Regiodivergent Annulation Reactions of Chalcones to Indenones and Indanones with C1 Reagents

One-pot direct regiodivergent annulations of chalcones, as exemplified by the drug metochalcone and a bioactive dichloro-substituted chalcone with a quinoline ring, to indanones and indenones are conveniently achieved with single-carbon reagent Kukhtin-Ramirez adducts. A Cs2CO3-promoted unusual selective cleavage of the cyclopropyl C-C bond distal to the strong carbonyl acceptor, further driven to completion by follow-up regiodivergent annulations via Pd(OAc)2-catalyzed Heck reaction or Cs2CO3-mediated SNAr process, is key for the success.

Convenient one-step construction of fused or zwitterionic indanes from tetraynes

A straightforward technique has been developed for the construction of fused or zwitterionic indanes via a one-pot, cascade hexadehydro-Diels-Alder (HDDA) reaction of different functionalized tetraynes with nucleophilic reagents (vinyl carbazole or DMSO). The reaction proceeds under mild conditions with no metal catalysts, bases, or oxidants and exhibits excellent regioselectivity and high yields. A plausible reaction mechanism for the formation of zwitterionic indanes is proposed based on literatures and isolated fused indanes.

Mechanochemical Synthesis of Indene-Containing Spirolactones via Tf2O-Promoted Cascade Cyclization of 2-Benzoylbenzoic Acids with Arylalkynes

The Tf2O-promoted cascade cyclization of 2-benzoylbenzoic acids with arylalkynes was achieved under solvent-free ball-milling conditions. This process renders rapid entry to the rare indene-containing spirolactones via intramolecular cyclization of 2-benzoylbenzoic acids and subsequent annulation with arylalkynes, which resulted in one C-O and two C-C bond formations. As the reactions utilize easily available starting materials and proceed in the absence of organic solvents, the present protocol constitutes an expedient and environmentally friendly access to indene-containing spirolactones.

Base-Assisted and Silica Gel-Promoted Indole-Substituted Indene Synthesis

Herein, we report for the first time a transition-metal-free and mild protocol that requires inexpensive K2CO3 and silica gel for direct access to polysubstituted indenes from readily obtainable starting precursors. Notably, sequential Michael addition, intramolecular cyclization, and silica gel-promoted nucleophilic substitution reactions afford the desired products. A broad range of indoles and other aromatic nucleophiles are well-tolerated, affording indenes in moderate to good yields. Gratifyingly, indene could be easily converted into synthetically useful 3-indole-substituted indanone and indanol. Nonetheless, the successful isolation of a reaction intermediate highlights the crucial role of methanol in this reaction.

Novel Benzosuberone/Indanone-Linked Thiazoles as Small-Molecule SARS-CoV-2 Main Protease Inhibitors

Herein, novel benzosuberone/indanone-linked thiazoles were designed and synthesized as small-molecule SARS-CoV-2 Main protease (Mpro) inhibitors with potential anti-COVID activity. All thiazole derivatives were synthesized from the reaction of thiosemicarbazone derivatives with α-halocarbonyl derivatives. The structures of novel benzosuberone/indanone-linked thiazoles were confirmed based on their spectral data. Thiazolyl-benzosuberone 9d and thiazolyl-indanone 14 were the most potent against Mpro displaying one-digit IC50 values of 5.94 and 8.47 µM, respectively, compared to ritonavir (IC50 = 2.4 µM). Moreover, antiviral assay revealed the ability of compounds 9d and 14 to inhibit the replication of SARS-CoV-2 in Vero cells at EC50 values of 9.33 and 28.75 µM, respectively, relative to ritonavir (EC50 = 1.72 µM). Cytotoxicity assay in Vero cells was also conducted. 9d and 14 showed CC50 values of 289.63 and 229.42 µM and SI of 31.0 and 7.9, respectively. In addition, a docking study revealed proper orientation and well-fitting of title compounds into the binding pocket of SARS-CoV-2 Mpro.

Pd-Catalyzed Cross-Coupling of Cyclopropanols with 2-Br-p-Quinone Methides/2-Br-Cinnamate Esters Followed by a 1,6- and 1,4-Conjugate Addition Reaction

A novel cascade Pd-catalyzed cross-coupling reaction of cyclopropyl alcohol-derived ketone homoenolate with 2-Br-p-quinone methides and 2-Br-cinnamate esters followed by a 1,6- and 1,4-conjugate addition reaction is disclosed. This protocol converts various cyclopropyl alcohols into ketone homoenolate, which undergoes C-C bond formation by a cross-coupling reaction with 2-Br p-quinone methides and 2-Br-cinnamate esters. The salient features of this methodology include its operational simplicity, mild reaction conditions, an environmentally benign protocol, high efficiency, good to excellent yields, and a wide substrate scope.

