Abstract
A palladium‐catalyzed reaction of methylenespiropentane (11) with iodobenzene (12) under typical Heck conditions [Pd(OAc)~2~, PPh~3~, Et~3~N, DMF] produced a mixture of the unstable [3]dendralene 13 and allylidenecyclopropane 14 in 38 % yield. When an analogous reaction with iodobenzene was carried out in the presence of morpholine (25) and of tris(2‐furyl)phosphane (TFP) instead of triphenylphosphane, the dienes 26, 28 and 31 were generated by nucleophilic trapping of π‐allylpalladium intermediates 30 and 32. The cross coupling of methylenespiropentane (11) with the functionalized aryl iodides 33a–g in the presence of a palladium precatalyst [Pd(OAc)~2~, TFP, Et~3~N, DMF] at 80 °C, 3 h, provided the seven‐membered 3,4‐dimethylene‐substituted heterocycles 34a–g and 35b which, upon addition of dimethyl fumarate (19), underwent Diels–Alder reactions to furnish bicyclic and higher oligocyclic dihydrobenzoxepine and‐benzazepine derivatives 36a–g and 37b, yet in rather moderate yields of 18–29 % only. The overall process constitutes a one‐pot, two‐step, three‐component queuing cascade.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)