Natural Product Chemistry-retrospect and Prospect

As a part of this Symposium, with its specialist lectures and scientific communications in which the latest results in natural product research are being reported, it is my task-and a rather difficult one-to attempt a broad review of the field, to consider its development and its present status, and to attempt an estimate of its future. Natural product chemistry is essentially a part of organic chemistry, itself one of the most remarkable of all the sciences, and one which is usually regarded by the layman as one of the most abstruse and remote from everyday life and thought. This view, is, perhaps, based on its content of jargon and its use of abbreviated molecular formulae as a kind of hieroglyphic script. It is hard to believe, however, that a science can properly be described as abstruse which permeates almost every material aspect of modern civilization, which stands as the bridge linking the physical with the biological sciences, and which is perhaps the biggest of the sciences in its factual content and in the number of its adherents. Organic chemistry is, I believe, the most logical of the sciences, and in its history of little more than a hundred and fifty years it has suffered fewer theoretical upsets than other science. It is a remarkable fact that the whole towering edifice of modern organic chemistry rests essentially on three basic concepts propounded in the third quarter of the nineteenth century-the concept of fixed combining power or valence due to Frankland, the Kekule-Couper theory of the tetravalency of carbon and the capacity of carbon atoms to join together into chains and rings, and the van't Hoff-Le Bel tetrahedral carbon atom which gave us stereochemistry. All of these concepts were purely empirical, but they have stood the test of time and, on them, the whole of the science rests; advances in theory have certainly occurred since they were enunciated, but these advances have been essentially refinements giving more precise meaning to them, and have in no way upset or destroyed their essential validity. I doubt whether the same couldbe said of any other science. There have been two definitions of organic chemistry. Historically the first, due to Berzelius, was " the chemistry of substances found in living matter". The second, commonly ascribed to Gmelin, first appeared about fifty years later, when more was known about the peculiarities of substances found in living matter, and was quite simply" the chemistry of the carbon compounds". Each of these definitions has some validity, but neither is wholly satisfactory, since the first is too restricted and the second, in certain respects, too general. A very large number of the carbon compounds known today are of purely synthetic origin and do not, as far as we are aware, occur in living matter. But it is undoubtedly true that the study