Sulfuric Acid → HCID 23048179, compound

Participants

Reaction Steps

A stirred mixture of 4-[1-(4-trifluoromethylphenyl)-1H-indazol-3-yl]piperidine-1-carbonitrile of Example 101 (15 g, 0.041 moles) and 25% H2SO4 (100 ml) was refluxed for 20 hours. The mixture was cooled, poured into H2O, and basified with a 25% NaOH solution. The product was extracted (dichloromethane), dried (MgSO4), and concentrated which yielded 13 g (93%) of 1-[4-(trifluoromethyl)phenyl]-3-(4-piperidinyl)-1H-indazole as an oil. A mixture of formic acid (1 ml, 0.027 moles) and acetic anhydride (2.4 ml, 0.025 moles) was warmed at 55° C. for 1.5 hours. The solution was cooled to 30° C. and a suspension of the indazole (4.0 g, 0.012 moles) in ether (10 ml) was added. The mixture was stirred at ambient temperature for 3.5 hours and then poured into H2O and basified with a 5% NaOH solution. The product was extracted (CHCl3), dried (MgSO4) and concentrated to yield 5.1 g of an oil. The oil was purified on the high pressure liquid chromatograph (silica gel, 100% ethyl acetate) to yield 3.1 g (72%) of 1-formyl-4-[1-[4-(trifluoromethyl)phenyl]-1H-indazol-3-yl]piperidine, m.p. 109°-111° C.

Provenance & Evidence