Prelog-Lektoren 1986-1999 und deren Laudatien

1986

Prof. Dr. Kurt Mislow

Mislow is the premier stereochemical theorist and experimentalist of the second half of the 20th century, whose work has helped define modern stereochemistry. His textbook "Introduction to Stereochemistry" (1965) was built around the theme that the major principles of stereochemistry rest on considerations of symmetry and group theory. It introduced into chemistry the concept of topicity (enantio-, diastereo-, chiro-). Among his "firsts" are a general method for determining enantiomeric ratios by NMR spectroscopy, a general method for establishing the absolute configuration of optically active biaryls, the synthesis of a chemically achiral compound composed exclusively of asymmetric conformations, and the demonstration that conformational interconversion rates are affected by steric isotope effects. He designed novel types of stereoisomers among molecular propellers and molecular gears based on an analysis of ring-flipping and internal gearing motions. He published well over 150 papers, mainly in the area of stereochemistry.

Mislow was born in 1923 in Berlin, Germany. He attended Tulane University (B.S. 1944) and obtained the Ph.D. degree with Linus Pauling at Cal Tech (1947). He then joined the New York University faculty, and in 1964 was appointed the first Hugh Stott Taylor Professor of Chemistry at Princeton University (1964). Among his many awards were Sloan and Guggenheim fellowships, the ACS James Flack Norris Award in Physical Organic Chemistry (1975). He is the first recipient of the Prelog Medal.

1987

Prof. Dr. Meir Lahav
Prof. Dr. Leslie Leiserowitz

Meir Lahav was born in Sofia in 1936 and emigrated in 1948 to Israel, where he studied chemistry at the Hebrew University, obtaining his M. Sc. in polymer chemistry in 1962. He then moved to the Weizmann Institute, where he joined Gerhard Schmidt' s research group in solid-state chemistry, obtaining his Ph.D. in 1967. Lahav carried out post-doctoral research with Paul Bartlett at Harvard In 1971, on his return to Israel, Lahav embarked on a programme for the design of systems for the spontaneous generation and amplification of optical activity via crystallization. It was during this period that the close Leiserowitz-Lahav collaboration started with a series of mechanistic studies of photochemical reactions in solids, especially in inclusion complexes of the bile acids. This teamwork then continued (together with Lia Addadi and Ziva Berkovitch-Yellin) with their new approach to the study of crystal nucleation, growth, and dissolution in the presence of tailor-made additives, which has had important theoretical and practical repercussions.
Since 1982 Lahav has been Full Professor at the Weizmann Institute, where he holds the Margaret Thatcher Chair of Chemistry. He was awarded the Bergman Prize for Chemistry in 1975 and the Haifa Technion Kolthoff Prize in Chemistry in 1985. He was Centenary Lecturer of the Royal Society of Chemistry in 1984 and gave the F. M. C. Lectures in Stereochemistry at Princeton University in 1987. He is married and has a son and twin daugthers.

Leslie Leiserowitz was born in Johannesburg in 1934. He obtained a B. Sc. in electrical engineering from the University of Capetown, followed by an M. Sc. in X-ray crystallography. In 1959 he joined the research group of the late Gerhard Schmidt at the Weizmann Institute of Science, where he worked on the problem of solid-state thermochromism. After completion of his doctoral work in 1966, Leiserowitz spent some time in Germany, where he helped to introduce crystallographie methods of molecular structure analysis at the Organic Chemistry Institute of the University of Heidelberg. It was during this period that he began the systematic investigation of the structural patterns and physical properties of organic crystals that has remained one of his major interests to this day. In particular, his experimental and theoretical studies on the packing modes of hydrogen-bonded molecules have secured him a world reputation in this area.
Leiserowitz was awarded the Bergman Prize for Chemistry in 1979. Since 1983 he has been Full Professor in the Department of Structural Chemistry and is presentIy Chairman of the Board of Studies in Chemistry at the Weizmann Institute. He is married and has three daughters.
Meir Lahav and Leslie Leiserowitz are the leaders of a team of researchers in structural chemistry at the Weizmann Institute of Science. By a superb combination of simple experiment painstaking observation, and logical deduction, they were able to provide for the first time a straightforward connection between macrascopic and molecular chirality. They thereby solved a problem that has puzzled chemists since the time of Pasteur and so furnished a welcome confirmation of the correctness of the more abstract Bijvoet method involving the sign of the phase shift associated with anomalous scattering in an X-ray diffraction experiment.


1988

Prof. Dr. K. Barry Sharpless

K. Barry Sharpless was born in Philadelphia in 1941. He studied chemistry at Dartmouth College where he did undergraduate research with Thomas A. Spencer to whom he is attached by friendship and a lang collaboration in the field of steroid demethylation (first joint paper in 1964, last in 1975) For his Ph. D. work Sharpless joined E. E. von Tamelen's group at Stanford (thesis in 1968. "Featuring Enzymic Cyclizatioil of Modified Squalene Oxides"). In a subsequent postdoctoral period he vacillated between biochemistry (with K. Bloch, Harvard) and inorganic chemistry (with J. Collman, Stanford) until he joined the faculty of the chemistry department at MIT in 1970 and settled for organic chemistry, more specifically, for the oxidation of organic compounds using inorganic reagents. Apart from another interlude on the Pacific Coast (Stanford 1977-1980) he has remained loyal to his institution and his field of research until today.
Sharpless's contributions cover a wide field and are documented in almost 150 papers and patents, many of them likely to be of lasting value. Among the oxidants he has studied are derivatives of sulfur, seIenium, titanium, vanadium, chromium, molybdenum, tungsten, manganese, ruthenium emd osmium, the corresponding synthetic transformation being hydroxylation, epoxidation and amination of C,C-double bonds as weil as allylic amination and oxidation. The transition-metal mediated regio- and diastereoselective epoxidation of olefins with t-butyl hydroperoxide was first described by Sharpless and his group in 1973. It took seven more years until the enantioselective version of that reaction was discovered with Katsuki. The stoichiometric or catalytic epoxidation of allylic alcohals by peroxides in the presence of titanates and dlethyl tartrate became an instant name reaction: indeed, it has been referred to as the reaction of the decade and its discoverer has stated in a somewhat jocular mood that "these new catalysts will work under more flexible conditions than biological systems, also, they don't need to work in water and don't have complicated cofactors and all this other garbage around that has to be gotten rid of when the product is purified". The Sharpless reaction has been exploited for the synthesis of numerous enantiomerically pure products in research laboratories and on an industrial scale. RecentIy, a highly enantioselective catalytic hydroxylation of double bonds with N-oxide/Os04/ chiral base has been developed in Sharpless's laboratoly. Many national and international awards and distinguished lectureships have followed the excellent work. Sharpless is a Fellow of the American Academy of Arts and Sciences and of the American Association for the Advancement of Science, he is a Member of the US National Academy of Seiences, and he received the ACS Award for Creative Work in Synthetic Organic Chemistry and the Janssen prize in Belgium.
Besides chemistry, Sharpless likes other exciting activities such as adventurous journeys, competition motorcycle racing against colleagues, and his daily jogging,


