p-Toluenesulfonic acid → HCID 20161352, compound

Participants

Reaction Steps

A solution of 1-(n-butyl)-3-ethoxycarbonyl-pyrrolidin-2,4-dione (1.02 g.) in wet acetonitrile (23 ml.) was heated under reflux for 1.5 hours. The acetonitrile was evaporated under reduced pressure, leaving a clear oil which was immediately dissolved in toluene (28 ml.). To this solution was added 5-amino-1-(pent-3-ynyl)-4-cyanopyrazole (0.6 g.) and a catalytic amount of toluene-p-sulphonic acid (0.05 g.). The mixture was heated under reflux overnight, collecting water in a Dean-Stark trap. The reaction mixture was cooled to 0° and diluted with ether. The resulting precipitate was collected by filtration, giving 0.89 g. of 5-[N-(n-butyl)-2-oxo-3-pyrrolin-4-yl]amino-1-(pent-3-ynyl)-4-cyanopyrazole, which was used without further purification.

Provenance & Evidence