Oxindole Derivatives Research Articles

COAP/Pd-Catalyzed Linear Asymmetric Allylic Alkylation for Optically Active 3,3-Disubstituted Oxindole Derivatives with a Four-Carbon Amino Side Chain

An asymmetric linear selective allylic alkylation of vinylaziridines with 3-aryl oxindoles has been developed by using a chiral oxamide-phosphine (COAP-Bn-OMe-p)/palladium complex in methanol, which furnished a wide variety of 3,3-disubstituted oxindole derivatives in good yields with excellent regio- and enantioselectivities.

Asymmetric Synthesis of Spiro-3,3'-cyclopropyl Oxindoles via Vinylogous Michael Initiated Ring Closure Reaction.

A novel organocatalytic cascade approach for the synthesis of spiro-cyclopropyl oxindole derivatives has been developed. The methodology is based on asymmetric vinylogous Michael addition of 4-nitroisoxazole derivatives to N-Boc isatylidene malonates followed by intramolecular alkylation. Its remarkable stereocontrol, wide substrate scope, and scalability highlight this new developed strategy. Moreover, this work represents the first example of vinylogous Michael initiated ring closure (MIRC) reaction for the synthesis of chiral 3,3'-cyclopropyl oxindole.

Diisobutylaluminium hydride mediated efficient synthesis of Morita–Baylis–Hilman adducts through α‐functionalization of alkyl propiolates

AbstractGenerally, oxindole derivatives are biologically important molecules and valuable building blocks in organic synthesis. Herein, we report a diisobutylaluminium hydride mediated efficient one‐pot synthesis of oxindole derivatives using N‐substituted isatins with methyl or ethyl propiolates at lower temperature (−78°C) through Morita‐Baylis‐Hillman (MBH) reaction. Within a short reaction time, a wide range of N‐alkyl or N‐aryl 3‐hydroxy oxindole derivatives (MBH adducts) were easily accessed in excellent yields under mild reaction conditions.

Discovery of oxindole-based FLT3 inhibitors as a promising therapeutic lead for acute myeloid leukemia carrying the oncogenic ITD mutation.

FMS-like tyrosine kinase 3 (FLT3) mutations occur in approximately 30% of acute myeloid leukemia (AML) patients. In the current study, the oxindole chemotype is employed as a structural motif for the design of new FLT3 inhibitors as potential hits for AML irradiation. Cell-based screening was performed with 18 oxindole derivatives and 5a-c inhibited 68%-73% and 83%-91% of internal tandem duplication (ITD)-mutated MV4-11 cell growth for 48- and 72-h treatments while only 0%-2% and 27%-39% in wild-type THP-1 cells. The most potent compound 5a inhibited MV4-11 cells with IC50 of 4.3 µM at 72 h while it was 8.7 µM in THP-1 cells, thus showing two-fold selective inhibition against the oncogenic ITD mutation. The ability of 5a to modulate cell death was examined. High-throughput protein profiling revealed low levels of the growth factors IGFBP-2 and -4 with the blockage of various apoptotic inhibitors such as Survivin. p21 with cellular stress mechanisms was characterized by increased expression of HSP proteins along with TNF-β. Mechanistically, compounds 5a and 5b inhibited FLT3 kinase with IC50 values of 2.49 and 1.45 µM, respectively. Theoretical docking studies supported the compounds' ability to bind to the FLT3 ATP binding site with the formation of highly stable complexes as evidenced by molecular dynamics simulations. The designed compounds also provide suitable drug candidates with no violation of drug likeability rules.

