Total synthesis of hamigerans and analogues thereof. Photochemical generation and Diels-Alder trapping of hydroxy-o-quinodimethanes

A general and streamlined method for the construction of benzannulated bi- and polycyclic frameworks is developed and its scope and limitations are explored. On the basis of the photonlization of substituted benzaldehydes and subsequent Diels-Alder trapping of the generated hydroxy-o-quinodimethanes, this method is optimized to set the stage for the total synthesis of several naturally occurring members of the hamigeran class.