PYRAZOLO[1,5-A]PYRIMIDINE-6-CARBOXYLIC ACID synthesis

Yield:-

Reaction Conditions:

Stage #1: pyrazolo[1,5-a]pyrimidine-6-carboxylic acid ethyl esterwith sodium hydroxide;water at 20; for 1 h;
Stage #2: with acetic acid in water;

Steps:

1.4

Stage 1.4: Pyrazolo[1,5-a]pyrimidine-6-carboxylic acid Pyrazolo[1,5-a]pyrimidine-6-carboxylic acid ethyl ester (350 mg; 1.83 mMol) (Example 1; stage 1.3) is suspended in NaOH (2N; 8 mL)and stirred at RT for 1 h. 10 mL of acetic acid is added to the yellowish reaction mixture followed by removal of the solvent under reduced pressure (high vacuum, 30°C). The residue is taken up into water (50 mL) and extracted with EtOAc (2 x 150 mL). The combined organics are washed with water, dried (Na₂SO₄), concentrated under reduced pressure to a small volume. The crystalline product is filtered off to obtain the title compound 1.4 as slightly beige crystals (200 mg); mp. 228-233 °C; MS(ESI⁺):m/z= 63.9 (M+H)⁺;HPLC: _tRet = 3.39 minutes (System1).

References:

EP1918291,2008,A1 Location in patent:Page/Page column 23