Chloroform → 4-(5-Chloro-2-methylphenyl)-2,2,6,6-tetramethylpyran-3,5-dione

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a mixture of 2,2,6,6-tetramethylpyran-3,5-dione (described in U.S. Pat. No. 5,089,046A) (0.504 g, 2.96 mmol) and N,N-dimethylaminopyridine (1.45 g, 11.84 mmol) is added anhydrous chloroform (40 ml). To this solution is added crude 5-chloro-2-methylphenyllead triacetate (2.26 g, 4.44 mmol) in one portion, and the mixture is then heated at 40° C. for 17 hours (analysis), then for a further 23 hours at 45-50° C. The mixture is allowed to cool to room temperature, then diluted with ethyl acetate (100 ml) and washed with dilute aqueous hydrochloric acid (3×30 ml). The organic phase is dried over anhydrous magnesium sulfate, then concentrated to give a yellow gum which is purified by column chromatography (ethyl acetate/hexane/acetic acid 8:18:1 ratio) then triturated with hexanes to afford 4-(5-chloro-2-methylphenyl)-2,2,6,6-tetramethylpyran-3,5-dione (0.53 g) as a white solid.

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