Regioselective Catalytic Asymmetric C-Alkylation of Isoxazolinones by a Base-Free Palladacycle-Catalyzed Direct 1,4-Addition
作者:Tina Hellmuth、Wolfgang Frey、René Peters
DOI:10.1002/anie.201410933
日期:2015.2.23
asymmetric alkylations of isoxazolinones forming all‐C‐substituted quaternary stereocenters. The present studies were driven by the question of how to control the regioselectivity in the competition of different nucleophilic positions. The investigation of a direct 1,4‐addition uncovered that a sterically demanding palladacycle catalyst directs the reactivity in the absence of a base nearly exclusively to
Studies on heterocyclic chemistry. Part XII. Tautomerism of α-(5-oxo-Δ<sup>3</sup>-isoxazolin-4-yl)benzylphosphonates
作者:Tarozaemon Nishiwaki、Koichi Kondo
DOI:10.1039/p19720000090
日期:——
α-(5-Oxo-Δ3-isoxazolin-4-yl)benzylphosphonates (2) mostly exist in the NH form in the solid state, and in the OH form in non-polar solvents, owing to chelation with the phosphonyl group. The tautomeric equilibrium in solution is influenced by the nature of the 3-substituent in the isoxazole ring; the 3-methyl compounds exist partially in the NH form. A modified synthesis of these compounds is described
Asymmetric α-Regioselective [3 + 2] Annulation of Morita–Baylis–Hillman Carbonates: Construction of Three Contiguous Stereocenters with Vicinal Quaternary Carbon Centers
作者:Xiaochen Tian、Yongxing Zhang、Hao Dong、Weiwu Ren、Yang Wang
DOI:10.1021/acs.joc.2c00582
日期:2022.8.5
spirocyclic oxindole derivatives containing three contiguous stereogenic centers and vicinal all-carbonquaternarychiralcenters. This reaction exhibits a broad substrate scope and excellent functional group tolerance. Excellent yields with high diastereo- and enantioselectivities were obtained in this efficient organocatalytic reaction.
Asymmetric Construction of Bis‐Spirocyclic Pyrazolones Bearing Vicinal Quaternary Carbon Centers
作者:Mengjie Yang、Aiqi Xue、Xingfu Wei、Yue Huang、Jingping Qu、Baomin Wang
DOI:10.1002/ejoc.202400305
日期:——
A catalytic asymmetric (3+2) cyclization of pyrazolone-based MBH adducts with alkylidenyl isoxazolones was presented by using DMAP-derived chiral catalyst, affording bis-spirocyclic pyrazolones bearing vicinal all-carbon quaternary stereocenters within an imbedded cyclopentene ring scaffold in good yields with excellent stereoselectivities under mild conditions.