Tetrahydrofuran → 4-(2-Phenylethynyl)benzoic acid

Participants

Reaction Conditions

Reaction Steps

The 4-iodo-benzoic acid methyl ester 1 (20.0 g, 76.34 mmol), ethynyl-benzene 2 (8.56 g, 83.96 mmol), PdCl2(PPh3)2 (0.65 g, 0.92 mmol), and CuI (0.35 g, 1.83 mmol) were mixed with THF (110 ml) in a round bottom under argon. The dry THF was sparged with dry, oxygen-free argon for at least 5 min. immediately before use. The reaction was cooled to 10° C. and TEA (16 ml) was added. The cooling bath was removed and the reaction was stirred at RT under argon. After 2.5 h, the reaction was diluted with EtOAc (400 ml) and the solids were filtered off through a pad of celite. The organic filtrate was washed with 1M HCl (60 ml), sat. aq. NaHCO3 (60 ml), water (60 ml), brine (60 ml), dried with Na2SO4, filtered and concentrated under reduced pressure. The crude solid methyl ester was dissolved in MeOH (400 ml), 6M NaOH (30 ml) and water (50 ml). The reaction was stirred at 70° C. until a clear solution was formed (about 1 h). The reaction could be followed by LCMS. The reaction was cooled and diluted with water (500 ml) and hexane (100 ml). The pH was adjusted to pH 6-7. The white solid that formed was collected and washed with water (3×60 ml) and hexane (3×60 ml). The solid 3 was dried in vacuo yielding 17.3 g (approximately quantitative yield in 99% purity).

Provenance & Evidence