Piperidine → 5-(p-Cyanophenyl)-4-pentynoic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of 4-pentynoic acid (2.15 g, 22 mmol), 4-bromobenzonitrile (3.64 g, 20 mmol), and piperidine (40 mL) was degassed by bubbling nitrogen through the solution for 5 min. prior to the addition of tetrakis(triphenylphosphine)palladium(0) (240 mg, 0.2 mmol). The reaction vial was sealed and warmed to 80° C. for 1.5 hours. After cooling to 23° C., the reaction mixture was diluted with ethyl acetate (200 mL), filtered, and concentrated in vacuo. The residue was diluted with ethyl acetate (300 mL), washed with 5% HCl (2×100 mL), washed with water (1×100 mL), and extracted with 3% sodium carbonate (2×200 mL). The basic aqueous layer was treated with decolorizing carbon, filtered, and acidified to pH=2. The resultant solid was filtered, washed with water, dried, and purified by flash chromatography (gradient ethyl acetate:methylene chloride:acetic acid 1:9:0.005) and fractional recrystallization (methylene chloride-ether) to afford 5-(p-cyanophenyl)-4-pentynoic acid as a white solid: m.p. 149°-152° C.

Herkunft & Nachweise