Since the major breakthrough in asymmetric catalysis made by William Knowles and his colleagues in 1970s, the demand for chiral compounds, usually as single enantiomers, has escalated sharply. This was driven particularly by the demands of the pharmaceutical industry, but also by other applications, including agricultural chemicals, flavors, fragrances, and materials. Several strategies for synthesizing such compounds to meet this increasing demand for chiral compounds, such as transition metal catalysis, bio-catalysis, and organocatalysis have been developed. Interest in organocatalysis has increased spectacularly in the last decade as a result of both the novelty of the concept and more importantly, the fact that efficiency and selectivity of many organocatalytic reactions without the assistance of transition metal catalysts meet the standard of established organic reactions combined with a green chemistry concept.
Organocatalysis uses small organic molecules predominantly composed of C, H, O, N, S and P to accelerate chemical reactions. The advantages of organocatalysts include their lack of sensitivity to moisture and oxygen, their ready availability, low cost, and low toxicity, which confers a huge direct benefit in the production of pharmaceutical intermediates when compared with (transition) metal catalysts.
Enantioselective organocatalysis, as a new asymmetric catalytic methodology in catalytic chemistry, has had a major impact on sterecochemistry over the past ten years, and has bridged the fields of stereochemistry and pharmaceutically active molecules. The development in organocatalysis initiated new methodologies for synthetic chemistry has provided new strategies to construct bioactive molecules. Amino acids, as versatile catalysts, have been one of most important parts of organocatalysis, and it is anticipated that the scale of amino acid catalysis will expand rapidly, and future amino acid derivative catalysis will become a core asymmetric synthetic methodology. In addition, compared with transition metal catalysed processes of chemical synthesis, the most prominent advantages of organocatalysis are low toxicity and lack of sensitivity to moisture and oxygen. Although amino acids, as basic units of protein, have low toxicity, there is not a systemic study of structure-toxicity-relationships of amino acids and their derivatives. This will enable better understanding and design of sustainable catalysts for the pharmaceutical industry.
In summary, enantioselective organocatalysis, associated with advantages over traditional metal-catalysed processes, is directing the way to an ideal synthesis: highly efficient, simply designed and constructed molecules being applied to sustainable processes.
