One‐Pot Tandem Diastereoselective and Enantioselective Synthesis of Functionalized Oxindole‐Fused Spiropyrazolidine Frameworks

A highly efficient palladium(0)‐catalyzed asymmetric [3+2] cycloaddition using 3‐diazooxindoles serving as dipolarophiles affords functionalized pyrazolidine derivatives in an atom‐economical way. In addition, by trapping the pyrazolidine derivatives with maleimides, the corresponding spiropyrazolidine oxindoles containing multiple stereogenic centers have been obtained in high yields along with moderate to good levels of diastereoselectivity and enantioselectivity under mild conditions. Thus, a novel three‐component one‐pot tandem reaction has been developed.     

Synthesis of spiropyrrolidine oxindoles through Rh(II)-catalyzed olefination/cyclization of diazooxindoles and vinyl azides

A simple and efficient process involving the Rh(II)-catalyzed [1+1+3] annulation of diazooxindoles and vinyl azides has been developed for the synthesis of spiropyrrolidine oxindoles with potential biological activity and significant synthetic applications. This process involves a novel rhodium-catalyzed olefination of diazo compounds, followed by annulation with vinyl azides. This method is compatible with a broad range of substrates and affords moderate to good yields under mild reaction conditions.     

CH Functionalization/Asymmetric Michael Addition Cascade Enabled by Relay Catalysis: Metal Carbenoid Used for CC Bond Formation

A combination of either ruthenium(II) or rhodium(II) complexes and quinine‐derived squaramide enables 3‐diazooxindoles, indoles, and nitroalkenes to undergo highly efficient asymmetric three‐component reactions, thus affording optically active 3,3′‐bis(indole)s through a consecutive C? C bond‐forming sequence, which turned out to be applicable to the facile total synthesis of (?)‐folicanthine.     

Asymmetric Construction of Spirooxindoles by Organocatalytic Multicomponent Reactions Using Diazooxindoles

The first highly diastereo‐ and enantioselective multicomponent reaction of diazooxindoles, nitrosoarenes, and nitroalkenes using a newly developed hydrogen‐bond catalyst has been successfully developed for the efficient construction of a series of spirooxindole derivatives with excellent functional‐group tolerance. Spirooxindoles are formed in excellent yields and stereoselectivities, and the method represents an unprecedented approach for trapping the active intermediate with a nitroalkene to form biologically important compounds having three contiguous stereogenic centers with excellent asymmetric induction.     

C?H Functionalization/Asymmetric Michael Addition Cascade Enabled by Relay Catalysis: Metal Carbenoid Used for C?C Bond Formation

A combination of either ruthenium(II) or rhodium(II) complexes and quinine‐derived squaramide enables 3‐diazooxindoles, indoles, and nitroalkenes to undergo highly efficient asymmetric three‐component reactions, thus affording optically active 3,3′‐bis(indole)s through a consecutive C C bond‐forming sequence, which turned out to be applicable to the facile total synthesis of (−)‐folicanthine.     

Diastereodivergent Asymmetric 1,4‐Addition of Oxindoles to Nitroolefins by Using Polyfunctional Nickel‐Hydrogen‐Bond‐Azolium Catalysts

Diastereodivergency is a challenge for catalytic asymmetric synthesis. For many reaction types, the generation of one diastereomer is inherently preferred, while the other diastereomers are not directly accessible with high efficiency and require circuitous synthetic approaches. Overwriting the inherent preference by means of a catalyst requires control over the spatial positions of both reaction partners. We report a novel polyfunctional catalyst type in which a Ni^II‐bis(phenoxyimine) unit, free hydroxy groups, and an axially chiral bisimidazolium entity participate in the stereocontrol of the direct 1,4‐addition of oxindoles to nitroolefins. Both epimers of the 1,4‐adduct are accessible in excess on demand by changes to the ligand constitution and configuration. As the products have been reported to be valuable precursors to indole alkaloids, this method should allow access to their epimeric derivatives.     

Catalytic Asymmetric Synthesis of 3‐(α‐Hydroxy‐β‐carbonyl) Oxindoles by a ScIII‐Catalyzed Direct Aldol‐Type Reaction

A direct catalytic asymmetric aldol‐type reaction of 3‐substituted‐2‐oxindoles with glyoxal derivatives and ethyl trifluoropyruvate, catalyzed by a chiral N,N′‐dioxide–Sc(OTf)₃ (Tf=trifluoromethanesulfonyl) complex, has been developed that tolerates a wide range of substrates. The reaction proceeds in good yields and excellent enantioselectivities (up to 93 % yield, 99:1 diastereomeric ratio (dr), and >99 % enantiomeric excess (ee)) under mild conditions, to deliver 3‐(α‐hydroxy‐β‐carbonyl) oxindoles with vicinal quaternary–tertiary or quaternary–quaternary stereocenters. Even with 1 mol % catalyst loading or on scaleup (10 mmol of starting material), maintenance of ee was observed, which showed the potential value of the catalyst system. In studies probing the reaction mechanism, a positive nonlinear effect was observed and Sc^III‐based enolate intermediates were detected by using ESIMS. On the basis of the experimental results and previous reports, a possible catalytic cycle was assumed.     

