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

Participants

Reaction Conditions

Reaction Steps

1702 mL of chloroform were added to a reaction system and cooled to −15° C. followed by blowing in 218.60 g (2.21 moles) of phosgene over the course of 3.7 hours. A mixed solution containing 108.19 g (1.00 moles) of 2-amino-6-picoline, 101.13 g (1.00 moles) of triethylamine, 185.18 g (2.50 moles) of t-butanol and 295 mL of chloroform were dropped into this phosgene solution over the course of 2.8 hours while holding the internal temperature at −15° C. to −5° C. Following completion of dropping, the solution was stirred for 1.4 hours. Next, 343.7 g (3.40 moles) of triethylamine were dropped in over the course of 2.6 hours while holding the internal temperature at −15° C. to 2° C. Following completion of dropping, the solution was stirred for 0.2 hours. Next, 238 mL of water and 931 mL of 28% sodium hydroxide were added sequentially. The aqueous phase was extracted with 50 mL of chloroform. The organic phases were combined and subjected to quantitative analysis by HPLC. The target (6-methyl-pyridin-2-yl)-carbamic acid tert-butyl ester was obtained at a yield of 96%. The yield of 1,3-bis-(6-methyl-pyridin-2-yl)-urea (urea compound) was 3%.

Provenance & Evidence