反应详情

Treat a solution of 4-benzyloxycarbonyl-1-methylpiperazin-2-one (1.4 g, 5.7 mmol) in THF (4 mL) cooled at −78° C. with lithium bis(trimethylsilyl)amide (1.0 M solution in THF, 5.7 mL, 5.7 mmol) dropwise and stir 30 min. Add 2-(dibenzylamino)-3-phenylpropanal (1 g, 3.1 mmol) in THF (2 mL) and stir at −78° C. for 45 min. Quench with saturated aqueous ammonium chloride solution. Separate organic layer and wash with water, saturated aqueous sodium chloride, dry (magnesium sulfate), concentrate and purify (silica gel chromatography, eluting with 1:1 hexanes:ethyl acetate) to provide the title compound as a mixture of four diastereoisomers which are separated by HPLC (normal phase, eluting with 85:15 hexanes:isopropanol) (828 mg, 45% total yield).

1. customQuench with saturated aqueous ammonium chloride solution
2. washSeparate organic layer and wash with water, saturated aqueous sodium chloride
3. dry with materialdry (magnesium sulfate)
4. concentrationconcentrate
5. custompurify
6. wash(silica gel chromatography, eluting with 1:1 hexanes:ethyl acetate)