DMAP-Catalyzed Annulation Approach for Modular Assembly of Furan-Fused Chromenes.

With a tandem DMAP-catalyzed reaction between -AQM, in which it is generated in situ from propargylic amine, and acyl carbene surrogate (from pyridinium ylide), a variety of polyarylated chromenes are assembled in good yields. This process does not require transition-metal catalyst and exhibits easy manipulation of the arene group and good functional group compatibility, particularly the -Br group which can be further transformed to other functionalities by cross-coupling reactions. The modular feature of -AQM substrates and the simple operation procedures add further advantages to this synthetic method.

Rapid Access of Alkynyl and Alkenyl Coumarins via a Dipyridinium Methylide and Propargylamine Cascade Reaction.

A DMAP-catalyzed cascade approach allowing facile assembly of alkynyl coumarins is reported. By virtue of reactive -AQM (in situ generated from modular propargylamine) and a new synthetic equivalent of acyl carbene (from pyridinium ylide), the reaction proceeds smoothly to afford a variety of alkynyl coumarins in good-to-excellent yields. This transition-metal-free and oxidant-free process features moderate functional group tolerance, particularly the -Br group; thus, this protocol circumvents the inherent shortcomings of the existing Sonogashira coupling of coumarin triflates.

A ZnI-catalyzed regioselective cascade 1,4-conjugate addition/5-exo-dig annulation pathway for one-pot access to heterobiaryl frameworks.

Facile access to π-extended heterobiaryl compounds via a non-cross-coupling strategy has been achieved. In the presence of an inexpensive ZnI2 catalyst and versatile propargylamine and β-naphthol (or β-naphthylamine and β-naphthyl mercaptan) starting materials, a variety of sterically hindered heterobiaryl frameworks can be easily obtained. The present catalytic system offers excellent selectivity, good-to-excellent product yields, and good functional group tolerance including, for instance, -CN, -COOH, -C(O)R, -Br and -Cl groups.

Palladium-Catalyzed N-Arylation of Sulfoximines with Aryl Sulfonates.

Palladium-catalyzed C-N bond coupling reaction between NH-sulfoximines and aryl halides (e.g., -Br, -I, and -Cl and pseudohalides -OTf and -ONf) was successfully achieved.

Palladium-Catalyzed Direct Arylation of Polyfluoroarenes for Accessing Tetra- ortho-Substituted Biaryls: Buchwald-type Ligand Having Complementary -PPh Moiety Exhibits Better Efficiency.

The first general examples of direct C-H arylation of electron-deficient polyfluoroarenes with challenging di- ortho-substituted aryl(heteroaryl) chlorides for tetra- ortho-substituted biaryl synthesis are reported. Key to success is the use of Buchwald-type biaryl phosphine ligand, notably with inexpensive -PPh moiety (instead of -PCy group). Pd(OAc) associated with ligand L9 exhibits even higher efficiency than the corresponding SPhos toward this reaction.