title: Remote Regiocontrol by a Thioether Group in Diels-Alder Reactions of Naphthazarin: Regioselective Access to Tetracyclic Polyhydroxyquinones.
abstract: The synthesis of tetracyclic polyhydroxyquinones 5a and 5b was achieved through a sequence involving two Diels-Alder reactions with 1-methoxy-1,3-cyclohexadiene: the first with 2-(p-tolylthio)naphthazarin and the second on the resulting tricyclic derivative previously transformed into a (p-tolylsulfinyl)naphthazarin. The success of this strategy stemmed from the efficient remote regiocontrol exerted by the thioether substituent in the first step.
authors.affiliation: Departamento de Química Orgánica (C-I), Universidad Autónoma, Cantoblanco, 28049-Madrid, Spain.
authors.forename: M. Carmen
authors.initials: MC
authors.lastname: Carreño
authors.forename: José L.
authors.initials: JL
authors.lastname: García Ruano
authors.forename: Antonio
authors.initials: A
authors.lastname: Urbano