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Catalytic enantioselective [4+3] cycloaddition reaction between o-quinone methides and oxiranes was achieved by using a chiral N,N′-dioxide/TbIII complex as the catalyst, affording medium-sized hydrodioxepine derivatives in high yields (up to 99%) with good to excellent diastereo-(up to 94 : 6 dr) and enantioselectivities (up to 97% ee). The topographic steric maps and distribution of the buried volume (% VBur) of the catalysts via Cavallo's SambVca 2 tool were collected to effectively represent the chiral pocket of metal complexes of chiral N,N′-dioxides. [ABSTRACT FROM AUTHOR]

The desymmetrization of p-quinols through a chiral bisguanidinium hemisalt catalyzed enantioselective Michael addition/lactonization cascade reaction with azlactones was reported. 3-Amino-benzofuran-2,5-diones containing a chiral amino acid residue were achieved with up to 99% ee and ＞19 : 1 dr. An exploration of the structure of the catalyst bisguanidinium was undertaken, revealing a bifunctional catalytic model. [ABSTRACT FROM AUTHOR]

Enantioselective cyclopropanation and C–H insertion reactions of α-substituted vinyl ketones with α-diazoesters have been accomplished using a N,N′-dioxide-scandium(iii) complex catalyst. Various tetrasubstituted cyclopropanes and E-enone derivatives bearing a chiral ester substituent were obtained simultaneously with good yields and excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

Isatin-derived ketimines undergo enantioselective alkynylation reactions in the presence of copper iodide and easily accessible guanidine-amides. The corresponding 3-alkynyl-3-aminooxyindoles are obtained in up to 95% yield and 96% ee. The guanidine plays a role in the formation of copper acetylide and the enantiodetermining step and the basic additive is excluded. [ABSTRACT FROM AUTHOR]

Highly efficient asymmetric Diels–Alder reactions of methyleneindolinones with 1,3-dienylcarbamates and 1,2-dihydropyridines have been accomplished by using a chiral N,N′-dioxide/nickel(ii) complex as an efficient catalyst. New kinds of spirooxindole-cyclohexaneamides were achieved in up to 99% yield, ＞95 : 5 dr, and 99% ee. [ABSTRACT FROM AUTHOR]

The availability of enantiomerically enriched 1,3-dienyl substituted quaternary stereocenters is highly valuable for the synthesis of complex natural compounds. Despite great advances in the area of construction of alkenyl-substituted types, a general, practical catalytic system that works for enantioselective formation of 1,3-diene derivatives still remains to be developed. Herein, we disclose the first asymmetric Claisen rearrangement of allenyl vinyl ethers to access optically active β-ketoesters, containing branched 1,3-butadienyl substituted stereocenters. A variety of substrates bearing a range of useful functional groups were well tolerated, thus affording the corresponding products with excellent enantioselectivities (up to 99% ee) and high yields (up to 91%). [ABSTRACT FROM AUTHOR]

A highly efficient catalytic asymmetric [4+2] cycloaddition of silyloxyvinylindoles with β,γ-unsaturated α-ketoesters has been accomplished by an available chiral N,N′-dioxide/yttrium triflate complex. A widespread range of carbazole derivatives were obtained in 47–98% yield with 86–99% ee under mild reaction conditions. [ABSTRACT FROM AUTHOR]

An asymmetric inverse-electron-demand hetero-Diels–Alder reaction between o-quinone methides and azlactones to generate potentially pharmacological active dihydrocoumarins has been achieved efficiently by using a chiral N,N′-dioxide–Sc(iii) complex as the catalyst. The desired products were obtained in high yields with excellent enantioselectivities and diastereoselectivities (up to 94% yield, 96% ee and ＞19 : 1 dr) under mild reaction conditions. A concerted reaction pathway was confirmed by Operando IR and control experiments. [ABSTRACT FROM AUTHOR]

An efficient lanthanide(iii)-catalyzed diastereo- and enantioselective Michael addition of 3-substituted benzofuran-2(3H)-ones to 4-oxo-enoates was developed. The desired adducts with contiguous quaternary–tertiary stereocenters were obtained in up to 99% yield with up to >95/5 dr and 98% ee. [ABSTRACT FROM AUTHOR]

An efficient catalytic asymmetric intermolecular C2 Friedel–Crafts alkylation reaction between N-methyl skatole and β,γ-unsaturated α-ketoesters has been realized by a chiral N,N′-dioxide-Ni(ii) complex. The corresponding indole derivatives were obtained in good yield (up to 96%) with excellent enantioselectivities (up to 99% ee) under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Enantioselective cyclization of α-isocyano esters with azodicarboxylates catalyzed by FeII–N,N′-dioxide complexes has been developed. Under mild conditions, a variety of 1,2,4-triazoline derivatives was obtained in high yields and enantioselectivities. [ABSTRACT FROM AUTHOR]

The catalytic asymmetric aza-Michael reaction of benzoyl hydrazine toward chalcones through the nonactivated amine moiety conjugated addition was facilitated by the developed N,N′-dioxide-Sc(OTf)3complex under mild conditions, affording the pharmacologically and synthetically useful products in moderate to high yields with up to 97% ee. [ABSTRACT FROM AUTHOR]

Enantioselective Michael addition of malononitrile to chalcones was catalyzed by a simple quinine and Al(OiPr)3complex and products were obtained in good ee as well as high yields, which facilitated the asymmetric synthesis of a biologically active 4H-pyran compound. [ABSTRACT FROM AUTHOR]