Multiple Absolute Stereocontrol in Pd-Catalyzed [3+2] Cycloaddition of Oxazolidinones and Trisubstituted Alkenes Using Chiral Ammonium–Phosphine Hybrid Ligands
The development of a Pd-catalyzed highly enantio- and diastereoselective [3+2] cycloaddition of 5-vinyloxazolidinones and activated trisubstituted alkenes is described in detail. This protocol for ...
Catalytic asymmetric (4 + 1) annulation of nitroalkenes with allylic acetates: stereoselective synthesis of isoxazoline <i>N</i>-oxides
作者:Jinghua Luo、Rongshun Chen、Xia Fan、Junyu Gong、Jie Han、Zhengjie He
DOI:10.1039/c9ob01058k
日期:——
acetates catalyzed by α-isocupreine is reported. It provides chiral isoxazolineN-oxides in moderate to good yields with 88-99% ee, and represents the first catalytic asymmetric (4 + 1) annulation of activated nitroalkenes with in situ generated ammonium ylides. It also affords a practical and efficient access to chiral isoxazolineN-oxides.
Enantioselective total synthesis of furofuran lignans <i>via</i> Pd-catalyzed asymmetric allylic cycloadditon of vinylethylene carbonates with 2-nitroacrylates
作者:Can Zhao、Ijaz Khan、Yong Jian Zhang
DOI:10.1039/d0cc05640e
日期:——
Pd-catalyzed asymmetric allylic cycloaddition of vinylethylene carbonates (VECs) with 2-nitroacrylates under mild conditions. By using this asymmetric catalytic reaction as a key step, several furofuran lignans with stereodivergency have been effectively synthesized through 5- or 6-step sequences from readily available starting materials.
A novel [4 + 1] dearomative spiroannulation of α-halo-β-naphthol and nitroolefin has been developed for the direct construction of various spiroisoxazolidines in high chemo- and diastereoselectivity. Notably, halophenols (X = Cl and I) were also tolerated by this reaction. This transformation was realized through a sequence of electrophilic dearomatization/dehalogenation, and mechanistic studies revealed