PUB - Publikationen an der Universität Bielefeld

Herein, ring-opening of mesoionic carbenes (iMICs) (iMIC = [ArC{N(Dipp)}2C(SiMe3)C:) (Dipp = 2,6-iPr2C6H3, Ar = Ph, 4-Me2NC6H4 or 4-PhC6H4) based on an 1,3-imidazole scaffold to yield N-ethynylformimidamide (eFIM) derivatives as crystalline solids (eFIM = {(Dipp)N=C(Ar)N(Dipp)}C≡CSiMe3) is reported. eFIMs are thermally stable under inert gas atmosphere and show moderate air stability (t1/2 = 3h for Ar = Ph). eFIMs are excellent surrogates of iMICs, which generally have a limited shelf-life, and readily undergo ring-closing click reactions with a variety of main-group as well as transition metal Lewis acids to form hitherto challenging iMIC-compounds in good to excellent yields. In addition to the relevance of eFIMs in the synthesis of iMIC-compounds, quantification of the stereoelectronic properties of a representative iMIC (Ar = Ph) by experimental and theoretical methods suggests remarkably σ-donor property and steric profile of these new ligand sets.