Pyrazolo[1,5-a]pyrimidine-3-carboxylic acid, 5,7-dichloro-, ethyl ester synthesis

Yield: 85.82%

Reaction Conditions:

with N,N-diethylaniline;trichlorophosphate at 80; for 3 h;

Steps:

1 Synthesis of Compound 1.2.
To a mixture of 1.1 (3 g, 13.44 mmol, 1.0 eq) in phosphorous oxychloride (8.7 mE) was added diethyl aniline (3.37 g, 22.56 mmol, 1.68 eq). The reaction mixture stirred at 80° C. for 3 h. Afier completion of reaction, the mixture was diluted with ice cold water, neutralized with saturated sodium bicarbonate solution and extracted with dichioromethane. The organic layers were combined, washed with a brine solution, dried over sodium sulphate and concentrated under reduced pressure to pressure to obtain the crude material. This was further purified by column chromatography and the compound was eluted in 15% ethyl acetate in hexane to obtain pure 1.2 (3.0 g, 85.82%). MS(ES): mlz 261 [M+H].

References:

Nimbus Lakshmi, Inc.;Masse, Craig E.;Greenwood, Jeremy Robert;Mondal, Sayan;Cowen, Scott D.;McLean, Thomas H. US2019/31664, 2019, A1 Location in patent:Paragraph 0407; 0411; 0412; 0443; 0446; 0447