Concise Synthesis and Transannular Inverse Electron Demand Diels−Alder Reaction of [3](3,6)Pyridazino[3](1,3)indolophane. Rapid Access to a Pentacyclic Indoloid System

[reaction: see text] The title compound was synthesized concisely from indole. A 2-fold sequential hydroboration/Suzuki-Miyaura cross-coupling was employed to generate the cyclophane. When heated in N,N-diethylaniline, it underwent a transannular inverse electron demand Diels-Alder (IEDDA) reaction to form a pentacyclic product, which appears to be well suited as a precursor to a variety of indole alkaloids such as strychnine.