Cesium carbonate → 1-(3-fluorobenzyl)-5-nitro-1H-indazole

Participants

Reaction Conditions

Reaction Steps

5-nitro indazole (1 equiv.), cesium carbonate (1.1 equiv.) and DMF (5 volumes) were charged to a vessel. The mixture was heated to 70–80° C. and 3-fluoro benzyl bromide was added over 75 mins. The reaction was assayed by HPLC for completion (<2 AP of nitro indazole vs combined isomers) and then cooled to 20° C. The salts were filtered and the cake was washed with DMF (2.7 volumes). The product was crystallized by charging water (1.35 to 1.45 volumes) between 15–21° C. The crystal slurry was held for 4 h, crystals were filtered and washed with 2:1 DMF:water mix (2.1 volumes), water (2 volumes) and finally 3:1 cold ACN:water mix (1.5 volumes). The wet cake was dried <45° C. to LOD <1% and the yield was about 49%

Provenance & Evidence