A general method for acylation of indoles at the 3-position with acyl chlorides in the presence of dialkylaluminum chloride

Boron Trifluoride Etherate Promoted Regioselective 3-Acylation of Indoles with Anhydrides

An efficient, high-yielding and scalable procedure for the regioselective 3-acylation of indoles with anhydrides promoted by boron trifluoride etherate under mild conditions was reported. This novel protocol provided a simple way to prepare 3-(benzofuran-2-yl) indole in three steps.

Dearomative (4 + 3) Cycloaddition Reactions of 3-Alkenylindoles and 3-Alkenylpyrroles to Afford Cyclohepta[b]indoles and Cyclohepta[b]pyrroles

The dearomative (4 + 3) cycloaddition reactions of 3-alkenylindoles with in situ-generated oxyallyl cations furnish cyclohepta[b]indoles, functionality-rich frameworks found in many bioactive compounds, including all pentacyclic ambiguine alkaloids. The analogous reactions between oxyallyl cations and 3-alkenylpyrroles afford cyclohepta[b]pyrroles. The cycloadducts are generally formed in good to high yields and diastereoselectivities and can be readily transformed into useful derivatives. Additionally, we report preliminary investigations into the enantioselective catalysis of the dearomative (4 + 3) cycloaddition using imidodiphosphorimidate catalysts.

(NH4)2S2O8-Mediated Metal-Free Decarboxylative Formylation/Acylation of α-Oxo/Ketoacids and Its Application to the Synthesis of Indole Alkaloids

A metal-free method for the formylation/acylation of indoles and β-carbolines with (NH₄)₂S₂O₈ via direct decarboxylative cross-coupling of α-oxo/ketoacids in moderate to good yields is described. The reaction occurs between ambient temperature and 40 °C under mild reaction conditions with commercially available starting materials. This methodology can be expanded to some biologically active indole alkaloids like pityriacitrins, eudistomins Y₁ and Y₃, and marinacarbolines A-D.

Adjusting and visualizing the stability of an acyl chloride through the delocalization effect and introducing AIEgens

Acyl chloride is an important functional group in acylation reactions, though its compounds are difficult to store and transport due to their high reactivity. In this research, phenanthro[9,10-d]imidazole is introduced into an acyl chloride agent of TPEPCl to enhance the stability via the delocalization effect. Meanwhile, rarely reported acyl chloride crystals have been achieved which could further prove its stability. The tetraphenylethylene group is also employed to visually monitor the changes of TPEPCl via fluorescent variation with the help of aggregation-induced emission (AIE) characteristics. The reactivity of TPEPCl could be stimulated by a strong alkaline solution or high temperature. Crystallography analyses of acyl TPE-PI derivatives are also discussed and the relationship between the delocalization structure and stability is determined. These findings help to stabilize, control and monitor the reactivities of active functional materials for applications.

Copper-Catalyzed Regiospecific Amination of Heteroarenes with Quinoneimides

In this work, an unprecedented and widely applicable strategy for the regioselective C-3 amination of indoles and C-2 amination of heteroarenes (pyrrole and benzofuran) is presented in a simple, high-efficiency way. This protocol is also one of the few methods for the efficient construction of C-N bonds of quinoneimides by the 1,6-addition reaction.

Palladium Metallaphotoredox-Catalyzed 3-Acylation of Indole Derivatives

Aldehydes and indoles generally undergo nucleophilic addition reactions to generate alcohols rather than ketones. Here, we report a method for synthesis of 3-acyl indoles from aldehydes by a combination of...

A General and Scalable Synthesis of Polysubstituted Indoles

A consecutive 2-step synthesis of N-unprotected polysubstituted indoles bearing an electron-withdrawing group at the C-3 position from readily available nitroarenes is reported. The protocol is based on the [3,3]-sigmatropic rearrangement of N-oxyenamines generated by the DABCO-catalyzed reaction of N-arylhydroxylamines and conjugated terminal alkynes, and delivers indoles endowed with a wide array of substitution patterns and topologies.

Rapid access to 3-acyl indoles using ethyl acetate/triflic acid couple as the acylium donor and Cu(OAc)2 catalysed aerial oxidation of indole benzoins

Esters are potential acyl donors but are relatively unexplored for that purpose. A facile installation of acyl groups at the C-3 position of indoles under triflic acid catalysed conditions with easily available and cheap esters as new acylating agents is described herein. Furthermore, heterocycles like N-protected pyrrole, furan and thiophene were also suitable substrates for similar C-2 acylation. Analogous C-3 benzoylated products of indole were obtained, albeit in lower yields, by using methyl benzoate as a benzoyl donor. The benzoylated products were synthesised in much better yields via a copper(ii) catalysed aerial oxidation of indole containing benzoins.

Synthesis of 3-acylindoles via copper-mediated oxidative decarbethoxylation of ethyl arylacetates

An efficient regioselective C-3 acylation of free indoles (N-H) has been accomplished via oxidative decarbethoxylation of easily available ethyl arylacetates using Cu(OAc)2 and KOtBu in DMSO.

