Dimethyl Sulfoxide → 4-Chloroheptane-3,5-dione

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Reaction Steps

Chlorotrimethylsilane (29.7 ml, 0.234 mol) was added dropwise to a stirred pale yellow solution of tetrabutylammonium bromide (1.26 g, 3.9 mmol) in dry acetonitrile (16 ml) at room temperature under nitrogen. The resulting solution was cooled in ice and 3,5-heptanedione (10.6 ml, 78.0 mmol) and then dry dimethylsulphoxide (16.6 ml, 0.234 mol) were added dropwise over 5 minutes producing a yellow solution which was allowed to warm slowly to room temperature, with stirring, over 4 hours. The mixture was diluted with water (litre), stirred for 10 min and then extracted with ether (1×500 ml, 2×250 ml). The combined ether layers were dried over magnesium sulphate, filtered and concentrated under reduced pressure to leave a yellow oil. The crude product was purified by distillation under reduced pressure to afford the title compound (5.5 g) as a pale yellow oil, b.p. 102-105° C./54 mmHg containing ca. 10% 4,4-dichloro-3,5-heptanedione as estimated by microanalysis.

Provenance & Evidence