Methanesulfonic Acid → 5,7-Di-tert-butyl-3-(2-methyl-dihydrobenzofuran-5-yl)benzofuran-2-one

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Reaction Steps

3.80 g (10.0 mmol) of 3-(4-allyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one are kept under nitrogen for about 4 hours at 220° C. After cooling, 10 ml of acetic acid and 0.3 ml of methanesulfonic acid are added and the reaction mixture is refluxed for 7 hours. After dilution with 100 ml of water, the product is extracted with dichloromethane. The organic phases are washed with water, combined, dried over sodium sulfate and concentrated on a vacuum rotary evaporator. Chromatography of the residue on silica gel with the eluant system dichloromethane/hexane=1:2 and crystallisation of the pure fractions from ligroin gives 1.07 g (28%)of 5,7-di-tert-butyl-3-(2-methyl-dihydrobenzofuran-5-yl)benzofuran-2-one, m.p. 136°-152° C. as a mixture of diastereoisomers (compound (101), Table 1).

Provenance & Evidence