Synthesis of 1-indanones with a broad range of biological activity

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

We describe the use of bismuth(III) triflate as an efficient and environmentally friendly catalyst for the Nazarov reaction of aryl vinyl ketones, leading to the synthesis of 3-aryl-2-ethoxycarbonyl-1-indanones and 3-aryl-1-indanones. By changing the temperature and reaction time, it was possible to modulate the reactivity, allowing the synthesis of two distinct product classes (3-aryl-2-ethoxycarbonyl-1-indanones and 3-aryl-1-indanones) in good to excellent yield. The reaction did not require additives and was insensitive to both air and moisture. Preliminary biological evaluation of some indanones showed a promising profile against some human cancer line cells.

Silver-Promoted Rapid Synthesis of 3-Arylindan-1-ones: Microwave-Assisted Reductive Coupling of N-Tosylhydrazone and Boronic Acids

An efficient and straightforward one-pot tandem synthesis of 3-arylindan-1-ones was consummated through silver nitrate-promoted C-C coupling of simple indane-1,3-dione with arylboronic acid via 1,3-indanedione monotosylhydrazone under microwave conditions. The resulting series of 3-arylindan-1-ones exhibited impressive yields, surpassing those achievable with traditional methods and requiring a shorter time frame. This innovative approach significantly accelerated the synthesis of biologically active compounds such as (+)-indatraline (Lu 19-005) and several other industrially relevant substances.

Exploration of bioactive compounds from Olea dioica in Western Ghats of Karnataka using GC-MS

Bioactive compounds in plants are essential for the formation of novel chemotherapeutic drugs, which have been used in Ayurveda to treat a variety of illnesses. Indian medicinal herbs have been used for thousands of years to treat a variety of illnesses, such as fever, cancer, snake bites, rheumatism, skin problems, and neurodegenerative diseases. GC-MS was used to locate and categorize bioactive components in Olea dioica leaves. The results showed that presence of octanoic acid, methyl ester, decanoic acid, methyl ester, desulphosinigrin, l-gala-l-ido-octose, methyl tetradecanoate, Tetradecanoic acid, 6-benzoxazolesulfonamide, N-(2-hydroxyethyl)-2-methyl-, 10-chloro-5-methoxy-5H-dibenzo[a,d][7]annulene, pentadecanoic acid, oleic acid, n-hexadecanoic acid, hexanedioic acid, dioctyl ester, and squalene. The methanol extract of Olea dioica was effective against a wide spectrum of pathogenic bacteria at four different concentrations, with the highest activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Xanthomonas campestris, and Salmonella typhimurium. It also showed moderate activity against Agrobacterium tumefaciens, Pseudomonas aeruginosa, Streptomyces pneumonia, and Pseudomonas syringae. The pharmacological properties of O. dioica, as well as their variety and comprehensive phytochemistry, could be exploited as a potent antimicrobial agent for future therapeutics.

Carbon-Carbon Bond Cleavage for Late-Stage Functionalization

Late-stage functionalization (LSF) introduces functional group or structural modification at the final stage of the synthesis of natural products, drugs, and complex compounds. It is anticipated that late-stage functionalization would improve drug discovery's effectiveness and efficiency and hasten the creation of various chemical libraries. Consequently, late-stage functionalization of natural products is a productive technique to produce natural product derivatives, which significantly impacts chemical biology and drug development. Carbon-carbon bonds make up the fundamental framework of organic molecules. Compared with the carbon-carbon bond construction, the carbon-carbon bond activation can directly enable molecular editing (deletion, insertion, or modification of atoms or groups of atoms) and provide a more efficient and accurate synthetic strategy. However, the efficient and selective activation of unstrained carbon-carbon bonds is still one of the most challenging projects in organic synthesis. This review encompasses the strategies employed in recent years for carbon-carbon bond cleavage by explicitly focusing on their applicability in late-stage functionalization. This review expands the current discourse on carbon-carbon bond cleavage in late-stage functionalization reactions by providing a comprehensive overview of the selective cleavage of various types of carbon-carbon bonds. This includes C-C(sp), C-C(sp2), and C-C(sp3) single bonds; carbon-carbon double bonds; and carbon-carbon triple bonds, with a focus on catalysis by transition metals or organocatalysts. Additionally, specific topics, such as ring-opening processes involving carbon-carbon bond cleavage in three-, four-, five-, and six-membered rings, are discussed, and exemplar applications of these techniques are showcased in the context of complex bioactive molecules or drug discovery. This review aims to shed light on recent advancements in the field and propose potential avenues for future research in the realm of late-stage carbon-carbon bond functionalization.

