Organocatalytic Diversity-Oriented Asymmetric Synthesis of Structurally and Stereochemically Complex Heterocycles

Qiao, Liang; Duan, Zhongwei; Wu, Xiao-na; Li, Dehai; Gu, Qianqun; Liu, Yankai

doi:10.1021/acs.orglett.8b00377

Cited by 26 publications

(7 citation statements)

References 31 publications

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“…As illustrated in Scheme 2b, the N ‐unprotected spirocyclic oxindole 3 fa could be easily transferred to Boc‐protected spirocyclic oxindole 4 fa in 90% yield. Inspired by previous studies on the further transformations of spirooxindoles, [6c,18] the structurally complex enantioenriched 1‐benzazepine derivative 5 fa with bridge ring could be facilely delivered in 98% yield with 18:1 dr and 97% ee by treatment of isolated 4 fa with conc. HCl in MeOH at 80 °C (for details, see the Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Organocatalytic Remote Asymmetric Inverse‐Electron‐Demand Oxa‐Diels‐Alder Reaction of Allyl Ketones with Isatin‐Derived Unsaturated Keto Esters

Lin

Hou

et al. 2020

Adv Synth Catal

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A remote cascade asymmetric inverse-electron-demand oxa-Diels-Alder reaction of allyl ketones with isatin-derived β,γ-unsaturated α-keto esters has been developed in the presence of a chiral bifunctional squaramide catalyst. Taking advantage of the secondary amide activating group, a series of enantioenriched 3,4'-pyranyl spirooxindole derivatives bearing three contiguous chiral centers were attained in high yields (84 to > 99%) with excellent enantioselectivities (96-99% ee). Moreover, the gram-scale synthesis and the construction of 1-benzazepine scaffold by the product were also demonstrated.

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Section: Resultsmentioning

confidence: 99%

Organocatalytic Remote Asymmetric Inverse‐Electron‐Demand Oxa‐Diels‐Alder Reaction of Allyl Ketones with Isatin‐Derived Unsaturated Keto Esters

Lin

Hou

et al. 2020

Adv Synth Catal

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“…An asymmetric organocatalytic arylation reaction was described to achieve a sterically congested spirooxindole 119 with two quaternary stereogenic centers from 3‐keto‐oxindole 116 and the quinone 117 in the presence of the bifunctional catalyst 118 (1 mol‐%) in DCM at –40 °C for 3 h, as shown in Scheme . The reaction afforded chiral 3‐alkyl‐3‐aryloxindole II followed by a spiroketalization to form the hemi‐ketal III , being this reaction the key to avoid the oxidation of hydroquinone to a quinone.…”

Section: Asymmetric Synthesis Of Spirooxindoles In One Stepmentioning

confidence: 99%

“…The hemi‐ketal III in the presence of a catalytic amount of p ‐toluenesulfonic acid ( p TSA) (10 mol‐%) at 25 °C afforded the spirooxindole 119 in 78 % yield, with a diastereomeric ratio 20:1 and high enantioselectivity (92 % ee). The bifunctional catalyst 118 activated both starting materials, since the amino group of 118 acts as a base by abstracting the acid proton of 116 and activates by hydrogen bond the carbonyl group of the quinone 117 , where an asymmetric Michael reaction is carried out to form 3‐alkyl‐3‐aryloxindole II as an only product, as shown in Scheme …”

Section: Asymmetric Synthesis Of Spirooxindoles In One Stepmentioning

confidence: 99%

Organocatalytic Synthesis of Chiral Spirooxindoles with Quaternary Stereogenic Centers

Sansinenea

Martínez

2020

Eur J Org Chem

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The structure of spirooxindoles is present in a large number of natural compounds, with relevant and different biological activities. The organic synthesis of these compounds has been a synthetic challenge due to the fusion of two or more cycles with one or more contiguous stereogenic centers. In this review, it has been described, the feasibility of organocatalytic asymmetric synthesis for the achievement of chiral spirooxindoles through two‐ or three‐component reaction in the presence of a chiral organocatalyst producing the compounds with high yield, high diastereoselectivity and with high enantiomeric purity. This review covers literature from 2010 to 2019. The most explored reactions for this purpose have been 1,3‐dipolar cycloaddition, Diels‐Alder and nucleophilic heterocyclic carbenes reactions, where their reaction mechanisms showed in this review are an approach of a possible mechanism.