1989

Prof. Dr. Jeremy R. Knowles

Jeremy R. Knowles was born in Rugby (U.K) in 1935. After serving for two years in the R.A.F. as a pilot officer, he studied chemistry at Oxford, where he obtained his M.A., D. Phil. in 1961 with a thesis on "Intramolecular effects in aromatic systems". During a brief postdoctoral stay at Cal Tech with George Hammond he spent most of his time in the library, where he first became fascinated by the chemistry of enzymes. Since that time this fascination has never diminished. Armed with practical knowledge collected in Hager's laboratory at the University of Illinois, Urbana, he returned to Oxford as a Fellow of Wadham College and was appointed a University Lecturer in 1966. In 1974 he moved to Harvard University, where he now holds the Amory Houghton Chair of Chemistry and Biochemistry.
A leading protagonist of modern bio-organic chemistry, Knowles bridges the gap between enzymology and organic chemistry. The impact of his work on current thinking and practice is illustrated by the following selected highlights.
The work on triosephosphate isomerase (TIM), which resulted in the first delineation of a complete energy profile for an enzyme reaction.
The theoretical studies which led to the definition of "enzymatic perfection" as a new concept for assessing the catalytic efficiency of enzymes.
The invention of a new methodology for detecting the concerted vs. non-concerted nature of a given enzymatic transformation.
The synthesis of chirally labelled 16O,17O, 18O-phosphate groups and the ingenious development of the two independent techniques for the detection of their absolute configuration. This remarkable extension of the stereochemical domain has paved the way for many important mechanistic studies on a broad class of enzymes catalysing phosphate transfer reactions.
Knowles' intellectual rigour finds its expression in the lucidity of his prose and in the impeccable quality of his experimentation. He has changed the face of bioorganic chemistry and has succeeded in bringing one part of organic chemistry back to its original roots.
Knowles is a Fellow of the Royal Society, a Foreign Associate of the U.S. National Academy of Sciences, and a Fellow of the American Academy of Arts and Sciences. He is much in demand as a lecturer. He was the 1981 recipient of the Charmian Medal of the Royal Society of Chemistry, and in 1988 he won the Alfred Bader Award for Bio-organic and Bio-inorganic Chemistry, sponsored by the American Chemical Society.


1990

Prof. Dr. Henri B. Kagan

Henri-Boris Kagan est né en 1930 a Boulogne-sur-Seine (France). 11 entreprend ses études de chimie à Paris et effectue son travail de doctorat au Collège de France sous la direction du professeur J. Jacques. En 1960, il soutient la défense de sa thèse intitulée "Les steroides inversés".
Entre 1960 et 1967, mise à part une année passée comme post-docteur a I'université du Texas a Austin, il travaille comme chercheur puis comme sous-directeur dans le laboratoire du professeur A. Horeau au collège de France; il est coauteur, avec celui-ci, de nombreuses publications.
Depuis 1968 il est directeur des laboratoires de synthèse asymétrique et de chimie de coordination à Orsay. En 1978 il est nommé professeur titulaire à I'université de Paris-Sud (Orsay).
Les recherches du professeur Kagan sont principalement axées sur la stereochimie. Il s'est tout d'abord fait remarquer par ses travaux sur les réactions photochimiques énantio-sélectives dans lesquelles il met en oeuvre une lumière circulairement polarisée. Il est un des premiers à obtenir une énantio-sélectivité lors d'hydrogénation de liaisons doubles en employant des catalyseurs chiraux de Wilkinson (ces catalyseurs sont connus sous le sigle DIOP); il réussit la préparation énantiosélective d'acides aminés à partir de précurseurs déhydrogénés. Suivent des travaux sur la synthèse de sulfoxydes énantiomères purs, des époxidations catalysées et des réactions de Diels-Alder, toutes ces réactions étant conduites avec énantiosélectivité. Systématiquement, le professeur Kagan a essayé de déduire des informations sur le comportement stéréochimique et möcanistique des réactions qu'il mettait en oeuvre; il a ainsi mis en évidence des effets non-linéaires dans certaines réactions stéréosélectives, ce qui a conduit à une révision de leur mécanisme généralement admis à ce jour.
Le professeur Kagan a été le premier à reconnaître I'intérêt que présentent, pour la synthèse, les lanthanides organiques. Son premier travail sur ce sujet date de 1970 et ce domaine de recherches est activement poursuivi à ce jour dans son laboratoire. Les titres des quelques 200 publications du professeur Kagan montrent la diversité des thèmes qu'il aborde dans ses recherches: réactions dans SO2 liquide, réactions en phase cholestérique, réactifs incorporés dans le graphite, stokage de I'énergie lumineuse.
En plus des nombreux travaux originaux publiés, le professeur Kagan a écrit des articles de revue et des chapitres de livres. 11 y a lieu de signaler ici qu'il est I'auteur d'un précis intitulé "Stereochimie organique" qui a été traduit en cinq langues. Il est I'éditeur responsable des cinq volumes bien connus "Stereochemistry, Fundamentals and Methods" publiés par Thieme-Verlag, cinq volumes qui ont fortement influencé les chercheurs activement engagés en stéréochimie.
Les qualités intellectuelles et humaines du professeur Kagan ont favorisé I'établissement de collaborations entre son laboratoire et d'autres laboratoires français et étrangers; ses publications avec Ourisson, Salem, Snatzke ou Schuring en sont le témoignage.
L'étendue de ses connaissances et I'intérêt bienveillant qu'il porte à ses étudiants sont pour ceux-ci un stimulant constant. J.-L. Luche, probablement le plus brillant de ses élèves, témoigne de l’influence positive que peut avoir un tel maître sur ses élèves.
Les mérites scientifiques du professeur Kagan sont tels que son université et la société chimique de France lui ont confié de nombreuses responsabilités. Il est président de la "division pour la chimie organique" et vice-président de la Société chimique ainsi qu'éditeur du Nouveau Journal de Chimie.
En plus de nombreuses invitations dans différentes universités rénommées du monde, de nombreuses distinctions honorifiques ont été décernées au professeur Kagan: Prix LeBel (1967), Prix Cahours (1968), Médaille d'argent du CNRS (1974), Prix Raymond Berr (1976), Prix du Rayonnement Français (1989).
Depuis 1978, le professeur Kagan est membre correspondant de l’Académie des Sciences.


