Details

Autor(en) / Beteiligte

• Baroudi, Abdulkader
• Jaradat, Khaled
• Karton, Amir

Titel

6‐Endo‐dig versus 5‐exo‐dig: Exploring Radical Cyclization Preference with First‐, Second‐, and Third‐row Linkers using High‐level Quantum Chemical Methods

Ist Teil von

• Chemphyschem, 2023-09, Vol.24 (17), p.e202300426-n/a

Ort / Verlag

Germany: Wiley Subscription Services, Inc

Erscheinungsjahr

2023

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• As an expansion upon Baldwin rules, the cyclization reactions of hex‐5‐yn‐1‐yl radical systems with different first‐, second‐, and third‐row linkers are explored at the CCSD(T) level via means of the SMD(benzene)‐G4(MP2) thermochemical protocol. Unlike C, O, and N linkers, systems with B, Si, P, S, Ge, As, and Se linkers are shown to favor 6‐endo‐dig cyclization. This offers fundamental insights into the rational synthetic design of cyclic compounds. A thorough analysis of stereoelectronic effects, cyclization barriers, and intrinsic barriers illustrates that structural changes alter the cyclization preference by mainly impacting 5‐exo‐dig reaction barriers. Based on the high‐level computational modeling, we proceed to develop a new tool for cyclization preference prediction from the correlation between cyclization barriers and radical structural parameters (e. g., linker bond length and bond angle). A strong correlation is found between the radical attack trajectory angle and the reaction barrier heights, i. e., cyclization preference. Finally, the influence of stereoelectronic effects on the two radical cyclization pathways is further investigated in stereoisomers of hypervalent silicon system, which provides novel insight into cyclization control. Cyclization preference exploration using G4(MP2) protocol previses hex‐5‐yn‐1‐yl radical systems with second‐, and third‐row linkers to favor 6‐endo‐dig ring closure. A novel prediction tool emerges, as an expansion upon Baldwin rules, from the robust correlation between cyclization barriers and structural parameters. Furthermore, the inclusion of hypervalent silicon linker provides a more profound understanding of cyclization regioselectivity.