Presentation Speech by Professor Salo Gronowitz of the Royal Swedish Academy of Sciences
Translation from the Swedish text
Your Majesties, Your Royal Highnesses, Ladies and Gentlemen,
Organic synthesis – the preparation of complicated organic compounds, using simple and cheap starting materials – is one of the prerequisites of our civilization, the chemical age in which we live. As late as the 1820s it was still believed that organic natural products such as sugar, camphor or morphine were endowed with a special vital force and therefore could not be prepared in the laboratory. In 1828, the German chemist Friedrich Wöhler crushed this dogma by preparing the organic compound urea from inorganic ammonium cyanate. Today, the most complicated natural products can be prepared, which in their three-dimensional structure are completely identical with those isolated from nature. This year’s Nobel Laureate has made extremely important contributions in this area.
In spite of these developments, the delusion still thrives in many quarters that there are some special advantages in the natural product over the synthetically prepared one. However, Vitamin C is Vitamin C, regardless of whether it is isolated from citrus fruits or synthesized in chemical factories.
The development of organic synthesis during a period of a little over one hundred years has afforded efficient industrial methods for the preparation of paints and dyes, pharmaceuticals and vitamins, insecticides and herbicides, which increase our harvests, plastics and textile fibers, which clothe humanity. Organic synthesis has contributed to the high standards of living and health and the longevity enjoyed at least in the Western world. It is understandable that contributions to organic synthesis have often been rewarded with the Nobel Prize in Chemistry.
The synthesis of complicated organic compounds often shows elements of artistic creation. Many earlier syntheses were performed more or less intuitively, so that their planning was difficult to perceive. Asking a chemist why he chose precisely the starting materials and reactions that so elegantly led to the desired result would probably be as meaningless as asking Picasso why he painted as he did.
The process of synthetic planning has been compared to a game of three-dimensional chess using 40 pieces on each side. But the problem of synthesis may be even harder than this. Over 35,000 usable methods of synthesis are described in the chemical literature, each with its possibilities and its limitations. During synthesis, moreover, new methods appear which can modify the strategy. It is like allowing new moves during a game of chess.
Beginning in the 1960s Professor E.J. Corey coined the term and developed the concept of retrosynthetic analysis. Starting from the structure of the molecule he was to produce, the target molecule, he established rules for how it should be dissected into smaller parts, and what strategic bonds should be broken. In this way, less complicated building blocks were obtained, which could later be assembled in the process of synthesis. These building blocks were then analyzed in the same way until simple compounds had been reached, whose synthesis was already described in the literature or which were commercially available. Corey showed that strict logical retrosynthetic analysis was amenable to computer programming. He is the leader in this rapidly developing field.
Through his brilliant analysis of the theory of organic synthesis, Corey has been able to carry out total syntheses of around a hundred naturally occurring biologically active compounds, according to simple logical principles, which previously were very difficult to achieve. Only a few of his achievements in organic synthesis can be mentioned here. In 1978, he prepared gibberellic acid, which belongs to a class of very important plant hormones of complicated structure. Corey has furthermore synthesized gingkolid B, which is the active substance in an extract from the ginkgo tree and is used as a folk medicine in China.
Corey’s most important syntheses are concerned with prostaglandins and related compounds. These often very instable compounds are responsible for multifarious and vital regulatory functions of significance in reproduction, blood coagulation and normal and pathological processes in the immune system. Their importance is witnessed by the awarding of the 1982 Nobel Prize in Physiology or Medicine to Professors Sune Bergström, Bengt Samuelsson and Sir John Vane for their discovery of prostaglandins and closely related biologically active compounds.
With enormous skill Corey has carried out the total syntheses of a large number of such compounds. It is thanks to Corey’s contributions that many of these important pharmaceuticals are commercially available.
To perform these total syntheses successfully, Corey was also obliged to develop some fifty entirely new or considerably improved synthesis reactions. His systematic use of different types of organometallic reagents has revolutionized recent techniques of synthesis in many respects. In recent years, he has also introduced a number of very effective enzyme – like catalysts, which yield only one mirror isomer of the target product in certain types of synthetically important reactions. No other chemist has developed such a comprehensive and varied assortment of methods, often showing the simplicity of genius, which have become commonplace in organic synthesis laboratories.
Corey has thus been rewarded with the Prize for three intimately connected contributions, which form a whole. It can be summarized in the following way. Through retrosynthetic analysis and introduction of new synthetic reactions, he has succeeded in preparing biologically important natural products, previously thought impossible to achieve. Corey’s contributions have turned the art of synthesis into a science.
In these few minutes I have tried to explain your immense impact on the theory and methodology of organic synthesis. In recognition of your important contribution to chemistry, the Royal Swedish Academy of Sciences has decided to confer upon you this years’ Nobel Prize for Chemistry. It is an honour and pleasure for me to extend to you the congratulations of the Royal Swedish Academy of Sciences and to ask you to receive your Prize from the hands of His Majesty the King.
Their work and discoveries range from the Earth’s climate and our sense of touch to efforts to safeguard freedom of expression.
See them all presented here.