Catalytic Enantioselective Synthesis of 3,4,5-Trisubstituted Isoxazoline <i>N</i>
-Oxides and Regioselective Synthesis of 3,4,5-Trisubstituted Isoxazoles
作者:Subas Chandra Sahoo、Subhas Chandra Pan
DOI:10.1002/ejoc.201801693
日期:2019.2.14
A convenient catalytic asymmetric synthesis of 3,4,5‐trisubstituted isoxazoline N‐oxides and regioselective synthesis of 3,4,5‐trisubstitutedisoxazoles has been developed.
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
Catalytic Asymmetric Formal [4 + 1] Annulation Leading to Optically Active <i>cis</i>-Isoxazoline <i>N</i>-Oxides
作者:Zugui Shi、Bin Tan、Wendy Wen Yi Leong、Xiaofei Zeng、Min Lu、Guofu Zhong
DOI:10.1021/ol102181r
日期:2010.12.3
The catalytic asymmetric synthesis of densely functionalized cis-isoxazoline N-oxides was realized with novel use of an organocatalyst, (S)-2-(azidodiphenylmethyl)pyrrolidine (4e) (Tan, B.; Zhu, D.; Zhang, L.; Chua, P. J.; Zeng, X.; Zhong, G. Chem.-Eur. J. 2010, 16, 3842; Olivares-Romero, J. L.; Juaristi, E. Tetrahedron 2008, 64, 9992), via an elegant formal [4 + 1] annulation strategy using readily available 2-nitroacrylates and alpha-iodoaldehydes.
Selective Amination Reactions of α-Nitro Aryl and Heteroaryl Enoates
Highly functionalized tetrasubstituted alkenes were obtained by an unexpected amination reaction promoted by ethyl nosyloxycarbamate on various alpha-nitro aryl and heteroaryl enoates. A nitrene is likely the aminating species responsible for the observed insertion reaction leading to (E)-beta-amino alpha-nitro enoates as the major products, regardless of the substrate configuration. The compounds, bearing two nitrogenous functional groups in different oxidation states, can be regarded as interesting synthons. In contrast, aziridination was observed for alpha-nitro alkyl enoates or beta-nitro allylic alcohols.