1991

Prof. Dr. Clayton H. Heathcock

Clayton Howell Heathcock was born in San Antonio (Texas) in 1936. He spent his early years there and received a B.S. degree in chemistry from Abilene Christian College, Abilene (Texas) in 1958. After spending two years as supervisor of Chemical Tests for the Champion Paper and Fibre Company in Pasadena (Texas), he returned to school at the University of Colorado and received the Ph. D. in organic chemistry under Alfred Hassner in 1963. After a year of postdoctoral work with Gilbert Stork at Columbia University he joined the Chemistry Department of the University of California in Berkeley, where he was promoted to associate professor in 1970 and to full professor in 1975; at present he has the distinguished position of a Miller Research Professor at the department. Over the years he has served as chairman of the chemistry department at Berkeley, of an NIH Medicinal Chemistry study group, of the ACS Organic Chemistry Division and of a Gordon Research Conference on Stereochemistry. He has edited an Organic Synthesis Volume and is at present Editor-in-Chief of the Journal of Organic Chemistry.
In 1971 he spent six months at the organic chemistry laboratory at ETH as an academic guest.
In his research Heathcock is what one might call a central organic chemist. His scientific work is rooted in the field of natural product chemistry, the problems he attacks and the tools he uses are those of organic synthesis, target- as weil as method-oriented. Underlying all his work is a distinct inclination to tackle problems whose solutions contribute to our understanding of chemical reactivity. Heathcock's research achievements are documented in over 200 papers and in a series of important review articles. After his doctoral work under Hassner, with whom he had an exceptionally fruitful and productive collaboration on the chemistry of aziridines, he started independent research at Berkeley by working on natural product syntheses in the terpene field; he announced himself to the international community of organic chemists in 1966 with the first total synthesis of the complex tricyclic sesquiterpene hydrocarbon copaene, an achievement carried out single-handedly and notable for the lucidity of the synthesis strategy. Over the years, Heathcock' s special flair for the development of strategy as well as methodology has led him to engage in comprehensive research on a wide series of projects in natural product synthesis with target structures varying from sesquiterpenes and pentacyclic triterpenes to compounds of medicinal interest e.g. vernolepin, compactin, quassinoids and alkaloids. While Heathcock's 1978 synthesis of Iycopodine is an important contribution of his earlier research in alkaloid synthesis, his work in this field has culminated recently in brilliant and spectacularly successful syntheses of Daphniphyllum alkaloids. Heathcock's work on these complex hexacyclic triterpenoid alkaloids constitutes a fine example of natural product synthesis evolving from a level of «biophobic» hardcore chemosynthesis into that of self-propelling biomimetic chemosynthesis, making use of the specific reaction channels through which the biosynthesis is expected to proceed chemomimetically, so to say. This is the level on which an achieved natural product synthesis amounts to a chemical rationalization of the natural product structure.
In the Woodwardian era of natural product synthesis, the dominating strategy for diastereoselection was based on the concept of «Synthesis via Transient Rings». During the last 15 years we have witnessed the development of the concepts and methods of «Acyclic Diastereoselection». Through them, diastereoselective syntheses of highly complex acyclic or macrocyclic molecules containing multiple stereogenic centers have become feasible. These developments - brought about by the contributions of various research groups represent a great step forward in the strategy and methodology of chemical synthesis and in our understanding of stereocontrol. Clayton Heathcock has been the pioneer of this development in the field of natural product synthesis. Starting with his first paper «Stereoselection in the Aldol Condensation» in 1977, about 50 papers on «Acyclic Stereoselection» have come out of his laboratory; as a whole, they constitute a comprehensive contribution to our knowledge of stereocontrol of reactivity.
Within the last five years, Heathcock has won the Ernest Guenther Award, the Award for Creative work in Synthetic Organic Chemistry and the A. C. Cope Scholar Award, all from the American Chemical Society. This year - besides receiving the Prelog Medal - he has been elected a member of the prestigious American Academy of Arts and Sciences.
Let us not forget: Heathcock is also a distinguished teacher. Together with his colleague Andrew Streitwieser he has written a most successful textbook «Introduction to Organic Chemistry»; this book has helped many of our students here at ETH to enjoy and to understand our science.


