A cheap metal for a challenging task: nickel-catalyzed highly diastereo- and enantioselective hydrogenation of tetrasubstituted fluorinated enamides.
Chem Sci
; 10(1): 252-256, 2019 Jan 07.
Article
en En
| MEDLINE
| ID: mdl-30746080
ABSTRACT
Nickel-catalyzed asymmetric hydrogenation of challenging tetrasubstituted fluorinated enamides has been achieved, affording chiral α-fluoro-ß-amino esters in high yields with excellent diastereo- and enantioselectivities (up to 98% yield, >99 1 dr, up to >99% ee). Deuterium-labeling experiments and control experiments were conducted to probe the mechanism, and the results indicated that the acidity of the solvent plays a critical role in the control of diastereoselectivity by trapping the adduct of nickel hydride to C[double bond, length as m-dash]C bonds via protonolysis, giving the hydrogenation product with stereospecific syn-selectivity. This protocol provides efficient access to chiral α-fluoro-ß-amino esters which have important potential applications in organic synthesis and medicinal chemistry.
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Chem Sci
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2019
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Article