反应详情

To a solution of benzenethiol (11.16 ml, 108.65 mmol), (R)-methyl 3-(benzyloxycarbonylamino)-4-hydroxybutanoate (INTERMEDIATE 4, 26.4 g, 98.77 mmol) and tributylphosphine (34.5 ml, 138.28 mmol) in anhydrous THF (350 ml) under nitrogen atmosphere was added. A solution of (E)-diazene-1,2-diylbis(piperidin-1-ylmethanone) (34.9 g, 138.22 mmol) in anhydrous THF (350 ml) was added dropwise over a 30 minute period. During the addition a white precipitate was formed and stirring was continued for 2 hours after the addition was complete. The white precipitate was filtered off and evaporation of the volatiles under reduced pressure gave a residue, which was purified by column chromatography (ISCO, eluting with 0→100% EtOAc/hexanes) to give the title product (25.0 g, yield: 70%).

1. additionDuring the addition a white precipitate
2. customwas formed
3. additionafter the addition
4. filtrationThe white precipitate was filtered off
5. customevaporation of the volatiles under reduced pressure
6. customgave a residue, which
7. customwas purified by column chromatography (ISCO, eluting with 0→100% EtOAc/hexanes)