Methyl Isocyanate → 3-(n-Methylcarbamoyloxy)-5-methyl-7-tert-butyl-3h-benzofuran-2-one

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Reaction Steps

A mixture of 5.5 g (25.0 mmol) of 7-tert-butyl-3-hydroxy-5-methyl-3H-benzofuran-2-one (compound (202), Example la), 3 ml (50.0 mmol) of methyl isocyanate and 2 drops of methanesulfonic acid are refluxed for 3 114 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).

Provenance & Evidence