[OH:1][CH2:2][CH:3]1[CH2:7][N:6]([CH2:8][C:9]2[CH:14]=[CH:13][C:12]([O:15][CH3:16])=[CH:11][CH:10]=2)[C:5](=[O:17])[CH2:4]1.CCN(CC)CC>C(Cl)Cl>[CH3:16][O:15][C:12]1[CH:11]=[CH:10][C:9]([CH2:8][N:6]2[C:5](=[O:17])[CH2:4][CH:3]([CH:2]=[O:1])[CH2:7]2)=[CH:14][CH:13]=1In a three necked flask, under argon, a solution 4-hydroxymethyl-1-(4-methoxy-benzyl)-pyrrolidin-2-one a2 (4.3 g, 0.018 mol) and Et3N (8.9 ml) in CH2Cl2 (25 ml) cooled down to −10° C. Pyridine-SO3 (10.1 g, 0.064 mol, 3.5 eq) is added by portions and the temperature raised up to 1° C. After 3 h at −10° C., the reaction is quenched with water (100 ml) and extracted with CH2Cl2 (3 times). The organic phase is washed with successively a 1M solution of KHSO4, water, brine, dried over MgSO4, filtered and evaporated in vacuo to give the crude aldehyde a3 (3.2 g, 87%). It is dried several times by azeotropic distillation with toluene and used as such in the next step.
Wird geladen…
