Synthesis of 2-arylpyridines by the Suzuki-Miyaura cross coupling of PyFluor with hetero(aryl) boronic acids/esters and Synthesis of ring oxidized phthalocyanine metal fluorides
Date
2024-10-02
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Abstract
Recently, there has been considerable interest in Sulfonyl fluorides owing to their distinctive chemical and biological characteristics. The exceptional strength of the S-F bond and the S(VI) center is responsible for the inertness and stability of sulfonyl fluorides against reactions such as hydrolysis, and reduction. However, the C-S bond of sulfonyl fluorides has been considered unreactive until recently. In particular, the activation of the C-S bond under Suzuki-Miyaura coupling conditions has not been extensively investigated. In chapter 2, we present the Suzuki-Miyaura cross-coupling reaction of pyridine-2-sulfonyl fluoride (PyFluor) with hetero (aryl) boronic acids and pinacol boronic esters. With Pd(dppf)Cl2 as the catalyst, the reaction can be carried out within a temperature range of 65 °C to 100 °C to produce 2-aryl pyridines as the product with yields spanning from moderate to good. This approach enables the synthesis of heteroatom-rich biaryls, which are important in the field of drug discovery. Phthalocyanine (Pc) ligands are chemically and thermally stable symmetric 18 π electron aromatic macrocycles, closely related to the naturally occurring porphyrins. They have been widely used as pigments/dyes, photoconducting materials, industrial catalysts, and photosensitizers in biomedical applications. The characteristics of the Pc ring, such as its solubility and electronic properties, are strongly influenced by incorporating metals inside the Pc macrocycle and by adding substituents in the alpha or beta positions of the ring. The most stable oxidation state of Pc is Pc-2, but it is redox active and can access oxidation states from Pc0 to Pc-6. The oxidation of the Pc ring can be confirmed by UV-Visible spectroscopy, Nuclear Magnetic Resonance (NMR) Spectroscopy, and single-crystal X-ray diffraction. Ring oxidized and reduced metallophthalocyanine (PcM) compounds have not been extensively investigated (and especially, not generally isolated) possibly due to the high reactivity of these complexes. In chapter 3, we detail a preliminary study on the synthesis of substituted and unsubstituted ring-oxidized phthalocyanine metal fluorides, using a range of strong oxidizing agents which also incorporate fluorides.
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Keywords
Suzuki Miyaura Cross Coupling, PyFluor, C-S activation, Sulfonyl Fluorides
Citation
Ramanayake, D. J. (2024). Synthesis of 2-arylpyridines by the Suzuki-Miyaura cross coupling of PyFluor with hetero(aryl) boronic acids/esters and synthesis of ring oxidized phthalocyanine metal fluorides (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.