The total synthesis of the Diels–Alder-type adducts (±)-kuwanol E and the heptamethyl ether derivative of (±)-kuwanon Y has been accomplished via a convergent strategy involving 2′-hydroxychalcone 6 or 9 and dehydroprenylstilbene 7, in nine steps. The synthesis features, as a key step, a Lewis acid-mediated biomimetic intermolecular Diels–Alder [4+2] cycloaddition for the construction of the cyclohexene skeleton with three stereogenic centers. Notably, the endo/exo diastereoselectivity of the reaction proved to be temperature-controlled.
Total Synthesis of (±)-Kuwanol E / Calcaterra, Andrea; Botta, Bruno; Fabrizi, Giancarlo; D'Acquarica, Ilaria; Sabia, Rocchina; Benni, Irene; Iovine, Valentina. - In: JOURNAL OF NATURAL PRODUCTS. - ISSN 1520-6025. - 10:79(2016), pp. 2495-2503. [10.1021/acs.jnatprod.6b00350]