C–H activation through late transition metal cyclometallation. Addressing selectivity and reactivity problems

Abstract: Popular Abstract in English Synthetic chemicals are the basis of the modern civilisation. Nowadays, they have a bad reputation, but it is only due to them that we are able to live healthier, longer, receive improving medical treatments, use the comforts of modern technologies and not die of thirst and starvation, despite the immense population growth. The main task of organic synthesis is to transform molecules into other molecules. Since molecules consist of atoms bound to each other, transforming one molecule into another molecule is essentially a question of breaking some of the existing bonds and making new ones. One typical recurrent problem in synthesis is breaking C—H bonds. Most of our organic chemical feedstock consists of hydrocarbons (molecules that have only carbon and hydrogen atoms in them). This very special chemical composition makes these molecules suitable for a limited amount of applications. The majority of chemicals we need require nitrogen, oxygen, phosphorus, sulfur, halogens and other elements to be present in the molecule in order to have the required properties. Hence, we need to break C—C and C—H bonds and make new ones to get the molecules we want. At this point we stumble at a problem: not only is a C—H bond, typically, a very strong bond, but it is also fairly unpolar, which makes it difficult for this bond to undergo many interactions. Also, large organic molecules usually contain many C—H bonds, which can have fairly similar properties and only some of them should be broken to produce a certain target molecule. During the past decades metal-catalysed C—H bond activation has emerged as a huge field of research, providing numerous new methods for cheap and facile transformation of C—H bonds into other bonds. The current work is dedicated to some of the auxiliary problems existing in this field. In order to progress faster in the creation of new methods, we need to know more about the properties of the metal catalysts and their interaction with C—H bonds. In this thesis I was able to study the behaviour of different metal catalysts towards a specific substrate, which could point out the difference between their properties. My attempt to expand the scope of catalysts and reagents used in C—H activation reactions was unsuccessful, but it indicated important specifics of the properties of relevant catalysts. At last, I was able to study an old, well-known reaction and show that it can proceed under completely unexpected conditions, resulting in a C—H activation at one of the lowest temperatures registered.