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

Trichloromethyl-substituted enones (1-aryl-4,4,4-trichlorobut-2-en-1-ones, ArCOCH=CHCCl3, CCl3-enones) undergo intramolecular transformation into 3-trichloromethylindan-1-ones (CCl3-indanones) in Brønsted superacid CF3SO3H (triflic acid, TfOH) at 80 °C within 2-10 h in yields up to 92%. Protonation of the carbonyl oxygen of the starting CCl3-enones by TfOH affords the key reactive intermediates, the O-protonated forms ArC(=OH+)CH=CHCCl3, which are then cyclized into the target CCl3-indanones. These cations have been studied experimentally by means of NMR spectroscopy in TfOH and theoretically by DFT calculations. Under the same superacidic conditions in TfOH, CCl3-hydroxy ketones (1-aryl-4,4,4-trichloro-3-hydroxybutan-1-ones; ArCOCH2CH(OH)CCl3) undergo dehydration to the corresponding CCl3-enones, which are further cyclized into CCl3-indanones. The yields of CCl3-indanones starting from CCl3-hydroxy ketones are up to 86% in TfOH at 80 °C within 3-18 h.

Palladium-catalyzed addition of acylsilanes across alkynes via the activation of a C-Si bond

Palladium-catalyzed addition of a C-Si bond in acylsilanes across the triple bonds in an alkyne bearing a carbonyl group at one terminal is reported. The reaction proceeds with excellent regioselectivity, in which a silyl group is incorporated into the carbon α to the carbonyl group, allowing for straightforward access to a variety of functionalized alkenylsilane derivatives. Catalytic synthesis of indanones by annulation between acylsilanes and alkynes with an identical catalytic system is also reported.

Novel 1-Indanone derivatives containing oxime and oxime ether moieties as immune activator to resist plant virus

BACKGROUND

Vegetable viruses are difficult to prevent and control in the field, causing massive economic losses of agricultural production in the world. A new natural product-based antiviral agent would be an effective means to control viral diseases. As a class of natural products, 1-indanones present various pharmacologically actives, while their application in agriculture remains to be found.

RESULTS

A series of novel 1-indanone derivatives were designed and synthesized and the antiviral activities were systematically evaluated. Bioassays showed that most compounds exhibited good protective activities against cucumber mosaic virus (CMV), tomato spotted wilt virus (TSWV), and pepper mild mottle virus (PMMoV). Notably, compound 27 exhibited the best protective effects against PMMoV with EC₅₀ values of 140.5 mg L^-1 , superior to ninanmycin (245.6 mg L^-1 ). Compound 27 induced immunity responses through multilayered regulation on mitogen-activated protein kinase, plant hormone signal transduction and phenylpropanoid biosynthesis pathways.

CONCLUSION

These 1-indanone derivatives especially compound 27 can be considered as potential immune activators to resist plant virus. © 2023 Society of Chemical Industry.

Indane-1,3-Dione: From Synthetic Strategies to Applications

Indane-1,3-dione is a versatile building block used in numerous applications ranging from biosensing, bioactivity, bioimaging to electronics or photopolymerization. In this review, an overview of the different chemical reactions enabling access to this scaffold but also to the most common derivatives of indane-1,3-dione are presented. Parallel to this, the different applications in which indane-1,3-dione-based structures have been used are also presented, evidencing the versatility of this structure.

