Chiral N,N′-dioxide/Y(OTf)3 and Sc(OTf)3 complexes have been developed as efficient catalysts for the bisvinylogous Mukaiyama aldol reaction of silyl ketene acetal with α-ketoesters and aldehydes, respectively. The catalytic systems were highly ε-selective, and the substrate scope was wide. The corresponding ε-hydroxy-α,β,γ,δ-unsaturated esters were obtained in up to 95% yield and 98% ee.

An efficient N,N′-dioxide–scandium(III) complex catalytic system has been developed for the asymmetric dearomatization of β-naphthols through conjugate addition to alkynones. A variety of Z-predominated β-naphthalenone compounds were obtained in moderate to high yields with excellent enantioselectivities (up to 98% ee). Moreover, a possible transition state was proposed to explain the origin of the stereoselectivity.

The first catalytic asymmetric dynamic resolution of unprotected racemic 3-(4-alkylcyclohexylidene)indolin-2-ones via a one-step direct vinylogous Michael reaction with chalcones was realized using a chiral N,N′-dioxide/Sc(III) complex catalytic system. A variety of (Z)-4-alkyl-2-((3-oxo-1,3-diarylpropyl)cyclohexylidene)-indolin-2-ones with three stereogenic centers at ξ-, γ- and δ′-positions were obtained in up to 95% yield, 98% ee and 99/1 dr. A possible transition state was proposed to explain the origin of the stereoselectivity.

A chiral N,N′-dioxide/Co(BF4)2·6H2O complex catalytic system has been developed to efficiently catalyze the asymmetric 1,3-dipolar cycloaddition of nitrones with methyleneindolinones. The corresponding chiral multisubstituted spiroisoxazolidines with three contiguous quaternary–tertiary stereocenters were obtained in moderate to high yields with excellent dr and ee values (up to 97% yield, >19 : 1 dr and 98% ee).

An asymmetric Meerwein–Ponndorf–Verley (MPV) reduction of glyoxylates was for the first time accomplished via an N,N′-dioxide/Y(OTf)3 complex with aluminium alkoxide and molecular sieves (MSs) as crucial additives. A variety of optically active α-hydroxyesters were obtained with excellent results. A possible reaction mechanism was proposed based on the experiments.

The catalytic asymmetric bromoamination of chalcones with N-bromosuccinimide as both bromine and amide source was realized by using a chiral N,N′-dioxide-Sc(NTf2)3 complex as an efficient catalyst. The corresponding chiral bromoamination products were obtained in high yields with high dr and good ee values (up to 92% yield, 93 : 7 dr and 97% ee) under mild reaction conditions.

A N,N′-dioxide/Y(III) complex catalyzed highly enantioselective domino reaction between electron-deficient enynes and a malonate-derived α,β-unsaturated ester was described. A range of multisubstituted diquinanes were obtained in good yields with excellent ee values (91–98% ee). Moreover, the products could be easily transformed into various chiral [3.3.0]bicycle compounds, which were important skeletons of many biologically active compounds and pharmacologicals.

AbstractAn asymmetric epoxidation of electron-deficient enynes with environmentally benign aqueous hydrogen peroxide as oxidant has been accomplished by developing a chiral N,N′-dioxide-Scandium(III) complex catalytic system. In the presence of 0.5–2 mol% catalyst, a variety of trisubstituted alkynyl oxiranes were obtained in high yields (up to 97%) with excellent ee values (up to 99%). Furthermore, control experiments provide a fundamental insight into the reaction mechanism.

AbstractAn efficient N,N′-dioxide–lanthanum(III) complex catalytic system has been developed for the diastereo- and enantioselective Michael-initiated ring-closure (MIRC) reaction of 2-cyano-3-arylacrylates with 2-bromomalonates. Various chiral cyclopropanes with multiple substitutions were obtained in high yields (up to 93%) with excellent dr (>95:5 dr) and good ee values (up to 91% ee). The catalytic system also worked for the tandem halogenation/asymmetric MIRC reaction of α,β-unsaturated nitriles, malonates and NBS. Besides, a possible catalytic model has been proposed to explain the origin of the stereoselectivity.

An enantioselective tandem Friedel–Crafts alkylation–hemiketalization between electron-rich phenols and α,β-unsaturated ketoesters gave a direct approach to chiral 2,3-disubstituted chromans in the presence of a chiral N,N′-dioxide/Sc(OTf)3 complex. High enantioselectivities (up to 95% ee), high diastereoselectivities (up to 14 : 1) and high yields (up to 97%) were obtained for a broad range of substrates under mild reaction conditions.

A chiral N,N′-dioxide/Ni(OTf)2 complex-catalyzed asymmetric Diels–Alder reaction of cyclopentadiene with 2,3-dioxopyrrolidines and 2-alkenoyl pyridines has been achieved. The corresponding chiral bridged compounds were obtained in high yields with excellent dr and ee values (up to 97% yield, 95:5 dr and 97% ee).

