反应详情

Partially purified residue containing lactol 7 from a procedure in accordance with Example 3E (6.24 g, 12.5% detected by NMR, 40.5 mmol, 1 eq.) was dissolved in CH2Cl2 (90 ml) and stirred at room temperature. Cyclohexanol (14.2 g, 14.9 ml, 3.5 eq.) was added via syringe and Amberlyst 15 (825 mg) and MgSO4 (16.83 g) were added as solids. The reaction mixture was stirred at r.t. for 36 h. The reaction mixture was filtered through a sinter funnel and the solids washed with CH2Cl2 (2×30 ml). The filtrate was concentrated under reduced pressure and the excess cyclohexanol was removed by distillation at 65° C. under high vacuum. The residue was purified by column chromatography (silica), eluting with petrol/EtOAc (10:1), to give the cyclohexyl acetal 50, (as an approximately 1.5:1 mixture of diastereoisomers, 6.10 g, 64% from lactol 7) as a yellow solid.

1. stirringThe reaction mixture was stirred at r.t. for 36 h
2. filtrationThe reaction mixture was filtered through a sinter funnel
3. washthe solids washed with CH2Cl2 (2×30 ml)
4. concentrationThe filtrate was concentrated under reduced pressure
5. customthe excess cyclohexanol was removed by distillation at 65° C. under high vacuum
6. customThe residue was purified by column chromatography (silica)
7. washeluting with petrol/EtOAc (10:1)