Discovery of non-nucleoside oxindole derivatives as potent inhibitors against dengue RNA-dependent RNA polymerase

A series of thiazole linked Oxindole-5-Sulfonamide (OSA) derivatives were designed as inhibitors of RNA-dependent RNA polymerase (RdRp) activity of Dengue virus. These were synthesized and then evaluated for their efficacy in ex-vivo virus replication assay using human cell lines. Among 20 primary compounds in the series, OSA-15 was identified as a hit. A series of analogues were synthesized by replacing the difluoro benzyl group of OSA-15 with different substituted benzyl groups. The efficacy of OSA-15derivatives was less than that of the parent compound, except OSA-15-17, which has shown improved efficacy than OSA-15. The further optimization was carried out by adding dimethyl (DM) groups to both the sulfonamide and oxindole NH’s to produce OSA-15-DM and OSA-15-17-DM. These two compounds were showing no detectable cytotoxicity and the latter was more efficacious. Further, both these compounds were tested for inhibition in all the serotypes of the Dengue virus using an ex-vivo assay. The EC50 of OSA-15-17-DM was observed in a low micromolar range between 2.5 and 5.0 µg/ml. Computation docking and molecular dynamics simulation studies confirmed the binding of identified hits to DENV RdRp. OSA15-17-DM blocks the RNA entrance and elongation site for their biological activity with high binding affinity. Overall, the identified oxindole derivatives are novel compounds that can inhibit Dengue replication, working as non-nucleoside inhibitors (NNI) to explore as anti-viral RdRp activity.

Synthesis of Spiro-Epoxy oxindole derivatives via unexpected oxidation/consecutive Corey-Chaykovsky reaction

Unexpected oxidation/consecutive Corey-Chaykovsky reaction of N-2,2,2-trifluoroethylisatin ketimines is conducted via a one-pot process using sulfur ylide to form spiro-epoxy oxindole derivatives. This unprecedented reaction proceeds smoothly under mild conditions, is operationally simple, and tolerates various functional groups. Notably, while the general Corey-Chaykovsky reaction of imines affords aziridines, this work describes the first oxidation step to produce isatins as intermediates followed by the Corey-Chaykovsky reaction.

Evaluation of oxindole derivatives as a potential anticancer agent against breast carcinoma cells: In vitro, in silico, and molecular docking study

In this study we have performed the in vitro anticancer activity of spiro oxindole derivatives against MCF-7 (human Adreno carcinoma) and MDA-MB-231 (triple negative breast cancer) cell lines to propose a possible role of these derivatives in the treatment of cancer. Compound 6, which has an N-benzyl substitution with a chloro group on the indolin-2-one scaffold, had the most potent activity against MCF-7 (3.55 ± 0.49 μM) and MDA-MB-231 (4.40 ± 0.468 μM) of all the synthesized molecules. A normal mouse embryonic fibroblast (NIH/3 T3) cell line was used to test the cellular toxicity of these derivatives. The results showed that none of the compounds were cytotoxic to normal cells. In addition, pharmacokinetic (ADME) and toxicity study profiles were predicted in silico. All the synthesized derivatives (1 to 7) demonstrated the necessary physicochemical properties for bioavailability. Finally, in vitro results of promising compound 6 were validated using molecular docking and dynamic simulation studies, which revealed their binding affinities and conformational stability in the binding cavity. Thus, these derivatives may serve as lead structures for a new generation of anticancer agents.

Lewis Acid-Catalyzed Chemodivergent and Regiospecific Reaction of Phenols with Quaternary Peroxyoxindoles.

The indium-catalyzed regiospecific coupling of substituted phenol derivatives and quaternary peroxyoxindoles for the synthesis of C2 or C4 benzoxazin-3-one-substituted phenols via skeletal rearrangement is described. This reaction is demonstrated with 17 examples with good yields and diverse aryl substituents. In contrast to the indium-catalyzed reaction, the Cu(OTf)2-catalyzed reaction of the phenol with quaternary peroxyoxindoles afforded C2 or C4 2-oxindole-substituted phenol derivatives. This diverse catalytic reaction generated various biologically important phenol-substituted 2-oxindole derivatives directly without any skeleton rearrangement and was demonstrated with 19 examples in high yield. The regiospecificity and the reaction pathways were explained with the support of density functional theory (DFT).

Experimental and Theoretical Investigation of an Azaoxyallyl Cation-Templated Intramolecular Aryl Amination Leading to Oxindole Derivatives.

