Synthesis of Tricyclic Heterocycles via a Tandem Aryl Alkylation/Heck Coupling Sequence

A palladium-catalyzed reaction, accelerated by microwave heating, forms two alkyl-aryl bonds and one alkenyl-aryl bond in a single vessel. This method produces a range of symmetrical and unsymmetrical tricyclic heterocycles containing oxygen, nitrogen, silicon, or sulfur atoms, starting from a Heck acceptor and an aryl iodide with two attached alkyl halides. The approach was used to synthesize a tricyclic analogue of mescaline.

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Abstract

A norbornene-mediated palladium-catalyzed sequence is described in which two alkyl-aryl bonds and one alkenyl-aryl bond are formed in one pot with use of microwave irradiation. A variety of symmetrical and unsymmetrical oxygen-, nitrogen-, silicon-, and sulfur-containing tricyclic heterocycles were synthesized from a Heck acceptor and an aryl iodide containing two tethered alkyl halides. This approach was further applied to the synthesis of a tricyclic mescaline analogue.