The role of halogen bonds in the catalytic mechanism of the iso-Nazarov cyclization reaction: a DFT study

With the continuous development of halogen bonds, halogen bond donors have been used as clean and efficient catalysts in organic reactions. In this work, with inorganic halides (I₂, IBr, ICl, and ICl₃) as catalysts and the iso-Nazarov cyclization as the benchmark reaction, we aim at investigating the role of the halogen bond in the catalytic mechanism. The halogen bond catalyzed iso-Nazarov cyclization reaction involves three steps: carbon-carbon coupling process, [1,2]-H shift process, and [1,4]-H shift process. The halogen-bonding interaction promotes the charge accumulation of the oxygen atom in the carbonyl group and decreases the activation energy of the reaction. The catalytic activity of the halogen bond donor is enhanced in the order of I₂ < IBr < ICl < ICl₃, and it could be predicted that the partial covalent interaction of the I⋯O halogen bond between the catalyst ICl₃ and the oxygen atom of the reactant may exhibit good catalytic activity in the experiments. In the [1,4]-H shift process, the two-step hydrogen bond/halogen bond co-catalyzed mechanism exhibits the lowest reaction energy barrier than the one-step water co-catalyzed proton transfer mechanism and the direct one.

Solvent controlled synthesis of 2,3-diarylepoxy indenones and α-hydroxy diarylindanones and their evaluation as inhibitors of DNA alkylation repair

Herein, we report a novel and unexpected metal-free oxygenation of 2,3-diphenyl-1-indenones, under an oxygen atmosphere (air), to either 2,3-epoxy-2,3-diphenyl-1-indenone or 2-hydroxy-2,3-diphenyl-1-indanone, depending on the conditions. Several bioactive epoxy indenones and one-pot α-hydroxy indanones (α-acyloin) were synthesized from 2,3-diaryl dihydroindanone and 2,3-diarylindenone, respectively. A plausible reaction mechanism is also proposed, where oxygenation would take place at the α-position and further proton abstraction from the β-position leads to epoxy indenone derivatives. A one-pot cis-hydroxy indanone protocol is also achieved directly from biaryl indenone via reduction, epimerization, and oxygenation. The synthesized compounds were evaluated for inhibitory activity against the DNA repair protein AlkB. Among the screened (17 tested) compounds, one epoxide derivative was found to be a specific inhibitor of AlkB enzyme function.

Activation of o-Propargyl Alcohol Benzaldehydes under Acetalization Conditions for Intramolecular Electrophile Intercepted Meyer-Schuster Rearrangement

The reactivity of o-propargyl alcohol benzaldehydes has been increased tremendously toward Brønsted acid-catalyzed intramolecular electrophile intercepted Meyer-Schuster (M-S) rearrangement under acetalization conditions using trimethyl orthoformate (TMOF). The in situ formed acetal transfers the methoxy group intramolecularly to generate the M-S intermediate in even less reactive substrates, and the formed oxocarbenium ion makes the carbonyl more electrophilic for an effective intramolecular trapping of the M-S intermediate to furnish the indanone derivatives.

Concise Six-Step Asymmetric Approach to Ramelteon from an Acetophenone Derivative Using Ir, Rh, Cu, and Ni Catalysis

A concise six-step asymmetric synthesis of nearly enantiomerically pure ramelteon was developed from a monocyclic precursor with a 17% overall yield and a 97% ee in the asymmetric step. The synthetically challenging tricyclic 1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan core of ramelteon was assembled by using Ir-catalyzed O-vinylation and Rh-catalyzed vinyl ether annulation through directed C–H bond activation, while the chirality was introduced with enantioselective reduction of an α,β-unsaturated nitrile moiety under hydrosilylation conditions using a Cu^II/Walphos type catalyst. The presented methodology represents the shortest synthetic approach to ramelteon.

Hydrogen radical-shuttle (HRS)-enabled photoredox synthesis of indanones via decarboxylative annulation

Hydrogen atom transfer (HAT) process is a powerful and effective strategy for activating C-H bonds followed by further functionalization. Intramolecular 1,n (n = 5 or 6)-HATs are common and frequently encountered in organic synthesis. However, intramolecular 1,n (n = 2 or 3)-HAT is very challenging due to slow kinetics. Compared to proton-shuttle process, which is well established for organic synthesis, hydrogen radical-shuttle (HRS) is unexplored. In this work, a HRS-enabled decarboxylative annulation of carbonyl compounds via photoredox catalysis for the synthesis of indanones is developed. This protocol features broad substrate scope, excellent functional group tolerance, internal hydrogen radical transfer, atom- and step-economy. Critical to the success of this process is the introduction of water, acting as both HRS and hydrogen source, which was demonstrated by mechanistic experiments and density functional theory (DFT) calculations. Importantly, this mechanistically distinctive HAT provides a complement to that of typical proton-shuttle-promoted, representing a breakthrough in hydrogen radical transfer, especially in the inherently challenging 1,2- or 1,3-HAT.