Herein, development and detailed investigation of a SN '-type intramolecular aromatic substitution reaction involving α-arylazaoxyallyl cation intermediate, is disclosed. The study showcased that while α-aryl-α-chlorohydroxamate could be activated by a combination of base and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) into the corresponding azaoxyallyl cations, it could further emerge into a π-extended species involving the adjacent α-aryl moiety, and this transition is contingent on electronic effects of the aromatic ring as well as on α-substituents. An effective activation of the α-aromatic ring could pave the path for intramolecular Ar(Csp2 )-N bond formation towards oxindoles. Control experiments and DFT calculations suggested that a non-pericyclic nucleophilic amination pathway is most likely operative and precluded the possibility of concerted or electrophilic amination mechanism. HFIP as the reaction solvent plays pivotal roles in the transformation.

Non-Palladium-Catalyzed Approach to the Synthesis of (E)-3-(1,3-Diarylallylidene)Oxindoles.

Two novel synthetic approaches for synthesizing (E)-3-(1,3-diarylallylidene)oxindoles from oxindole were developed. All previously reported methods for synthesizing 3-(1,3-diarylallylidene)oxindoles utilized palladium-catalyzed reactions as a key step to form this unique skeleton. Despite high efficiency, palladium-catalyzed reactions have limitations in terms of substrate scope. Especially, an iodoaryl moiety cannot be introduced by the previous methods due to its high reactivity toward the palladium catalyst. Our Knoevenagel/allylic oxidation/Wittig and Knoevenagel/aldol/dehydration strategies complement each other and show broad substrate scope, including substrates with iodoaryl groups. The current methods utilized acetophenones, benzylidene phosphonium ylides, and benzaldehydes that are commercially available or easily accessible. Thus, the current synthetic approaches to (E)-3-(1,3-diarylallyldiene)oxindoles are readily amendable for variety of oxindole derivatives.

Diastereo‐ and Enantioselective Construction of Vicinal All‐Carbon Quaternary Stereocenters via Iridium/Europium Bimetallic Catalysis

The diastereo- and enantioselective construction of vicinal all-carbon quaternary stereocenters is a formidable task. We here report a synergistic bimetallic catalysis via a chiral N,N′-dioxide-europium (Eu) complex and a phosphoramidite-iridium (Ir) catalyst for the asymmetric allylation of oxindole derivatives by using challenging trisubstituted allylic esters. The allylated products bearing vicinal all-carbon quaternary stereocenters were obtained with good diastereoselectivities (up to 20 : 1 dr) and excellent enantioselectivities (up to 99 % ee). Control experiments showed that the complementary diastereomers of the products were not accessible by the change of the stereochemistry of the chiral N,N′-dioxide ligand.

Diastereo- and Enantioselective Construction of Vicinal All-Carbon Quaternary Stereocenters via Iridium/Europium Bimetallic Catalysis.

The diastereo- and enantioselective construction of vicinal all-carbon quaternary stereocenters is a formidable task. We here report a synergistic bimetallic catalysis via a chiral N,N'-dioxide-europium (Eu) complex and a phosphoramidite-iridium (Ir) catalyst for the asymmetric allylation of oxindole derivatives by using challenging trisubstituted allylic esters. The allylated products bearing vicinal all-carbon quaternary stereocenters were obtained with good diastereoselectivities (up to 20 : 1 dr) and excellent enantioselectivities (up to 99 % ee). Control experiments showed that the complementary diastereomers of the products were not accessible by the change of the stereochemistry of the chiral N,N'-dioxide ligand.

