title: Triflate-functionalized calix[6]arenes as versatile building-blocks: application to the synthesis of an inherently chiral Zn(ii) complex.
abstract: Cavity-based metal complexes can find many applications notably in the fields of catalysis and biomimicry. In this context, it was shown that metal complexes of calix[6]arenes bearing three aza-coordinating arms at the small rim provide excellent structural models of the poly-imidazole sites found in the active site of many metallo-enzymes. All these N-donor ligands were synthesized from the 1,3,5-tris-methoxy-p-tBu-calix[6]arene platform, which presents some limitations in terms of functionalization. Therefore, there is a need for the development of new calix[6]arene-based building-blocks selectively protected at the small rim. Herein we describe the regioselective one step synthesis of two calix[6]arenes decorated with triflate groups, i.e. X6H4Tf2 and X6H3Tf3, from the parent calix[6]arene X6H6. It is shown that the triflate groups can either act as protecting or deactivating groups, allowing the elaboration of sophisticated calixarene-based systems selectively functionalized at the large and/or at the small rim. In addition, X6H3Tf3 is functionalized on the A, B, and D rings and thus gives access to inherently chiral compounds, as demonstrated by the synthesis of a rare example of inherently chiral cavity-based metal complex.
authors.affiliation: Laboratoire de Chimie Organique, Université libre de Bruxelles (ULB), Avenue F. D. Roosevelt 50, CP160/06, B-1050 Brussels, Belgium. ijabin@ulb.ac.be.
authors.forename: Sara
authors.initials: S
authors.lastname: Zahim
authors.affiliation: Laboratoire de Chimie Organique, Université libre de Bruxelles (ULB), Avenue F. D. Roosevelt 50, CP160/06, B-1050 Brussels, Belgium. ijabin@ulb.ac.be and Laboratoire de Résonance Magnétique Nucléaire Haute Résolution, Université libre de Bruxelles (ULB), Avenue F.D. Roosevelt 50, CP160/08, B-1050 Brussels, Belgium.
authors.forename: Roy
authors.initials: R
authors.lastname: Lavendomme
authors.affiliation: Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques (CNRS UMR 8601), Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints Pères, 75006 Paris, France.
authors.forename: Olivia
authors.initials: O
authors.lastname: Reinaud
authors.affiliation: Laboratoire de Résonance Magnétique Nucléaire Haute Résolution, Université libre de Bruxelles (ULB), Avenue F.D. Roosevelt 50, CP160/08, B-1050 Brussels, Belgium.
authors.forename: Michel
authors.initials: M
authors.lastname: Luhmer
authors.affiliation: Laboratoire de Chimie Organique, Université libre de Bruxelles (ULB), Avenue F. D. Roosevelt 50, CP160/06, B-1050 Brussels, Belgium. ijabin@ulb.ac.be.
authors.forename: Gwilherm
authors.initials: G
authors.lastname: Evano
authors.affiliation: Laboratoire de Chimie Organique, Université libre de Bruxelles (ULB), Avenue F. D. Roosevelt 50, CP160/06, B-1050 Brussels, Belgium. ijabin@ulb.ac.be.
authors.forename: Ivan
authors.initials: I
authors.lastname: Jabin