反应详情

温度

-25 °C

To racemic intermediate 1, one enantiomer being (S)-2-phenyl-1-(toluene-4-sulfonyl)-2,5-dihydro-1H-pyrrole-3-carboxylic acid ethyl ester (1.8 g, 5.0 mmol), was dissolved in methylene chloride (60 mL) in a three necked flask equipped with an addition funnel and an internal thermometer. The mixture was cooled to −25° C., DIBAL (1M/toluene, 12.5 mL, 12.5 mmol) was added dropwise and the reaction stirred for an additional 0.5 hours. Methanol was added to the cold solution until gas evolution ceased and the solvents were then removed at reduced pressure. The residue was partitioned between a saturated solution of Rochelle's salt and methylene chloride. The organics were washed with brine, dried over sodium sulfate, filtered, and concentrated. The crude product was chromatographed on silica gel using a gradient of 20% to 60% ETOAc/Hexanes to yield the title compound as a sticky foam (1.6 g, 98% yield).

1. customequipped with an addition funnel
2. customthe solvents were then removed at reduced pressure
3. customThe residue was partitioned between a saturated solution of Rochelle's salt and methylene chloride
4. washThe organics were washed with brine
5. dry with materialdried over sodium sulfate
6. filtrationfiltered
7. concentrationconcentrated
8. customThe crude product was chromatographed on silica gel using a gradient of 20% to 60% ETOAc/Hexanes