Yellow Twig (Nauclea orientalis) from Thailand: Strictosamide as the Key Alkaloid of This Plant Species

Comprehensive phytochemical examination from different perspectives using preparative and analytical chromatographic techniques combined with spectroscopic/spectrometric methods of the so-called “yellow twig” Nauclea orientalis (L.) L. (Rubiaceae) led to the identification of 13 tryptamine-derived (=monoterpene-indole) alkaloids. The identified alkaloids comprise strictosamide and four of its glucosidic derivatives, three oxindole derivatives, and five yellow-colored angustine-type aglycones. Qualitative and quantitative HPLC analyses showed the enrichment of strictosamide in all studied organs. Based on these results, we performed metabolomic analyses of monoterpene-indole alkaloids and made a 1H NMR in vitro monitoring of enzymatic deglucosylation of strictosamide. A comparison of the stability of strictosamide and its enantiomer vincoside lactam by theoretical calculations was also performed revealing a slightly higher stability of vincoside lactam. Additionally, we conducted two different anti-feedant assays of strictosamide using larvae of the polyphageous moth Spodoptera littoralis Boisduval. The obtained results indicate that generally two different biosynthetic pathways are most likely responsible for the overall alkaloid composition in this plant. Strictosamide is the key compound in the broader pathway and most likely the source of the identified angustine-type aglycones, which may contribute significantly to the yellow color of the wood. Its cross-organ accumulation makes it likely that strictosamide is not only important as a reservoir for the further biosynthesis, but also acts in the plants’ defense strategy.

Efficient One-pot Synthesis of 3,3-di(indolyl)indolin-2-ones from Isatin and Indole Catalyzed by VOSO4 as Non-Sulfonamide Carbonic Anhydrase Inhibitors.

A high yielding green protocol has been developed and delineated for the synthesis of 3,3- di(indolyl)indolin-2-ones, potentially bioactive compounds, involving one pot aqueous medium condensation of isatin with indole in the presence of VOSO4. The synthesized compounds were screened for their carbonic anhydrase inhibitory activity against human (h) isoforms hCA I, hCA II, hCA IX, and hCA XII. These non-sulfonamide derivatives selectively inhibited hCA II in the micromolar range. To develop a high yielding green protocol to synthesize 3,3-diindolyl oxindole derivatives using water as solvent media and screening the synthesized molecules for their carbonic anhydrase inhibitory activity. The target compound is obtained by taking isatin, indole, VOSO4, and H2O in one-pot at 70oC. The designed molecules were synthesized by using the new method. The molecules were screened for their CA inhibitory activity, which shows selective inhibition toward hCA II.The result showed an excellent yield without any loss or decrease in catalytic activity, proving the catalyst's performance and recyclability. An efficient, simple, and green protocol was established that provides a facile and straightforward approach for the preparation of 3,3-diindolyl oxindole derivatives (3a-r) from Isatin and Indole by using 10 mol% VOSO4 in high yields in a short period of time by a one-pot coupling reaction. Furthermore, the catalyst can also be recovered and reused for three consecutive catalytic cycles without any loss of its efficiency, which was confirmed by performing the experiment with 3a. The newly synthesized molecules (3a-r) were screened for their carbonic anhydrase inhibition potency against four isoforms, hCA I, II, IX, and XII and most of the compounds were found potent against hCA II with potency low to submicromolar range.

Stereoselective Synthesis of Spiro-Decalin Oxindole Derivatives via Sequential Organocatalytic Michael-Domino Michael/Aldol Reaction.

A highly stereoselective procedure for the synthesis of spiro-polycyclic oxindoles bearing five contiguous stereogenic centers including two tetrasubstituted carbons has been developed. Under sequential organocatalysis performed by a pyrrolidine-based organocatalyst and DBU, a highly atom-economical Michael–domino Michael/aldol reaction sequence was optimized, yielding variously functionalized spiro-decalin oxindoles with excellent stereoselectivity (>99:1 dr, up to 92% ee).

Asymmetric α-Regioselective [3 + 2] Annulation of Morita-Baylis-Hillman Carbonates: Construction of Three Contiguous Stereocenters with Vicinal Quaternary Carbon Centers.