A highly diastereo- and enantioselective [3 + 3] annulation of donor–acceptor cyclopropanes with mercaptoacetaldehyde has been developed. In the presence of a N,N′-dioxide–Sc(III) complex as the catalyst, a number of aromatic substituted cyclopropyl ketones reacted with mercaptoacetaldehyde smoothly, providing the corresponding chiral tetrahydrothiopyranols in moderate yields with excellent ee (up to 99% ee) and dr values (up to >19:1).

An efficient diastereo- and enantioselective [3 + 2] cycloaddition of heterosubstituted alkenes with oxiranes via selective C–C bond cleavage of epoxides has been developed. The reaction was catalyzed by a chiral N,N′-dioxide/Ni(II) catalyst, and a variety of chiral highly substituted tetrahydrofurans were obtained in up to 99% yield, 92/8 dr, and 99% ee.

A racemic N,N′-dioxide-iron(III) complex was first found to be an efficient chemosensor for simultaneous determination of the absolute configuration, concentration, and enantiomeric excess (ee) of hydroxy carboxylic acids in aqueous solution via circular dichroism (CD) and fluorescence. The accuracy of the ee measurement is very good, within 3%. And the analysis is fast, eliminating laborious derivatization and elaborating purification steps.

An easily available N,N′-dioxide/Cu(I) complex has been developed for the catalytic asymmetric nitroaldol (Henry) reaction of aldehydes with nitroethane. Under mild reaction conditions, a series of substituted aromatic, heteroaromatic and α,β-unsaturated aldehydes are transformed to the corresponding anti-β-nitroalcohols in good to excellent yields (up to 99%) with moderate to good dr (up to 16.7:1 anti/syn) and high ee values (up to 97%). Besides nitroethane, nitromethane and 1-nitropropane were also employed as nucleophiles, and good enantioselectivities were obtained.

A highly efficient N,N′-dioxide–Zn(II) complex catalytic system for the asymmetric Diels–Alder reaction of Brassard-type diene with methyleneindolines was developed. The optically pure spiro[cyclohex[3]ene-1,3′-indoline]-1′-carboxylate-2, 2′-dione derivatives containing three stereocenters were obtained in moderate yields with 98% to >99% ee in a stereospecific manner.

The catalytic asymmetric bromoamination of chalcones with N-bromosuccinimide as both bromine and amide source was realized by using a chiral N,N′-dioxide-Sc(NTf2)3 complex as an efficient catalyst. The corresponding chiral bromoamination products were obtained in high yields with high dr and good ee values (up to 92% yield, 93:7 dr and 97% ee) under mild reaction conditions.

A chiral N,N′-dioxide/Co(BF4)2·6H2O complex catalytic system has been developed to efficiently catalyze the asymmetric 1,3-dipolar cycloaddition of nitrones with methyleneindolinones. The corresponding chiral multisubstituted spiroisoxazolidines with three contiguous quaternary–tertiary stereocenters were obtained in moderate to high yields with excellent dr and ee values (up to 97% yield, >19:1 dr and 98% ee).

An enantioselective tandem Friedel–Crafts alkylation–hemiketalization between electron-rich phenols and α,β-unsaturated ketoesters gave a direct approach to chiral 2,3-disubstituted chromans in the presence of a chiral N,N′-dioxide/Sc(OTf)3 complex. High enantioselectivities (up to 95% ee), high diastereoselectivities (up to 14:1) and high yields (up to 97%) were obtained for a broad range of substrates under mild reaction conditions.

An asymmetric Meerwein–Ponndorf–Verley (MPV) reduction of glyoxylates was for the first time accomplished via an N,N′-dioxide/Y(OTf)3 complex with aluminium alkoxide and molecular sieves (MSs) as crucial additives. A variety of optically active α-hydroxyesters were obtained with excellent results. A possible reaction mechanism was proposed based on the experiments.

The first catalytic asymmetric dynamic resolution of unprotected racemic 3-(4-alkylcyclohexylidene)indolin-2-ones via a one-step direct vinylogous Michael reaction with chalcones was realized using a chiral N,N′-dioxide/Sc(III) complex catalytic system. A variety of (Z)-4-alkyl-2-((3-oxo-1,3-diarylpropyl)cyclohexylidene)-indolin-2-ones with three stereogenic centers at ξ-, γ- and δ′-positions were obtained in up to 95% yield, 98% ee and 99/1 dr. A possible transition state was proposed to explain the origin of the stereoselectivity.

A highly diastereo- and enantioselective [3 + 3] annulation of donor–acceptor cyclopropanes with mercaptoacetaldehyde has been developed. In the presence of a N,N′-dioxide–Sc(III) complex as the catalyst, a number of aromatic substituted cyclopropyl ketones reacted with mercaptoacetaldehyde smoothly, providing the corresponding chiral tetrahydrothiopyranols in moderate yields with excellent ee (up to 99% ee) and dr values (up to >19:1).

A chiral N,N′-dioxide/Ni(OTf)2 complex-catalyzed asymmetric Diels–Alder reaction of cyclopentadiene with 2,3-dioxopyrrolidines and 2-alkenoyl pyridines has been achieved. The corresponding chiral bridged compounds were obtained in high yields with excellent dr and ee values (up to 97% yield, 95:5 dr and 97% ee).