A novel [1,2,4] triazolo [1,5-a] pyrimidine-based phenyl-linked steroid dimer: Synthesis and its cytotoxic activity

Discovery of Novel [1,2,4]Triazolo[1,5-a]pyrimidine Derivatives as Novel Potent S-Phase Kinase-Associated Protein 2 (SKP2) Inhibitors for the Treatment of Cancer

Skp1-CUL1-ROC1-F-box E3 ubiquitin ligases' main component S-phase kinase-associated protein 2 (Skp2) is responsible for specifically recognizing ubiquitination-modified substrates to be degraded such as p27 and p21 in the case of binding with adaptor protein Cks1. Pharmacological inhibition of Skp2 has exhibited promising antitumor activity. Herein, we present the design and optimization of a series of [1,2,4]triazolo[1,5-a]pyrimidine-based small molecules targeting Skp2. Among them, E35 demonstrated excellent inhibitory activities against the binding of Skp2-Cks1. In addition, compound E35 significantly inhibited colony formation and migration, as well as arrested the cell cycle at the S-phase. Mechanistically, compound E35 markedly decreased the expression of Skp2, as well as increased the expression of its substrates p21 and p27. Furthermore, compound E35 showed an obvious inhibitory effect on MGC-803 xenograft mice without obvious toxicity. All of these results suggest that compound E35 might be a valuable lead compound for antitumor agents targeting Skp2.

Exploring Triazole-Connected Steroid-Pyrimidine Hybrids: Synthesis, Spectroscopic Characterization, and Biological Assessment

Molecules originating from natural sources are physicochemically and biologically diverse. The conjugation of two active biomolecules has become the foundation for medical and pharmaceutical sciences. An effective synthesis of 11 new steroid-pyrimidine conjugates containing 1,2,3-triazole rings was carried out. The group of 3α-OH bile acids (lithocholic, deoxycholic, cholic) and 3β-OH sterols (cholesterol, cholestanol) were respectively modified to azidoacetates. 2-thiouracil was converted into N(1)S and N(3)S dipropargyl derivatives. Azide-alkyne cycloaddition in the presence of copper(I) of the obtained compounds led to the preparation of 1,2,3-triazole derivatives. Based on a series of spectroscopic (1H NMR, 13C NMR, Fourier-transform infrared (FT-IR)), spectrometric analyses (Electrospray ionization-mass spectrometry (ESI-MS), electron impact-mass spectrometry (EI-MS)), and semiempirical calculations, the structures of all compounds were confirmed. In silico biological tests and molecular docking (for domain 1KZN, 2H94, 5V5Z, 1EZF, 2Q85) were performed for selected compounds. The tests performed indicate the theoretical antimicrobial potential of the obtained ligands.

Recyclable LaF3·Pd nanocatalyst in Suzuki coupling: green synthesis of biaryls from haloarenes and phenylboronic acids

Herein we prepared the novel LaF3·Pd nanocatalyst characterized by XRD and TEM analysis. The nanocatalyst was applied in Suzuki coupling reaction for the synthesis of biaryls in aqueous medium from readily available aryl halides (bromides and iodides) and substituted phenylboronic acids in the presence of K2CO3 as the base at 70 °C. The present method is capable of giving the C-C coupled product in good to excellent yields (up to 97%). The reactions were conducted under green conditions in aqueous medium and the nanocatalyst used in this study was recyclable. The recyclability and reusability of the catalyst was checked for seven consecutive cycles without significant loss in reactivity.

Design, synthesis and molecular modeling of novel D-ring substituted steroidal 4,5-dihydropyrazole thiazolinone derivatives as anti-inflammatory agents by inhibition of COX-2/iNOS production and down-regulation of NF-κB/MAPKs in LPS-induced RAW264.7 macrophage cells

It has been reported that 4,5-dihydropyrazole and thiazole derivatives have many biological functions, especially in the aspect of anti-inflammation. According to the strategy of pharmacophore combination, we introduced thiazolinone and dihydropyrazole moiety into steroid skeleton to design and synthesize a novel series of D-ring substituted steroidal 4,5-dihydropyrazole thiazolinone derivatives, and assessed their in vitro anti-inflammatory profiles against Lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophage cells. The anti-inflammatory activities assay demonstrated that compound 12e was considered as the most effective anti-inflammatory drug, which suppressed the expression of pro-inflammatory mediators including nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), it also dose-dependently inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-induced RAW 264.7 macrophage cells. Furthermore, the results of the Western blot analysis showed a correlation between the inhibition of the Nuclear factor-kappa B (NF-κB) and Mitogen-activated protein kinases (MAPKs) signaling pathways and the suppressive effects of compound 12e on pro-inflammatory cytokines. Molecular docking studies of compound 12e into the COX-2 protein receptor (PDB ID: 5IKQ) active site was performed to rationalize their COX-2 inhibitory potency. The results were found to be in line with the biological findings as they exerted more favorable interactions compared to that of dexamethasone (DXM), explaining their remarkable COX-2 inhibitory activity. The findings revealed that these candidates could be identified as potent anti-inflammatory agents, compound 12e could be a promising drug for the treatment of inflammatory diseases.

