The first total synthesis of (+)-dimericbiscognienyne A1 is described. Key to the successful access to (+)-dimericbiscognienyne A was the biosynthetically inspired Diels–Alder reaction between two differential epoxyquinoid monomers and the subsequent intramolecular hemiacetal formation. The selective formation of the natural product among other potential diastereomers during the late stage [4+2] cycloaddition reaction was investigated by DFT calculations and experimental control studies.