Thiyl Radicals: Versatile Reactive Intermediates for Cyclization of Unsaturated Substrates

• Published in: Molecules (Basel, Switzerland) Vol. 25; no. 13; p. 3094
• Main Authors: Lynch, Dylan M, Scanlan, Eoin M
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 07.07.2020; MDPI
• Subjects: Alkynes; carbocyclization; Carbon; Cascade chemical reactions; cyclisation; Cyclization; Free Radicals - chemistry; Intermediates; Molecular structure; Natural products; radical; Radicals; Review; Sulfhydryl Compounds - chemical synthesis; Sulfhydryl Compounds - chemistry; Sulfur; thiyl radicals; sulfur; cyclisation; carbocyclization; radical; thiyl radicals
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules25133094

Sulfur centered radicals are widely employed in chemical synthesis, in particular for alkene and alkyne hydrothiolation towards thioether bioconjugates. The steadfast radical chain process that enables efficient hydrothiolation has been explored in the context of cascade reactions to furnish complex molecular architectures. The use of thiyl radicals offers a much cheaper and less toxic alternative to the archetypal organotin-based radical methods. This review outlines the development of thiyl radicals as reactive intermediates for initiating carbocyclization cascades. Key developments in cascade cyclization methodology are presented and applications for natural product synthesis are discussed. The review provides a chronological account of the field, beginning in the early seventies up to very recent examples; a span of almost 50 years.