反应详情

26.06 g (0.096 mol) of the title compound of Step C, 250 mL of ethylene glycol, 170 mL of trimethyl orthoformate (purchased from Aldrich Chemical Company), and 0.06 g of p-toluenesulfonic acid monohydrate were stirred together at 80° C. under nitrogen overnight. The mixture was diluted with 400 mL of diethyl ether. The resulting mixture was washed with a 1:1 mixture of 1N sodium hydroxide:saturated aqueous NaCl (2×600 mL) and then with saturated aqueous NaCl (1×600 mL). The organic layer was dried (Na2SO4), filtered, and evaporated to dryness. The crude product was chromatographed over silica gel eluting with a mixture of ethyl acetate:hexane (1:9) to yield 24.73 g of the title compound of Step D as a solid melting at 97° C. (dec). 1H NMR (CDCl3): δ2.2 (s,3H), 2.3 (m,2H), 2.4 (s,3H), 3.0 (m,2H), 4.15 (m,2H), 4.3 (m,2H), 7.3 (s,1H).

1. washThe resulting mixture was washed with a 1:1 mixture of 1N sodium hydroxide
2. dry with materialThe organic layer was dried (Na2SO4)
3. filtrationfiltered
4. customevaporated to dryness
5. customThe crude product was chromatographed over silica gel eluting with a mixture of ethyl acetate:hexane (1:9)