Novel 3-aryl indoles as progesterone receptor antagonists for uterine fibroids

Enantioselective synthesis of chiral α,α-dialkyl indoles and related azoles by cobalt-catalyzed hydroalkylation and regioselectivity switch

General, catalytic and enantioselective construction of chiral α,α-dialkyl indoles represents an important yet challenging objective to be developed. Herein we describe a cobalt catalyzed enantioselective anti-Markovnikov alkene hydroalkylation via the remote stereocontrol for the synthesis of α,α-dialkyl indoles and other N-heterocycles. This asymmetric C(sp3)-C(sp3) coupling features high flexibility in introducing a diverse set of alkyl groups at the α-position of chiral N-heterocycles. The utility of this methodology has been demonstrated by late-stage functionalization of drug molecules, asymmetric synthesis of bioactive molecules, natural products and functional materials, and identification of a class of molecules exhibiting anti-apoptosis activities in UVB-irradiated HaCaT cells. Ligands play a vital role in controlling the reaction regioselectivity. Changing the ligand from bi-dentate L6 to tridentate L12 enables CoH-catalyzed Markovnikov hydroalkylation. Mechanistic studies disclose that the anti-Markovnikov hydroalkylation involves a migratory insertion process while the Markovnikov hydroalkylation involves a MHAT process.

Organocatalyzed [4 + 2] cycloaddition of α,β-unsaturated ketones and isatylidene malononitrile: accessing spiro[3-arylcyclohexanone]oxindole derivatives

Herein, we developed a series of compounds featuring spiro[3-arylcyclohexanone]oxindoles through Barbas [4 + 2] cycloaddition reactions between isatylidene malononitrile and α,β-unsaturated ketones using l-proline as an organocatalyst. The reported methodology offers many advantages such as mild reaction conditions, diverse substrate scope with high yields, easy reaction setup, and use of easily synthesizable starting materials.

Ag(I)-catalyzed cyclization of o-alkynylacetophenones facilitated through acetal formation: synthesis of C3-naphthyl indole derivatives

A mild method for an efficient synthesis of C3-naphthyl indoles from o-alkynylacetophenones has been developed. This Ag-catalyzed transformation is assisted by the acetal formed under the reaction condition employing trimethyl orthoformate (TMOF). The role of acetal in promoting the reaction under ambient conditions has been established with control experiments. A range of C3-naphthyl indole derivatives have been synthesized in moderate to very good yields.

StackPR is a new computational approach for large-scale identification of progesterone receptor antagonists using the stacking strategy

Progesterone receptors (PRs) are implicated in various cancers since their presence/absence can determine clinical outcomes. The overstimulation of progesterone can facilitate oncogenesis and thus, its modulation through PR inhibition is urgently needed. To address this issue, a novel stacked ensemble learning approach (termed StackPR) is presented for fast, accurate, and large-scale identification of PR antagonists using only SMILES notation without the need for 3D structural information. We employed six popular machine learning (ML) algorithms (i.e., logistic regression, partial least squares, k-nearest neighbor, support vector machine, extremely randomized trees, and random forest) coupled with twelve conventional molecular descriptors to create 72 baseline models. Then, a genetic algorithm in conjunction with the self-assessment-report approach was utilized to determine m out of the 72 baseline models as means of developing the final meta-predictor using the stacking strategy and tenfold cross-validation test. Experimental results on the independent test dataset show that StackPR achieved impressive predictive performance with an accuracy of 0.966 and Matthew’s coefficient correlation of 0.925. In addition, analysis based on the SHapley Additive exPlanation algorithm and molecular docking indicates that aliphatic hydrocarbons and nitrogen-containing substructures were the most important features for having PR antagonist activity. Finally, we implemented an online webserver using StackPR, which is freely accessible at http://pmlabstack.pythonanywhere.com/StackPR. StackPR is anticipated to be a powerful computational tool for the large-scale identification of unknown PR antagonist candidates for follow-up experimental validation.

HOAc catalyzed three-component reaction for the synthesis of 3,3'-(arylmethylene)bis(1H-indoles)

An efficient HOAc catalyzed three-component reaction of 2-(arylethynyl)anilines with arylaldehydes has been achieved, which leads to the generation of 3,3'-(arylmethylene)bis(1H-indoles) with good to excellent yields and high regioselectivity under transition-metal-free conditions. Four new C-C and C-N bonds were effectively formed in a one-pot procedure. Subsequent research on the reaction mechanism indicated that the reaction likely involved the processes of intramolecular cyclization and cascade intermolecular dehydration condensation.

Synthesis of meta-(Indol-3-yl)phenols from Indoles and Cyclohexenone via Palladium(II)-Catalyzed Oxidative Heck Reaction and Dehydrogenative Aromatization in a One-Step Sequence

Facile construction of a meta-(indol-3-yl)phenol framework with a wide substrate scope (a total of 25 compounds) via a palladium(II)-catalyzed oxidative Heck reaction and dehydrogenative aromatization in a one-step sequence is reported. This methodology affords a novel route for the privileged structures that are challenging to access via a direct link between indole and phenol, in a highly efficient and atom-economical manner.