Although hydrogen atom transfer is widely observed in synthetic organic chemistry, intramolecular hydrogen atom transfer between atoms separated by fewer than four bonds is kinetically slow. Here the authors show a method to form indanones, with hydrogen atoms shuttled across short distances by water.

Synthesis of 2-(Cyanomethyl)benzoic Esters via Carbon-Carbon Bond Cleavage of Indanones

A novel synthesis of 2-(cyanomethyl)benzoic esters from indanone derivatives has been established. This reaction proceeds via a deprotonation of alcohols with a chemical base, followed by a nucleophilic addition to indanones and Beckmann fragmentation. In addition, this reaction could also work under electrochemical conditions, and no external chemical bases were needed. This mild method offers a novel strategy for the late-stage functionalization of various natural alcohols.

Tandem (2 + 2) Annulation/Retro-4π Electrocyclization/Imino-Nazarov Cyclization Reaction of p-Quinone Methides with Ynamides: Expeditious Construction of Functionalized Aminoindenes

A new tandem annulation of p-quinone methides (p-QMs) with ynamides is described. This cascade reaction features a unique combination of (2 + 2) annulation, retro-4π electrocyclization, and imino-Nazarov cyclization, wherein vinyl p-quinone methides (p-VQMs) as one of the key intermediates have been identified chemically. Significantly, an unusual structural reconstruction of p-QMs involving the cleavage of the C5-C6 bond and the late-stage formation of the C4-C6 bond is involved, leading to a methodology development for the construction of functionalized aminoindenes.

Advances of α-activated cyclic isothiocyanate for the enantioselective construction of spirocycles

The efficient and enantioselective synthesis of pharmaceutically important spirocycles has attracted the focus of organic and medicinal chemists. In this context, with the excellent reactivity of α-activated isothiocyanate as formal 1,3-dipoles in the (3 + 2) cyclization process, the cyclic isothiocyanates featuring important pharmacophores, such as oxindole, pyrazolone, and indanone moieties, have emerged as powerful precursors to access a variety of spirocycles with highly structural diversities. In addition, the facile transformations of these spirocycles have shown potential applications in drug design. This review will cover the recent advances of α-activated cyclic isothiocyanates in the enantioselective construction of spirocycles since 2015, and the applications of corresponding products in organic and medicinal chemistry.

Synthesis of Indanones and Spiroindanones by Diastereoselective Annulation Based on a Hydrogen Autotransfer Strategy

An unprecedented nickel-catalyzed domino reductive cyclization of alkynes and o-bromoaryl aldehydes is described. The reaction features broad substrate scope and is tolerant of a variety of functional groups, providing straightforward access to biologically significant indanones and spiroindanone pyrrolidine derivatives in good yields with excellent regio- and diastereoselectivity. Preliminary mechanistic studies have shown that indanones are formed by the cyclization of o-bromoaryl aldehydes and alkynes to form indenol intermediates, followed by hydrogen autotransfer.

Tunable Synthesis of Indeno[1,2-c]furans and 3-Benzoylindenones via FeCl3-Catalyzed Carbene/Alkyne Metathesis Reaction of o-Alkynylbenzoyl Diazoacetates

An efficient synthesis of indeno[1,2-c]furan and 3-benzoylindenone derivatives through a FeCl₃-catalyzed carbene/alkyne metathesis reaction of o-alkynylbenzoyl diazoacetates is presented. Mechanistically, the key intermediate, vinyl iron carbene, is formed by 5-exo-dig carbocyclization and terminated with a formal [3 + 2] cycloaddition or carbonylation. To the best of our knowledge, this is the first example in which FeCl₃ is used as a catalyst for a carbene/alkyne metathesis reaction. Finally, derivatization reactions were carried out to showcase the value of the products.

