of compound (27) (35 g, 98.6 mmol) and thiocarbonate (11) (34.6 g, 148 mmol) in dichloromethane at 0° C. was dropwise added a 32% solution of peracetic acid (300 mmol) in acetic acid over 2 h. The reaction temperature was kept below 35° C. during the addition of peracetic acid. After the addition was complete, the reaction mixture was stirred overnight at room temperature. The resulting white precipitate was filtered and washed successively with water, and a mixture of ether and hexane (1:2), then dried under vacuum to afford the crude title compound. This product was crystallized once from a mixture of ethyl acetate and hexane (1:1) to afford (1R)-1-[((3S,4S)-2,5-dioxo-3,4-dibenzoyloxypyrrolidinyl)-oxycarbonyloxy]-2-methylpropyl 2-methylpropanoate (25) (13.7 g, 25% yield). The diastereomeric purity of the product was determined to be 98.4% d.e. by HPLC using a chiral column. 1H NMR (CDCl3, 400 MHz): δ 1.06 (d, 6H), 1.22 (d, 3H), 1.22 (d, 3H), 2.20 (m, 1H), 2.64 (hept. 1H), 6.01 (br. s, 2H), 6.64 (d, 1H), 7.47 (m, 4H), 7.63 (m, 2H), 8.07 (m, 4H).

Provenance & Evidence