反应详情

To a solution of 38.2 g (0.142 mol) of the above methyl ester 7 in 500 mL methanol was added 140 mL (0.28 mol) of freshly-prepared 2 M aqueous LiOH with stirring to give a colorless solution. This was stirred overnight, after which HPLC showed no starting material. The solution was reduced by 50% in vacuo and partitioned between 1 N HCl and CH2Cl2 (˜200 mL each). The phases were separated and the aqueous layer was washed again with CH2Cl2. The organic phases were combined, dried (MgSO4), and concentrated to a white solid. This was recrystallized twice from ethyl acetate/hexanes to give 34.7 g (0.136 mol, 96%) of 8 as fine white needles. M/z=256.2 (M+H+).

1. customto give a colorless solution
2. stirringThis was stirred overnight
3. custompartitioned between 1 N HCl and CH2Cl2 (˜200 mL each)
4. customThe phases were separated
5. washthe aqueous layer was washed again with CH2Cl2
6. dry with materialdried (MgSO4)
7. concentrationconcentrated to a white solid
8. customThis was recrystallized twice from ethyl acetate/hexanes