Synthetic studies en route to the first total synthesis of a naturally occurring quinone from Acorus gramineus, iso-merrilliaquinone, iso-magnoshinin and 2-epi-3,4-dihydro magnoshininElectronic supplementary information (ESI) available. CCDC 1548143. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7ra05148d

A unified synthetic strategy based on [4 + 2] cycloaddition of readily accessible coupling fragments was conceptualized for the racemic total synthesis of recently isolated bioactive merrilliaquinone and other closely related quinones such as gramineusquinone B as well as neolignan, magnoshinin. The present article discloses our efforts in this direction which culminated in the total syntheses of gramineusquinone B, iso-merrilliaquinone, iso-magnoshinin and 2- epi -3,4-dihydro magnoshinin. An elegant Diels-Alder based approach has been demonstrated for the first racemic total synthesis of gramineusquinone B, iso-merrilliaquinone, iso-magnoshinin and 2- epi -3,4-dihydro magnoshinin.