Nucleophilic Substitution at Unactivated Arene C-H: Copper-Catalyzed anti-Selective Silylative Cyclization of Substituted Benzylacetylenes

A new mode of carbon-carbon bond formation via electrophilic activation of a C-H bond has been developed in the context of a copper-catalyzed anti-selective silylative cyclization of benzylacetylenes with silylboronates for the synthesis of 2-silyl-1H-indenes. The reaction proceeds with high regioselectivity for various substituted benzylacetylenes, and the resulting products could be further functionalized. The arene that undergoes cyclization acts as an electrophile with the release of hydride under redox neutral conditions, and the reaction mechanism was probed by the deuterium-labeling experiments and the density functional theory calculations.

Facile construction of benzofulvene frameworks via a palladium-catalysed three-component reaction

Here we report a three-component reaction of 2-formylarylboronic acids, N-sulfonyl amines and 1,3-enynes, proceeding through a cascade imine formation/Pd0-catalysed vinylogous addition/intramolecular Suzuki coupling/isomerization process. This protocol exhibited broad substrate scope and good functionality tolerance, and a spectrum of multifunctionalised benzofulvene derivatives were furnished in moderate to good yields and E/Z-selectivity.

Amide-derived enols in enol-Ugi reactions: expanding horizons for peptidomimetic scaffold synthesis

A highly efficient enol-Ugi reaction of β,β-diketoamides has been developed using a novel non-heterocyclic amide-stabilised enol. This approach enables a broad reaction scope, affording β-enaminoamide peptidomimetics with constrained conformations due to CH-π interaction and C(sp3)H⋯O hydrogen bonding. Notably, the use of a five-membered cyclic enol is crucial for achieving stable products in excellent yields. This work highlights the potential of the enol-Ugi reaction for constructing diverse peptidomimetic scaffolds.

Sustainable C-H Methylation Employing Dimethyl Carbonate

The use of CO2 and CO2-derived chemicals offers society sustainable and biocompatible chemistry for a variety of applications, ranging from materials to medicines. In this context, dimethyl carbonate (DMC) stands out owing to its low toxicity, high biodegradability, tunable reactivity, and sustainable production. Further, the ability of DMC to act as an ambient electrophile at varied temperatures and reaction conditions in order to produce methoxycarbonylated (via BAC2) and methylated products (via BAL2) is very promising. While the methylation of hetero-H (N-, O-, and S-methylation) with DMC is established and well-reviewed, the C-H methylation reaction with DMC is limited, and there is no specific literature detailing the C-methylation reaction using DMC, creating new opportunities as well as challenges in the same domain. In this context, the present perspective focuses on the new breakthroughs, recent advances, and trends in C-H methylation reactions employing DMC. A critical analysis of the mechanistic course of reactions under each category was undertaken. We believe this timely perspective will offer an in-depth analysis of existing literature with critical remarks, which will certainly inspire fellow researchers across disciplines to understand and pursue cutting-edge research in the area of C-H methylation (alkylation) using DMC and related organic carbonates.

Aliphatic Nitrile Template Enabled meta-C-H Olefination of Indene Enoate Esters under Microwave Accelerating Conditions

Site-selective activation of a particular remote C-H bond in molecules with multiple C-H bonds remains challenging in organic synthesis. In addition, evolving such transformations via the utilization of unconventional techniques is highly desirable. We demonstrated hitherto unexplored double bond geometry-guided and end-on nitrile-template-assisted meta-C-H functionalization of indene enoate esters under microwave-accelerated conditions. Significantly, the strategy exhibited broad compatibility concerning the substrates and olefin coupling partners. Remarkably, drug diversification has also been showcased.

Helicase-primase inhibitors for the treatment of herpes simplex virus infections - patent evaluation of WO2023/225162 from Gilead Sciences Inc

Helicase-primase is an interesting target for small-molecule therapy of herpes simplex virus (HSV) infections. With amenamevir already approved for varicella-zoster virus and herpes simplex in Japan and with pritelivir's granted breakthrough therapy designation for the treatment of acyclovir-resistant HSV infections in immunocompromised patients, the target has sparked interest in helicase-primase inhibitors (HPIs). Here, we analyze the first patent application from Gilead in this field, which pursued a me-too approach combining elements from an old Bayer together with a recent Medshine HPI application (which covers the Phaeno Therapeutics drug candidate HN0037). The asset was contributed to Assembly Biosciences, where it is under development as ABI-1179 at the investigational new drug (IND) enabling stage for high-recurrence genital herpes. A structure proposal for indolinoyl derivative ABI-1179 is presented, showing its potential opportunities and limitations compared to other HPIs.

