Enantioselective Synthesis of Pyridines with All‐Carbon Quaternary Carbon Centers via Cobalt‐Catalyzed Desymmetric [2+2+2] Cycloaddition
作者:Ke Li、Linsheng Wei、Minghe Sun、Bing Li、Min Liu、Changkun Li
DOI:10.1002/anie.202105452
日期:2021.9.6
A Co-catalyzed enantioselective desymmetric [2+2+2] cycloaddition for synthesis of pyridines with all-carbon quaternary carbon centers has been developed. The regio- and enantioselectivities are controlled by the inherent nature of terminal alkynes and the substituents on the bisoxazolinephosphine ligands. Pyridines with 5-substitutents could be obtained with >20:1 regioselectivity and up to 94 % ee
Enantioselective Nickel-Catalyzed Reductive Aryl/Alkenyl–Cyano Cyclization Coupling to All-Carbon Quaternary Stereocenters
作者:Zi-Hao Chen、Rui-Ze Sun、Fei Yao、Xu-Dong Hu、Long-Xue Xiang、Hengjiang Cong、Wen-Bo Liu
DOI:10.1021/jacs.2c01237
日期:2022.3.23
An enantioselective nickel-catalyzed intramolecular reductive cross-coupling of C(sp2) electrophiles and cyano groups is reported. Enantioenriched CN-containing all-carbonquaternarystereocenters are assembled by desymmetrizing cyclization of aryl/alkenyl halide-tethered malononitriles. The use of an organic reductant, (EtO)2MeSiH, is crucial to the enantioselectivity and reactivity. Applications
Intramolecular Diels-Alder reactions of 1,2,4-triazines: Exploitation of the Thorpe-Ingold effect for the synthesis of 2,3-cyclopentenopyridines and 5,6,7,8-tetrahydroquinolines
作者:Edward C. Taylor、John E. Macor
DOI:10.1016/s0040-4039(00)84460-3
日期:1986.1
Intramolecularinverseelectron-demandDiels-Alderreactions of 1,2,4-triazines assisted by the Thorpe-Ingold effect have been utilized in novel syntheses of 2,3-cyclopentenopyridines and 5,6,7,8-tetrahydroquinolines.
gold catalysis highly enantioenriched bicyclic enones are available via an operationally simple one-pot procedure. Iminium-ion activation by cinchona alkaloid-derived primary amine catalysts induces the Michael addition of propargylated malononitriles and cyanoacetates to α,β-unsaturated ketones. The resulting intermediates undergo an exo-dig cyclization, forming a new C–C bond followed by double-bond
Synthese carbocyclisch anellierter Pyridazine durch intramolekulareDiels-Alder-Reaktion mit inversem Elektronenbedarf
作者:Xiao-Guang Yang、Gunther Seitz
DOI:10.1002/ardp.19923250906
日期:——
Die Titelreaktion mit einer Reihe von Tetrazinen 5, die mit verschiedenen ω‐Alkin‐Seitenkettendienophilen versehen sind, führt in guten Ausbeuten zu den bisher unbekannten, carbocyclisch anellierten Pyridazinen 7–10.