[CH3:1][C:2]1([CH3:9])[CH:7]=[CH:6][C:5](=[O:8])[CH:4]=[CH:3]1.C(O[CH2:15][N:16]([CH2:22][C:23]1[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1)[CH2:17][Si](C)(C)C)CCC.C(=O)([O-])[O-].[K+].[K+]>ClCCl.FC(F)(F)C(O)=O>[CH2:22]([N:16]1[CH2:17][CH:6]2[CH:7]([C:2]([CH3:9])([CH3:1])[CH:3]=[CH:4][C:5]2=[O:8])[CH2:15]1)[C:23]1[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1To a solution of 15.96 g of 4,4-dimethyl-2,5-cyclohexadienone and 46 cm3 of N-butoxymethyl-N-trimethylsilylmethylbenzylamine in 200 cm3 of dichloromethane are added, at a temperature of 10° C., 8 drops of trifluoroacetic acid. The reaction mixture is brought to reflux for 2 hours and potassium carbonate is then added and the solution is filtered through a sinter funnel and concentrated to dryness under reduced pressure (2.7 kPa). The residue is chromatographed on a column of silica gel (particle size 0.04-0.06 mm, diameter 8.5 cm, height 30 cm), eluting under a pressure of 0.5 bar of nitrogen with a mixture of cyclohexane and ethyl acetate (80/20 by volume) and collecting 100 cm3 fractions. Fractions 38 to 56 are combined and concentrated to dryness under reduced pressure (2.7 kPa). 14.7 g of (3aRS,7aRS)-2-benzyl-7,7-dimethyl-2,3,3a, 4,7,7a-hexahydro-1H-4-isoindolone are obtained in the form of a yellow oil.
読み込み中…
