反应详情

温度

55 °C

To a solution of thoroughly dried product from Step C (5.9 g, 0.98 mol) in 140 ml absolute ethanol (warming necessary to promote solubility) was added 467 mg (0.0018 mol) pyridinium 4-toluenesulfonate (PPTS). After stirring under N2 at 55° C. for 3 hours, no reaction was detected by TLC. The solvent was removed under reduced pressure. Then, 125 ml absolute ethanol was added and PPTS was added until pH 3 was achieved. After 4 hours under N2 at 55° C. the solvent was removed under reduced pressure. The residue was chromatographed on silica gel first with 85:15 CHCl3 :CH3OH (v:v) and a second time with 90:10 CHCl3 :CH3OH (v:v) saturated with NH3. The product was recrystallized from H2O after decolorizing with charcoal, yielding 700 mg (17%) of product mp 102°-103° C.

1. customThe solvent was removed under reduced pressure
2. additionThen, 125 ml absolute ethanol was added
3. additionPPTS was added until pH 3
4. customAfter 4 hours under N2 at 55° C. the solvent was removed under reduced pressure
5. customThe residue was chromatographed on silica gel first with 85:15 CHCl3
6. customThe product was recrystallized from H2O