dimethylaluminum chloride in hexane T=-78°C; Diels-Alder reaction; 5 h; Title compound not separated from byproducts.;

1: cyclopentadienyldimethylsilane; fumaric acid dimethyl ester With dimethylaluminum chloride in hexane T=-78°C; Diels-Alder reaction; 5 h; 2: With tetrabutyl ammonium fluoride; dihydrogen peroxide; potassium hydrogencarbonate in tetrahydrofuran; methanol Tamao-Fleming oxidation; 3: dimethyl sulfate With potassium carbonate in acetone Further stages.;