Air oxidized activated carbon catalyst for aerobic oxidative aromatizations of N-heterocycles

Air oxidized activated carbon offers a robust, efficient, metal-free and recyclable catalyst for aromatizations of N-heterocycles, O2 being the terminal oxidant.

Arylation of indoles using cyclohexanones dually-catalyzed by niobic acid and palladium-on-carbons

3-Arylindoles were easily constructed from indoles and cyclohexanone derivatives using a combination of catalytic niobic acid-on-carbon (Nb₂O₅/C) and palladium-on-carbon (Pd/C) under heating conditions without any oxidants. The Lewis acidic Nb₂O₅/C promoted the nucleophilic addition of indoles to the cyclohexanones, and the subsequent dehydration and Pd/C-catalyzed dehydrogenation produced the 3-arylindoles. The additive 2,3-dimethyl-1,3-butadiene worked as a hydrogen acceptor to facilitate the dehydrogenation step.

Metal-free and regiospecific synthesis of 3-arylindoles

A convenient, metal-free, and organic acid-base promoted synthetic method to prepare 3-arylindoles from 3-aryloxirane-2-carbonitriles and arylhydrazine hydrochlorides has been developed. In the reaction, the organic acid catalyzes a tandem nucleophilic ring-opening reaction of aryloxiranecarbonitriles and arylhydrazine hydrochlorides and Fischer indolization. The organic base triethylamine plays a crucial role in the final elimination step in the Fischer indole synthesis, affording 3-arylindoles regiospecifically. The reaction features advantages of microwave acceleration, non-metal participation, short reaction time, organic acid-base co-catalysis, and broad substrate scope.

Synthesis of Tridentate [1,2,4] Triazinyl-Pyridin-2-yl Indole Lewis Basic Complexants via Pd-Catalyzed Suzuki-Miyaura Cross-Coupling

Full closure of the nuclear fuel cycle is predicated, in part, on defining efficient separations processes for the effective speciation of the neutron-absorbing lanthanides from the minor actinides post-PUREX. Pursuant to the aforementioned, a class of tridentate, Lewis basic procomplexants have been prepared leveraging a Pd-catalyzed Suzuki-Miyaura cross-coupling between 6-bromo-[1,2,4]-triazinylpyridine derivatives and various protected indole-boronic acids to afford functionalized 2-[6-(5,6-diphenyl-[1,2,4]triazin-3-yl)-pyridin-2-yl]-1H-indoles. A highly active catalyst/ligand system with low loadings was employed rapidly affording 26 examples in yields as high as 85%. Method optimization, substrate and indole scope, comparative analysis between coupling reagents, and a scale-up experiment are reported.

Design, Synthesis and Biological Evaluation of Novel Nonsteroidal Progesterone Receptor Antagonists Based on Phenylamino-1,3,5-triazine Scaffold

We report here the development of phenylamino-1,3,5-triazine derivatives as novel nonsteroidal progesterone receptor (PR) antagonists. PR plays key roles in various physiological systems, including the female reproductive system, and PR antagonists are promising candidates for clinical treatment of multiple diseases. By using the phenylamino-1,3,5-triazine scaffold as a template structure, we designed and synthesized a series of 4-cyanophenylamino-1,3,5-triazine derivatives. The synthesized compounds exhibited PR antagonistic activity, and among them, compound 12n was the most potent (IC₅₀ = 0.30 µM); it also showed significant binding affinity to the PR ligand-binding domain. Docking simulation supported the design rationale of the compounds. Our results suggest that the phenylamino-1,3,5-triazine scaffold is a versatile template for development of nonsteroidal PR antagonists and that the developed compounds are promising lead compounds for further structural development of nonsteroidal PR antagonists.

Divergent Functionalization of N-Alkyl-2-alkenylanilines: Efficient Synthesis of Substituted Indoles and Quinolines

An efficient divergent functionalization of N-alkylated ortho-alkenylanilines to substituted indoles and quinolines has been accomplished by employing rhodium-catalyzed cross-dehydrogenative coupling and silver-mediated oxidative cyclization, respectively. The developed methods tolerate various functional groups and allow the synthesis of substituted indoles and quinolines in good to excellent yield. Synthetic utility is demonstrated through conversion to an indole with antimicrobial activity and C-H bond functionalization of 2-arylquinolines. Furthermore, a plausible mechanism was proposed based on preliminary mechanistic investigations.

