{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"submitter":["Zhao Q"],"funding":["American Chemical Society","National Institutes of Health","NIH HHS","NIGMS NIH HHS","National Science Foundation"],"pagination":["e202318703"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC10922840"],"repository":["biostudies-literature"],"omics_type":["Unknown"],"volume":["63(8)"],"pubmed_abstract":["IMes (IMes=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene) and IPr (IPr=1,3- bis(2,6-diisopropylphenyl)imidazol-2-ylidene) represent by far the most frequently used N-heterocyclic carbene ligands in homogeneous catalysis, however, despite numerous advantages, these ligands are limited by the lack of steric flexibility of catalytic pockets. We report a new class of unique unsymmetrical N-heterocyclic carbene ligands that are characterized by freely-rotatable N-aromatic wingtips in the imidazol-2-ylidene architecture. The combination of rotatable N-CH<sub>2</sub> Ar bond with conformationally-fixed N-Ar linkage results in a highly modular ligand topology, entering the range of geometries inaccessible to IMes and IPr. These ligands are highly reactive in Cu(I)-catalyzed β-hydroboration, an archetypal borylcupration process that has had a transformative impact on the synthesis of boron-containing compounds. The most reactive Cu(I)-NHC in this class has been commercialized in collaboration with MilliporeSigma to enable broad access of the synthetic chemistry community. The ligands gradually cover %V<sub>bur</sub> geometries ranging from 37.3 % to 52.7 %, with the latter representing the largest %V<sub>bur</sub> described for an IPr analogue, while retaining full flexibility of N-wingtip. Considering the modular access to novel geometrical space in N-heterocyclic carbene catalysis, we anticipate that this concept will enable new opportunities in organic synthesis, drug discovery and stabilization of reactive metal centers."],"journal":["Angewandte Chemie (International ed. in English)"],"pubmed_title":["Wingtip-Flexible N-Heterocyclic Carbenes: Unsymmetrical Connection between IMes and IPr."],"pmcid":["PMC10922840"],"funding_grant_id":["DNI-55549","R35GM133326","R35 GM133326","CHE-1650766"],"pubmed_authors":["Szostak M","Szostak R","Zhao Q","Zhou T","Lalancette R","Rahman M","Yang S"],"additional_accession":[]},"is_claimable":false,"name":"Wingtip-Flexible N-Heterocyclic Carbenes: Unsymmetrical Connection between IMes and IPr.","description":"IMes (IMes=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene) and IPr (IPr=1,3- bis(2,6-diisopropylphenyl)imidazol-2-ylidene) represent by far the most frequently used N-heterocyclic carbene ligands in homogeneous catalysis, however, despite numerous advantages, these ligands are limited by the lack of steric flexibility of catalytic pockets. We report a new class of unique unsymmetrical N-heterocyclic carbene ligands that are characterized by freely-rotatable N-aromatic wingtips in the imidazol-2-ylidene architecture. The combination of rotatable N-CH<sub>2</sub> Ar bond with conformationally-fixed N-Ar linkage results in a highly modular ligand topology, entering the range of geometries inaccessible to IMes and IPr. These ligands are highly reactive in Cu(I)-catalyzed β-hydroboration, an archetypal borylcupration process that has had a transformative impact on the synthesis of boron-containing compounds. The most reactive Cu(I)-NHC in this class has been commercialized in collaboration with MilliporeSigma to enable broad access of the synthetic chemistry community. The ligands gradually cover %V<sub>bur</sub> geometries ranging from 37.3 % to 52.7 %, with the latter representing the largest %V<sub>bur</sub> described for an IPr analogue, while retaining full flexibility of N-wingtip. Considering the modular access to novel geometrical space in N-heterocyclic carbene catalysis, we anticipate that this concept will enable new opportunities in organic synthesis, drug discovery and stabilization of reactive metal centers.","dates":{"release":"2024-01-01T00:00:00Z","publication":"2024 Feb","modification":"2025-04-18T13:00:30.82Z","creation":"2025-04-04T02:01:08.552Z"},"accession":"S-EPMC10922840","cross_references":{"pubmed":["38135660"],"doi":["10.1002/anie.202318703"]}}