1992

Prof. Dr. J. Michael McBride

J. Michael McBride was born in Lima, Ohio in 1940, After his undergraduate studies (B.A. Harvard College, 1962) he entered the research group of Paul D. Bartlett at Harvard and received his doctorate in 1966 with a thesis entitled "Caged Free Radicals". He then went to Yale University, where he has remained, since 1982 as full professor.
McBride is distinguished in two areas: in solid-state chemistry and in the history of chemistry.
In solid-state chemistry he has made a speciality of studying the steric interactions that control the very fIrst stages of radical reactions at low temperature in ordered phases where the molecules have identical structures and environments. One problem in solidstate chemistry is that reaction products and intermediates are usually detectable only when their concentration rises above the order of a percent or so. Even at the one percent level the initial, ordered crystal structure will be appreciably distorted, so that it may be no longer be a reliable model for analysis of the topochemical aspects of the reaction. McBride was the fIrst to exploit electron spin resonance (ESR) to follow what happens in radical-pair reactions in single crystals at much lower concentrations of product (less than one molecule in 2000) where the environment around the re action centre can safely be assumed to be that of the initial, ordered crystal structure. Typical systems studied are azoalkanes and diacyl peroxides. For these, the radical pair is initiated photochemically, using weakly absorbed ultraviolet light (to avoid surface reaction) and the fate of the intermediates is followed by ESR spectroscopy.
The main lessons that have been learned through a long series of such studies are: (1) Reactions in crystals are often selective in ways that are unprecedented by reactions in fluid media. (2) Successive structures that differ only in their relative position and orientation can be identifIed as distinct intermediates on the reaction path. (3) Motion rather than the making or breaking of chemical bonds is usually rate determining in solid-state reactions. (4) This motion is controlled by the stress fIelds set up in the immediate environment of the reaction intermediates.
This is not and will never be a fashionable area of research. It provides no quick answers and the experiments are demanding, both from the experimental and interpretative angles. Yet it probes deep into the topochemical details of how such radicals react with one another and is thus an enrichment of the stereochemical view of the world.


1993

Prof. Dr. Hisashi Yamamoto

Hisashi Yamamoto was born in 1943 In Kobe, a city of many traditions on Honshu, the main island of Japan, and hometown of several illustrious chemists. He studied chemistry at Kyoto University and received a bachelor's degree in 1967, with a thesis done under the supervision of Professor H. Nozaki. He then Joined Professor E. J. Corey's group at Harvard University for graduate studies and received the Ph. D. degree in 1971. Back in Japan, he first spent a year working for Toray Industries, where his advisor was Professor J Tsuji, and then returned to Kyoto University as a member of Nozaki's Koza, where he was an Instructor and Lecturer from 1972 through 1977. Being too young for promotion to professor in the Japanese system of those days, he moved to the United States and became an Associate Professor of Chemistry at the University of Hawaii. In 1980 he returned to Japan, first as an Associate and since 1983 as a Full Professor in the Department of Applied Chemistry of the School of Engineering at Nagoya University. He serves on the board of editors of Organic Syntheses (since 1988) and of Synlett (since 1989).
As might be expected from his choice of teachers, Hisashi Yamamoto is especially strong in the field of synthetic methodology, particularly in the use of organo-metallic compounds for synthesis, and within this realm, stereoselectivity has moved to the center of his interest recently. At Harvard he was involved in the work on steroid biosynthesis and on the total synthesis of juvenile hormone and of prostaglandins (12 papers). In Kyoto and Hawaii, where he kept publishing with Nozaki (altogether ca. 40 papers), the use of Li, AI, and Cu derivatives, notably of carbenoids in organic synthesis was the general theme. His independent work is documented in ca. 200 publications, and during the last ten years has been characterized by a true burst of productivity and creativity. Much of this recent work is devoted to the development of new types of B-, AI- and Ti-Lewis acids for activating cuprates; for diastereoselective epoxide and cyclic acetal ring openings; for pinacol-type, Beckmann, and Claisen rearrangements; for enolate alkylation and aldol additions; and for Mannich and Diels-Alder reactions. In many of these reactions bulky aluminium derivatives such as methylalu minium bis (2,6-di-ter-butyl-4-methylphenoxide) or bis(2,6-diphenylphenoxide) (MAD, MAPH, the Yamamoto Lewis acids) are employed. They are specific complexing agents which can, for instance, differentiate less from more sterically hindered carbonyl groups and thus induce highly selective conversions. Most recently, chiral versions of these Lewis acids with bulky binaphthoiligands on the metal have been added to the arsenal and used for enantioselective (4+2)-cycloadditions and Mannich reactions. Hisashi Yamamoto's research is carefully described with experimental detail for those who want to use the result in their own work. Besides original research papers, he regularly publishes review articles which are evidence ur his insight and understanding of the reactivity of organic molecules. A recent example is his appropriate contribution to the book entitled Organic Synthesis in Japan. Past, Present, and Future.
It has been predicted that the coming years of organic synthesis will be devoted to developing enantioselective variations of all the classlcal reactions. It looks as if the wizards in this field live and work in Japan, and Yamamoto is likely to be one of the leaders. His contributions have recently been acknowledged by the IBM Science Award, and by the Houkou and Chunichi Awards.


