反应详情

A solution of 22 (50.6 g, 250 mmol), and Dowex 50W X8-100 H+ resin (76.5 g) in MeOH (500 ml), was heated at 50° C. for 2 hours, cooled to room temperature, filtered, and the resin washed with MeOH (1×200 ml). The methanol fractions were combined and concentrated in vacuo. The crude product was passed through a plug of silica gel using ethyl acetate:hexanes (1:1) as the eluent. Fractions containing the product were combined and concentrated in vacuo to afford 23 (32.8 g, 200 mmol, 81%) as an oil. The material was used in the next step without any further purification.

1. filtrationfiltered
2. washthe resin washed with MeOH (1×200 ml)
3. concentrationconcentrated in vacuo
4. additionFractions containing the product
5. concentrationconcentrated in vacuo