Tetrahydrofuran → Dibenzylidene acetone

Participants

Reaction Steps

A slurry of 3-bromopyridine (19 g, 120 mmol), 2-(2-fluoro-5-nitrophenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (40 g, 150 mmol) and KF (23 g, 396 mmol) in THF (600 ml) and water (30 ml) was degassed with nitrogen for 10 min, then treated with tris(dibenzylideneacetone)-dipalladium(0) (2.2 g, 2.4 mmol) followed by tri-tert-butylphosphine (0.2 M solution in 1,4-dioxane; 2.4 ml, 0.48 mmol), and the reaction was stirred mechanically at ambient temperature for 30 min. The mixture was then heated at 50° C. for 1 h before being cooled to ambient temperature. The reaction was poured into ice-cold 0.5 N aqueous NaOH solution and stirred for 1 h. The solid product was collected by filtration, washed with water, allowed to dry under suction, then washed with isohexane and dried to give 3-(2-fluoro-5-nitrophenyl)pyridine as a grey solid (26.2 g, contaminated with dibenzylideneacetone): δH (400 MHz, CDCl3) 7.37 (1H, t, J 9), 7.45 (1H, ddd, J 8, 5 and 1), 7.89-7.93 (1H, m), 8.28-8.33 (1H, m), 8.40 (1H, dd, J 7 and 3), 8.71 (1H, d, J 4), 8.84 (1H, s).

Provenance & Evidence