Just a DAB: A new metal-free [2+2] cycloaddition/S-centered radical induced 1,4-addition sequence of benzene-linked allene-ynes has been established by treatment with aryldiazonium tetrafluoroborates and DABCO-bis(sulfur dioxide) under convenient reaction conditions, thus providing practical access to functionalized cyclobuta[a]naphthalen-4-ols of chemical and biomedical importance. DABCO=1,4-diazabicyclo[2