1994

Prof. Dr. Jean-Pierre Sauvage

Jean-Pierre Sauvage was born in 1944 in Paris. He studied chemistry at the Ecole Nationale Supérieure de Chimie de Strasbourg and received the degree of Ingénieur in 1967. He then joined the group of Professor Jean-Marie Lehn at the Université Louis Pasteur de Strasbourg for his doctoral work and received the Doctorat d'Etat in 1971. Professor W. Simon from the Laboratorium für Organische Chemie at ETHZ was one of the members of his thesis committee. In 1971, he became Attaché de Recherche au CNRS in Strasbourg and, in 1973-1974, he spent time as a postdoctoral fellow with Professor Malcolm Green at Oxford University. He returned to Strasbourg where he was promoted in 1979 to Maître de Recherche au CNRS, in 1982 to Directeur de Recherche de 2ème classe au CNRS, and in 1988 Directeur de Recherche de 1ère classe. In 1981, he was named Professeur des Universités in Strasbourg. Over the years, he has spent time as a visiting professor at the Universities of Utrecht, Pavia, Berne, Bologna, and Louvain-La-Neuve.
The research career of Jean-Pierre Sauvage started with milestone results obtained in his Ph. D. thesis work on «Les diazapolyoxa-macrocycles et leurs cryptates». The content of this thesis was the subject of the first publications between 1969 and 1973 on cryptates and their cation selectivities, co-authored by Bernard Dietrich, Jean-Pierre Sauvage, and thesis supervisor Prof. Jean-Marie Lehn. After his return to Strasbourg from the postdoctoral stay at Oxford, where he expanded his practical knowledge in transition metal complex chemistry, he started, in collaboration with Prof. Lehn, a program on the development of catalysts for the photochemical hydrogen production by visible light irradiation of neutral aqueous solutions. The work from the mid seventies to the early eighties on photochemical water splitting and chemical storage of light energy is not only documented in ca. 20 scientific papers but also led to the award of several patents. This work illustrates nicely a common denominator of the entire research program by Jean-Pierre Sauvage, nameIy the search for the creation of function through novel structural assembly. This basic underlying research theme is also expressed in a second major catalysis program in his group, the development of efficient Ni(II)cyclam-based electrocatalysts for the reduction of CO2 in water, which was pursued all through the eighties.
Around 1983, Jean-Pierre Sauvage started the research in supramolecular chemistry and topological stereochemistry, that led the Laboratorium für Organische Chemie at ETHZ to award him the Prelog medal. Following initial explorations of copper(l) phenanthroline complexes for use in the photochemical dissociation in water, he published in 1983 the first paper on a new efficient metal (Cu(I)) template assisted assembly of catenands and their complexes, the catenates. Previously known syntheses of catenands had been exceedingly lengthy, tedious, and very low-yielding. Sauvage's introduction of templated self-assembly techniques made these compounds for the first time available in large quantities. The technique of interlacing molecular threads on transition metals which, in the following, paved the way to a great variety of catenands and catenates culminated in 1989 with the first synthesis of a molecular trefoil knot. Highlights of developments in subsequent years were the synthesis of topologically chiral catenands and multiring catenanes, the detection of C-H activation in Pd(ll)catenates, and the development of new concepts such as topological kinetic effects. Of particular interest have been the unusual electrochemical and photophysical properties of these supramolecular systems, which have been extensively studied, partially in collaboration with Prof. V. Balzani in Bologna. All this original work on new topological supramolecular objects has so far been described in ca. 80 publications, many of them full papers, in the finest journals and have laid the ground work for a variety of important developments in supramolecular chemistry by others.
In his most recent work, Jean-Pierre Sauvage has constructed efficient model systems to study fast photoinduced electron transfer processes in supramolecular devices such as rotaxanes with two porphyrins as terminal stoppers, which resemble the assembly of chromophores in the photosynthetic reaction centre. His studies now have helped clarifying the conditions for pathways for ultrafast photoinduced electron transfer between porphyrin subunits.
The entire research of Jean-Pierre Sauvage is characterized by love and admiration for complex supramolecular structure of unusual beauty and stereochemistry, and, most importantly, by the determination to create function through novel structural assembly. Jean-Pierre Sauvage is a pioneer and leader of supramolecular chemistry. He has been awarded several honors for his highly original research, among others the Prix de la Société Chimique de France, Section Chimie de Coordination (1979), the Prix Jean-Baptiste Dumas de l'Académie des Sciences (1980), the Prix de la Société Chimique de France, Section de Chimie Organique (1987), and the Izatt-Christensen Award (1990). He also has been elected Correspondant de l'Académie des Sciences in 1990.


1995

Prof. Dr. Yoshito Kishi

Yoshito Kishi was born in Japan in 1937 and received the B.S. (1961) and Ph.D. (1966) degrees from Nagoya University under the supervision of Professors Yoshimasa Hirata and Toshio Goto. In 1966 he was appointed as Instructor at the Department of Chemistry at Nagoya University, and from 1966 to 1968 he conducted research at Harvard University with Professor Robert Burns Woodward. Upon returning to Nagoya University, he was promoted to the rank of Associate Professor (1969 to 1974). He was invited back to Harvard University as a Visiting Professor in 1972 and then appointed as Professor of Chemistry in 1974. Since 1984 he is the incumbent of the Morris Loeb professorship. From 1989 through 1992 Professor Kishi acted as Chairman of the Department of Chemistry.
Professor Kishi's first important contribution - his Ph.D. work - dealt with the elucidation of the structure of tetrodotoxin, the unique neurotoxin of the pufferfish. After obtaining his Ph. D. degree, Professor Kishi devoted himself to the synthesis of natural products. Characteristically, the targets were judiciously selected for the challenge inherent in the complexity of their structure as well as for their unusual biological activities, many of which have since stimulated research in the areas of biology and medicinal chemistry. The list of successes is long and impressive, including the synthesis of Cypridina luciferin, anti-tumoral compounds (mitomycins, halichondrins), tumor-promoters (aplysiatoxins, etc.), polyether antibiotics (monensin, lasalocid A, salinomycin, etc.), ansamycin antibiotics (rifamycin S), b-lactam antibiotics, toxic metabolites of micro-organisms (gliotoxins, sporidesmins), and carba–oligosaccharides. Highlights are, inter alia, the synthesis of neurotoxins such as tetrodotoxin (a paradigm for the synthesis of intricately functionalised hexasubstituted cyclohexanes), saxitoxin (a convincing demonstration of how insight into reactivity can lead to a surprising, efficient synthesis), and last, but certainly not least, palytoxin (embodying 63 stereocenters!), the benchmark for the synthesis of a very large, very complicated, and very active compound. Here again, structural analysis and synthesis went hand in hand, providing yet another illustration of the fact that, for a chemist with deep insight into reactivity, there is no real difference between analysis and synthesis.
The assemblage of such complex products required a range of tactical innovations, each one of them distinguished by an innovative and rigorous analysis of reactivity. This search for underlying principles has made Professor Kishi a protagonist in the unavoidable strategical transition which led from the well-established approach of configurational control of chemical transformations through ring formation to a new concept of reaction control by ingenious exploitation of the conformational properties of acyclic intermediates. A characteristic example of the benefits of such an in–depth analysis of conformation and reactivity is the establishment of rules predicting the diastereoselectivity of reactions of allylic alcohols. More recently, knowledge gained during his unique efforts in the synthesis of palytoxin has proven highly fruitful in a reappraisal of the factors that govern the conformational behaviour of complex oligosaccharides, and hence for the analysis of the molecular basis of biological activities.
Professor Kishi is a member of the American Academy of Arts and Sciences. His awards include the 1967 Shinppo-sho, the 1973 Chunichi Press Award, the 1980 American Chemical Society Award for Creative Work in Organic Synthesis, the 1981 Harrison Howe Award, the 1988 Javits Neuroscience Investigator Award, the 1993 Naito Prize, and the Nagoya Medal of Organic Chemistry in 1995.