Selective Synthesis of Boron-Functionalized Indenes and Benzofulvenes by BCl3-Promoted Cyclizations of ortho-Alkynylstyrenes

A selective, metal-free synthesis of boron-functionalized indenes and benzofulvenes via BCl3-mediated cyclization of o-alkynylstyrenes is described. The method allows precise control over product formation by adjusting reaction conditions. These borylated products were utilized in diverse C-B bond derivatizations and in the total synthesis of Sulindac, a nonsteroidal anti-inflammatory drug, demonstrating the versatility and practicality of the developed methodology for synthetic applications.

Denitrogenative dismantling of heteroaromatics by nucleophilic substitution reactions with diazomethyl compounds

Nucleophiles from deprotonation of diazomethyl compounds having diverse electron withdrawing groups react with 4-carboxylato-1,2,3-triazines at the 6-position to extrude dinitrogen and produce diazovinylketoesters compounds with five or six linear contiguous sp2-hybridized carbons, whereas these same nucleophiles react with 4-carboxylato-1,2,3-triazine 1-oxides, also at the 6-position, to form pyrazolines with the expulsion of nitrous oxide and cyanocarboxylate. This disparity is due to the significant difference in reactivity of the nucleophilic addition products.

Replacement of sulfonamide by sulfoximine within a helicase-primase inhibitor with restricted flexibility

Helicase-primase is an interesting target for the therapy of herpes simplex virus (HSV) infections. Since amenamevir is already approved for varicella-zoster virus (VZV) and HSV in Japan and pritelivir has received breakthrough therapy status for the treatment of acyclovir-resistant HSV infections in immunocompromised patients, the target has sparked interest in me-too approaches. Here, we describe the attempt to improve nervous tissue penetration in Phaeno Therapeutics drug candidate HN0037 to target the latent reservoir of HSV by installing less polar moieties, mainly a difluorophenyl instead of a pyridyl group, and replacing the primary sulfonamide with a methyl sulfoximine moiety. However, all obtained stereoisomers exhibited a weaker inhibitory activity on HSV-1 and HSV-2.

Site-selective synthesis of indanyl-substituted indole derivatives via 1,3-dithiane induced Nazarov cyclization

We report an efficient site-selective synthetic method to C2 and C3 indanyl-substituted indole derivatives via 1,3-dithianyl induced Nazarov-type cyclization. In particular, C2-selective indanyl-substituted indoles were directly obtained by a BF3·Et2O-promoted sequence of intramolecular C3-C2 migration and Nazarov-type cyclization process.

Ring expansion of indene by photoredox-enabled functionalized carbon-atom insertion

Skeletal editing has received unprecedented attention as an emerging technology for the late-stage manipulation of molecular scaffolds. The direct achievement of functionalized carbon-atom insertion in aromatic rings is challenging. Despite ring-expanding carbon-atom insertion reactions, such as the Ciamician-Dennstedt re-arrangement, being performed for more than 140 years, only a few relevant examples of such transformations have been reported, with these limited to the installation of halogen, ester and phenyl groups. Here we describe a photoredox-enabled functionalized carbon-atom insertion reaction into indene. We disclose the utilization of a radical carbyne precursor that facilitates the insertion of carbon atoms bearing a variety of functional groups, including trifluoromethyl, ester, phosphate ester, sulfonate ester, sulfone, nitrile, amide, aryl ketone and aliphatic ketone fragments to access a library of 2-substituted naphthalenes. The application of this methodology to the skeletal editing of molecules of pharmaceutical relevance highlights its utility.

Synthesis and Insecticidal Activity of Novel Anthranilic Diamide Insecticides Containing Indane and Its Analogs

Diamide insecticides have always been a hot research topic in the field of pesticides. To further discover new compounds with high activity and safety, indane and its analogs were introduced into chlorantraniliprole, and a battery of chlorfenil derivatives, including indane and its analogs, were designed and prepared for biological testing. Their characterization and verification were carried out through nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). Biological detection showed that all the compounds exhibited good insecticidal activity against Mythimna separata. At 0.8 mg/L, the insecticidal activity of compound 8q against Mythimna separata was 80%, which was slightly better than that of chlorantraniliprole. The results of the structure-activity relationship (SAR) analysis indicated that the indane moiety had a significant effect on insecticidal activity, especially in the R-configuration. The results indicated that chlorantraniliprole derivatives containing indane groups could serve as pilot compounds for the further development of new insecticides.

