1,10-Phenanthroline → 7-(1-Ethyl-propyl)-3-(2,4-dichloro-thiazol-5-yl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidine

Participants

Reaction Conditions

Reaction Steps

7-(1-ethyl-propyl)-3-iodo-2,5-dimethyl-pyrazolo[1,5-a]pyrimidine (10 g, 29.17 mmoles), 2,4-dichlorothiazole (5.2 g, 33.76 mmoles), cesium carbonate (19.9 g, 61.07 mmoles) and 1,10-phenanthroline (1 g, 5.5 mmoles) are charged into a 250 mL 3-necked round bottomed flask, followed by 2-MeTHF (36 mL, 3.6 volumes). The reaction mixture is degassed with nitrogen and then evacuated. Cuprous chloride (0.57 g, 5.7 mmoles), DMAC (10 mL, 1 volume) and 2-MeTHF (4 mL, 0.4 volumes) are added in succession. The reaction mixture is degassed with nitrogen and then evacuated. The contents are refluxed for 20 hr. The reaction mixture is cooled to ˜70° C. and 2-MeTHF (100 mL, 10 volumes) is added. The contents are filtered at ˜70° C. and the residual cake is washed with 2-MeTHF (80 mL, 8 volumes) at about 65-72° C. The filtrate is transferred into a separatory funnel and extracted with water. The organic layer is separated and washed with dilute HCl. The resulting organic layer is treated with Darco G60, filtered hot (60° C.). The filtrate is concentrated at atmospheric pressure to ˜2.8 volumes. 25 mL 2-propanol is added, followed by re-concentration to ˜2.8 volumes. An additional 25 mL 2-propanol is added, followed again by re-concentration to ˜2.8 volumes. Finally, 48 mL 2-propanol is added. The contents are cooled to −7° C., maintained at −7° C. for 1 hr., filtered and rinsed with 20 mL chilled 2-propanol. Product is suction dried and then vacuum dried at 60° C. to afford 9.41 g 7-(1-ethyl-propyl)-3-(2,4-dichloro-thiazol-5-yl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidine (purity of product by HPLC assay is 95.88%). MS (ES)=369 (M+1).

Provenance & Evidence