Cyclopentadienone Formation from β,γ-Unsaturated Cyclopentenones and Its Application in Diels–Alder Reactions

We report that α-acyloxy-β,γ-unsaturated cyclopentenones were used as starting substrates to make various trisubstituted cyclopentadienones. The substrates are easily available in one step from our previously developed protocol, and the potential of this cyclopentadienone formation method was demonstrated in a series of Diels–Alder reactions, forming dimerization products, dimethyl phthalate derivatives, and polyaryl benzene compounds.