Highly efficient construction of chiral dispirocyclic oxindole/thiobutyrolactam/chromanone complexes through Michael/cyclization cascade reactions with a rosin-based squaramide catalyst

An efficient asymmetric Michael/cyclization cascade reaction of 4-chromanones with isothiocyanato oxindoles has been revealed. Under bifunctional organocatalysis by rosin-based squaramide catalyst, a series of spiro[oxindole/thiobutyrolactam/chromanone] complexes were conveniently constructed in a highly stereoselective manner (up to 99% yields, > 20:1 dr and >99% ee). The reaction leads to the formation of three contiguous stereogenic centers and two spiro quaternary stereocenters.     

Organocatalytic double arylation of 3-isothiocyanato oxindoles: Stereocontrolled synthesis of complex spirooxindoles

Quinones, precursors of aromatic structures, were firstly employed as the electrophiles for the organocatalytic Michael addition/cyclization cascade reaction with versatile 3-isothiocyanato oxindoles. Chiral bifunctional organocatalyst was appropriate for this enantioselective transformation to afford a variety of novel spirooxindoles, possessing a spirocyclic stereocenter adjacent to the aromatic ring, via asymmetric double arylation. These synthesized spirooxindoles are very difficult to access by the reported methods and were obtained in excellent chemical yields with excellent enantioselectivities.     

Amino Acid Derived Phosphine‐Catalyzed Enantioselective 1,4‐Dipolar Spiroannulation of Cyclobutenones and Isatylidenemalononitrile

Cyclobutenones have been explored as a new type of chiral 1,4‐dipole four‐carbon synthon, which readily undergoes organophosphine‐mediated C?C bond cleavage and asymmetric intermolecular 1,4‐dipolar spiroannulation with isatylidenemalononitrile in the presence of amino acid‐derived chiral phosphine catalyst to furnish enantioenriched 3‐spirocyclohexenone 2‐oxindoles in good yield with up to 87 % ee. To our knowledge, this is the first example of asymmetric transformation of cyclobutenones and the phosphine‐catalyzed asymmetric 1,4‐dipolar cycloaddition consisting of C?C bond activation is unprecedented.     

Organocatalytic Asymmetric Conjugate Addition of 3‐Monosubstituted Oxindoles to (E)‐1,4‐Diaryl‐2‐buten‐1,4‐diones: A Strategy for the Indirect Enantioselective Furanylation and Pyrrolylation of 3‐Alkyloxindoles

An asymmetric conjugate addition of 3‐monosubstituted oxindoles to a range of (E)‐1,4‐diaryl‐2‐buten‐1,4‐diones, catalyzed by commercially available cinchonine, is described. This organocatalytic asymmetric reaction affords a broad range of 3,3′‐disubstituted oxindoles that contain a 1,4‐dicarbonyl moiety and vicinal quaternary and tertiary stereogenic centers in high‐to‐excellent yields (up to 98 %), with excellent diastereomeric and moderate‐to‐high enantiomeric ratios (up to 99:1 and 95:5, respectively). Subsequently, cyclization of the 1,4‐dicarbonyl moiety in the resultant Michael adducts under different Paal–Knorr conditions results in two new kinds of 3,3′‐disubstituted oxindoles—3‐furanyl‐ and 3‐pyrrolyl‐3‐alkyl‐oxindoles—in high yields and good enantioselectivities. Notably, the studies presented here sufficiently confirm that this two‐step strategy of sequential conjugate addition/Paal–Knorr cyclization is not only an attractive method for the indirect enantioselective heteroarylation of 3‐alkyloxindoles, but also opens up new avenues toward asymmetric synthesis of structurally diverse 3,3′‐disubstituted oxindole derivatives.     

Dual-function cinchona alkaloid catalysis: catalytic asymmetric tandem conjugate addition-protonation for the direct creation of nonadjacent stereocenters

Catalytic tandem asymmetric reactions constitute a powerful strategy for the asymmetric construction of nonadjacent stereocenters in acyclic molecules directly from achiral precursors. In this Communication, we report a highly enantioselective and diastereoselective addition of trisubstituted carbon donors to 2-chloroacrylonitrile catalyzed by bifunctional cinchona alkaloid catalysts. This represents the first asymmetric tandem conjugate addition-protonation with efficient catalytic control of two nonadjacent stereocenters. As demonstrated in a concise and highly stereoselective formal total synthesis of (-)-manzacidin A, this asymmetric tandem reaction establishes a new and versatile catalytic approach for the enantioselective and diastereoselective creation of 1,3-tertiary-quaternary stereocenters.     

