ethyl 4-acetyloxy-3-(acetyloxymethyl)but-2-enoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A 3.5 L reactor equipped with a mechanical stirrer, a Pt-100 thermometer and a nitrogen inlet was charged with 127 g (731 mmol) 1,3-diacetoxyacetone, 1.95 L TBME and 309 g (877 mmol) carbethoxymethylene triphenylphosphorane. The solution was refluxed for 5 h, then allowed to cool to RT during 14 h. Then TBME was exchanged with 2.3 L heptane at 40° C./300 mbar and the mixture was stirred overnight at RT before 400 ml toluene was added. The suspension was stirred for 1 h at RT, then 2 h at 0-4° C., filtered, and the filter cake was washed portionwise with totally 600 ml pre-cooled toluene. The combined filtrates were concentrated on a rotatory evaporator at 45° C./10 mbar to give 193 g crude product as reddish oil. This material was dissolved in 200 ml of a heptane/ethyl acetate (3:1) mixture and was chromatographically filtered over a column containing 400 g silica gel 60 using heptane/ethyl acetate (3:1) as the eluent, to give 174 g 4-acetoxy-3-acetoxymethyl-but-2-enoic acid ethyl ester (98% yield; assay: 99.9%) as a colorless oil. A 3.5 L reactor equipped with a mechanical stirrer The solution was refluxed for 5 h was added 2 h at 0-4° C., filtered the filter cake was washed portionwise with totally 600 ml pre-cooled toluene The combined filtrates were concentrated on a rotatory evaporator at 45° C./10 mbar to give 193 g crude product as reddish oil was chromatographically filtered over a column containing 400 g silica gel 60 using heptane/ethyl acetate (3:1) as the eluent