Phenyl isocyanate → 1-Piperidinecarboxamide

Participants

Reaction Steps

A stirred mixture of 4-[1-[4-(trifluoromethyl)phenyl]-1H-indazol-3-yl]piperidine-1-carbonitrile of Example 77 (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 to yield 13 g (93%) of 1-[4-(trifluoromethyl)phenyl]-3-(4-piperidinyl)-1H-indazole as an oil. To a stirred suspension of the indazole (4.0 g, 0.012 moles) in toluene (60 ml) was added phenyl isocyanate (1.38 ml, 0.013 moles). The reaction temperature rose to 35° C. and the product precipitated from the solution. The product was collected and recrystallized twice from toluene to yield 3.57 g (66%) of N-phenyl-4-[1-(4-trifluoromethyl)phenyl]-1H-indazol-3-yl]piperidine-1-carboxamide, m.p. 190°-192° C.

Provenance & Evidence