Catalytic Asymmetric Construction of Axially Chiral Indole-Based Frameworks: An Emerging Area

Axially chiral indole-based frameworks have been recognized as a class of important five-membered heterobiaryls and developing catalytic asymmetric approaches for constructing these frameworks in an enantioselective manner is highly desirable. In recent years, synthetic chemists have paid much attention to this research field, and rapid developments have occurred. At this point, a range of axially chiral indole-based scaffolds have been constructed via various catalytic asymmetric reactions based on different strategies. Thus, the catalytic asymmetric construction of axially chiral indole-based frameworks has become an emerging area. This minireview summarizes the rapid advances in this field and gives some insights into future developments, which will help this research field to thrive.     

Iridium-catalyzed asymmetric hydrogenation of 3-substituted unsaturated oxindoles to prepare C3-mono substituted oxindoles

An efficient and enantioselective hydrogenation of 3-substituted unsaturated oxindoles has been developed by an iridium complex of tropos phosphine-oxazoline ligands. It is the first example to prepare chiral C3-mono substituted oxindoles via asymmetric catalysis. And the reaction provides instant access to this kind of compounds with excellent conversion and enantioselectivities (up to 93% ee).     

离子液体在不对称催化反应中的应用进展

综述了近年来离子液体在不对称催化反应中的应用,包括不对称Aldol反应、不对称氟化反应、酶催化的不对称还原反应、不对称催化氢化反应、不对称硅腈化反应、不对称环丙烷化反应、烯丙基的不对称取代反应、环氧化物的不对称开环反应、不对称环氧化反应、烯烃的不对称双羟基化反应、酶催化的醇的动力学拆分。参考文献43篇。     

Synthesis of 3,3‐Disubstituted Oxindoles by Palladium‐Catalyzed Asymmetric Intramolecular α‐Arylation of Amides: Reaction Development and Mechanistic Studies

Palladium complexes incorporating chiral N‐heterocyclic carbene (NHC) ligands catalyze the asymmetric intramolecular α‐arylation of amides producing 3,3‐disubstituted oxindoles. Comprehensive DFT studies have been performed to gain insight into the mechanism of this transformation. Oxidative addition is shown to be rate‐determining and reductive elimination to be enantioselectivity‐determining. The synthesis of seven new NHC ligands is detailed and their performance is compared. One of them, L8 , containing a tBu and a 1‐naphthyl group at the stereogenic centre, proved superior and was very efficient in the asymmetric synthesis of fifteen new spiro‐oxindoles and three azaspiro‐oxindoles often in high yields (up to 99 %) and enantioselectivities (up to 97 % ee; ee=enantiomeric excess). Three palladacycle intermediates resulting from the oxidative addition of [Pd(NHC)] into the aryl halide bond were isolated and structurally characterized (X‐ray). Using these intermediates as catalysts showed alkene additives to play an important role in increasing turnover number and frequency.     

手性炔丙醇的不对称催化合成研究进展

手性炔丙醇是一种重要中间体化合物,作为合成多种光学活性化合物的重要合成前体受到学者们广泛关注。目前通过酮的不对称催化反应合成手性炔丙醇的研究开发具有极大发展前景,因此本文围绕酮类化合物的不对称催化反应来进行综述,结合相关反应最新研究进展,全面总结并分类了不对称催化还原、催化不对称加成等反应类型,介绍了合成不同结构手性炔丙醇的新思路,并对酮的不对称催化反应在未来能成为工业化重要生产途径作出展望。     

有机小分子催化的不对称Strecker反应研究进展

有机小分子催化的不对称合成反应是目前研究最为活跃的领域之一. 不对称Strecker反应是合成光学活性α-氨基酸衍生物的有效手段. 目前报道的催化不对称Strecker反应的有机催化剂主要有手性胍类、手性(硫)脲衍生物、氮-氧偶极化合物、手性Brønsted酸等, 取得了良好的催化活性和对映选择性. 对各类有机小分子催化剂在有机催化不对称Strecker反应中的应用研究进展, 以及催化剂结构与反应条件对催化活性和不对称诱导作用的影响进行了简要评述.     

Asymmetric catalytic cycloetherification mediated by bifunctional organocatalysts

Oxacyclic structures such as tetrahydrofuran (THF) rings are commonly found in many bioactive compounds, and this has led to several efforts toward their stereoselective syntheses. However, the process of catalytic asymmetric cycloetherification for their straightforward synthesis has remained a challenge. In this study, we demonstrate a novel asymmetric synthesis method for THF via the catalytic cycloetherification of ε-hydroxy-α,β-unsaturated ketones mediated by cinchona-alkaloid-thiourea-based bifunctional organocatalysts. This catalytic process represents a highly practical cycloetherification method that provides excellent enantioselectivities, even with low catalyst loadings at ambient temperature.     

Asymmetric Synthesis of Fully Substituted Cyclopentane‐Oxindoles through an Organocatalytic Triple Michael Domino Reaction

An efficient, highly stereoselective asymmetric synthesis of fully functionalized cyclopentanes bearing an oxindole moiety and several other functional groups in one pot has been developed. Key step is an organocatalytic triple Michael domino reaction forming three C?C bonds and six stereocenters, including a quaternary one. Starting from equimolar amounts of simple substrates, a high molecular complexity can be reached after a Wittig olefination in one pot. The new protocol can easily be scaled up to gram amounts.