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- PublicationFunctional Group Interconversion Reactions in Continuous Flow Reactors(Bentham Science, 2021-07-06)An overview of the current uptake of continuous flow techniques for various functional group interconversion reactions is presented. Besides highlighting a variety of prominent examples and their main features, this review provides insights into specific reaction classes, such as oxidations, reductions, rearrangements as well as different C-H functionalization processes. While this review can only include key examples from the last decade, the reader will find a solid foundation of important transformations along with further references to inform and appreciate the opportunities arising from modern synthesis technologies such as flow synthesis.
Scopus© Citations 4 162 - PublicationOvercoming the Hurdles and Challenges Associated with Developing Continuous Industrial Processes(Wiley, 2020-12-31)Continuous flow chemistry is often viewed as a very simple concept on paper, however scientists with significant flow chemistry experience will highlight a number of challenges that need to be overcome. Critical for the successful development of any flow process is a high level of understanding of potential pitfalls that may be encountered. A collaborative and multi-disciplinary team of chemists and chemical engineers is essential in the development of a process from lab scale through to production. This Minireview will identify and highlight relevant risks and their subsequent mitigation strategies to ensure successful flow processing.
Scopus© Citations 32 35 - PublicationContinuous Flow Synthesis of Cyclobutenes Using LED Technology(Georg Thieme Verlag, 2023-05-04)Cyclobutenes are highly strained ring systems of considerable synthetic interest that can be accessed via cycloaddition reactions between alkenes and alkynes. However, their traditional preparation relies on photochemical [2+2]-cycloadditions that exploit low wavelength UV radiation emitted from inefficient medium-pressure Hg-lamps. This paper reports on the development of a modern approach using a high-power LED set-up emitting at the boundary of UV-A and visible light in conjunction with a continuous flow reactor. The resulting flow process renders a series of cyclobutenes from maleimides and various commercial alkynes. This provides a more energy-efficient approach that is readily scalable to access multigram quantities of cyclobutenes in high chemical yields and short residence times. The value of these products is exemplified by flow-based hydrogenations yielding highly substituted cyclobutanes which represent sought after building blocks in modern medicinal chemistry programs.
92 - PublicationDevelopment of a Continuous Photochemical Benzyne-Forming Process(Georg Thieme, 2021-02-01)A continuous-flow process is presented that enables the safe generation and derivatization of benzyne under photochemical conditions. This is facilitated by a new high-power LED lamp emitting light at 365 nm. The resulting flow process effectively controls the release of gaseous by-products based on an adjustable backpressure regulator and delivers a series of heterocyclic products in a short residence time of 3 minutes. The robustness of this methodology is demonstrated for the rapid generation of benzotriazoles, 2 H -indazoles and various furan-derived adducts, facilitating the preparation of these important heterocyclic scaffolds via a simple and readily scalable flow protocol.
51Scopus© Citations 11 - PublicationCoupling biocatalysis with high-energy flow reactions for the synthesis of carbamates and β-amino acid derivatives(Beilstein-Institut, 2021-02-04)A continuous flow process is presented that couples a Curtius rearrangement step with a biocatalytic impurity tagging strategy to produce a series of valuable Cbz-carbamate products. Immobilized CALB was exploited as a robust hydrolase to transform residual benzyl alcohol into easily separable benzyl butyrate. The resulting telescoped flow process was effectively applied across a series of acid substrates rendering the desired carbamate structures in high yield and purity. The derivatization of these products via complementary flow-based Michael addition reactions furthermore demonstrated the creation of β-amino acid species. This strategy thus highlights the applicability of this work towards the creation of important chemical building blocks for the pharmaceutical and speciality chemical industries.
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