51631-64-2Relevant articles and documents
Forming All-Carbon Quaternary Stereocenters by Organocatalytic Aminomethylation: Concise Access to β2,2-Amino Acids
Shao, Ying,Sun, Jiangtao,Tang, Shengbiao,Wang, Kai,Yu, Jianliang
supporting information, p. 23516 - 23520 (2020/10/21)
The asymmetric synthesis of β2,2-amino acids remains a formidable challenge in organic synthesis. Here a novel organocatalytic enantioselective aminomethylation of ketenes with stable and readily available N,O-acetals is reported, providing β2,2-amino esters bearing an all-carbon quaternary stereogenic center in high enantiomeric ratios with a catalytic amount of chiral phosphoric acid. Typically, this transformation probably proceeds through an asymmetric counter-anion-directed catalysis. As a result, a concise, practical, and atom-economic protocol toward rapidly access to β2,2-amino acids has been developed.
N-heterocyclic carbene-mediated enantioselective addition of phenols to unsymmetrical alkylarylketenes
Concellon, Carmen,Duguet, Nicolas,Smith, Andrew D.
supporting information; experimental part, p. 3001 - 3009 (2010/03/26)
Chiral N-heterocyclic carbenes (NHCs) mediate the enantioselective addition of 2-phenylphenol to unsymmetrical alkylarylketenes, delivering α-alkyl-α-arylacetic acid derivatives with good levels of enantiocontrol (up to 84% ee). Enantiodivergent stereochemical outcomes are observed using 2-phe-nylphenol and benzhydrol in the NHC-promoted esterification reaction using a triazolium precatalyst derived from pyroglutamic acid, consistent with distinct mechanistic pathways operating within these processes.
