Diisopropylethylamine → (1-[4-(6-Chloro-1H-indol-2-yl)-benzyl]-3,5-dimethyl-1H-pyrazol-4-yl)-acetic acid

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 1-(4-ethynylbenzyl)-3,5-dimethyl-1H-pyrazol-4-yl-acetic acid tert.-butyl ester (4.4 g) and 5-chloro-2-iodophenylamine (3.4 g) in tetrahydrofuran (100 ml) at room temperature is added diisopropylethylamine (5.8 ml). The reaction is degassed and put under argon. Copper(I)iodide (260 mg) and bis(triphenylphosphine)palladiumdichloride (475 mg) are added. After 18 h, the reaction mixture is absorbed onto Extrelut and purified by flash chromatography (7:3 isocratic-cyclohexane:ethyl acetate) to yield a solid (4.3 g; HPLC retention time 1.66 min (Method J)). The solid (4.2 g) is dissolved in N-methyl-2-pyrrolidone (25 ml) and the solution degassed and put under argon. Potassium tert-butoxide (4.1 g) is added and the reaction is then heated to 50° C. After 15 h, further potassium tert-butoxide (1.0 g) is added. After 15 h the reaction temperature is increased to 75° C. After 3 h, the reaction mixture is allowed to cool to room temperature and a copious amount of water is added. The reaction mixture is extracted twice with ethyl acetate and the aqueous phase is acidified to pH 3 with 1M aqueous hydrochloric acid. The resultant precipitate is filtered off and triturated with hot acetonitrile to yield (1-[4-(6-Chloro-1H-indol-2-yl)-benzyl]-3,5-dimethyl-1H-pyrazol-4-yl)-acetic acid (2.0 g; [M+H]=394; HPLC retention time 1.51 min (Method E)).

Provenance & Evidence