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“…The absolute configuration of products was determined by X-ray analysis. The Li, Liu and co-workers prepared a series of spiro-, dispiro-, fused, and bridged heterocycles by the reaction of quinones and 3-keto-oxindoles (Scheme 40) [56]. The absolute configuration of products was determined by X-ray analysis.…”

Section: Miscellaneousmentioning

confidence: 99%

Recent Advances in Organocatalyzed Asymmetric Synthesis of Benzopyran and Benzodihydropyran (Chromane) Nuclei

Dalpozzo

Mancuso

2019

Symmetry

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Benzopyran and benzodihydropyran (chromane) nuclei are the core structure of many natural products, in particular flavonoids. Many compounds possessing this structure are nutraceuticals, pharmaceutical nutrients. Therefore, benzopyran and chromane scaffolds are important building blocks in organic synthesis and many efforts have been made to set up efficient methods for their synthesis. In particular, asymmetric methods are of great importance, being natural products, and generally chiral substances. This review aims to cover literature in the range 2017-first half of 2019.It should be noted that the oxa-Michael-Henry reaction between two molecules of nitrostyrene was not observed. Symmetry 2020, 12, x FOR PEER REVIEW 4 of 33 Scheme 2. Heterogeneous enantioselective synthesis of chromanes.Xia, Xu and co-workers performed an enantioselective, organocatalytic oxa-Michael-nitro-Michael reaction, but in this case, too, 2-hydroxynitrostyrenes reacted only with β-nitroolefins different from themselves [10]. The reaction afforded chiral chromane derivatives bearing three contiguous stereogenic centers (Scheme 3). The all-S stereochemistry was assigned by X-ray analysis. Subsequently, Andrés, Pedrosa and co-workers extended the reaction to polymer-supported squaramides [11]. Initially, they tested some 4-vinylphenyl-substituted squaramides and found that Squa2 (see Scheme 1, 5 mol%, rt, 12-72 h in dichloromethane) gave the best results (65-88% yields, 63:27 to >99:1 dr, 70-> 99% ee, 13 examples). The absolute configuration was once more (2S,3S,4S) and was established by X-ray analysis. The configuration of the minor isomer was instead established as (2S,3R,4S) by comparison of the 1 H-NMR coupling constants of the two diastereomers. Then Squa2 was co-polymerized with styrene and divinylbenzene and the experiments were repeated (65-86% yields, 58:42 to >99:1 dr, 56-74% ee). The polymer-supported catalyst was also recovered and recycled five times without affecting yields and selectivity. Finally, the enantiomers were obtained from a squaramide derived from (1R,2R)-1,2-cyclohexanediamine instead of Squa2 derived from α-amino acid. The authors attributed the opposite stereochemistry to a different assembly of the ternary complex formed by catalyst, nitroalkene and 2-hydroxynitrostyrene in the two cases. S O HN HO HO OHC Symmetry 2019, 11, 1510 5 of 31 Symmetry 2020, 12, x FOR PEER REVIEW 5 of 33 Scheme 3. Organocatalytic oxa-Michael nitro-Michael domino reaction.Another domino Michael/hemiacetalization (see also Scheme 2, eq 3) was carried out between aliphatic aldehydes and (E)-2-(2-nitrovinyl)phenols under modularly designed organocatalysts (Scheme 4) [12]. Cis-3,4-disubstituted chroman-2-ones were obtained after oxidation of the hemiacetal intermediate or chromanes after dehydroxylation. The reaction was scaled up to 0.5 mmol scale, without significant modification of yield and selectivity. The absolute stereochemistry was determined by the optical rotation of known compounds. Scheme 4. Domino reaction catalyzed by MDO o...

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Organocatalytic Diversity-Oriented Asymmetric Synthesis of Structurally and Stereochemically Complex Heterocycles

Cited by 26 publications

References 31 publications

Organocatalytic Remote Asymmetric Inverse‐Electron‐Demand Oxa‐Diels‐Alder Reaction of Allyl Ketones with Isatin‐Derived Unsaturated Keto Esters

Organocatalytic Remote Asymmetric Inverse‐Electron‐Demand Oxa‐Diels‐Alder Reaction of Allyl Ketones with Isatin‐Derived Unsaturated Keto Esters

Organocatalytic Synthesis of Chiral Spirooxindoles with Quaternary Stereogenic Centers

Recent Advances in Organocatalyzed Asymmetric Synthesis of Benzopyran and Benzodihydropyran (Chromane) Nuclei

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