Expanding the scope of the tail-to-tail dimerization of vinyl compounds catalyzed by N-heterocyclic carbene

Article abstract of DOI:10.1246/bcsj.20150048

The tail-to-tail dimerization of vinyl compounds catalyzed by an N-heterocyclic carbene was found to show a very broad substrate scope and tolerance to various functional groups. The optimization of the dimerizations of 2-vinylpyridine and n-butyl acrylate, as low and high electrophilicity model substrates, indicates that high reaction temperatures around 150 °C are required for both substrates. In addition to methacrylates and methacrylonitrile, the applicable substrates range from an activated styrene and vinyl pyridines to highly reactive acrylonitrile, dimethyl acrylamide, and various functionalized acrylates. The alcohol additives significantly increase the catalytic turnover number to 18 for the dimerization of acrylates. Deuterium labeling experiments indicate that the alcohols promote the intermolecular proton transfers.