A photoredox decarboxylative coupling of N-hydroxyphthalimide esters with aldimines is reported for synthesizing α-amino esters. A broad scope of alkyl radicals generated under visible light irradiation adds to glyoxylate aldimines in reliably good to excellent yields. Adding inorganic bases such as potassium carbonate significantly enhanced the yields by suppressing the umpolung side reaction. The
The first Fe(OTf)2-catalyzed radical addition to aldimines with Hantzsch ester as a two-hydrogen atom donor is reported. The tin-free reaction works well for electron-deficient substrates and provides a potentially useful approach to α-branched amines and α-amino acids.
Alkyl Radical Addition to Aliphatic and Aromatic <i>N</i>-Acylhydrazones Using an Organic Photoredox Catalyst
作者:Stephen T. J. Cullen、Gregory K. Friestad
DOI:10.1021/acs.orglett.9b03053
日期:2019.10.18
biscatecholatosilicates with organocatalyst 4CzIPN, add successfully to both aromatic and aliphatic N-acylhydrazones in the presence of MgCl2. With N-benzoylhydrazones, a simplereductivecleavage of the N–N bond of the hydrazine adduct furnishes the free amine. Synthetic utility is exemplified in a synthetic application toward repaglinide, a clinically important hypoglycemic agent.