Silyl vinyl cations enable mild C-C bond formation

Chemical bonds between carbon atoms are omnipresent in Nature since they constitute the backbone of all living matter at a molecular level. Thus, synthetic chemists have long been interested in methods for their selective construction to build up compounds of functional or biological interest (ranging from pharmaceuticals to materials to cosmetics). One of the most efficient processes for carbon-carbon bond formation requires the use of transition metal catalysts such as palladium. However, such metals tend to be expensive and their natural abundance is dwindling. An alternative which has gained pace in recent years is to make use of skeletal rearrangements that achieve often dramatic modifications of the linkages between atoms. The Maulide group has been working on the latter, metal-free alternative for several years, and has recently developed a technique in which a positively charged high-energy intermediate (termed a vinyl cation) is harnessed for such a rearrangement. However, this method is still in its infancy and displays strong drawbacks namely the requirement for high reaction temperatures and a structural limitation in terms of the substituents surrounding the so-called vinyl cation. This proposal aims at using silicon as a stabilizing element for vinyl cations, thus enabling milder conditions and a much broader scope for the overall process. Several variations of this reaction as well as the use of the obtained products in further carbon-carbon bond forming reactions will also be explored. These ultimately pave the way for complex reaction sequences with the ability to rapidly increase molecular complexity starting from rather simple building blocks.

Chemical bonds between carbon atoms are omnipresent in Nature since they constitute the backbone of all living matter at a molecular level. Thus, synthetic chemists have long been interested in methods for their selective construction to build up compounds of functional or biological interest (ranging from pharmaceuticals to materials to cosmetics). One of the most efficient processes for carbon-carbon bond formation requires the use of transition metal catalysts such as palladium. However, such metals tend to be expensive and their natural abundance is dwindling. An alternative which has gained pace in recent years is to make use of skeletal rearrangements that achieve often dramatic modifications of the linkages between atoms. However, this type of transformations features the formation of a positively charged high-energy intermediate which requires harsh conditions. This project enabled the development of milder conditions for this transformation by using silicon as a stabilizing element for the intermediate. Therefore, this reaction could be extended to the formation of different molecular skeletons which were not accessible with the previously-developed method.