Reactions of imidazol(in)-2-ylidenes with electron deficient fluoroolefins

GRAPHICAL ABSTRACT

ABSTRACT

1,3-Bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene forms stable 1:1 adducts with tetrafluoroethylene (2), hexafluorocyclobutene (3), and octafluorocyclopentene (4). Adduct 2 shows properties typical for nonpolarized olefins, as indicated by NMR spectroscopy and X-ray crystallography. By contrast, adducts 3 and 4 are best described as ylides with a significant charge separation between the imidazoline ring and the perfluorocycloalkyl unit. Similarly, 1,3-di-1-adamantylimidazol-2-ylidene reacts with tetrakis(trifluoromethyl)allene to form a polarized trimethylenemethane derivative, and bis(trifluoromethyl)ketene to form an imidazolium enolate zwitterion. The synthesis and characterization of a number of fluorinated methyleneimidazolines are described herein.

KEYWORDS:

• Carbenes
• ylides
• ylenes
• fluoroolefin
• zwitterion
• pentafluorosiliconate

Funding

AJA gratefully acknowledges the Saxon Endowment of the University of Alabama. AJA and JWR were supported in part by a University of Alabama Research Award: RG14648 “Technology for a Sustainable Chemical Economy” - StanCE. JRG and HVRD gratefully acknowledge DuPont for support through research fellowships. AJ acknowledges support through a Feodor-Lynen Fellowship from the Alexander von Humboldt Foundation.