Thionyl Chloride → 7-tert-butyl-3-chloro-5-methyl-3H-benzofuran-2-one

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Reaction Steps

To a suspension of 2.2 g (10.0 mmol) of 7-tert-butyl-3-hydroxy-5-methyl-3H-benzofuran-2-one (compound (102), Example 2, Table 1) in 2.4 ml (55.0 mmol) of thionyl chloride is added one drop of dimethyl formamide and the mixture is stirred for 2 hours at room temperature. Excess thionyl chloride is afterwards distilled off on a vacuum rotary evaporator. Chromatography of the residue on silica gel with the solvent system dichloromethane/hexane=1:1 and crystallisation of the pure fractions from methanol yields 0.30 g (13%) of 7-tert-butyl-3-chlor-5-methyl-3H-benzofuran-2-one, m.p. 81°-86° C. (compound (108), Table 1).

Provenance & Evidence