Novel Notch signaling inhibitor NSI‑1 suppresses nuclear translocation of the Notch intracellular domain

The Notch receptor serves a fundamental role in the regulation of cell fate determination through intracellular signal transmission. Mutation of the Notch receptor results in abnormal active signaling, leading to the development of diseases involving abnormal cell growth, including malignant tumors. Therefore, the Notch signaling pathway is a useful pharmacological target for the treatment of cancer. In the present study, a compound screening system was designed to identify inhibitors of the Notch signaling targeting Notch intracellular domain (NICD). A total of 9,600 compounds were analyzed using the Michigan Cancer Foundation‑7 (MCF7) human breast adenocarcinoma cell line and the SH‑SY5Y human neuroblastoma cell line with the reporter assay system using an artificial protein encoding a partial Notch carboxyl‑terminal fragment fused to the Gal4 DNA‑binding domain. The molecular mechanism underlying the inhibition of Notch signaling by a hit compound was further validated using biochemical and cell biological approaches. Using the screening system, a potential candidate, Notch signaling inhibitor‑1 (NSI‑1), was isolated which showed 50% inhibition at 6.1 µM in an exogenous Notch signaling system. In addition, NSI‑1 suppressed the nuclear translocation of NICD and endogenous gene expression of hairy and enhancer of split‑1, indicating that NSI‑1 specifically targets Notch. Notably, NSI‑1 suppressed the cell viability of MCF7 cells and another human breast adenocarcinoma cell line, MDA‑MB‑231 exhibiting constitutive and high Notch signaling activity, whereas no significant effect was observed in the SH‑SY5Y cells bearing a lower Notch signaling activity. NSI‑1 significantly suppressed the viability of SH‑SY5Y cells expressing exogenous human Notch1. These results indicate that NSI‑1 is a novel Notch signaling inhibitor and suggest its potential as a useful drug for the treatment of diseases induced by constitutively active Notch signaling.

Selective N1-Acylation of Indazoles with Acid Anhydrides Using an Electrochemical Approach

An electrochemical synthesis method for the selective N1-acylation of indazoles has been developed. This "anion pool" approach electrochemically reduces indazole molecules generating indazole anions and H₂. Acid anhydrides are then introduced to the solution resulting in selective acylation of the N1-position of the indazoles. This procedure can also be applied to the acylation of benzimidazoles and indoles. The reaction can also be performed using a 9 V battery without loss of reaction efficiency.

Recent Advances in the Addition of Amide/Sulfonamide Bonds to Alkynes

The addition of amide/sulfonamide bonds to alkynes is not only one of the most important strategies for the direct functionalization of carbon⁻carbon triple bonds, but also a powerful tool for the downstream transformations of amides/sulfonamides. The present review provides a comprehensive summary of amide/sulfonamide bond addition to alkynes, including direct and metal-free aminoacylation, based-promoted aminoacylation, transition-metal-catalyzed aminoacylation, organocatalytic aminoacylation and transition-metal-catalyzed aminosulfonylation of alkynes up to December 2018. The reaction conditions, regio- and stereoselectivities, and mechanisms are discussed and summarized in detail.

Ruthenium(ii)-catalyzed selective C–H bond activation of imidamides and coupling with sulfoxonium ylides: an efficient approach for the synthesis of highly functional 3-ketoindoles

Ruthenium-catalyzed selective C–H bond activation of imidamides and annulation of sulfoxonium ylides were achieved, which afforded a series of 3-ketoindole derivatives in good yields, with good functional group compatibility.

Discovery of Indole Derivatives as Novel and Potent Dengue Virus Inhibitors

3-Acyl-indole derivative 1 was identified as a novel dengue virus (DENV) inhibitor from a DENV serotype 2 (DENV-2) phenotypic antiviral screen. Extensive SAR studies led to the discovery of new derivatives with improved DENV-2 potency as well as activity in nanomolar to micromolar range against the other DENV serotypes. In addition to the potency, physicochemical properties and metabolic stability in rat and human microsomes were improved during the optimization process. Chiral separation of the racemic mixtures showed a clear preference for one of the two enantiomers. Furthermore, rat pharmacokinetics of two compounds will be discussed in more detail, demonstrating the potential of this new series of pan-serotype-DENV inhibitors.

In vitro metabolism of synthetic cannabinoid AM1220 by human liver microsomes and Cunninghamella elegans using liquid chromatography coupled with high resolution mass spectrometry

Purpose

Identifying intake of synthetic cannabinoids generally requires the metabolism data of the drugs so that appropriate metabolite markers can be targeted in urine testing. However, the continuous appearance of new cannabinoids during the last decade has made it difficult to keep up with all the compounds including {1-[(1-methylpiperidin-2-yl)methyl]-1H-indol-3-yl}(naphthalen-1-yl)methanone (AM1220). In this study, metabolism of AM1220 was investigated with human liver microsomes and the fungus Cunninghamella elegans.

Methods

Metabolic stability of AM1220 was analysed by liquid chromatography–tandem mass spectrometry in multiple reaction monitoring mode after 1 µM incubation in human liver microsomes for 30 min. Tentative structure elucidation of metabolites was performed on both human liver microsome and fungal incubation samples using liquid chromatography–high-resolution mass spectrometry.

