Enantioselective Decarboxylative Alkylation of β-Keto Acids to <i>ortho</i>-Quinone Methides as Reactive Intermediates: Asymmetric Synthesis of 2,4-Diaryl-1-benzopyrans
作者:Hyun Jung Jeong、Dae Young Kim
DOI:10.1021/acs.orglett.8b00993
日期:2018.5.18
efficient asymmetric synthesis of 2,4-diaryl-1-benzopyrans via enantioselective decarboxylative alkylation of β-keto acids to o-QM intermediates, followed by sequential cyclization and dehydration, has been developed. The synthetically useful chiral 2,4-diaryl-1-benzopyran derivatives were obtained in moderate to high yields and high enantioselectivities through a one-pot, two-step sequence. This approach
A new light‐driven asymmetricion‐pair catalysis procedure for the metal‐free enantioselectivehydrogenation of in situ generated pyryliumions from readily available chalcones was developed (see scheme). The photo‐assisted Brønsted acid catalyzed procedure has broad scope and allows, for the first time, access to valuable 4H‐chromenes in good yields and with excellent enantioselectivities.