Dominic Ming-Tak Chan

New N- and O-arylations with phenylboronic acids and cupric acetate

Abstract A new method of arylating NH and OH containing compounds at room temperature with phenylboronic acids and cupric acetate in the presence of a tertiary amine promoter is described. Substrates include phenols, amines, anilines, amides, imides, ureas, carbamates, and sulfonamides.

New aryl/heteroaryl CN bond cross-coupling reactions via arylboronic acid/cupric acetate arylation

Abstract A new aryl/heteroaryl CN bond cross-coupling reaction via the arylboronic acid/cupric acetate arylation of NH containing heteroarenes has been discovered. This new methodology is mild, proceeds at room temperature exposed to air, and works for many heteroarenes and arylboronic acids providing good yields of N-arylated heteroarenes.

Copper promoted CN and CO bond cross-coupling with phenyl and pyridylboronates

Abstract Acyclic and cyclic esters, as well as anhydride (boroxine) of phenylboronic acids are efficient phenylating agents in copper promoted CN and CO bond cross-coupling reactions. The first successful CN cross-coupling of a heterocyclic boronate with heteroarenes, such as indazole, has been demonstrated.

Promotion of reaction of NH boths with triarylbismuth and cupric acetate

Abstract Arylation of a diverse group of NH containing compounds at room temperature with triarylbismuth and cupric acetate in the presence of a tertiary amine promoter, such as triethylamine or pyridine, is described. This mild and highly efficient procedure, which is based on Bartons earlier work on the arylation of amines, can be applied to amides, imides, ureas, carbamates, and sulfonamides.

Transition Metal Mediated Cycloadditions

Five-membered ring systems are rapidly emerging as important structural features in a large number of natural products and theoretically interesting molecules. The development of methodologies for the construction of these systems has thus become a subject of great interest and intense effort for synthetic chemists. In recent years, one has seen a number of C5 annulation procedures, with the majority focusing on multistep sequences based on 1,4-dicarbonyl compounds or their functional equivalents.

Mechanistic studies of the rhodium-catalysed cyclization of α,ω-alkynoci acids to alkylidene lactones. Crystals structures of two iridium model catalytic intermediates

A mechanism for the Rh-catalysed cyclization of alkynoic acids to alkylidene lactones which accounts for the formation of Z-isomers only, is presneted with the structures of Ir cis-hydrido-carboxylate and cis-hydrido-σ-vinyl model intermediates.

Synthesis and molecular structures of a rhoda-lactone and its alkylation product; insertion of a pendant alkyne into a rhodium–hydrogen bond

Reaction of [(PMe3)3RhCl] with pent-4-ynoic acid yields the novel exocyclic methylene-substituted rhoda-lactone [(PMe3)3Cl[graphic ommitted]], which reacts with Me3O+BF4– to give [(PMe3)3ClR[graphic ommitted]]BF4; both complexes have been structurally characterized.

Homogeneous Models for Mechanisms of Surface Reactions: Propene Ammoxidation

The proposed active sites on the surface of the catalyst for propene ammoxidation have been successfully modeled by structurally characterized pinacolato W(VI) tert-butyl imido complexes. These compounds exist as an equilibrating mixture of amine-bis(imido) and imido-bis(amido) complexes, the position of this equilibrium being dependent on the electronic nature of the glycolate ligand. Both of the C-N bond-forming reactions proposed in recent studies by Kartisek and Grasselli [J. Catal. 81, 489 (1983)] have been reproduced using discrete Group VI d° organoimido complexes under mild conditions suitable for detailed mechanistic studies. These reactions are 1) oxidative trapping of radicals at molybdenum imido sites and 2) migration of the allyl group from oxygen to an imido nitrogen atom.