A nickel-catalyzed β-selective hydrocarboxylation of ynamides to give protected dehydro-β-amino acids was developed. The key to exclusive β-selectivity was the use of diethylzinc as a reductant in the presence of a magnesium salt. The reaction was conducted with bis(acetylacetonato)nickel(II) instead of costly and sensitive bis(1,5-cyclooctadiene)nickel(0). In addition, the optimized ligand was inexpensive 1,5-cyclooctadiene. Investigation of the substrate scope revealed that both nitrogen and alkyne substituents have marked effects on the reaction efficiency. We obtained experimental clues that indicated the formation of a vinylzinc intermediate that forms a C-C bond with CO 2 .
|Number of pages||5|
|Publication status||Published - 1 Jan 2019|
- carbon dioxide
- nickel catalysis
- β-amino acids