反应详情

Palladium on charcoal catalyst (10%; 50 mg) was added to a degassed solution of 5-(2,4-Bis-benzyloxy-5-styrylphenyl)-isoxazole-3-carboxylic acid ethylamide (690 mg, 1.30 mmol) in 1,4-dioxane (50 mL) under a nitrogen atmosphere. The reaction mixture was hydrogenated for a total of 4.75 hrs with further Pd on charcoal catalyst (50 mg) added at 0.75 and 2.5 hrs. The reaction mixture was filtered through a pad of celite, which was washed with 1,4-dioxane (20 mL) and dichloromethane (20 mL). The combined filtrate solvents were removed in vacuo to afford a cream-coloured solid, which was purified by flash chromatography on silica gel (20 g, IST) eluting with 10 to 50% ethyl acetate in hexane. This affords 5-(2,4-Bis-benzyloxy-5-phenethylphenyl)-isoxazole-3-carboxylic acid ethylamide as a pale yellow solid (609 mg, 88%). LCMS: [M+H]+ 533. 1H NMR (400 MHz, CDCl3) δ1.26 (t, 3H), 2.86-2.96 (m, 4H), 3.49 (m, 2H), 5.03 (s, 2H), 5.18 (s, 2H), 6.56 (s, 1H), 6.81 (t, 1H), 7.07 (s, 1H), 7.15-7.20 (m, 3H), 7.23-7.28 (m, 2H), 7.31-7.42 (m, 10H), 7.73 (s, 1H).

1. additionadded at 0.75 and 2.5 hrs
2. filtrationThe reaction mixture was filtered through a pad of celite, which
3. washwas washed with 1,4-dioxane (20 mL) and dichloromethane (20 mL)
4. customThe combined filtrate solvents were removed in vacuo
5. customto afford a cream-coloured solid, which
6. customwas purified by flash chromatography on silica gel (20 g, IST)
7. washeluting with 10 to 50% ethyl acetate in hexane