Design principles of the use of alkynes in radical cascades

• Published in: Nature reviews. Chemistry Vol. 7; no. 6; pp. 405 - 423
• Main Authors: Hu, Chaowei, Mena, Justice, Alabugin, Igor V.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.06.2023; Nature Publishing Group
• Subjects: 639/638/403/933; 639/638/403/934; Alkynes; Analytical Chemistry; Biochemistry; Carbon; Cascade chemical reactions; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Functional groups; Inorganic Chemistry; Organic Chemistry; Physical Chemistry; Review Article; Substrates
• ISSN: 2397-3358; 2397-3358
• DOI: 10.1038/s41570-023-00479-w

One of the simplest organic functional groups, the alkyne, offers a broad canvas for the design of cascade transformations in which up to three new bonds can be added to each of the two sterically unencumbered, energy-rich carbon atoms. However, kinetic protection provided by strong π-orbital overlap makes the design of new alkyne transformations a stereoelectronic puzzle, especially on multifunctional substrates. This Review describes the electronic properties contributing to the unique utility of alkynes in radical cascades. We describe how to control the selectivity of alkyne activation by various methods, from dynamic covalent chemistry with kinetic self-sorting to disappearing directing groups. Additionally, we demonstrate how the selection of reactive intermediates directly influences the propagation and termination of the cascade. Diverging from a common departure point, a carefully planned reaction route can allow access to a variety of products. This Review focuses on the fundamental reasons for the increasing role of alkynes in radical cascades and highlights the unique opportunities provided by the inherent structural, energetic and stereoelectronic features of a carbon–carbon triple bond for the controlled design of cascade reactions.