79-50-5

13031-04-4

The general procedure for the synthesis of dihydro-4,4-dimethyl-2,3-furandione from DL-pantolactone was carried out as follows: 29.5 g of DL-pantolactone, 300 mg of ruthenium(III) chloride were added to a mixture of 29.5 g of DL-pantolactone, 300 mg of ruthenium(III) chloride in a microwave reactor (Ethos 1600, MLS GmbH, D-88299 Leutkirch im Allgau, Germany), A mixture of 400 mL of water and 200 mL of ethyl acetate was heated to reflux temperature with stirring and the microwave power was set to 700 W. Over a period of 10 min, 145.5 g of sodium meta-periodate was added to the boiling mixture in batches. The reaction mixture continued to be stirred for 20 min and then cooled rapidly. The organic and aqueous phases were separated using a separatory funnel and the sodium iodate precipitate in the organic phase was removed by diafiltration and washed five times with 20 mL of ethyl acetate. The aqueous phase was extracted twice with 50 mL of ethyl acetate. All organic phases were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. This step yields ketolactone with 98% purity and 60% yield based on starting DL-pantolactone. An additional 12% of the product as well as unreacted DL-pantolactone is recovered from the aqueous phase. The conversion of DL-pantolactone under these process conditions was 80% with a selectivity of 0.95.