Synthesis of Estrone Heterodimers and Evaluation of Their In Vitro Antiproliferative Activity

Directed structural modifications of natural products offer excellent opportunities to develop selectively acting drug candidates. Natural product hybrids represent a particular compound group. The components of hybrids constructed from different molecular entities may result in synergic action with diminished side effects. Steroidal homo- or heterodimers deserve special attention owing to their potentially high anticancer effect. Inspired by our recently described antiproliferative core-modified estrone derivatives, here, we combined them into heterodimers via Cu(I)-catalyzed azide-alkyne cycloaddition reactions. The two trans-16-azido-3-(O-benzyl)-17-hydroxy-13α-estrone derivatives were reacted with 3-O-propargyl-D-secoestrone alcohol or oxime. The antiproliferative activities of the four newly synthesized dimers were evaluated against a panel of human adherent gynecological cancer cell lines (cervical: Hela, SiHa, C33A; breast: MCF-7, T47D, MDA-MB-231, MDA-MB-361; ovarian: A2780). One heterodimer (12) exerted substantial antiproliferative activity against all investigated cell lines in the submicromolar or low micromolar range. A pronounced proapoptotic effect was observed by fluorescent double staining and flow cytometry on three cervical cell lines. Additionally, cell cycle blockade in the G2/M phase was detected, which might be a consequence of the effect of the dimer on tubulin polymerization. Computational calculations on the taxoid binding site of tubulin revealed potential binding of both steroidal building blocks, mainly with hydrophobic interactions and water bridges.

Synthesis, biological activities, and future perspectives of steroidal monocyclic pyridines

Steroidal pyridines are a class of compounds that have been the subject of extensive research in recent years due to their potential biological activities. The introduction of a pyridine ring into the steroid skeleton can significantly alter the chemical and biological properties of the compound, making it more potent and/or selective for a particular target. Different synthetic methods have been developed for the preparation of steroidal pyridines. This review provides an overview of the synthesis, biological activities, and future perspectives of steroidal monocyclic dihydropyridines, tetrahydropyridines, and pyridines from 2005 to the present. The different synthetic methods that have been developed for the preparation of these steroids are discussed, as well as the proposed mechanisms and the biological activities that have been reported. Finally, the potential of steroidal monocyclic pyridines for the development of new drugs is discussed. This review is intended to provide a comprehensive overview of the field of steroidal monocyclic pyridines for researchers and scientists who are interested in this area of research. It is also hoped that this review will stimulate further research into the synthesis and biological activities of steroidal pyridines to develop new and improved drugs for the treatment of diseases.

Formation of nitrogen-containing six-membered heterocycles on steroidal ring system: A review

Steroidal heterocyclic compounds constitute interesting and promising scaffolds for drug discovery as they have displayed diverse chemical reactivity and several types of biological activities. This study is a concise report on the most recent advancements in the chemistry of the steroid skeleton, including reactions at the A, B, and D ring systems. The modern synthetic methods for the steroidal nitrogen-containing six-membered heterocyclic derivatives from 3-keto-, 6-keto-, 17-keto-, and 20-keto-steroids, as well as 2-Aldo-, 4-Aldo-, 6-Aldo-, and 16-Aldo-steroids, are discussed. However, some other methods for the synthesis of steroidal N-containing 6-membered heterocyclic derivatives are also included. These compounds have shown therapeutic potential as cytotoxic agents against various cell lines and have also shown antiproliferative, anti-inflammatory, and antioxidant activities. Therefore, they could be used as prospective candidates for the development of various medications. This paper not only describes synthetic details involved in creating N-containing 6-membered heterocyclic steroid derivatives, but also provides a brief overview of the medicinal applications of these compounds. This information will be highly useful for the medicinal chemists conducting research in this field.

