[C:1]([OH:5])([CH3:4])([CH3:3])[CH3:2].[C:6](Cl)(Cl)=[O:7].[NH2:10][C:11]1[CH:16]=[CH:15][CH:14]=[C:13]([CH3:17])[N:12]=1.C(N(CC)CC)C.[OH-].[Na+]>O.C(Cl)(Cl)Cl>[C:1]([O:5][C:6](=[O:7])[NH:10][C:11]1[CH:16]=[CH:15][CH:14]=[C:13]([CH3:17])[N:12]=1)([CH3:4])([CH3:3])[CH3:2]
55.6 g (0.75 moles) of t-butanol and 450 mL of chloroform were added to a reaction system followed by blowing in 65.3 g (0.66 moles) of phosgene over the course of 2.5 hours while holding the internal temperature at −5° C. to 0° C., and then simultaneously supplying a mixed solution containing 32.4 g (0.30 moles) of 2-amino-6-picoline, 133.5 g (1.32 moles) of triethylamine and 300 mL of chloroform to the reaction system over the course of 2.5 hours using a metering pump (supply rate: 3 mL/min). After supplying the mixed solution, the solution was stirred for 1 hour at 0° C. Next, water and 28% sodium hydroxide were sequentially added while holding the internal temperature at 0° C. or lower. After separating the liquid, the aqueous phase was extracted with chloroform, and the organic phases were combined and mixed. A portion of the organic phase was sampled and subjected to quantitative analysis by HPLC. The target (6-methyl-pyridin-2-yl)-carbamic acid tert-butyl ester was obtained at yield of 98%. Only an extremely small amount of 1,3-bis-(6-methyl-pyridin-2-yl)-urea (urea compound) was present.
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