Results

Half-life of AM1220 was estimated to be 3.7 min, indicating a high clearance drug. Nine metabolites were detected after incubating human liver microsomes while seven were found after incubating Cunninghamella elegans, leading to 11 metabolites in total (five metabolites were common to both systems). Demethylation, dihydrodiol formation, combination of the two, hydroxylation and dihydroxylation were the observed biotransformations.

Conclusions

Three most abundant metabolites in both human liver microsomes and Cunninghamella elegans were desmethyl, dihydrodiol and hydroxy metabolites, despite different isomers of dihydrodiol and hydroxy metabolites in each model. These abundant metabolites can potentially be useful markers in urinalysis for AM1220 intake.

Iridium- and Rhodium-Catalyzed Directed C-H Heteroarylation of Benzaldehydes with Benziodoxolone Hypervalent Iodine Reagents

The C-H heteroarylation of benzaldehydes with indoles and pyrroles was realized using the benziodoxolone hypervalent iodine reagents indole- and pyrroleBX. Functionalization of the aldehyde C-H bond using either an o-hydroxy or amino directing group and catalyzed by an iridium or a rhodium complex allowed the synthesis of salicyloylindoles and (2-sulfonamino)benzoylindoles, respectively, with good to excellent yields (74-98%). This new transformation could be carried out under mild conditions (rt to 40 °C) and tolerated a broad range of functionalities, such as ethers, halogens, carbonyls, or nitro groups.

Regioselective direct arylation of indoles on the benzenoid moiety

Recent advances in transition metal-catalyzed selective C–H functionalization of indoles have garnered tremendous attention.

Oxidative organocatalytic chemoselective N-acylation of heterocycles with aromatic and conjugated aldehydes

The oxidative organocatalytic acylation of indoles with aldehydes serves as an alternative to sensitive acyl chlorides and coupling agents.

New Friedel–Crafts strategy for preparing 3-acylindoles

A new Friedel–Crafts acylation generates diverse high-biological value 3-acylindoles, and forms a new C–C bond under transition-metal-free conditions.

Direct and Selective 3-Amidation of Indoles Using Electrophilic N-[(Benzenesulfonyl)oxy]amides

Selective C-H amidation of 1H-indoles at the C3 position is reported as a direct entry to biologically important 3-aminoindoles. This transformation is achieved using novel N-[(benzenesulfonyl)oxy]amides as electrophilic nitrogen agents in the presence of ZnCl₂. Interestingly, analogous reactions in the absence of ZnCl₂ resulted in the formation of indole aminal products.

Direct C-2 acylation of indoles with toluene derivatives via Pd(ii)-catalyzed C–H activation

A simple and efficient Pd-catalyzed method for the C2-acylation of indoles is described using toluene derivatives.

Synthesis of 3-acylindoles by oxidative rearrangement of 2-aminochalcones using a hypervalent iodine reagent and cyclization sequence

An efficient one-pot 3-acylindole synthesis by oxidative rearrangement of 2-aminochalcones and sequential cyclization has been developed.

Collective Synthesis of 3-Acylindoles, Indole-3-carboxylic Esters, Indole-3-sulfinic Acids, and 3-(Methylsulfonyl)indoles from Free (N-H) Indoles via Common N-Indolyl Triethylborate

A general and direct C3 functionalization of free (N-H) indoles with readily available electrophiles such as acid chlorides, chloroformates, thionyl chloride, and methylsulfonyl chloride via a common N-indolyl triethylborate intermediate is reported. The reaction proceeds smoothly under mild conditions in up to 93% yield. Indoles with substituents at the C2, C4, C5, C6, and C7 positions are well tolerated. The easy accessibility of a variety of important 3-acylindoles, indole-3-carboxylic esters, indole-3-sulfinic acids, and 3-(methylsulfonyl)indoles demonstrates the high degree of compatibility and practicability of this method.

A new methodology for functionalization at the 3-position of indoles by a combination of boron Lewis acid with nitriles

We discovered that a reagent comprising a combination of PhBCl2 and nitriles was useful for syntheses of both 3-acylindoles and 1-(1H-indol-3-yl)alkylamine from indoles. The reaction proceeded selectively at the 3-position of indoles providing 3-acylindoles in moderate to high yields on treatment with the above reagent. Furthermore, the reaction provided the corresponding amine products in moderate to high yields after the intermediate imine was reduced by NaBH3CN. These reactions proceeded under mild conditions and are applicable to the formation of indoles functionalized at the 3-position.

Data on individual metabolites of synthetic cannabinoids JWH-018, JWH-073 and AM2201 by Cunninghamella elegans

Synthetic cannabinoids JWH-018, JWH-073 and AM2201 were metabolised by the fungus Cunninghamella elegans. In this article, data on individual metabolites of their retention times, mass accuracies, major product ions and structures indicated by product ions are presented. The data in this article is related to "Biotransformation of synthetic cannabinoids JWH-018, JWH-073 and AM2201 by Cunninghamella elegans" [1].