Hydrochloric Acid → (E)-1-(2-chloro-4-hydroxyphenyl)-7-(4-hydroxyphenyl)hept-1-ene-3,5-dione

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Reaction Steps

6-(4-Hydroxyphenyl)hexane-2,4-dione (18 mg, 87 μmol) and boron trioxide (22 mg, 0.32 mmol) was placed in a 20 mL reaction vessel, and dissolved in 0.4 mL of ethyl acetate. To the stirring solution at 80° C. were added 2-chloro-4-hydroxybenzaldehyde (12 mg, 78 μmol) and tri-n-butyl borate (50 μL, 0.19 mmol). After the reaction mixture was stirred for 2 h at the same temperature, n-butylamine (19 μL, 0.19 mmol) was added with additional stirring for 1 h. The reaction mixture was treated with a 1:1 solution (1 mL) of 1N HCl and brine, and was stirred at 50° C. for 5 min to 1 h (if necessary, the reaction mixture was neutralized by saturated NaHCO3 aqueous solution). The organic layer was purified directly by silica gel column chromatography (eluting with hexane/ethyl acetate or chloroform/methanol) to obtain the title compound as a solid (9.2 mg, 34%) having the following characteristics.

Provenance & Evidence