1996

Prof. Dr. David Lilley

David Lilley was born in Colchester, England, in 1948. He studied chemistry at the University of Durham, where he obtained his BSc in 1969 with a dissertation on "The mechanism of action of Chymotrypsin" and his PhD in physical chemistry with a thesis carried out under the supervision of Prof. D.T. Clark and entitled "Theoretical and experimental investigations of structure, reactivity and bonding in some organic systems". In 1973 he passed with distinction his MSc in biochemistry at Imperial College and was awarded the Ewart Stickings Memorial Prize for Excellence in Biochemistry. After spending four years as a Research Fellow at the Universities of Warwick and Oxford and then five years as a Senior Research Investigator in the Biophysics Department of the Searle Research Laboratories, High Wycombe, UK, he was appointed in 1981 as Lecturer in Biochemistry at the University of Dundee, where he was later promoted to Reader (1984), and eventually to Professor of Molecular Biology (1989). Since 1993 he has acted as Director of the CRC Nucleic Acid Structure Research Group. David Lilley is married and father of two daughters.
Following an interest in the structure of chromatin and nucleosomes, Lilley turned his attention to the high-order structure of DNA and rapidly won reputation as a leading authority in this area. He is responsible for the first demonstration of a cruciform stabilising the supercoiled conformation of DNA. These investigations paved the way for his best known work, in which he established the solution structure of the four-way helical junctions in DNA; such folded structures are believed to represent the central feature of homologous genetic recombination. To unravel the details of what is now known as the stacked X-structure Lilley pioneered new approaches including a gel-electrophoretic method for estimating the angles subtended between the different arms and fluorescence resonance energy transfer (FRET) for assessing the relative end-to-end distances of such arms. Knowledge of the geometry of the junctions was then exploited for gaining an understanding of the interactions with the resolvases, i.e. with the structure specific nucleases that catalyse their cleavage. Lilley also investigated three-way DNA junctions, analysed the consequences of single and multiple mismatches on DNA distortion and demonstrated for the first time that base bulges cause axial kinking of helical DNA. The expertise gained in these investigations is now being applied to the study of the folding and dynamic properties of RNA molecules, including a number of important catalytic species such as the hammerhead ribozyme, the hairpin ribozyme and the ribozyme from hepatitis delta virus.
Lilley's research activity is documented in ca. 160 publications. He has co-edited four books on nucleic acids and shares editorial responsibility for a number of established biochemical journals. Lilley is a Member of the European Molecular Biology Organisation (1984) and a Fellow of the Royal Society of Edinburgh (1988). In 1982 he was selected as the winner of the Colworth Medal of the Biochemical Society for "work of outstanding merit" carried out by a British biochemist under the age of 35. In 1994 the Czech Academy of Sciences awarded him the G.J. Mendel Gold Medal in Biological Sciences.
The bestowal of the Prelog Medal on David Lilley is intended as an homage of the Organic Chemistry Laboratory to a scientist who has dared to venture far beyond the traditional limits of our discipline in tackling unusual stereochemical aspects of biologically important macromolecules.


