Much of modern asymmetric catalysis has its origins in enzyme biocatalysis. Although only about half of known enzymes contain metals in their active site, synthetic reactions mediated by metal catalysts are much more highly developed than those mediated by non-metals. This is despite the huge economic and environmental costs of extracting metals (e.g. Pd, Pt, Au), as well as their toxicity. Recently, significant efforts have been directed towards reactions mediated by small organic molecules (organocatalysis). This young field has generated many reactions that occur with impressive selectivity and efficiency, but the potential for the discovery of new catalyst types and new organocatalytic reactions remains high.
Boronic acids are widely available (commercially, synthetically) due primarily to their use as reagents in Pd-catalysed cross coupling reactions. In contrast to their use as reagents, use of boronic acids as organocatalysts remains rare. This is despite several attractive features that they possess, including the Lewis acidity of the boron atom, their low toxicity, high stability to air and moisture, and solubility in organic solvents. Our research program is based on exploiting these properties to develop new synthetic methods using catalysts based on boronic acids and related derivatives. In many cases these methods are complimentary to or improve upon transition metal catalysed reactions. We apply our new methods to the synthesis of medicinally important molecules, such as bio-active natural products and pharmaceuticals. Avoiding the use of transition metals in these syntheses has the advantage of reducing toxic byproducts and simplifying purification, thus reducing environmental impact.
