Upper Rim-Bridged Calix[4]arenes via Cyclization of meta Alkynyl Intermediates with Diphenyl Diselenide

0585017 - ÚFCH JH 2025 RIV CH eng J - Journal Article
Surina, A. - Salvadori, Karolína - Poupě, M. - Čejka, J. - Šimková, Ludmila - Lhoták, P.
Upper Rim-Bridged Calix[4]arenes via Cyclization of meta Alkynyl Intermediates with Diphenyl Diselenide.
Molecules. Roč. 29, č. 6 (2024), č. článku 1237. E-ISSN 1420-3049
Institutional support: RVO:61388955
Keywords : electrophilic cyclization * sonogashira * calixarenes * calixarene * Sonogashira coupling * meta-substitution * alkyne cyclization * diphenyl diselenide * 6-exo-dig and 5-endo-dig cyclization * regioselectivity * electrochemistry * X-ray analysis
OECD category: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)
Impact factor: 4.6, year: 2022
Method of publishing: Open access
https://www.mdpi.com/1420-3049/29/6/1237

A Sonogashira coupling of meta-iodocalix[4]arene with various terminal acetylenes confirmed that the meta position of calixarene is well addressable, and that both thermal and microwave protocols led to good yields of alkynylcalixarenes. Alkynes thus obtained were subjected to the ferric chloride and diphenyl diselenide-promoted electrophilic closure. It turns out that the calix[4]arenes give completely different bridging products than those described for the non-macrocyclic starting compounds. This can be demonstrated not only by the isolation of products with a six-membered ring (6-exo-dig), but mainly by the smooth formation of the 5-endo-dig cyclization, which has never been observed in the aliphatic series. An attempt at electrocyclization led to a high yield of the 1,2-diketone (oxidation of the starting alkyne), again in contrast to the reaction described for the acyclic derivatives. The structures of the unexpected products were unequivocally established by X-ray analysis and clearly demonstrate how the preorganized macrocyclic skeleton favors a completely different regioselectivity of cyclization reactions compared to common aliphatic compounds.
Permanent Link: https://hdl.handle.net/11104/0352786