Rhodium-catalyzed enone carbonyl directed C–H activation for the synthesis of indanones containing all-carbon quaternary centers

Rhodium(iii)-catalyzed enone carbonyl directed C–H activation/annulation of α-aroyl ketene dithioacetals with diazo compounds has been realized for the synthesis of β-quaternary indanones.

Efficient kinetic resolution in the asymmetric transfer hydrogenation of 3-aryl-indanones: applications to a short synthesis of (+)-indatraline and a formal synthesis of (R)-tolterodine

Efficient kinetic resolution occurs in ATH of racemic 3-arylindanones using (R,R)-or (S,S)-Ts-DENEB catalyst and HCO₂H/Et₃N mixture providing near equal yields of cis-3-arylindanols and unreacted 3-arylindanones with excellent stereoselectivities.

Recent advances in transition-metal-catalyzed annulations for the construction of a 1-indanone core

Transition metal-catalyzed carbon–carbon bond forming reactions are a well accepted strategy for the synthesis of organic compounds. This review gives a brief update on the transition-metal-catalyzed annulations to construct 1-indanone scaffolds.

Regioselective cobalt(II)-catalyzed [2 + 3] cycloaddition reaction of fluoroalkylated alkynes with 2-formylphenylboronic acids: easy access to 2-fluoroalkylated indenols

[2 + 3] cycloaddition reactions of fluorinated alkynes with 2-formylphenylboronic acids under the influence of Co(acac)₂·2H₂O in two-component solvents of acetonitrile/2-propanol at reflux temperature for 18 h took place smoothly, affording the corresponding fluoroalkylated indenol derivatives in good yields. This reaction shows excellent regioselectivity, giving 2-fluoroalkylated indenols, together with a very small amount of 3-fluoroalkylated indanones as side products.

Synthesis of cyclopentaquinolinone and cyclopentapyridinone from ortho-alkynyl-N-arylaldehyde via superbase-promoted C-N, C-O and C-C bond formation

An environmentally benign, transition metal-free, superbase-mediated intramolecular annulation of o-alkynylaldehydes with primary amines forms highly functionalized amino-substituted cyclopentaquinolinones and cyclopentapyridinones via C-N, C-C, and C[double bond, length as m-dash]O bond formation. Contrary to the traditional approaches of ring closures, a different mode of annulation is disclosed. The protocol involves the in situ generations of imine intermediate followed by potassium hydroxide-promoted intramolecular cyclization and subsequent dimethyl sulfoxide induced dehydrogenation leads to the formation of N-heterocycles. X-ray crystallographic studies support the assigned structures of the amino-fused N-heterocycles.

Fischer Carbene Pentannulation with Alkynes Having Adjacent Carbonate or Acyloxy Groups: Synthesis of 3-Substituted 1-Indanones

Various aryl Fischer carbenes reacted with alkynes having adjacent acyloxy or carbonate groups to regioselectively deliver 3-substituted 1-indanones. The acyloxy or carbonate group probably coordinates with the Cr metal to give a tetra-coordinated chromium complex forming a six-membered ring that retards CO insertion for ketene formation, which is required for benzannulation. Alternatively, the ortho position aryl ring attack results in pentannulation, providing regioselectively 3-substituted 1-indanones. The method is extended to the synthesis of the core structure of 3-epi-mutisianthol.

Recent applications of ninhydrin in multicomponent reactions

Ninhydrin (1,2,3-indanetrione hydrate) has a remarkable breadth in different fields, including organic chemistry, biochemistry, analytical chemistry and the forensic sciences. For the past several years, it has been considered an important building block in organic synthesis. Therefore, there is increasing interest in ninhydrin-based multicomponent reactions to rapidly build versatile scaffolds. Most of the works described here are simple reactions with readily available starting materials that result in complex molecular architectures. Some of the synthesized compounds exhibit interesting biological activities and constitute a new hope for anticancer agents. The present review aims to highlight the multicomponent reactions of ninhydrin towards diverse organic molecules during the period from 2014 to 2019.