1997

Prof. Dr. Günter Helmchen

Günter Helmchen ist im August 1940 in Gross-Lipke in der damaligen deutschen Provinz Posen, jetzt Polen, geboren. Nach dem Ende des zweiten Weltkrieges besuchte er Grund- und Mittelschule sowie ein neusprachlich-naturwissenschaftliches Gymnasium im Raume Hannover, wo er 1960 auch das Studium der Chemie begann und 1965 mit einer Diplomarbeit über benzylische Radikale bei Walter Theilacker (Autor eines Houben-Weyl-Kapitels "Methoden zur Herstellung optisch aktiver aus inaktiven Verbindungen") an der Technische Universität Hannover abschloss. Danach siedelte er als Stipendiat der Studienstiftung des Deutschen Volkes nach Zürich um und fertigte von 1966 - 1970 eine Doktorarbeit mit dem Thema "Untersuchung über pseudoasymmetrische organische Verbindungen" unter der Leitung von Vlado Prelog an. Wanderjahre führten Günter Helmchen 1972 zunächst an die Universität Stuttgart, zu einer Zusammenarbeit mit Hans Muxfeld, bei dessen Erkrankung und nach dessen Tod er die Arbeitsgruppe betreute, so dass er erst ab 1975 wissenschaftlich eigenständig und unabhängig werden konnte, was 1980 zur Habilitation führte. Im Jahre 1981 erhielt er ein Karl-Winnacker-Stipendium und folgte einem Ruf auf eine Professur in Würzburg, und seit 1985 ist er Professor am Organisch-Chemischen Institut der Universität Heidelberg, wo er 1995-1997 auch Dekan der Fakultät für Chemie war.
In den wissenschaftlichen Beiträgen von Günter Helmchen stellt die Stereochemie den roten Faden dar, welcher sich eng verwoben durch alle seine Arbeiten zieht. Schon die Wahl des Doktorvaters signalisierte das Interesse an grundlegenden Fragen über den dreidimensionalen Bau der Moleküle; in der mit der Medaille der ETH ausgezeichneten Dissertation ist neben den präparativen Ergebnissen über die erstmalige Herstellung von Verbindungen mit Pseudoasymmetrieachsen und -ebenen denn auch das Prinzip der Prochiralität, der Chiralität im zweidimensionalen Raum, definiert, welches in Helmchens allererster, richtungsweisender Veröffentlichung 1972 be-schrieben wurde. Diskussionen über Stereochemie führten ihn in den darauffolgenden Jahren immer wieder nach Zürich, in den Bannkreis von Prelog, mit dem er 1982 einen umfangreichen Artikel über die Revision des CIP-Systems zur stereochemischen Spezifikation fertigstellte. Sein Streben nach sauberer Definition und klarer Sprache bei der Beschreibung stereochemischer Sachverhalte war wohl auch Motivation für ihn, zusammen mit drei Herausgeber-Kollegen das schier unmögliche erscheinende Projekt eines zehnbändigen Houben-Weyl-Werkes "Stereoselective Synthesis" mit sage und schreibe 120 Autoren erfolgreich durchzuziehen, mit einer von ihm selbst verfassten Einführung in die Nomenklatur der Organischen Stereochemie (einschliesslich einem Glossar problematischer und nicht empfehlenswerter Ausdrücke!).
Der Wandel in Helmchens Forschungsinteressen spiegelt perfekt den Weg wieder, welchen die organische Synthese der letzten 20 Jahre genommen hat, wobei seine Arbeiten oft wegweisend waren und sind. In Stuttgart beschäftigte er sich mit der Trennung und Zuordnung des Chiralitätssinnes von Enantiomeren (NMR-Spektroskopie, Mittel- und Hochdruckchromatographie diastereomerer Derivate). In Würzburg wandte er sich der asymmetrischen Synthese über covalent gebundene chirale Hilfsstoffe zu, die er nach dem Konzept der konvexen und konkaven Lage funktioneller Gruppen in einem Molekül oder Molekülteil auswählte oder konstruierte, wodurch - nach Abspaltung des Auxiliars - a-verzweigte Carbonsäuren, sekundäre Alkohole, a- und b-Hydroxycarbonylderivate oder Michael- und Diels-Alder-Addukte in praktisch enantiomerenreiner Form hergestellt werden konnten, was auch zu originellen Naturstoffsynthesen führte; mit oder ohne Hinweis auf die Arbeiten von Helmchen fanden die von ihm entwickelten Konzepte viele Anwendungen und wurden nachgeahmt. In Heidelberg verlagerte sich der Schwerpunkt der Arbeiten dann in Richtung enantioselektive Katalyse mit Übergangsmetallderivaten, das heute weltweit am intensivsten bearbeitete Gebiet der organischen Chemie (die Synthetiker sind auf dem besten Weg, für jede klassische Reaktion, die von achiralen Edukten zu chiralen Produkten führt, eine enantioselektiv katalysierte Variante zu entwickeln - und die wundersamsten, gar nicht klassischen Übergangsmetall-vermittelten Transformationen zu entdecken). Helmchen hat jetzt neuartige P-, S- und Se-haltige Ligandsysteme für Palladium-, Rhodium- und Kupfer-Komplexe synthetisiert und z. B. für enantioselektive katalytische Hydroxylierungen, Alkylierungen und konjugierte Additionen mit Rekordselektivitäten eingesetzt. Diese Arbeiten waren wiederum Vorbild für andere Gruppen und sind nicht durch blindes Probieren, sondern durch ein tiefgründiges Verständnis von Reaktivität und Stereochemie entstanden. Einen Rekord hat Günter Helmchen unter den organischen Synthetikern auch dadurch aufgestellt, dass der Prozentsatz an fundamental bedeutsamen und wegweisenden Beiträgen in einem Publikationsverzeichnis von weniger als 100 Arbeiten unerreicht hoch ist, was in der heutigen Zeit der "Titel- und Abstract-Leser"unter den Wissenschaftlern nicht immer zur verdienten Anerkennung führte.
Die Kollegen des Laboratoriums für Organische Chemie sind besonders stolz darauf und erfreut darüber, dass der dieses Jahr mit der Prelog-Medaille ausgezeichnete Gunter Helmchen ein Schüler unseres verehrten "Dorfältersten" ist, wie sich der jetzt 91-jährige Vlado Prelog scherzhaft selbst bezeichnet!


