Efficient synthesis of polycycles bearing prenylated, geranylated, and farnesylated citrans: application to 3′-prenylrubranine and petiolin D regioisomer

Efficient synthetic routes for biologically interesting polycycles with prenylated, geranylated, and farnesylated citrans were developed from several trihydroxybenzenes with prenyl, geranyl, and farnesyl groups on the benzene rings. Ethylenediamine diacetate-catalyzed cyclization by a domino aldol-type/electrocyclization/H-shift/hetero Diels–Alder reaction of prenylated, geranylated, and farnesylated trihydroxybenzenes with citral or trans,trans-farnesal provided a variety of tetracycles bearing prenylated, geranylated, and farnesylated citrans. The mechanistic pathway for regio- and stereochemistry of synthesized polycycles was described. As an application of this methodology, 3′-prenylrubranine and petiolin D regioisomer were first synthesized.