Nitrogen → 4-[2-(4-Butylphenyl)ethynyl]benzaldehyde

Participants

Reaction Steps

A solution of p-bromobenzaldehyde (50 g, 270 mmol), 1-butyl-4-ethynylbenzene (47.0 g, 297 mmol), Et3N (540 mmol, 75 mL), CuI (0.52 g, 2.70 mmol), and PPh3 (1.42 g, 5.40 mmol) in 500 mL dry THF was degassed for 15 min by passing a stream of N2 through the solution. Pd(OAc)2 (1.21 g, 5.40 mmol) was then added and the black solution was stirred at rt for 17 hours. 1-butyl-4-ethynylbenzene (4.3 g) was added and the reaction stirred for an additional 3 hours. The reaction was filtered and 20 g of activated charcoal was added to the combined filtrates. This suspension was stirred for 2 hours at rt and was filtered over a pad of celite and reduced to a dark brown solid. The solid was taken up in DCM and added 100 g silica gel and removed the solvent. The product, now disposed on silica gel, was added to the top of a silica gel plug, preconditioned with 5% EtOAc in c-Hex, and filtered using 5% EtOAc in c-Hex, then up to 50%. The fractions containing the product were concentrated to a dark solid. The solid was taken up in 500 mL EtOAc and reduced to half volume. The solution was allowed to stand at rt and solids appeared. Then 200 mL pentane was added and cooled to 0° C. This was allowed to stand overnight. The solids were filtered and washed with 10% MTBE in pentane. The solids were still very dark. This material was further purified by flash chromatography on SiO2 (10/90 EtOAc/c-Hex). The combined pure fractions were evaporated to give a light brown solid. This solid was crystallized by dissolving in 100/150 EtOAc/MTBE with slight heating. Upon cooling to rt, solids appeared. 400 mL of pentane were added and the resulting mixture was then cooled to 0° C. and allowed to stand overnight. The solids were filtered and washed with 750 mL 1/3 MTBE/Pentane to give the title compound as a slightly off-white colored solids (a plate like crystal) (41.0 g, 58%). 1H NMR (CDCl3) δ: 10.03 (s, 1H), 7.87 (d, J=8.3 Hz, 2H), 7.67 (d, J=8.3 Hz, 2H), 7.49 (d, J=8.3 Hz, 2H), 7.21 (d, J=8.3 Hz, 2H), 2.66 (t, J=7.9 Hz, 2H), 1.71-1.56 (m, 2H), 1.46-1.31 (m, 2H), 0.98 (t, J=7.2 Hz, 3H). HPLC, Rt: 5.3 min (purity: 100%).

Provenance & Evidence