Jeroen Rintjema, PhD student under the supervision of Prof. Arjan W. Kleij (ICIQ), has defended his PhD Thesis entitled “Aluminum-Catalyzed Coupling of Carbon Dioxide and Cyclic Ethers” (assigned to the Organic and Analytical Chemistry Department of the Universitat Rovira i Virgili) publicly on October 31st at the ICIQ Auditorium.

The members of the evaluation committee were: Prof. Anna Maria Masdeu (Universitat Rovira i Virgili), Dr. Christopher Whiteoak (Sheffield Hallam University) and Prof. Carmine Cappachione (Università degli Studi di Salerno)

Abstract

Utilization of carbon dioxide as a C1-building block for organic chemistry has become increasingly popular over the last decades. Within this area we are interested in the formation of cyclic carbonates and carbamates that have found application in many fields of chemistry. In the first part we introduce the aluminum aminotriphenolate catalyst as a highly potent system to activate epoxides and compare its performance with the current state of the art in cyclic carbonate formation. Afterwards we applied this system to provide the first general methodology for the coupling of oxetanes and CO₂, leading to the formation of various six-membered cyclic carbonates in high yield and selectivity.

The second part of the thesis describes the halide-free conversion of epoxides containing alcohol or amine functionalities, that mediate in-situ formation of linear carbonate or carbamate nucleophiles that can ring-open the epoxide. This strategy gave access to a broad scope of heterocyclic products. In addition, by selectively triggering either the conventional and the newly developed reaction mechanism we were able to induce product divergence from a single substrate using the same catalyst. A detailed mechanistic study on this new epoxide activation pathway was performed by combining classical mechanistic experiments, X-ray analysis, in-situ IR spectroscopy and DFT-analysis, resulting in a comprehensive description of the reaction mechanism.