Enantioselective Organocatalytic 1,6-Addition of Azlactones to <i>para</i>-Quinone Methides: An Access to α,α-Disubstituted and β,β-Diaryl-α-amino acid Esters
作者:Wenjun Li、Xianhong Xu、Yang Liu、Hua Gao、Yuyu Cheng、Pengfei Li
DOI:10.1021/acs.orglett.8b00072
日期:2018.2.16
This work describes the first enantioselective 1,6-additions of azlactones to para-quinone methides. In the presence of a chiral phosphoric acid, 1,6-adducts were obtained in high yields (up to 96%) with excellent diastereoselectivities and enantioselectivities (all >20:1 diastereoselectivity ratio (dr), up to 99% enantiomeric excess (ee)). Importantly, the method offers a facile synthetic approach
A Chiral Bis(betaine) Catalyst for the Mannich Reaction of Azlactones and Aliphatic Imines
作者:Wen-Quan Zhang、Ling-Feng Cheng、Jie Yu、Liu-Zhu Gong
DOI:10.1002/anie.201107741
日期:2012.4.23
By design: New chiralbis(betaine)s, for example 1, containing two catalytically active centers have been designed. They have proven to be promising organocatalysts for the direct Mannich‐type reaction of azlactones with a broad spectrum of aliphaticimines, thus affording α‐tetrasubstituted α,β‐diamino acid surrogates with excellent enantioselectivities.
Asymmetric synthesis of dihydrocoumarins via the organocatalytic hetero-Diels–Alder reaction of ortho-quinone methides
作者:Lili Zhang、Yang Liu、Kun Liu、Zhantao Liu、Ningning He、Wenjun Li
DOI:10.1039/c7ob02325a
日期:——
Enantioselective organocatalytic inverse-electron-demand hetero-Diels–Alderreactions of in situ generated ortho-quinone methides with azlactones have been developed. This strategy could generate various chiral dihydrocoumarins bearing a quaternary amino acid moiety in high yields (up to 94%) and stereoselectivities (up to 99 : 1 e.r., >20 : 1 dr) in the presence of a chiral phosphoric acid catalyst
Remote Stereocontrolled Construction of Vicinal Axially Chiral Tetrasubstituted Allenes and Heteroatom-Functionalized Quaternary Carbon Stereocenters
作者:Pei Zhang、Qiuhong Huang、Yuyu Cheng、Rongshi Li、Pengfei Li、Wenjun Li
DOI:10.1021/acs.orglett.8b03801
日期:2019.1.18
alcohols have been achieved in the presence of chiral phosphoric acids. The remote stereocontrolled activation protocol provides an efficient and facile approach for the construction of vicinal axially chiral tetrasubstituted allenes and heteroatom-functionalized quaternary carbon stereocenters, which expands the synthetic potential of chiral phosphoric acids.