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Our research is concerned with the design, assembly and understanding of molecular architectures that act as catalysts for sustainable chemical synthesis. The focus is placed on discovering and developing novel catalytic methodologies, aiming at:
(1) Faster, more productive and greener organic synthesis;
(2) Building molecular complexity from simple, renewable molecules;
(3) Gaining mechanistic understanding of the molecular catalytic machinery.

We devise molecular metal catalysts and engineer the catalytic systems for target reactions, and we do this by an integrated approach, harnessing chemistry ranging from organometallics through synthetic organic chemistry to physical chemistry, and by close collaborations with leading pharmaceutical and chemical organisations. To have a taste of our research, you may wish to go on to the few selected examples below.

 
Hydrogenation and Transfer hydrogenation in water
Hydrogenation and transfer hydrogenation are a most widely used technology for industrial chemical and pharmaceutical synthesis. We recently developed catalytic systems that allow these reactions to proceed in water in a fast, selective and productive fashion with no need for any organic solvents. Remarkably, some of these catalysts can be used for both hydrogenation and transfer hydrogenation. Commercial application of the aqueous-phase reduction is already underway.
Also see:
Angewandte Chemie International Edition 2009, 6524-6528
Journal of the American Chemical Society 2009, 131, 6967-6969
Journal of the American Chemical Society 2008, 130, 14450-14451
Journal of the American Chemical Society 2008, 130, 13208-13209
Angewandte Chemie International Edition 2006, 45, 6718-6722
Organic & Biomolecular Chemistry 2004, 2, 1818-1821

Controlling regioselectivity in C-C coupling
Ever since its discovery, the Heck reaction has been mainly limited to electron-deficient olefins, leading to linear olefinic products. When electron-rich olefins are used, however, a mixture of regioisomers results, thus limiting its synthetic utility.
Realising the key to controlling the regioselectivity hinges on an ionic Pd(II) species, we discovered that the Heck coupling of aryl halides with electron-rich olefins can be accomplished in >99/1 regioselectivities in ionic liquids, which promotes the ionic mechanism and hence the regioselective formation of branched olefins. This chemistry has been extended to a wide range of electron-rich olefins, providing a novel avenue for many synthetically useful compounds. If ionic liquids are inaccessible to you, no worries! Further studies in our group have enabled common solvents to be used without the expensive ionic liquids. For instance, we reported that simple hydrogen-bond donors are highly effective in promoting the formation of the ionic Heck intermediate and hence the regioselective coupling reaction.
Also see:
Journal of the American Chemical Society 2008, 130, 10510-10511
Journal of the American Chemical Society 2008, 130, 2424-2425
Journal of Organic Chemistry 2006, 71, 7467-7470
Angewandte Chemie International Edition 2006, 45, 4152-4157
Journal of the American Chemical Society 2005, 127, 751-760
Insight into the molecular pathway of catalysis
Mechanistic understanding of catalysis is key to the design of new enabling catalysts for green chemical and pharmaceutical manufacturing, and it satisfies our curiosity in nature and our desire in advancing chemistry. An example is seen in our work on the asymmetric transfer hydrogenation in water, where we showed a much faster reduction in water than in organic solvents. Mechanistic studies then revealed that water accelerates the hydrogenation by participating in the transition state via hydrogen bonding. However, the reaction is pH-dependent, with the active catalyst being protonated at low pH and forming hydroxyl species at high pH. So not only is water a green medium for the reaction, it is an active partner of the catalytic cycle as well.
Earlier, we showed that ionic liquids such as those based on imidazolium salts are not innocent spectators in catalysis. In particular, we demonstrated that hydrogen bonding in the ionic liquids can play a critical role in catalysis, and the imidazolium cations can in situ form catalytically active metal-carbene species.
Also see:
Chemistry - A European Journal 2008, 14, 7699-7715
Angewandte Chemie International Edition 2005, 44, 3407-3411
Organometallics 2000, 19, 1123-1127
 

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