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Regio- and Diastereoselective Intermolecular [2+2] Cycloadditions Photocatalyzed by Quantum Dots

Light-driven [2+2] cycloaddition is the most direct strategy to build tetrasubstituted cyclobutanes, core components of many lead compounds for drug development. Significant advances in the chemoselectivity and enantioselectivity of [2+2] photocycloadditions have been made, but exceptional and tunab...

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Detalles Bibliográficos
Autores principales: Jiang, Yishu, Wang, Chen, Rogers, Cameron R., Kodaimati, Mohamad S., Weiss, Emily A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6820707/
https://www.ncbi.nlm.nih.gov/pubmed/31654049
http://dx.doi.org/10.1038/s41557-019-0344-4
Descripción
Sumario:Light-driven [2+2] cycloaddition is the most direct strategy to build tetrasubstituted cyclobutanes, core components of many lead compounds for drug development. Significant advances in the chemoselectivity and enantioselectivity of [2+2] photocycloadditions have been made, but exceptional and tunable diastereoselectivity and regioselectivity (head-to-head vs. head-to-tail adducts), required for synthesis of bioactive molecules, have not yet been achieved. Here we show that colloidal quantum dots (QDs) serve as visible-light chromophores, photocatalysts, and reusable scaffolds for homo- and hetero-intermolecular [2+2] photocycloadditions of 4-vinylbenzoic acid derivatives, including aryl-conjugated alkenes, with up to 98% switchable regioselectivity and 98% diastereoselectivity for the previously minor syn-cyclobutane products, including the syn-head-to-tail cyclobutane, which has never before been accessed as the major product of a hetero-photocycloaddition. Transient absorption spectroscopy confirms that our system is the first example of catalysis triggered by triplet-triplet energy transfer from a QD. The precisely controlled triplet energy levels of QD photocatalysts facilitate efficient and selective heterocoupling, a major challenge in direct cyclobutane synthesis.