Field of Science

Organocatalysis: A new era in chemical synthesis

Magic Molecule?
Some time ago Oxford was host to a brilliant chemist, Prof. D.W.C. MacMillan of Princeton University. He delivered the Vertex Lecture at the Department of Chemistry speaking on ‘New concepts in Catalysis’. His research interests are in the area of Organocatalysis, or the use of small organic molecules to catalyze organic transformations, a new immerging field in enantioselective molecule synthesis. Simply put, it is the use of environmentally friendly and easily available chemicals to carry out reactions at normal conditions of room temperature and atmospheric pressure to create chemical bonds at a specific position and in a specific direction.

What is more special about this field apart from its scientific value and environmental friendliness is that in the period of 1998 to 2008 more than 1500 manuscripts described use of organocatalysis in more than 150 discrete reaction types. A remarkable number given that there were no reports of such catalysis in the year 1995 and on an average chemistry produces only a handful of new reaction types a decade. This field has taken the synthesis community by a storm.

It is interesting to look at these facts as they provide insight into how scientific communities can bypass an important research area for decades and then suddenly embrace it with fervent enthusiasm. MacMillan says in an essay in Nature, “It is hard to answer why a field was overlooked for so long. One perspective is that it is impossible to overlook a field that does not yet exist which is similar to the thought that scientists cannot work on a problem they haven’t found.”

And why was there such rapid growth in research in this area? Primarily, the field offered real advantages to researchers and industry and at an easy and low cost of carrying out such reactions in laboratory. Reactions were being discovered everyday which were able to replace use of organometallic systems which are expensive, toxic and sensitive to air or moisture. Organic molecules are generally insensitive to air or moisture, small chiral molecules can be derived from nature, thus are readily accessible and cheap to prepare, the by-products are non-toxic and environmental friendly. It is also widely recognized that during large scale production of chemicals the removal of toxic catalyst-related impurities from the waste stream can often have a large financial impact. All these factors led to rapid growth and increased competition in the area of organocatalysis, which in turn accelerated the pace of innovation and discovery.

Apart from MacMillan’s large contribution to the field in terms of new chemistry, there is one contribution which he particularly boasts of and that is, naming this field: Organocatalysis. So, what’s in a name? He answers, “Consider the success of the terms nanotechnology at globally shifting the visibility and perception of areas of research. Organocatalysis provided a strong identity and helped unify a fledgling field by attracting attention of the broader chemical synthesis community.” These reactions are similar in mechanism to the ones catalysed by enzymes, which are much more complex molecules than the one used under the term organocatalysis. These discoveries and innovations have brought chemists one step closer to be able to outwit nature. Very rarely in the history of science does a whole new field emerge that not only has the potential to change the way things are done today but also the ability to grow so quickly.

Further Reading: Review, Reactions, Nature Insight
MacMillan, D. (2008). The advent and development of organocatalysis Nature, 455 (7211), 304-308 DOI: 10.1038/nature07367

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