Asymmetric α-regioselective annulation of MBH carbonates with 4-arylmethylisoxazol-5-ones has been developed to afford spirocyclic oxindole derivatives containing three contiguous stereogenic centers and vicinal all-carbon quaternary chiral centers. This reaction exhibits a broad substrate scope and excellent functional group tolerance. Excellent yields with high diastereo- and enantioselectivities were obtained in this efficient organocatalytic reaction.

Regio- and Stereoselective Electrochemical Alkylation of Morita-Baylis-Hillman Adducts.

Electrosynthesis is effectively employed in a general regio- and stereoselective alkylation of Morita–Baylis–Hillman compounds. The exposition of N-acyloxyphthalimides (redox-active esters) to galvanostatic electroreductive conditions, following the sacrificial-anode strategy, is proved an efficient and practical method to access densely functionalized cinnamate and oxindole derivatives. High yields (up to 80%) and wide functional group tolerance characterized the methodology. A tentative mechanistic sketch is proposed based on dedicated control experiments.

Enantioselective Synthesis of Spirocyclopentane Oxindoles Bearing Five Consecutive Stereocenters through Secondary Amine‐Catalyzed [3+2] Cycloaddition

AbstractThis work delineates a Michael‐initiated ring‐closing [3+2] cycloaddition of newly designed 3‐(1‐benzyl‐2‐oxoindolin‐3‐yl)pentane‐2,4‐diones with α,β‐unsaturated aldehydes. During the chiral secondary amine‐catalyzed cascade reaction, highly functionalized spirocyclopentane oxindole derivatives containing five consecutive stereogenic centers were formed, two of which were tetrasubstituted carbon. All the desired products are smoothly obtained in good yields (up to 90 %) with excellent enantioselectivities (up to >99 : 1 er) and diastereoselectivities (up to >95 : 5 dr). Meanwhile, the practicality of this strategy was highlighted by the further gram‐scale experiment and a set of synthetic transformations.

Synthesis and computational studies of potent antimicrobial and anticancer indolone scaffolds with spiro cyclopropyl moiety as a novel design element

The indolones nucleus is the central core to develop new effective anticancer agents and its substitution at the 3-position can affect antitumor activity, 3-spirocyclopropyl-2-oxindoles have attracted the scientist's community to design and develop expedition's strategies towards their construction and explore the potential of this useful scaffold with their newer derivatives in medicinal world. The present paper describes the synthesis of 3-spirocyclopropyl-2-indolone derivatives in three steps via synthesis of ylide leading to methylene-indolinones followed by the formation of the final product spirocyclopropyl oxindole derivatives with improved yields. In this milieu we considered motivating to advance exploration the biological potencies and computational studies of our newly synthesized molecules. The aimed target molecules were screened for antimicrobial and anticancer activities where they exhibited substantial effective antimicrobial activities. Amongst them, potent compound, bromospirocyclopropyl indolone, 6d displayed encouraging MIC ranging from 0.007 to 0.49 μg/mL for gram positive microbes and also substantial anticancer activity with an IC50 of 11.5 μg/mL. Finally, the computational modelling studies were performed to explore structure-activity relationship analysis. Active site of receptor protein shows docking scores of these molecules as - 5.78 kcal/mol and −5.097 kcal/mol for the docked target proteins. The binding energy of the best score is found to be −41.67 kcal/mol to −44.67 kcal/mol. Thus, the present paper efficaciously validated spirocyclopropyl indolone framework for drug candidates as potent anticancer as well as antimicrobial compounds.

Asymmetric Synthesis of Spirooxazolidinone Oxindoles by the Thiourea‐Catalyzed Aldol Reaction of 2‐Isocyanatomalonate Diesters

AbstractA tertiary amino‐thiourea catalyzed asymmetric aldol reaction between 2‐isocyanatomalonate esters and isatins has been achieved. Optical active spirooxazolidinone oxindole derivatives could be obtained with excellent yields (80%–96%) and enantioselectivities (67%–99% ee) under mild conditions, providing an updated example to apply isatins as the electrophile in the asymmetric aldol reaction with 2‐isocyanatomalonate esters.magnified image