16691-79-5

2,5-Bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone is used a reagent for cycloaddition reactions.

Preparative Method of 2,5-Bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone: equimolar amounts of benzil and dimethyl 2-propanone-1,3-dicarboxylate in MeOH or EtOH with OH- are allowed to react at 25 °C for 1 day to give the intermediate dimethyl 3,4-diphenyl-4- hydroxycyclopent-2-enone-2,5-dicarboxylate in 70-96% yield. Treatment of the intermediate with acid in benzene or in Ac₂O with heating gives the dienone in 98% yield containing 3% of the Diels-Alder dimer^[1-2].

1. Cookson, R. C.; Henstock, J. B.; Hudec, J.; Whitear, B. R. D. JCS(C) 1967, 1986.
2. White, D. M. JOC 1974, 39, 1951.