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Chiral Lewis acid-promoted enantioselective α-alkylation of β-ketoamides with phenyliodonium ylide was developed. In the presence of a chiral N,N′-dioxide/Ni(ii) complex, the corresponding 1,4-dicarbonyl compounds were obtained with good results (up to 91% yield and 97% ee). Control experiments and EPR studies supported a radical process. [ABSTRACT FROM AUTHOR]

A highly enantioselective dearomative cascade reaction between 2-isocyanoethylindoles and 3-alkenyl-oxindoles was realized using a chiral N,N′-dioxide–Mg(ii) complex catalyst. This reaction provides a straightforward access to polycyclic 3-spirooxindoles bearing cyclopenta[b]indole units with four contiguous stereocenters in excellent yields and moderate to good stereoselectivities via a Michael/Friedel–Crafts/Mannich cascade. [ABSTRACT FROM AUTHOR]

A direct strategy to obtain N-acyl amino acid oxime esters has been developed through the dynamic kinetic resolution of azlactones with oximes. In the presence of a chiral bisguanidinium salt catalyst, a variety of chiral N-acyl amino acid oxime esters were generated in excellent enantiomeric excesses (up to 97%) and high yields (up to 99%). The active oxime esters could be used in dipeptide synthesis. [ABSTRACT FROM AUTHOR]

An environmentally benign catalyst, the N,N′-dioxide–FeCl3 complex, has been developed for the asymmetric intramolecular Cannizzaro reaction. Aryl and alkyl glyoxal monohydrates were applied to obtain α-hydroxy acid esters with excellent results. Deuterium-label and control experiments shed light on the reaction mechanism. [ABSTRACT FROM AUTHOR]

A series of amide-based bifunctional organocatalysts have been utilized in asymmetric reactions. Prolinamide analogues have been designed to catalyze asymmetric reactions viaenamine intermediates with the assistance of tunable hydrogen bonding. In addition, the combination of various Lewis base functional groups, such as guanidine, N-oxide and phosphane, with an amide moiety have also constituted efficient bifunctional organocatalysts with unique reactivity and selectivity. [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]

The first iron(iii)/N,N′-dioxide-catalyzed asymmetric haloamination of 3-alkylidene- and 3-arylidene-indolin-2-ones was developed, affording the corresponding chiral oxindole derivatives bearing vicinal haloamine substituents with excellent results (up to 99% yield, 99% ee, ＞19 : 1 dr). This iron catalyst also exhibits perfect enantioselectivity for chalcone derivatives. The cooperative activation of the substrate and the reagent in concert guarantees the high stereoselectivity. [ABSTRACT FROM AUTHOR]

A cooperative bimetallic catalyst system was applied in the catalytic asymmetric cross-dehydrogenative coupling of β-ketoesters and xanthene. Various optically active xanthene derivatives bearing a quaternary stereogenic carbon center were obtained in moderate to good yields (up to 90%) with excellent enantioselectivities (up to 99% ee). Meanwhile, a transition-state model was proposed to explain the origin of the asymmetric induction. [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]

An efficient catalytic enantioselective aza-ene-type reaction of glyoxal derivatives with enamides and enecarbamates has been realized using a nickel(ii)-N,N′-dioxide complex as the catalyst. [ABSTRACT FROM AUTHOR]

A C2-symmetric N,N′-dioxide-Sc(iii) complex has been developed to promote the asymmetric catalytic aldol reaction of α-ketoesters and diazoacetate esters to afford tertiary alcohols in good yields with excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

Asymmetric synthesis of 3-sulfonylated 3-substituted oxindoles through the addition of sodium sulfinate salts to 3-bromo-3-substituted oxindoles has been achieved using chiral nickel complexes of N,N′-dioxides. This method facilitates the creation of diverse chiral sulfonyl oxindoles, several of which display promising anticancer properties. Notably, the catalyst demonstrates remarkable tolerance to water, crucial for maintaining enantioselectivity. Furthermore, the utilization of topographic steric maps of the catalysts offers valuable insights into the mechanism underlying enantioselection reversal. [ABSTRACT FROM AUTHOR]

Using newly designed α-imino amide surrogates and azlactones as amphiphilic reactants, catalyzed by a chiral bifunctional guanidine, the construction of chiral 3,4-diaminopyrrolidine-2,5-diones and their derivatives was realized via formal [3+2]-cyclization. The role of guanidine as a multiple hydrogen bond donor was demonstrated by DFT calculations. [ABSTRACT FROM AUTHOR]

Catalytic enantioselective sulfenylation to construct diheteroatom-bearing carbon centres was achieved by employing chiral guanidine organocatalysts. This protocol provided a facile route towards the synthesis of α-fluoro-α-sulfenyl-β-ketoamides, azlactone adducts and α-sulfur-substituted amino acid derivatives in high yields with good to excellent enantioselectivities. A possible working mode was proposed to elucidate the chiral control of the process. [ABSTRACT FROM AUTHOR]

