Dimethylformamide → 5-(2,4-Bis-benzyloxy-5-styrylphenyl)-isoxazole-3-carboxylic acid ethylamide

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a mixture of trans-2-phenylvinylboronic acid (0.472 g, 3.2 mmol) and 5-(2,4-Bis-benzyloxy-5-bromophenyl)-isoxazole-3-carboxylic acid ethylamide (1.079 g, 2.13 mmol) was added sodium hydrogen carbonate (536 mg, 6.39 mmol) followed by DMF (25 mL) and water (5 mL). The mixture was degassed by evacuation and flushing with nitrogen (three times), followed by bubbling nitrogen gas through mixture for five minutes. Dichlorobis(triphenylphosphine)palladium (II) (149 mg, 0.21 mmol) was added and reaction mixture was heated under a nitrogen atmosphere at 80° C. for seven hours (reaction mixture becomes dark brown in colour after 10 minutes). The reaction mixture was allowed to cool to ambient temperature and the majority of solvents were removed in vacuo. The resulting residue was partitioned between ethyl acetate (100 mL) and water (100 mL) and this mixture was filtered through a pad of celite to remove Palladium residues. The phases were separated and the organic phase was washed with water (2×50 mL), saturated aqueous sodium chloride solution (100 mL) then dried over sodium sulphate. The mixture was filtered and the filtrate solvents were removed in vacuo to afford a brown solid (800 mg). The celite filter cake was washed with dichloromethane then dried over sodium sulphate. The mixture was filtered and the filtrate solvents were removed in vacuo to afford a brown solid (541 mg). The combined product batches were purified by trituration with ethyl acetate-hexane mixture. This affords 5-(2,4-Bis-benzyloxy-5-styrylphenyl)-isoxazole-3-carboxylic acid ethylamide as a light brown solid (808 mg, 71%). LCMS: [M+H]+ 531. 1H NMR (400 MHz, CDCl3) δ 1.12 (t, 3H), 3.37 (m, 2H), 4.95 (s, 2H), 5.07 (s, 2H), 6.46 (s, 1H), 6.70 (brt, 1H). 7.11 (s, 1H), 7.17 (d, 1H), 7.23 (d, 1H), 7.32-7.44 (m, 15H), 8.09 (s, 1H).

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