432 research outputs found
A Pioneering Career in Catalysis: Manfred T. Reetz
No full textIn this invited Account, we highlight the enormous scientific breadth of our mentor Professor Manfred T. Reetz. It stretches from the development of organometallic reagents and transition metal catalysts to the adventurous idea of directed evolution of chemo-, stereo-, and regioselective enzymes, which he considered to be most important. We hope to show that Reetz did not consider these research areas to be totally unrelated realms, and attempt to reveal his transdisciplinary way of thinking about methodology development. Since biocatalysis has become crucial for chemical synthesis, we mainly focus on Reetz's contributions in this area. Some personal reflections from some of his former co-workers are also included, which reveal the stimulating atmosphere in the Reetz group in terms of science, career advice, and the importance of ethical considerations. BT/Biocatalysi
Dyotropic Rearrangements in Organic Solvents, in the Gas Phase, and in Enzyme Catalysis
No full textThis short historical account outlines how Helmut Schwarz and Manfred T. Reetz first met almost half a century ago and remained personal friends ever since. It began by collaborations on dyotropic rearrangements and other transformations in the gas phase. Although their chemical interests diverged considerably over decades, which are briefly mentioned in this account, both were always driven by curiosity. Another common feature was the fact that they both collaborated with Israeli chemists in various projects up to the present day. They also contributed to the celebration in 2015 commemorating 50 years of diplomatic relationship between Israel and Germany
One Hundred Years of the Max‐Planck‐Institut für Kohlenforschung.
No full textThis Essay is an account of the institutional and scientific development of the Max-Planck-Institut für Kohlenforschung in Mülheim an der Ruhr (Germany), which is the successor to the Kaiser-Wilhelm-Institut für Kohlenforschung founded in 1914. The Essay is divided into four main parts, corresponding to the four major periods which are closely associated with the respective Directors of the Institute from 1914 to 2014: 1) Franz Fischer; 2) Karl Ziegler; 3) Günther Wilke; and 4) the period beginning with Manfred T. Reetz, who established a directorate comprising five Directors of equal status, each heading a different research department under the banner of catalysis. Along with key historical events associated with the Institute, research highlights of the four periods are featured
Witnessing the Birth of Directed Evolution of Stereoselective Enzymes as Catalysts in Organic Chemistry
No full textThis invited essay outlines how the idea of directed evolution of stereoselective enzymes was born and implemented experimentally at the Max-Planck-Institut für Kohlenforschung in Mülheim/Germany during the period 1994–1998, a time when Andreas Pfaltz was present in the Institute. As the new and sole director of the MPI, I initiated new research projects, and also started to restructure the Institute with the establishment of five departments, all dedicated to some form of catalysis and to be led by five independent directors. Andreas Pfaltz was the first director whom I hired, heading the Department of Homogeneous Catalysis. During his stay in Mülheim until 1998, the Pfaltz group invented effective chiral ligands for a number of particularly challenging enantioselective transformations. During this period, Andreas Pfaltz witnessed the birth and development of directed evolution of stereoselective enzymes as a new research direction in the Reetz group. Indeed, he was one of the very few organic chemists who realized at the time that a door to a novel research area had been opened. The widespread application of enzymes was hampered for decades due to limited enantio-, diastereo-, and regioselectivity, which was the reason why organic chemists were not interested in biocatalysis. This attitude slowly changed with the advent of directed evolution of stereoselective enzymes in 1997, in a publication from the Reetz group. Methodology development with emphasis on stereo- and regioselectivity as well as activity followed, the techniques and strategies becoming more and more rational. Today, semi-rational approaches and so-called rational enzyme design have merged, as evidenced, inter alia, by the development of focused rational iterative site-specific mutagenesis (FRISM). The toolbox of organic chemists now includes enzymes, primarily because the possibility of controlling stereoselectivity by protein engineering has ensured reliability when facing synthetic challenges
Biocatalysis in Organic Chemistry and Biotechnology: Past, Present, and Future
No full textEnzymes as catalysts in synthetic organic chemistry gained importance in the latter half of the 20th century, but nevertheless suffered from two major limitations. First, many enzymes were not accessible in large enough quantities for practical applications. The advent of recombinant DNA technology changed this dramatically in the late 1970s. Second, many enzymes showed a narrow substrate scope, often poor stereo- and/or regioselectivity and/or insufficient stability under operating conditions. With the development of directed evolution beginning in the 1990s and continuing to the present day, all of these problems can be addressed and generally solved. The present Perspective focuses on these and other developments which have popularized enzymes as part of the toolkit of synthetic organic chemists and biotechnologists. Included is a discussion of the scope and limitation of cascade reactions using enzyme mixtures in vitro and of metabolic engineering of pathways in cells as factories for the production of simple compounds such as biofuels and complex natural products. Future trends and problems are also highlighted, as is the discussion concerning biocatalysis versus nonbiological catalysis in synthetic organic chemistry. This Perspective does not constitute a comprehensive review, and therefore the author apologizes to those researchers whose work is not specifically treated her
Kombinatorische Übergangsmetallkatalyse: Mischungen einzähniger Liganden zur Kontrolle der Enantio-, Diastereo- und Regioselektivität
No full textOrganotitanium reagents in organic synthesis a simple means to adjust reactivity and selectivity of carbanions
No full textClassical organometallic reagents such as alkyl-lithium and magnesium compounds as well as a large number of lithiated species which are substituted by resonance-stabilizing groups or hetero-atoms can be convened into the titanium analogs using cheap quenching reagents. This increaseschemoselectivity dramatically and also has a profound influence on stereoseleetivity in reactions with carbonyl compounds. Since the nature of the ligands at titanium can ge varied systematically, it is possible to control the electronic and steric environment at the metal in a predictable manner. Besides increasing selectivity, several novel reaction types are possible
Breakthrough in the chemoenzymatic transformation of CO2 for the sustainable artificial synthesis of hexoses with complete control of stereochemistry
No full textWhat are the Limitations of Enzymes in Synthetic Organic Chemistry?
No full textEnzymes have been used in organic chemistry and biotechnology for 100 years, but their widespread application has been prevented by a number of limitations, including the often- obser ved limited thermostability, narrow substrate scope, and low or wrong stereo- and/or regioselectivity. Directed evolution provides a means to address and generally solve these problems, especially since recent methodology development has made this protein engineering method faster, more efficient, and more reliable than in the past. This Darwinian approach to asymmetric catalysis has led to a number of industrial applications. Metabolic-pathway engineering, mutasynthesis, and fermentation are likewise enzyme-based techniques that enrich chemistry. This account outlines the scope, and particularly, the limitations, of biocatalysis. The complementary nature of enzymes and man-made catalysts is emphasized
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