The aminoindanol core as a key scaffold in bifunctional organocatalysts

Sonsona, Isaac G.; Marqués‐López, Eugenia; Herrera, Raquel P.

doi:10.3762/bjoc.12.50

Cited by 21 publications

(11 citation statements)

References 59 publications

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“…The OH group present in the aminoindanol skeleton has been also found crucial, with the cis configuration, for the success of the catalytic examples previously studied. 48…”

Section: Discussionmentioning

confidence: 99%

Hydrogen Bonding Networks in Chiral Thiourea Organocatalysts: Evidence on the Importance of the Aminoindanol Moiety

Gimeno

Herrera

2016

Crystal Growth & Design

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The crystal structures of four chiral thioureas, which are normally used as organocatalysts, are reported by the first time. Each compound is assembled in the crystal in a different way according to their chiral moiety in the thiourea skeleton, being dependent on the presence or the absence of the OH group in the aminoindanol or aminoindane moiety, respectively. Thiourea 1, which contains an aminoindane group, is assembled into a zigzag chain linked via N-HꞏꞏꞏS hydrogen bonds. Thiourea 2, with an aminoindanol and a phenyl group, 2 interacts mainly through O-HꞏꞏꞏS and N-HꞏꞏꞏS bonds in a very congested structure. Thiourea 3 disposes in a zigzag chain mainly through SꞏꞏꞏOH bonds and in further superposed zigzag chains through NHꞏꞏꞏS hydrogen bonds. The compound 4 is coordinated in a coplanar organization via OꞏꞏꞏH-N interactions, forming very tight dimers, which are further arranged in chain of dimers through O-HꞏꞏꞏS interactions. The general trends in the patterns of packing of these four compounds are compared to those commonly observed in the crystalline solids of other thiourea and urea structures. The different arrangements adopted by our chiral thioureas in the solid state are rationalized and discussed in terms of molecular structure, remarking the importance of the OH group in the aminoindanol scaffold in the determination of the preferred solid assembly. A comparison correlating the crystal structures, specifically the interactions in the crystal network and the configuration adopted by the thioureas, with the catalytic efficiency previously observed by the same structures, is included.

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“…The OH group present in the aminoindanol skeleton has been also found crucial, with the cis configuration, for the success of the catalytic examples previously studied. 48…”

Section: Discussionmentioning

confidence: 99%

Hydrogen Bonding Networks in Chiral Thiourea Organocatalysts: Evidence on the Importance of the Aminoindanol Moiety

Gimeno

Herrera

2016

Crystal Growth & Design

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“…Next, we analyzed the effect on both ee and reaction yield using progressive amounts of ()-9a with respect to urea 1b (0.02 mmol) ( Figure 4). 55 Additional important aspects can also be concluded from the results disclosed in Table 3. For instance, the presence of an OH group in the skeleton of 1b with cis configuration seems to be crucial for both the enantioselectivity and the reactivity of the process (compare entry 2 against entries 7 and 8), which is in good agreement with our previous observations with thioureas [45].…”

Section: Bmentioning

confidence: 83%

“…Catalysts 2018, 8, x FOR PEER REVIEW 2 of 21 changed the most acidic moiety of the model catalyst (i.e., 3,5-bis-CF3-phenyl group) for different acidic moieties, while retaining the aminoindanol structure ( Figure 1) [55,56]. In this respect, Sigman and co-workers demonstrated that both the reaction rate and the enantioselectivity could be correlated to catalyst acidity and it could be efficiently used for the tuning and design of new catalyst structures for hydrogen-bond-catalyzed enantioselective reactions [57].…”

Section: Cooperative Effect In the Mixture (Urea Catalyst + Brønsted mentioning

confidence: 99%

Urea Activation by an External Brønsted Acid: Breaking Self-Association and Tuning Catalytic Performance

et al. 2018

Self Cite

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In this work, we hypothesize that Brønsted acids can activate urea-based catalysts by diminishing its self-assembly tendency. As a proof of concept, we used the asymmetric Friedel–Crafts alkylation of indoles with nitroalkenes as a benchmark reaction. The resulting 3-substituted indole derivatives were obtained with better results due to cooperative effects of the chiral urea and a Brønsted acid additive. Such synergy has been rationalized in terms of disassembly of the supramolecular catalyst aggregates, affording a more acidic and rigid catalytic complex.

