methyl (3R)-4-hydroxy-3-(phenylmethoxycarbonylamino)butanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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%). During the addition a white precipitate was formed after the addition The white precipitate was filtered off evaporation of the volatiles under reduced pressure gave a residue, which was purified by column chromatography (ISCO, eluting with 0→100% EtOAc/hexanes)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (R)-Benzyl 5-oxotetrahydrofuran-3-ylcarbamate (INTERMEDIATE 3, 27.0 g, 114.78 mmol) was dissolved in methanol (75 ml) and triethylamine (75 ml) was added at room temperature. The resulting mixture was allowed to stir overnight at this temperature. The mixture was concentrated in vacuo to provide the title product. This material was used to prepare INTERMEDIATE 5 without further purification. The mixture was concentrated in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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%). During the addition a white precipitate was formed after the addition The white precipitate was filtered off evaporation of the volatiles under reduced pressure gave a residue, which was purified by column chromatography (ISCO, eluting with 0→100% EtOAc/hexanes)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (R)-Benzyl 5-oxotetrahydrofuran-3-ylcarbamate (INTERMEDIATE 3, 27.0 g, 114.78 mmol) was dissolved in methanol (75 ml) and triethylamine (75 ml) was added at room temperature. The resulting mixture was allowed to stir overnight at this temperature. The mixture was concentrated in vacuo to provide the title product. This material was used to prepare INTERMEDIATE 5 without further purification. The mixture was concentrated in vacuo