Ag(i)-catalyzed intramolecular transannulation of enynone tethered donor-acceptor cyclopropanes: a new synthesis of 2,3-dihydronaphtho[1,2-b]furans.

An efficient AgOTf catalyzed tandem intramolecular transannulation of ((2-alkynyl)aryl)cyclopropyl ketones leading to the 2,3-dihydronaphtho[1,2-b]furans has been developed. The reaction features a regioselective alkyne hydration, cyclopropylketone-2,3-dyhydrofuran rearrangement, and benzannulation. The methodology gives direct access to the tricyclic core structure of biologically important 2,3-dihydronaphtho[1,2-b]furan natural products.

Rhodium-catalyzed pyridannulation of indoles with diazoenals: a direct approach to pyrido[1,2-a]indoles.

A novel rhodium catalyzed pyridannulation of 3-substituted indoles with diazoenals furnished privileged pyrido[1,2-a]indoles. The reaction is proposed to involve a [4 + 2]-annulation of the diacceptor rhodium enalcarbenoid via C-2 functionalization of the indole. The utility of the methodology was demonstrated with a short synthesis of the tetrahydropyrido[1,2-a]indole core, present in a large number of biologically important polycyclic indole alkaloids.

Synergistic rhodium(II) carboxylate and brønsted acid catalyzed multicomponent reactions of enalcarbenoids: direct synthesis of α-pyrrolylbenzylamines.

The design of a synergistic rhodium(II) carboxylate and BINOL phosphoric acid catalyzed efficient multicomponent reaction of enaldiazo compounds, arylamines, and aryl aldehydes leading to the first transition-metal-catalyzed direct synthesis of valuable α-pyrrolylbenzylamines is disclosed. The reaction is proposed to involve a transient ammonium ylide of a new class of electrophilic rhodium enalcarbenoid, its regioselective Mannich reaction, and a cyclocondensation cascade. The methodology was used in a highly diastereoselective synthesis of a binaphthyl based chiral pyrrole.

Rhodium enalcarbenoids: direct synthesis of indoles by rhodium(II)-catalyzed [4+2] benzannulation of pyrroles.

Disclosed herein is the design of an unprecedented electrophilic rhodium enalcarbenoid which results from rhodium(II)-catalyzed decomposition of a new class of enaldiazo compounds. The synthetic utility of these enalcarbenoids has been successfully demonstrated in the first transition-metal-catalyzed [4+2] benzannulation of pyrroles, thus leading to substituted indoles. The new benzannulation has been applied to the efficient synthesis of the natural product leiocarpone as well as a potent adipocyte fatty-acid binding protein inhibitor.