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“…10, 2017 substrates. [44][45][46] A variety of important reactions, especially those involving additions to C=O or C=N, which are accompanied by a change in the basicity of the heteroatom, are susceptible to asymmetric catalysis using derivatives of urea. Therefore, enantioselective reactions promoted by these types of organocatalysts are basically directed through non-covalent interactions, particularly hydrogen bonds, differing from those in which the catalysts depend on covalent interactions with substrates to products for inducing asymmetry.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of New Xanthenes Based on Lawsone and Coumarin via a Tandem Three‑Component Reaction

Cardoso¹,

Forezi²,

Cavalcante³

et al. 2017

J. Braz. Chem. Soc.

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The synthesis of several new xanthenes based on the 1,3-dicarbonyl scaffolds lawsone and coumarin was developed using tandem three-component reactions involving the reagents ortho-hydroxybenzaldehyde, as bifunctional reagent, and an appropriate thiol. These reactions generated two series of para-and ortho-naphthoxanthenes that are structurally related to α-and β-pyranaphthoquinones and one series of coumarin-xanthene derivatives.Keywords: 2-hydroxy-1,4-naphthoquinone, coumarin, multi-component reactions, organocatalysis, ortho-quinone methide IntroductionXanthenes are a class of heterocyclic compounds that are extensively found in natural products and have many biological applications and several applications in materials science. [1][2][3] Xanthenes are prepared by several synthetic methods and structurally possess carbocyclic or heterocyclic substituents fused to a central pyran ring. In general, the most commonly used methods for their preparation involve a cycloaddition reaction of a 1,3-dicarbonyl compound with aldehydes to form an adduct, a reactive α,β-unsaturated intermediate, which reacts with an appropriate nucleophile in the second step. [4][5][6] Lawsone (1) and 4-hydroxycoumarin (6) are two 1,3-dicarbonyl compounds that have been extensively used by synthetic organic chemists because of their peculiar chemical structures and their relationships with biologically important natural products. 7 Indeed, these natural products have a large variety of biological activity that has been studied in recent decades and stimulated the synthesis of a large number of synthetic analogues. [8][9][10][11] Naphthoquinones play vital roles in several biological processes and are considered to be of great importance in medicinal chemistry. Naphthoquinones are often associated with various biological activities, including anticancer, antibacterial, antimalarial, trypanocidal, tuberculostatic and fungicidal activities. 12 Some natural coumarins are found as secondary metabolites from plants, bacteria and fungi. 13 This family of compounds presents a wide variety of biological activities, including anti-inflammatory, antibacterial, antifungal, antiviral and anticancer. 14,15 In Figure 1, we highlight the following important natural and synthetic naphthoquinones that match this profile: lawsone (1), β-lapachone (2), α-lapachone (3), urdamycinone B (4), estreptonigrin (5), 4-hydroxycoumarin (6), calanolide A (7) and osthole (8). [16][17][18][19] Because of the importance of these naphthoquinones and coumarins, the search for new, simple and efficient methods of preparation of structurally related compounds remains of great interest.Tandem multi-component reactions (MCR) are convergent syntheses that begin with three or more reactants and, preferably, end with only one formed product that contains all of the starting atoms. 20 Usually, these types of reactions have a high atom economy and a high possibility of diversifying the structures of the final products. MCRs are important in industrial applications 21 and the devel...

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The aminoindanol core as a key scaffold in bifunctional organocatalysts

Cited by 21 publications

References 59 publications

Hydrogen Bonding Networks in Chiral Thiourea Organocatalysts: Evidence on the Importance of the Aminoindanol Moiety

Hydrogen Bonding Networks in Chiral Thiourea Organocatalysts: Evidence on the Importance of the Aminoindanol Moiety

Urea Activation by an External Brønsted Acid: Breaking Self-Association and Tuning Catalytic Performance

Synthesis of New Xanthenes Based on Lawsone and Coumarin via a Tandem Three‑Component Reaction

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