Diethyl Malonate → HCID 135973872, compound

Participants

Reaction Steps

A sodium ethoxide solution (EtOH/EtONa, 0.5 N, 400 ml) containing diethyl malonate (50 mmol, 1 eq., 5.8 ml, 6.6 g) and 5-cyclopropyl-1H-pyrazol-3-amine (50 mmol, 1 eq., 6.16 g) is refluxed for 7 hours. After cooling to room temperature, an aqueous hydrochloric acid solution (5 N, 240 ml) is added until pH 5 is obtained. Volatiles are then removed under reduce pressure and the residue dried under vacuum to afford 2-cyclopropyl-7-hydroxypyrazolo[1,5-a]pyrimidin-5(4H)-one x271. To this residue is successively added POCl3 (125 ml, 1.34 mol) and N,N-dimethylaniline (12.5 ml, 0.1 mol, 2 eq.) and the resulting mixture is refluxed during 3 hours. After cooling to room temperature, the reaction mixture is poured on ice and stirred during one hour at this temperature. The reaction mixture is extracted with dichloromethane, and the resulting organic phase is washed twice with water. The organic phase is dried over Na2SO4, filtered and evaporated under reduce pressure. The crude product is purified chromatography on silicagel (CH2Cl2/hexane: 40/60) to afford 5.85 g of 5,7-dichloro-2-cyclopropylpyrazolo[1,5-a]pyrimidine x272 as a solid.

Provenance & Evidence