Organocatalytic\nAsymmetric Tandem Reaction of Indene-Based\nDienes for the Synthesis of Enantioenriched Spirodihydrofluorenes\nand Fluorenylamine-ketoximes Containing Axial Elements

An\nefficient asymmetric tandem reaction of indene-based dienes\nwith isoxazole-5-ones catalyzed by chiral cinchona alkaloid-derived\nthioureas has been established, constructing a diverse array of novel\nenantioenriched spirodihydrofluorene compounds bearing isoxazolone\nmoieties. More importantly, the spirodihydrofluorene frameworks can\nbe effortlessly transformed into an atropisomeric fluorene skeleton\nbearing oxime groups. This work not only addresses the challenges\nin the construction of enantioenriched spirodihydrofluorene frameworks\nbut also provides a powerful strategy for structurally novel fluorenylamine-ketoximes\ncontaining axial elements.