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 (102), Example 2), 3 ml (50.0 mmol) of methyl isocyanate and 2 drops of methanesulfonic acid is refluxed for 31/4 hours. Then 3 ml (50.0 mmol) of methyl isocyanate and 2 drops of methanesulfonic acid are again added. The reaction mixture is refluxed for a further 16 hours, then cooled, diluted with dichloromethane and washed with water and 5% aqueous sodium hydrogencarbonate solution. 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 (112), Table 1), m.p. 138°-143° C.

Provenance & Evidence