Hydrochloric Acid → (2-Butyl-5-nitro-1-benzofuran-3-yl)(4-hydroxyphenyl)methanone

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Reaction Steps

50 ml of dry xylene, 2.1 ml (8.9 mmol) of tri-n-butylamine and 10 g of the recovered molecular sieve from example 3 were heated under reflux using a Dean-Stark condenser. Then 2.20 g (5.92 mmol) of 2-(2-pentanoyloxy-5-nitrophenyl)-1-(4-methoxyphenyl)-ethanone (example 2) dissolved in 5 ml of dry xylene were added to the reaction mixture. After 8 h LC-MS analysis indicated the complete consumption of the starting material. The reaction mixture was cooled to room temperature and the molecular sievel was filtered off. After evaporation of the solvent, 2.1 ml (8.9 mmol) of tri-n-butylamine were added followed by the addition of 17.8 mmol of gaseous HCl. The resulting mixture was heated at 200° C. for 4 h until LC-MS analysis indicated the complete consumption of the 2-n-butyl-3-(4-methoxybenzoyl)-5-nitrobenzofuran. The reaction mixture was cooled to room temperature and 20 ml of water and 50 ml MTBE were added. The organic phase was washed once with 25 ml of 1M aqueous HCl and 20 ml of water dried over MgSO4 and concentrated to dryness. Flash chromatography of the residue provided the pure title compound which crystallized directly to yield 1.30 g (65%).

Provenance & Evidence