Methylene C(sp3 )-H Arylation Enables the Stereoselective Synthesis and Structure Revision of Indidene Natural Products

The divergent synthesis of two indane polyketides of the indidene family, namely (±)-indidene A (11 steps, 1.7 %) and (+)-indidene C (13 steps, 1.3 %), is reported. The synthesis of the trans-configured common indane intermediate was enabled by palladium(0)-catalyzed methylene C(sp3 )-H arylation, which was performed in both racemic and enantioselective (e.r. 99 : 1) modes. Further elaboration of this common intermediate by nickel-catalyzed dehydrogenative coupling allowed the rapid installation of the aroyl moiety of (±)-indidene A. In parallel, the biphenyl system of (±)- and (+)-indidene C was constructed by Suzuki-Miyaura coupling. These investigations led us to revise the structures of indidenes B and C.

Transition-Metal-Catalyzed Dehydrogenative (3 + 2) Annulation of Aromatic Compounds: Synthesis of Indenes and Indanes via Dual Functionalization of Benzylic and ortho C-H Bonds

Intermolecular (3 + 2) annulation emerges as a potent approach for constructing 5-membered carbocycles through the fusion of two distinct components. This synopsis encapsulates recent strides in the realm of transition-metal-catalyzed dehydrogenative (3 + 2) annulation of aromatic hydrocarbons, achieved through the dual functionalization of benzylic and ortho C-H bonds. Encompassing three pivotal strategies, namely, (i) C-H bond activation, (ii) benzylic oxidation, and (iii) π-coordination activation, this review offers an overview of the field's recent developments.

Sulfoxides in medicine

In the review, current status of sulfoxides on the pharmaceutical market is discussed. In the first part of the article, natural sulfoxides will be described with a special focus on sulforaphane and amanitin, a mushroom toxin which has been developed as payload in antibody drug conjugates in the possible cancer treatment. Controversies associated with the medical use of dimethylsulfoxide are briefly described in the next section. In the part devoted to PPIs, the benefits of using pure enantiomers (chiral switch) are discussed. An interesting approach, repositioning of drugs is exemplified by new possible applications of modafinil and sulindac. The review is concluded by presentation of cenicriviroc and adezmapimod, both with the status of promising drug candidates.

Drug-Delivery Silver Nanoparticles: A New Perspective for Phenindione as an Anticoagulant

Anticoagulants prevent the blood from developing the coagulation process, which is the primary cause of death in thromboembolic illnesses. Phenindione (PID) is a well-known anticoagulant that is rarely employed because it totally prevents coagulation, which can be a life-threatening complication. The goal of the current study is to synthesize drug-loaded Ag NPs to slow down the coagulation process. Methods: A rapid synthesis and stabilization of silver nanoparticles as drug-delivery systems for phenindione (PID) were applied for the first time. Results: Several methods are used to determine the size of the resulting Ag NPs. Additionally, the drug-release capabilities of Ag NPs were established. Density functional theory (DFT) calculations were performed for the first time to indicate the nature of the interaction between PID and nanostructures. DFT findings supported that galactose-loaded nanostructure could be a proper delivery system for phenindione. The drug-loaded Ag NPs were characterized in vitro for their antimicrobial, cytotoxic, and anticoagulant activities, and ex vivo for spasmolytic activity. The obtained data confirmed the drug-release experiments. Drug-loaded Ag NPs showed that prothrombin time (PT, sec) and activated partial thromboplastin time (APTT, sec) are approximately 1.5 times longer than the normal values, while PID itself stopped coagulation at all. This can make the PID-loaded Ag NPs better therapeutic anticoagulants. PID was compared to PID-loaded Ag NPs in antimicrobial, spasmolytic activity, and cytotoxicity. All the experiments confirmed the drug-release results.