Novel Nonsteroidal Progesterone Receptor (PR) Antagonists with a Phenanthridinone Skeleton

The progesterone receptor (PR) plays an important role in various physiological systems, including female reproduction and the central nervous system, and PR antagonists are thought to be effective not only as contraceptive agents and abortifacients but also in the treatment of various diseases, including hormone-dependent cancers and endometriosis. Here, we identified phenanthridin-6(5H)-one derivatives as a new class of PR antagonists and investigated their structure-activity relationships. Among the synthesized compounds, 37, 40, and 46 exhibited very potent PR antagonistic activity with high selectivity for PR over other nuclear receptors. These compounds are structurally distinct from other nonsteroidal PR antagonists, including cyanoaryl derivatives, and should be useful for further studies of the clinical utility of PR antagonists.

Synthesis of topologically constrained naphthalimide appended palladium(ii)–N-heterocyclic carbene complexes – insights into additive controlled product selectivity

Pd(ii)–NHC catalyzed regioselective heteroannulation of o-haloanilines and arylethynyl-trimethylsilane to yield indoles and additive controlled switchable product selectivity has been demonstrated.

Aerobic oxidative amidation of alkynes using titanium oxide encapsulated cuprous iodide nanoparticles (CuI@TiO2)

A catalyst consisting of titanium oxide encapsulated cuprous iodide nanoparticles was prepared via a sol–gel method using inexpensive raw materials and was harnessed successfully in the oxidative amidation of alkynes via an environmentally benign and sustainable protocol.

Electronic effect of substituents on anilines favors 1,4-addition totrans-β-nitrostyrenes: access toN-substituted 3-arylindoles and 3-arylindoles

A simple and an efficient method for the regioselective synthesis ofN-alkyl/aryl/H 3-arylindole derivatives fromN-substituted anilines andtrans-β-nitrostyrenes has been described using 10 mol% of bismuth(iii) triflate as a catalyst in acetonitrile at 80 °C.

Transition-Metal-Free C3 Arylation of Indoles with Aryl Halides

We report an unprecedented transition metal-free coupling of indoles with aryl halides. The reaction is promoted by KOtBu and is regioselective for C3 over N. The use of degassed solvents devoid of oxygen is necessary for the success of the transformation. Preliminary studies implicate a hybrid mechanism that involves both aryne intermediates and non-propagative radical processes. Electron transfer is also a distinct possibility. These conclusions were substantiated by EPR data, isotopic labeling studies, and the use of radical scavengers and electron transfer inhibitors.

Synthesis of 3-arylindole derivatives from nitroalkane precursors

3-Arylindole derivatives were synthesized by Cu(i) catalysed intramolecular Ullmann coupling of 2-bromoarylaminoalkanes.

The cooperative FeCl3/DDQ system for the regioselective synthesis of 3-arylindoles from β-monosubstituted 2-alkenylanilines

A highly regioselective synthesis of 3-arylindoles by using the cooperative FeCl₃/DDQ system has been developed.

Pd-catalyzed steroid reactions

We review the most important achievements of the last decade in the field of steroid synthesis in the presence of palladium catalysts. Various palladium-catalyzed cross-coupling reactions, including Heck, Suzuki, Stille, Sonogashira, Negishi and others, are exemplified with steroid transformations.

Vinylic MIDA Boronates: New Building Blocks for the Synthesis of Aza-Heterocycles

A two-step synthesis of structurally diverse pyrrole-containing bicyclic systems is reported. ortho-Nitro-haloarenes coupled with vinylic N-methyliminodiacetic acid (MIDA) boronates generate ortho-vinyl-nitroarenes, which undergo a "metal-free" nitrene insertion, resulting in a new pyrrole ring. This novel synthetic approach has a wide substrate tolerance and it is applicable in the preparation of more complex "drug-like" molecules. Interestingly, an ortho-nitro-allylarene derivative furnished a cyclic β-aminophosphonate motif.

Remarkable enhancement of enantioselectivity in the asymmetric conjugate addition of dimethylzinc to (Z)-nitroalkenes with a catalytic [(MeCN)₄Cu]PF₆-Hoveyda ligand complex

An enantioselective copper-catalyzed asymmetric conjugate addition of Me2Zn to (Z)-nitroalkenes led to the formation of all-carbon quaternary stereogenic centers with high stereoselectivity. The key features of the new method are the unprecedented use of [(MeCN)4Cu]PF6 in conjunction with the Hoveyda ligand L1 and the use of (Z)-nitroalkene substrates so that undesired nitroalkene isomerization is minimized and enantioselectivity is enhanced dramatically. We also describe a novel, practical, and highly (Z)-selective nitroalkene synthesis.

Treatment for Uterine Fibroids: Searching for Effective Drug Therapies

Uterine fibroids are common reproductive-age benign tumors that contribute to severe morbidity and infertility. Cumulative incidence is 4 times higher in Africian-Americans compared to Caucasians and constitutes a major health disparity challenge. Fibroids are the leading indication for hysterectomy and their management averages $21 billion annually in the US. No long term minimally invasive therapies exist. Thus, promising drug therapies, their chemistry, pharmacology, and clinical efficacy, focusing first on innovative drug delivery approaches, are reviewed.