Cross-Coupling for Cross-Conjugation: Practical Synthesis and Diels−Alder Reactions of [3]Dendralenes

The parent [3]dendralene and 2-substituted [3]dendralenes are made easily through cross-coupling reactions. Contrary to some earlier reports,
[3]dendralene is sufficiently stable to be handled using standard synthetic methods. These compounds allow the one-step stereoselective
construction of polycyclic frameworks through reactions with dienophiles. Site selectivity and stereoselectivity in Diels−Alder reactions with
dienophiles are generally not influenced by the nature of the [3]dendralene's 2-substituent; these features can, however, be influenced with
Lewis acids.