The in-situ generation of o-quinone methides and their inverse-electron-demand Diels–Alder reaction in the presence of pentacarboxycyclopentadiene—an organic Brønsted acid—has been reported. The synthesis of xanthenones and chromanones in good to excellent yields from the [4 + 2] cycloaddition of quinone methides with 1, 3-dicarbonyls and Meldrum's acid has been accomplished. The development of this method helps in generating a number of biologically potent heterocycles with medicinal applications.

中文翻译：

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有机布朗斯台德酸催化邻醌甲基化物与 1, 3-二羰基化合物的环加成反应：轻松获得呫吨酮和色满酮

已经报道了在五羧基环戊二烯（一种有机布朗斯台德酸）存在下原位生成邻醌甲基化物及其逆电子需求 Diels-Alder 反应。已经完成了由醌甲基化物与 1, 3-二羰基和 Meldrum 酸的 [4 + 2] 环加成反应，以良好到极好的收率合成了呫吨酮和色满酮。这种方法的发展有助于产生许多具有药用价值的生物有效杂环。