The Chameleonic Nature of the Nitro Group Applied to a Base-Promoted Cascade Reaction To Afford Indane-Fused Dihydrofurans

We disclose a Michael/Conia-ene/SN2 cascade reaction for the synthesis of Indane-fused dihydrofurans from 1,3-dicarbonyl compounds and 2-alkynylnitrostyrenes promoted by potassium carbonate in DMSO at room temperature. In this reaction, the nitro group has a chameleonic role, first as an electron-withdrawing group for the Michael addition, then the nitronate behaves as a nucleophile, and finally, the allylic nitro acts as a leaving group. The product is obtained as a single diastereomer, affording up to 82% with 1,3-keto esters and 58% with 1,3-diketones. Furthermore, DFT calculations of the reaction mechanism explained the chemoselective addition of the nitronate over the enolate to the unactivated triple bond, with the enolate addition being highly endothermic.

A Mechanistically Deceiving Formation of Aryl(1-indanyl)ketones via Acid-Catalyzed Cyclization of ortho-Alkynylarylmethanols

The generation of reactive carbocation intermediates from ortho-alkynylarylmethanol substrates was utilized as a means for the synthesis of aryl(1-indanyl)ketones . Substrates with a tertiary carbon at the β-position to the arene generated a carbocation intermediate via dehydration/protonation, followed by cyclization and hydration to give indanylketone products. For substrates with a quaternary carbon at that position, a carbocation intermediate was generated by protonation/elimination of water, followed by a 1,2-shift and a subsequent cyclization/hydration to give highly substituted indanylketones.

Antioxidative Indenone and Benzophenone Derivatives from the Mangrove-Derived Fungus Cytospora heveae NSHSJ-2

Seven new polyketides, including four indenone derivatives, cytoindenones A–C (1, 3–4), 3′-methoxycytoindenone A (2), a benzophenone derivative, cytorhizophin J (6), and a pair of tetralone enantiomers, (±)-4,6-dihydroxy-5-methoxy-α-tetralone (7), together with a known compound (5) were obtained from the endophytic fungus Cytospora heveae NSHSJ-2 isolated from the fresh stem of the mangrove plant Sonneratia caseolaris. Compound 3 represented the first natural indenone monomer substituted by two benzene moieties at C-2 and C-3. Their structures were determined by the analysis of 1D and 2D NMR, as well as mass spectroscopic data, and the absolute configurations of (±)-7 were determined on the basis of the observed specific rotation value compared with those of the tetralone derivatives previously reported. In bioactivity assays, compounds 1, 4–6 showed potent DPPH· scavenging activities, with EC50 values ranging from 9.5 to 16.6 µM, better than the positive control ascorbic acid (21.9 µM); compounds 2–3 also exhibited DPPH· scavenging activities comparable to ascorbic acid.

Novel Indane Derivatives with Antioxidant Activity from the Roots of Anisodus tanguticus

Four novel indane derivatives, anisotindans A-D (1-4), were isolated from the roots of Anisodus tanguticus. Their structures were established using comprehensive spectroscopic analyses, and their absolute configurations were determined by electronic circular dichroism (ECD) calculations and single-crystal X-ray diffraction analyses. Anisotindans C and D (3 and 4) are two unusual indenofuran analogs. ABTS^•+ and DPPH^•+ assays of radical scavenging activity reveal that all compounds (1-4) are active. Specifically, the ABTS^•+ assay results show that anisotindan A (1) exhibits the best antioxidant activity with an IC₅₀ value of 15.62 ± 1.85 μM (vitamin C, IC₅₀ = 22.54 ± 5.18 μM).

Comprehensive Overview of β-Methoxyacrylate Derivatives as Cytochrome bc1 Inhibitors for Novel Pesticide Discovery

β-Methoxyacrylate derivatives represent a new class of pesticides, which have attracted increasing attention owing to their unique structure, broad biological activity, and unique mechanisms of action. They inhibit mitochondrial respiration via preventing electron transfer at the Qo site of the cytochrome bc₁ complex and thus are identified as cyt bc₁ inhibitors. A variety of β-methoxyacrylate derivatives have been reported by many research groups for discovery of novel pesticides with improved expected activities. This review focuses on development of β-methoxyacrylate derivatives with great significance as pesticides such as fungicides, acaricides, insecticides, herbicides, and antiviral agents. In addition, the structure-activity relationships (SARs) of β-methoxyacrylate derivatives are summarized. Moreover, the cause of resistance to β-methoxyacrylate fungicides and some solutions are also introduced. Finally, the development trend of β-methoxyacrylate derivatives as pesticides is explored. We hope the review will give a guide to develop novel β-methoxyacrylate pesticides in the future.

