A pseudo-C3-trisoxazoline was designed and synthesized. The improvement of the traditional bisoxazoline into a novel trisoxazoline by a sidearm approach resulted in highly catalytic enantioselective Michael addition of indoles to alkylidene malonates. Excellent catalytic reactivity and enantioselectivity (up to 99% yield and 93% ee) were achieved.
Dedicated to the 150th anniversary of Japan-UK diplomatic relations
FOCUS REVIEWSAbstract: Multicatalyst promoted asymmetric tandem reactions have emerged as a powerful strategy to improve the synthetic efficiency. It enables the synthesis of complex molecules with high selectivity from simple starting materials in an almost biomimetic-like way. The use of multiple catalyst systems can enlarge the substrate and reaction scope for the reaction design, improve the reactivity, and benefit the control of selectivity. In this FocusReview, the current achievement of this promising field is discussed, including the advantages and difficulties of this research, and the strategies applied to address these problems.
A spiroketal bisphosphine (SKP) derived chiral digold complex is identified as a powerful catalyst for the highly diastereo- and enantioselective synthesis of spirocyclopropyloxindoles from diazooxindoles and a broad range of alkenes, including both cis and trans 1,2-disubstituted alkenes.
A remarkable fluorine effect on "on water" reactions is reported. The CF⋅⋅⋅HO interactions between suitably fluorinated nucleophiles and the hydrogen-bond network at the phase boundary of oil droplets enable the formation of a unique microstructure to facilitate on water catalyst-free reactions, which are difficult to realize using nonfluorinated substrates. Accordingly, a highly efficient on water, catalyst-free reaction of difluoroenoxysilanes with aldehydes, activated ketones, and isatylidene malononitriles was developed, thus leading to the highly efficient synthesis of a variety of α,α-difluoro-β-hydroxy ketones and quaternary oxindoles.
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