We reported an efficient asymmetric amination of azlactones with N-aryl-N-aroyldiazenes through a chiral N,N′-dioxide-based Lewis acid catalyst. The multicoordination ability of Nd(III) enabled it to simultaneously activate and to locate the two reactants for N-selective addition. Hydrazine-bearing azlactone derivatives were obtained in moderate to good yields with high enantioselectivity. [ABSTRACT FROM AUTHOR]

Chiral Ni(ii)-complexes of N,N′-dioxides show high catalytic activity and enantioselectivity in catalysing the asymmetric Friedel–Crafts C3-alkylation of 2,5-dimethyl pyrrole to β,γ-unsaturated α-ketoesters. A dramatic reversal of enantioselectivity is realized with ligands derived from the same type of chiral source of l-ramipril, by slightly tuning the amide units. [ABSTRACT FROM AUTHOR]

A chiral Lewis acid-catalyzed enantioselective formal [2 + 2 + 2] cycloaddition of 1,3,5-triazinanes with azlactones or β,γ-unsaturated pyrazole amides was developed to synthesize chiral tertiary/quaternary tetrahydropyrimidin-4-one derivatives with good yields and enantioselectivities. Two competitive reaction pathways were proposed based on experiments. [ABSTRACT FROM AUTHOR]

An enantioselective tandem Friedel–Crafts alkylation/annulation of indoles with diazoacetoacetate enones is realized in one pot. A series of dihydrocarbazoles were obtained in moderate yields with good to excellent ee values by using a RhII/ScIII dual-metallic catalyst system. Control experiments revealed that ScIII is critical to both the alkylation and annulation. [ABSTRACT FROM AUTHOR]

Several unique chiral 3,4-dihydro-2H-pyrrole-2-thiones were made readily available by carrying out, in each case, a chiral-Mg(OTf)2/N,N′-dioxide-complex-promoted formal [2+1+2] cycloaddition in the presence of tetraethylenediamine. Control experiments revealed that in situ-generated ammonium thiocyanate was crucial for maintaining high enantioselectivity through its inhibition of the HNCS-induced racemization of the products. [ABSTRACT FROM AUTHOR]

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 chiral amide–guanidine-catalyzed asymmetric formal [3+2] cycloaddition of isatogens with azlactones is presented. This strategy provided a facile and feasible route to chiral indolin-3-one derivatives bearing two contiguous tetrasubstituted stereocenters in moderate to good yields with high diastereoselectivities and enantioselectivities. A possible working mode was proposed to elucidate the chiral control of the process. [ABSTRACT FROM AUTHOR]

A highly efficient enantioselective dicarbofunctionalization reaction of (E)-alkenyloxindoles with pyridinium salts was realized. The process includes the chiral N,N′-dioxide–Sc(III) complex-catalyzed regio-, diastereo-, and enantioselective [3+2] cycloaddition reaction and the following photo-promoted aza-Norrish II type rearrangement. A series of 2-pyridyl substituted oxindole derivatives were obtained in good yields with moderate to good diastereo- and enantioselectivities. [ABSTRACT FROM AUTHOR]

A nickel(II) catalyzed enantioselective thio-Claisen rearrangement of α-diazo pyrazoleamides with thioindoles was realized with modified chiral N,N′-dioxide ligands, affording a variety of C3-substituted indole derivatives in high yields (up to 95%) with excellent enantioselectivities (up to 96% ee) under mild reaction conditions. A possible transition state model was proposed based on previous reports and the X-ray crystal structure of the catalyst. [ABSTRACT FROM AUTHOR]

A chiral N,N′-dioxide–Ni(ii) complex was found to exhibit highly enantioselective fluorescent recognition of chiral amines and amino alcohols. It can be used to determine their concentration and ee value. Using a 96-well plate, high-throughput screening for enantiomer discrimination was accomplished. [ABSTRACT FROM AUTHOR]

A highly enantioselective sulfoxidation of various sulfides has been achieved by a N,N′-dioxide–iron(III) complex with 35% aq. H2O2 as the oxidant. The utility of the current method was demonstrated by asymmetric gram-scale synthesis of drug molecule (R)-modafinil. Moreover, a possible working mode was provided to elucidate the chiral induction. [ABSTRACT FROM AUTHOR]

An asymmetric one-pot hydrocyanation/Michael reaction of α-aryl diazoacetates with trimethylsilyl cyanide, tert-butanol, and N-phenylmaleimides has been realized. Using a chiral guanidinium salt/CuBr catalyst, a series of cyanide-containing pyrrolidine-2,5-diones could be obtained in good yields with excellent diastereo- and enantioselectivities. [ABSTRACT FROM AUTHOR]

A highly diastereo- and enantioselective intramolecular Alder-ene reaction with an alkene as the enophile has been developed by using a chiral N,N′-dioxide/nickel(ii) complex as the catalyst. This protocol provides a facile route towards the synthesis of diverse 3,4-disubstituted chroman, tetrahydroquinoline, piperidine and thiochroman derivatives in high yields with good to excellent diastereo- and enantioselectivities. [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]