1998

Prof. Dr. Lia Addadi

Lia Addadi was born in 1950 and raised in Padua, Italy. Her interest in chemistry developed at the Universita'degli Studi di Padova, where she studied from 1968 to 1973. She subsequently transferred to the Weizmann Institute of Science in Rehovot, Israel, for doctoral work and received a Ph.D. in Structural Chemistry in 1979 under the direction of Meir Lahav for studies on the synthesis of chiral polymers by reactions in chiral crystals. After a postdoctoral stay with J.R. Knowles at Haryard University, Dr. Addadi returned to the Weizmann Institute and became Associate Professor in 1988. She rose quickly through the ranks, becoming Full Professor in 1993 and head of the Department of Structural Biology in 1994.
Molecular recognition of ordered crystal arrays provides the unifying theme of Dr. Addadi's scientific program. Living organisms use minerals for many purposes, the construction of stable skeletal structures being perhaps only the most familiar, and they have evolved sophisticated strategies for controlling the process of mineralization. Over the past decade, Dr. Addadi has contributed significantly to our knowledge of the structures of mineralized tissues and the mechanisms by which they are produced. For example, she and her colleagues have explored the structural and stereochemical relationships between acidic proteins and calcite, carbonated apatite and other biominerals, showing how biological macromolecules nucleate oriented crystal growth and alter crystal morphology through interactions with specific surfaces. In structural studies of natural crystal-protein composites it was found that protein intercalation into the crystallattice can subtly alter a material's texture and mechanical properties, making these features amenable to biological control.
Her demonstration that immunoglobulins and serum albumins selectively adhere to crystal surfaces and nucleate crystal formation has provided fresh insight into diseases like gout and osteoarthritis that involve formation of unwanted crystals in bodily fluids, as has her discovery that crystals can serve as conventional antigens to elicit the production of antibodies which bear the imprint of distinct crystal surfaces and behave as nucleation catalysts. Observation that whole cells similarly distinguish different faces of a given crystal - and even the corresponding faces of enantiomorphous crystals - makes possible systematic investigation of the molecular recognition events that govern cell adhesion, a fundamental process affecting the structure and behavior of cells.
Dr. Addadi's work innovatively combines the tools of structural biology with those of organic, inorganic and analytical chemistry. In its originality and depth it has had a profound impact on the way we think about molecular recognition at crystal interfaces. Her efforts to elucidate the principles underlying controlled mineralization are fundamental in nature, providing mechanistic information not readily available from studies with conventional heterogeneous surfaces. They also have important practical implications for the fabrication of new and improved synthetic materials and for understanding and influencing biology at interfaces.
Lia Addadi has been widely recognized for her pioneering work. Among other major awards, she has received the Ernst David Bergmann prize in Chemistry (1986), the Annual Award of the Israel Chemical Society (1989), and the NIDR prize for distinguished scientists (1996). The Laboratorium für Organische Chemie is honored to add her name to the roster of distinguished Prelog medalists.


1999

Prof. Dr. David Evans

David Evans was born in Washington DC in 1941. He obtained an AB degree in chemistry in 1963 from Oberlin College, Oberlin, Ohio. His doctoral studies were conducted under the supervision of Professor Robert Ireland at California Institute of Technology where he received his PhD in 1967. In that same year he was appointed as an assistant professor at the University of California, Los Angeles (UCLA) where in a short period of time he rose quickly through the ranks to become associate (1972) and subsequently full professor in 1974. He then accepted a professorial position at California Institute of Technology (1974-83). In 1984 he moved to the Department of Chemistry at Harvard University where he subsequently was named the Abbott and James Lawrence Professor of Chemistry and in 1999 the Arthur and Ruth W. Sloan Research Professor. From 1995 through 1998 Professor Evans served as Chair of the Department of Chemistry and Chemical Biology.
Throughout his career, Professor Evans' scholarly work has been characterized by its fundamental contributions to science and its wide versatility and practicality. His research efforts have focussed on the design and study of stereoselective processes and their applications to complex natural products synthesis. Over the last two decades, reaction methods aimed at relative and absolute stereocontrol in carbon-carbon bond formation has been a central theme of his work, such as asymmetric (enantio- and diastereoselective) Diels-Alder, Michael, aldol, and alkylation reactions. Any reading of the scientific literature amply reveals the important impact Evans' pioneering work has had conceptually and practically in chemistry. He has made fundamental discoveries in reaction chemistry that has influenced inorganic, organometallic, physical-organic, and organic chemistry. Evans was the first to achieve the de novo synthesis of complex natural products through the exclusive use of chiral auxiliaries for asymmetric stereocontrol; this constituted a substantive and significant departure from the more traditional approach at the time which relied on the use of the chiral pool. The Evans auxiliaries and catalysts for asymmetric bond construction have become some of the most reliable and efficient systems for enantioselective synthesis world-wide in academic and industrial laboratories. The impact of his work is highlighted by the fact that his citation average of 50/paper ranks 13th in the world-wide chemical community. Thus, the design and successful realization of any modern asymmetric synthesis necessarily includes methods, strategies, and fundamental principles that have been developed by Professor Evans.
In parallel with the discovery and development of novel reaction methodology, Evans has established himself as one of the master practioners of the art and science of natural products total synthesis. The over forty natural products syntheses successfully completed by Evans constitute classics in organic synthesis and are characterized by meticulous attention to efficiency, innovation, and elegance. Each of the syntheses illustrates not only novel strategies and processes for molecular construction but is also marked by the highest degree of creativity and scholarship. His contributions to the field of natural products synthesis span the range from alkaloids to polyketides, including the syntheses of Macbecin, Tylonolide, Bafilomyicn, Oleandolide, Deoxyerythronolide, Calcimycin, X-206, Ionomycin, Premonensin, Cytovaricin, Lonomycin, Ferensimycin, Thienamycin, OF-4949, Calyculin, Altohyrtin, Zaragozic acid, Tetrahydrocannabinol, Colchicine, Cyancycline, Morphine, Histrinicotixin, and the Vancomycin antibiotic class.
Professor Evans' significant impact on science is exhibited by a commitment to the education, training, and mentoring of future teacher/scientists. He has served as a mentor to numerous young academicians and scientists. Over the last decade, over thirty-five individuals have been placed in Universities worldwide; it is thus not uncommon to find an Evans student or post-doctoral associate at the major research academic and industrial institutions world-wide.
Professor Evans has been the recipient of numerous awards such as Camille and Henry Dreyfus Teacher-Scholar Award (1971), A. P. Sloan Fellowship (1972), the American Chemical Society Award for Creative Work in synthetic Organic Chemistry (1982), Arthur C. Scope Scholar Award (1988), the ACS Remsen Award (1996), the Yamada Prize (1998), and the Tretrahedron Prize (1998). Recently he has been selected as the recipient of the Arthur C. Cope Award by the American Chemical Society (2000). He was elected to the National Academy of Sciences in 1984, the American Academy of Arts and Sciences in 1988, and named fellow of the American Association for the Advancement of Science in 1992. He was a consultant with Eli Lilly through 1989; he is currently a consultant with Merck Sharp and Dohme, DuPont-Merck, and Oxford Asymmetry. He has been on the advisory boards of Journal of the American Chemical Society, Journal of Organic Chemistry, Tetrahedron, Tetrahedron Letters, and Chemical Reviews.