Organic Photoredox Cycloadditions under Confinement
Open Access
- Author:
- Valentina Craescu, Cristina
- Area of Honors:
- Chemistry
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Elizabeth A Elacqua, Thesis Supervisor
Lauren Dell Zarzar, Thesis Honors Advisor
Benjamin James Lear, Faculty Reader - Keywords:
- Organic photoredox catalysis
SIngle-Chain Nanoparticle
Cycloadditions under confinement
[2+2] cycloaddition
[4+2] cycloaddition - Abstract:
- Inspired from the complexity and versatility of nature’s catalysts: enzymes, artificial biocatalysts have been of large interest for their applicability to non-natural syntheses. However, the limitations of these systems, such as substrate specificity, selectivity, and solubility, call for novel approaches. The hypothesis is that, by designing modular polymer frameworks that are highly adaptable and functionalized, the supramolecular confinement can facilitate substrate-active site interactions, and substrate activation with enzyme-like features. [2+2] and [4+2] cycloadditions rank among the most important transformations in organic synthesis, as they enable high-yielding, stereospecific access to cyclobutane and six-membered ring scaffolds. Due to the ubiquity of these cyclic motifs in bioactive natural products, therapeutic agents, and relevant intermediates for organic synthesis, achieving optimized yields and product selectivity is an important challenge. The research herein outlines progress in this direction, with the development of a photocatalytic single-chain nanoparticle (SCNP) with 2,4,6-tri(4-methoxyphenyl)pyrylium tetrafluoroborate (p-MeO-TPT) pendants as the active site, and styrylpyrene units as visible-light cross-linking agents. The SCNP demonstrated enhanced reactivity on the dimerization of trans-anethole when compared to the small molecule catalysis. Additionally, progress for the design and development of SCNPs as selective photocatalysts for the [4+2] cycloadditions of electronically-mismatched partners is reported for three different model systems. Notably, quantitative yields were obtained for the photoinduced, p-MeO-TPT mediated Diels-Alder between trans-anethole and 1,3-cyclohexadiene. Overall, these results strive to contribute to the understanding and development of organic photoredox catalysts as versatile, modular platforms for visible-light-promoted organic transformations.