Synthesis of highly substituted benzene ring systems through three-component coupling of enyne imines, Fischer carbene complexes, and electron-deficient alkynes.

Three-component coupling of Fischer carbene complexes, enyne aldehyde hydrazones, and electron-deficient alkynes leads to simple benzoate derivatives in a process involving the formation of an N-aminopyrrole derivative, Diels-Alder reaction, and nitrene extrusion. The products are readily converted into isoquinolones through reaction with primary amines. The reaction proceeds best with highly substituted and electron-rich pyrroles even though these are the sterically least favorable substrates, and this reactivity trend is supported by a computational study.

Direct synthesis of arenecarboxamides through Friedel-Crafts acylation using ureas.

The reaction of urea derivatives that contain the phenothiazine unit with trifluoromethanesulfonic anhydride in the presence of electron-rich aromatic compounds leads to the formation of arenecarboxamides. The reaction has been successfully demonstrated for several inter- and intramolecular systems.

Electronic Control of Product Distribution in the [5+5]-Coupling of ortho-Alkynylbenzaldehyde Derivatives and γ,δ-Unsaturated Carbene Complexes.

The coupling of highly oxygenated ortho-alkynylbenzaldehyde derivatives with γ,δ-carbene complexes was evaluated systematically. In all of the electron-rich systems investigated the exclusive product of the reaction is the dihydrophenanthrene derivative. Only the extremely electron withdrawing methanesulfonate group can prevent this process from occurring. The use of the base additive collidine resulted in a surprising yield enhancement but no other discernable effect on the course of the reaction. Dihydrophenanthrene formation was attributed to rapid dehydration after the opening of a benzo-oxanorbornene intermediate.