Nickel-Catalyzed β-Carboxylation of Ynamides with Carbon Dioxide

Abstract 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(I...

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Bibliographic Details
Published in:Synlett 2019-06, Vol.30 (9), p.1048-1052
Main Authors: Doi, Ryohei, Okano, Taichi, Abdullah, Iman, Sato, Yoshihiro
Format: Article
Language:English
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Summary:Abstract 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 .
ISSN:0936-5214
1437-2096
DOI:10.1055/s-0037-1611529