Enantioselective Synthesis of Bispiro[indanedione-oxindole-cyclopropane]s through Organocatalytic [2+1] Cycloaddition

A series of compounds featuring a novel bispiro[indanedione-oxindole-cyclopropane] moiety have been synthesized through a squaramide-catalyzed [2+1] cycloaddition reaction. The tandem Michael-alkylation reaction of 2-arylidene-1,3-indanediones with 3-bromooxindoles furnished the cycloadducts in high yields with excellent diastereo- and enantioselectivities. The ammonium ylide in the catalytic process, as a key intermediate, was revealed by the high-resolution mass spectrometry study.

4b-Aryltetrahydroindeno[1,2-a]indenes by Acid-Catalyzed Trans­annular Cyclization of Benzannulated Cyclooctene Alcohols

By starting from two simple building blocks, benzannulated cyclooctenones were obtained in three steps. Subsequent Grignard/aryl lithium addition to the ketone yielded the corresponding tertiary alcohols that underwent stereoselective acid-catalyzed transannular cyclization to provide a cis-fused 5/5 bicyclic indanylindane framework exclusively. Subsequent stereoselective nucleophilic addition to the indanyl cation by hydride, water, or electron-rich aromatics furnished the 4b-aryltetrahydroindano[1,2-a]indenes in good to excellent yields (up to 92%) in the trans-C9–C9a form in up to a >99:1 diastereomeric ratio.

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins have been developed to afford chiral dispiro[indene-pyrrolidine-pyrimidine]s. Through this strategy, the target products could be obtained in good to excellent yields with excellent stereoselectivities. In addition, the synthetic utility was verified through a gram-scale synthesis, one-pot three-component reactions and further transformation experiments of the products.

Reactions of linear conjugated dienone structures with arenes under superelectrophilic activation conditions. An experimental and theoretical study of intermediate multicentered electrophilic species

Reactions of conjugated dienones with arenes under superelectrophilic activation conditions result in the formation of conjugated enones, indanes, and carbocyclic structures.

An Efficient Merging of DBU/Enolate and DBU/Benzyl Bromide Organocycles for the Synthesis of alpha Benzylated1-Indanone Derivatives

The merging of dual organocycles of the bicyclic amidine base 1,8-diazabicyclo[5.4.0]undec-7-en (DBU) was demonstrated for the synthesis of alpha benzylated 1-indanones. A highly reactive enolate intermediate was formed in the...

Triflic Acid-Catalyzed Synthesis of Indole-Substituted Indane Derivatives via In Situ Formed Acetal-Facilitated Nucleophilic Addition and 4π-Electron-5-Carbon Electrocyclization Sequence

An efficient protocol for the synthesis of indole-substituted indanes from o-alkenylbenzaldehydes under acetalization conditions has been presented. The cyclization occurs via a nucleophilic addition of indole on the oxacarbenium ion generated from acetal formed under the reaction condition followed by a conrotatory 4π-electrocyclization reaction, which takes care of the exclusive diastereoselectivity observed during the cyclization step. Olefin geometry of o-alkenylbenzaldehyde and the amount of indole play a decisive role in the success of this cyclization process.

Design, Synthesis and Late-Stage Modification of Indane-Based Peptides via [2+2+2] Cyclotrimerization

Here, we prepared several dipeptides containing 2-aminoindane-2-carboxylic acid (Aic) and carried out further synthetic transformations. Synthesis and purification of modified peptides by using [2+2+2] cyclotrimerization is a challenging task. We are able to modify the unusual amino acids and peptide derivatives by late-stage incorporation of benzylhalo functionality. To incorporate benzylhalo moiety we used [2+2+2] cyclotrimerization in the presence of Mo(CO)₆ . These halo derivatives are potential substrates for further modification by Sonogashira reaction, Suzuki-Miyaura cross-coupling, sultine formation, and the Diels-Alder reaction sequence.

Synthesis of 1-Trifluorometylindanes and Close Structures: A Mini Review

This review describes methods for the synthesis of 1-trifluomethylindanes and close structures, which are still quite rare and scarcely available compounds. There are two main approaches to obtain 1-CF3-indanes. The first one is the construction of an indane system from CF3 precursors; the main methods are acid-mediated Friedel–Crafts cyclization, transition metal-catalyzed [3+2] annulation, and free-radical transformations. The second approach is the trifluoromethylation of a ready-made indane core by various CF3 sources, such as Ruppert–Prakash or Togni reagents. Many of these synthetic procedures possess high regio- and stereo-selectivity, allowing the preparation of unique 1-CF3-indane structures. In recent years, great attention has been paid to the synthesis of 1-CF3-indanes, due to the discovery of important biologically active properties for these compounds.