p-Toluenesulfonic acid → [2-Methyl-6-(4-trifluoromethyl-phenyl)-pyridin-3-yl]-carbamic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

4.30 g (15.3 mmol) of 2-methyl-6-(4-trifluoromethyl-phenyl)-nicotinic acid (prepared from 2-methyl-6-(4-trifluoromethyl-phenyl)-nicotinic acid methyl ester (example 1L]) in analogy to the procedure described in example 53B]) was dissolved in 85 ml of 2-methyl-2-propanol and 3.18 ml=2.32 g (22.9 mmol) of triethylamine was added. After 5 min., 4.97 ml=6.64 g (22.9 mmol) of diphenylphosphoryl azide (95%) was added. The reaction mixture was then stirred at reflux (oil bath 100° C.). After 10 min., 0.53 g (3.1 mmol) of anhydrous 4-toluene sulfonic acid was added and stirring continued for 1 hour at reflux. The solvent was then completely removed by evaporation at high vacuum; the residue was dissolved in Et2O and washed with H2O, 1N HCl, and NaHCO3 solution. The combined organic phases were dried over anhydrous magnesium sulfate and evaporated. The crude product was purified by crystallization (EtOAc, n-heptane) to give 4.05 g of the title compound as colorless solid.

Provenance & Evidence