4-Chlorobenzaldehyde → 2,2-Dimethyl-5-[2-(4-chlorophenyl)ethenyl]-3(2H)-furanone

Participants

Reaction Steps

To a solution of dry diisopropylamine (5.0 mL, 35.7 mM) in dry tetrahydrofuran (150 mL) at -78° C., was added dropwise a 2.3 N solution of nbutyllithium in hexane (15.5 mL, 35.7 mM). After the reaction solution was stirred 15 minutes, a solution of 2,2,5-trimethyl-3(2H)-furanone (3.0 g, 23.8 mM) in tetrahydrofuran (25 mL) was added dropwise. Hexamethylphosphoramide (6.4 mL, 34.7 mM) was added dropwise after 30 minutes. Finally, p-chlorobenzaldehyde (3.0 g, 2.7.8 mM) in tetrahydrofuran (25 mL) was added in one portion. The reaction solution was stirred 15 minutes when trifluoroacetic anhydride (10.5 mL, 276 mM) was added in one portion. Again the reaction mixture was stirred 15 minutes when triethylamine (5.9 mL, 48 mM) was added and the mixture was allowed to warm to room temperature. The reaction mixture was then partitioned between saturated aqueous sodium chloride (50 mL) and diethyl ether (50 mL). The organic layer was separated and washed with saturated aqueous sodium bicarbonate (2×25 mL) and saturated aqueous sodium chloride (25 mL). The organic layer was dried over magnesium sulfate, filtered and concentrated under reduced pressure to give an orange liquid which was purified by chromatography (silica gel, pet. ether-ethyl acetate) to afford yellow crystals (3.8 g, 65% yield), m.p. 91°-92° C.

Provenance & Evidence