Cesium carbonate → 2-Methyl-2-(3-phenylethynyl-pyrazin-2-yl)-propionic acid ethyl ester

Participants

Reaction Steps

To a solution of 2-(3-Chloro-pyrazin-2-yl)-2-methyl-propionic acid ethyl ester (0.70 g) in acetonitrile (7.0 ml) was added 1-ethynyl-2-trifluoromethylbenzene (0.781 g) and caesium carbonate (“Cs2CO3”) (2.99 g) and nitrogen bubbled through the solution for 20 min. To this solution was added as 4,5-(bisdiphenylphosphino)-9,9-dimethylxanthene (“Xantphos”) (0.133 g) and (1,1′-bis(diphenylphosphino)-ferrocene)dichloro palladium(2) (0.125 g) and the reaction mixture heated to reflux for 30 min. The reaction mixture was cooled to ambient temperature then filtered and concentrated. The residue was purified by chromatography on silica gel (eluent 5-95% ethyl acetate in isohexane) to give 2-methyl-2-(3-phenylethynyl-pyrazin-2-yl)-propionic acid ethyl ester (compound B1 of Table B) (0.52 g).

Provenance & Evidence