The catalytic asymmetric ene-type reactions of vinylogous hydrazone were accomplished by using chiral N,N′-dioxide–metal salt complexes as catalysts. A wide range of electrophiles, including isatins, α-ketoester, imines, and aldehydes reacted with (E)-2-methyl-N-(piperidin-1-yl)prop-2-en-1-imine efficiently, affording the corresponding homoallylic alcohols and amines in high yields (up to 99%) with excellent ee values (up to 99%). The methodology provided a convenient way to synthesize bioactive chiral α-methylene-γ-butyrolactone derivatives. [ABSTRACT FROM AUTHOR]

A highly enantioselective [2+2] cycloaddition reaction of alkylidene malonates with the internal C=C bond of N-allenamides was developed with a MgII/N,N′-dioxide complex as a catalyst. Various polysubstituted methylenecyclobutanes were afforded in good yields (up to 99%) and excellent enantioselectivities (up to 96% ee) under mild conditions. The utility of the donor–acceptor cyclobutane product was demonstrated as a masked 1,4-dipole in the formal [4+2] annulation reaction with a silyl enol ether. [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]

Here we report an efficient asymmetric [4+2] cycloaddition of β,γ-unsaturated α-ketoesters with cyclobutenones. The corresponding products were obtained in good yields (up to 92%) with excellent enantioselectivities (up to 98% ee) and diastereoselectivities (up to ＞19/1 dr). Moreover, based on the control experiments and previous reports, a possible catalytic cycle was proposed. [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]

A highly efficient asymmetric inverse-electron-demand oxa-Diels–Alder reaction of o-quinone methides with fulvenes has been realized using a chiral N,N′-dioxide/Sc(iii) complex as the catalyst. The corresponding optically active chromane derivatives were obtained in high yields with excellent dr and ee values (up to 99% yield, ＞19 : 1 dr and 94% ee). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

An efficient atroposelective synthesis of axially chiral biaryldiols via asymmetric Friedel–Crafts aromatization between p-quinones and 2-naphthols was developed. A chiral cobalt(ii) complex of N,N′-dioxide enabled the process to generate axially chiral biaryldiols in up to 98% yield and 95% ee. A large range of substituents at different positions of p-quinones and 2-naphthols was tolerable. The configuration of the product and the chiral N,N′-dioxide-Co(ClO4)2 catalyst was identified by X-ray crystal diffraction analysis and a possible catalytic model was suggested. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

The catalytic enantioselective [2+2] cycloaddition between quinones and fulvenes was achieved, for the first time, by the use of a chiral copper(ii) complex catalyst. The transformation afforded a series of enantiomerically enriched [6,4,5]-tricyclic cyclobutane derivatives in good yields with excellent regio- and stereoselectivities. Furthermore, the [2+2] adducts could be easily converted into formal [3+2] adducts efficiently and stereoselectively. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [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]

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). [ABSTRACT FROM AUTHOR]

The highly efficient catalytic asymmetric inverse-electron-demand hetero-Diels–Alder reaction of methyleneindolinones with hetero-substituted alkenes has been accomplished under mild reaction conditions. In the presence of chiral N,N′-dioxide/Ni(ii) complexes, a wide range of optically active dihydropyran-fused indoles were obtained in up to 99% yield, ＞95 : 5 dr and 99% ee. [ABSTRACT FROM AUTHOR]

A highly efficient catalytic kinetic resolution of 2,3-epoxy 3-aryl ketones via asymmetric ring-opening with pyrazole derivatives has been achieved by using a chiral N,N′-dioxide–Sc(iii) complex as the catalyst. A wide variety of substrates were readily scoped, and the selectivity factors obtained were excellent (up to ＞300). [ABSTRACT FROM AUTHOR]

The catalytic asymmetric Michael addition/desymmetrization reaction of N-(2-t-butylphenyl)maleimides with unprotected 3-substituted-2-oxindoles was successfully realized using a chiral N,N′-dioxide-Sc(iii) complex, leading to succinimides with two kinds of stereogenic elements―atom chirality and axial chirality―in up to 99% yield, 99% ee and ＞19 : 1 d.r. [ABSTRACT FROM AUTHOR]

A catalytic asymmetric carbonyl–ene reaction of β,γ-unsaturated α-ketoesters with 5-methyleneoxazolines was accomplished. The process was based on the utilization of a chiral N,N′-dioxide/MgII catalyst, providing the desired products with excellent outcomes (up to 99% yield, ＞99% ee) under mild reaction conditions. Based on the experimental investigations and previous reports, a possible transition state was proposed. [ABSTRACT FROM AUTHOR]

A highly efficient catalytic asymmetric formal [3+2] cycloaddition reaction of 5-alkoxyoxazoles with azodicarboxylate compounds has been realized by a chiral N,N′-dioxide/Co(BF4)2·6H2O complex. A series of poly-substituted 1,2,4-triazolines compounds were obtained in moderate to excellent yields (70–99%) with excellent enantioselectivities (82–98% ee). [ABSTRACT FROM AUTHOR]