反应详情

A mixture of 5.5 g (25.0 mmol) of 7-tert-butyl-3-hydroxy-5-methyl-3H-benzofuran-2-one (compound (202), Example 1a), 3 ml (50.0 mmol) of methyl isocyanate and 2 drips of methanesulfonic acid are refluxed for 3¼ hours. Then a further 3 ml (50.0 mmol) of methyl isocyanate and 2 drops of methanesulfonic acid are added. The reaction mixture is refluxed for another 16 hours, then cooled, diluted with dichloromethane and washed with water and a 5% aqueous solution of sodium hydrogencarbonate. The organic phases are combined, dried over magnesium sulfate and concentrated on a vacuum rotary evaporator. Crystallisation of the residue from toluene yields 4.45 g (65%) of 3-(N-methylcarbamoyloxy)-5 -methyl-7 -tert-butyl-3H-benzofuran-2-one (compound (212), Table 2), m.p. 138-143° C. (compound (212), Table 2).

1. temperatureare refluxed for 3¼ hours
2. temperatureThe reaction mixture is refluxed for another 16 hours
3. temperaturecooled
4. washwashed with water
5. dry with materialdried over magnesium sulfate
6. concentrationconcentrated on a vacuum rotary evaporator
7. customCrystallisation of the residue from toluene