反应详情

A solution of product from Step A (16.4 g, 0.1 mol), toluene (300 ml), p-toluenesulfonic acid (1.0 g) and ethylene glycol (20 ml) was heated at reflux with the aid of a Dean-Stark trap. After 6 hours, the organic layer was cooled, washed with saturated Na2CO3. The Na2CO3 layer was extracted with ethyl acetate (2×). The combined organic extracts were dried, filtered and concentrated to dryness. The residue was distilled at 149-153° C. at 0.3 mm Hg to yield 16.4 g (79%) of product.

1. temperatureat reflux with the aid of a Dean-Stark trap
2. temperaturethe organic layer was cooled
3. washwashed with saturated Na2CO3
4. extractionThe Na2CO3 layer was extracted with ethyl acetate (2×)
5. customThe combined organic extracts were dried
6. filtrationfiltered
7. concentrationconcentrated to dryness
8. distillationThe residue was distilled at 149-153° C. at 0.3 mm Hg