Phosgene → tert-Butyl (6-methylpyridin-2-yl)carbamate

Participants

Reaction Steps

556.0 g (500 mL) of monochlorobenzene were added to a reaction system followed by blowing in 107.8 g (1.09 moles) of phosgene over the course of 1 hour at −10° C. to −5° C. A mixed solution containing 54.07 g (0.5 moles) of 2-amino-6-picoline, 107 g (1.06 moles) of triethylamine, 92.7 g (1.25 moles) of t-butanol and 333 g (300 mL) of monochlorobenzene were dropped into this phosgene solution over the course of 4.5 hours while holding the internal temperature at −11° C. to −8° C. Following completion of dropping, the solution was stirred for 0.5 hours. Next, a mixed solution obtained by dissolving 120 g (1.19 moles) of triethylamine in 217.4 g (200 mL) of monochlorobenzene was dropped in over the course of 1 hour while holding the internal temperature at −10° C. to −5° C. Following completion of dropping, the solution was stirred for 0.2 hours. Next, 300 mL of water were added. The organic phase was washed with 150 mL of water. The organic phase was subjected to quantitative analysis by HPLC. The target (6-methyl-pyridin-2-yl)-carbamic acid tert-butyl ester was obtained at a yield of 92%. The yield of 1,3-bis-(6-methyl-pyridin-2-yl)-urea (urea compound) was 4%. 4% of the 2-amino-6-picoline used for the starting material remained.

Provenance & Evidence