This article aims to review recent multicomponent reactions of ninhydrin towards diverse organic scaffolds, such as indeno-fused heterocycles, spiro-indeno heterocycles, quinoxalines, propellanes, cage-like compounds, and dispiro heterocycles.

Rhodium(iii)-catalyzed synthesis of 3-trifluoromethylindanones from N-methoxybenzamides via C–H activation and Claisen/retro-Claisen reaction

An efficient synthesis of 3-trifluoromethylindanones via C–H annulation of N-methoxybenzamides with β-trifluoromethyl-α,β-unsaturated ketones under Rh(iii)-catalysis is described.

Annulations involving 2-arylidene-1,3-indanediones: stereoselective synthesis of spiro- and fused scaffolds

Stereoselective annulations of 2-arylidene-1,3-indanediones towards spiro-carbocycles as well as spiro/fused heterocycles based on various cycloadditions and tandem annulations are described.

Migratory Aptitudes in Rearrangements of Destabilized Vinyl Cations

The Lewis acid-promoted generation of destabilized vinyl cations from β-hydroxy diazo ketones leads to an energetically favorable 1,2-shift across the alkene followed by an irreversible C-H insertion to give cyclopentenone products. This reaction sequence overcomes typical challenges of counter-ion trapping and rearrangement reversibility of vinyl cations and has been used to study the migratory aptitudes of nonequivalent substituents in an uncommon C(sp²) to C(sp) vinyl cation rearrangement. The migratory aptitude trends were consistent with those observed in other cationic rearrangements; the substituent that can best stabilize a cation more readily migrates. However, density functional theory calculations show that the situation is more complex. Selectivity in the formation of one conformational isomer of the vinyl cation and facial selective migration across the alkene due to an electrostatic interaction between the vinyl cation and the adjacent carbonyl oxygen work in concert to determine which group migrates. This study provides valuable insight into predicting migration preferences when applying this methodology to the synthesis of structurally complex cyclopentenones that are differentially substituted at the α and β positions.

Synthesis, Biological and In Silico Evaluation of Pure Nucleobase-Containing Spiro (Indane-Isoxazolidine) Derivatives as Potential Inhibitors of MDM2-p53 Interaction

Nucleobase-containing isoxazolidines spiro-bonded to an indane core have been synthesized in very good yields by regio- and diastereoselective 1,3-dipolar cycloaddition starting from indanyl nitrones and N-vinylnucleobases by using environmentally benign microwave technology. The contemporary presence of various structural groups that are individually active scaffolds of different typology of drugs, has directed us to speculate that these compounds may act as inhibitors of MDM2–p53 interaction. Therefore, both computational calculations and antiproliferative screening against A549 human lung adenocarcinoma cells and human SH-SY5Y neuroblastoma cells were carried out to support this hypothesis.

Diastereoselective Construction of 2-Aminoindanones via an In(OTf)3-Catalyzed Domino Reaction

An In(OTf)₃-catalyzed domino reaction involving sequential oxidative ring opening of aziridines by using the solvent dimethyl sulfoxide and intramolecular Michael addition has been developed for the modular synthesis of 2-aminoindanone compounds by the formation of one new C═O bond and one new C-C bond. The notable feature of this strategy includes broad substrate scope, excellent trans-diastereoselectivities, highly functionalized products, and mild conditions. The catalyst In(OTf)₃ plays an important role in the formation of the indanone ring.

Diastereoselective access to 2-aminoindanonesviathe rhodium(ii)-catalyzed tandem reaction involving O–H insertion and Michael addition

A rhodium(ii)-catalyzed tandem reaction involving O–H insertion ofN-sulfonyl 1,2,3-triazoles and Michael addition has been described. A series of 2-amino-1-indanones were afforded in acceptable to good yields with high diastereoselectivities.

Intramolecular Vinylation of Aryl Rings by Vinyl Cations

A Lewis acid mediated intramolecular electrophilic vinylation of aryl rings by vinyl cations is reported. This reaction takes advantage of β-hydroxy-α-diazo ketones as vinyl cation precursors and provides good yields of tricyclic 1-indenones that contain a seven-membered ring. Extending the alkane chain that tethers the vinyl cation to the aromatic ring leads to 2-napthol and 2-indenone products.