Synthesis of steroidal dihydropyrazole derivatives using green ZnO NPs and evaluation of their anticancer and antioxidant activity

Zinc oxide nanoparticles (ZnO NPs) were synthesized by a green method using Azadirachta indica leaf extract. The structure of the prepared ZnO (NPs) were characterized by FT-IR, XRD, SEM-EDX and TEM analyses. The biosynthesized ZnO (NPs) were then used as a catalyst for the synthesis of steroidal dihydropyrazole derivatives through a one-pot multicomponent reaction involving phenyl acetylene and hydrazine derivatives. The anticancer activity of newly synthesized compounds were evaluated against three cancer cell lines namely HeLa (human cervical carcinoma), Hep3B (human hepatocellular carcinoma) and MCF7 (human breast adenocarcinoma) by MTT assay. The tested compounds were found to be active against all cancer cell lines and less toxic towards normal peripheral blood mononuclear cells (PBMCs). Antioxidant activity have also been investigated via free radical scavenging ability using DPPH, FRAP and ABTS assay. The tested compounds were found to exhibit moderate to good antioxidant activity which increases with increase in the concentration of steroidal dihydropyrazoles. Among all the tested steroidal dihydropyrazoles, compound 17 is found to be most active.

Design, synthesis and anticancer activity of novel steroidal derivatives with D-ring fused or substituted N-heterocyclic systems

A series of novel D-ring fused or substituted steroidal N-heterocycles were synthesized, and their chemical structures were characterized by spectroscopic analysis. The anticancer activity of these compounds against four human cancer cell lines (MCF-7, H1299, HeLa and HepG2) were evaluated and the structure-activity relationship (SAR) was also investigated. Compound 3c displayed significant inhibitory activity on the four cancer cells with IC 50 values ranging from 3.88 to 10.05 µ M. Overall, these studies indicated that construction of N-heterocyclic system with D-ring substituted containing a double bond at C-16 and C-17 or D-ring fused with [17,16-d]azolo[1,5-a]pyrimidine could be a promising strategy to improve antitumor activity for steroids deserved further investigation.

Dimeric Drugs

This review intends to summarize the structures of an extensive number of symmetrical-dimeric drugs, having two monomers linked via a bridging entity while emphasizing the large versatility of biologically active substances reported to possess dimeric structures. The largest number of classes of these compounds consist of anticancer agents, antibiotics/antimicrobials, and anti-AIDS drugs. Other symmetrical-dimeric drugs include antidiabetics, antidepressants, analgesics, anti-inflammatories, drugs for the treatment of Alzheimer's disease, anticholesterolemics, estrogenics, antioxidants, enzyme inhibitors, anti-Parkisonians, laxatives, antiallergy compounds, cannabinoids, etc. Most of the articles reviewed do not compare the activity/potency of the dimers to that of their corresponding monomers. Only in limited cases, various suggestions have been made to justify unexpected higher activity of the dimers vs. the corresponding monomers. These suggestions include statistical effects, the presence of dimeric receptors, binding of a dimer to two receptors simultaneously, and others. It is virtually impossible to predict which dimers will be preferable to their respective monomers, or which linking bridges will lead to the most active compounds. It is expected that the extensive number of articles summarized, and the large variety of substances mentioned, which display various biological activities, should be of interest to many academic and industrial medicinal chemists.

A review on steroid dimers: 2011-2019

The first review article on steroid dimers by Li and Dias in 1997, followed by the second review and a book on steroid dimers by Nahar and Sarker in 2007 and 2012, respectively, covered steroid dimers reported until the end of 2010. Since then, there have been considerable amounts of research carried out on steroid dimers, prompting the need for another comprehensive review on this topic. Therefore, this present review appraises the literature published during the period 2011-2019 on various aspects of steroid dimers, including isolation from natural sources, synthesis and applications. A structured and systematic literature search was performed, using the key words: steroid dimer, steroidal dimer, dimeric steroid, bis-steroid, bis-steroidal conjugates, molecular umbrella, cephalostatins, ritterazines and crellastatins. Several databases like Web of Knowledge, Science Direct, PubMed and Google Scholar were consulted. During the period covered in this review, well over 200 new synthetic steroidal dimers, ring A-ring A connection being the major group, have been reported, only one natural steroid dimer has been isolated, and potential applications of steroid dimers in the treatment of cancers and tumors, and microbial infections have been indicated.

Novel d-Annulated Pentacyclic Steroids: Regioselective Synthesis and Biological Evaluation in Breast Cancer Cells

The acid-catalyzed cyclization of benzylidenes based on 16-dehydropregnenolone acetate (16-DPA) was studied. It was found that these compounds readily undergo regioselective interrupted Nazarov cyclization with trapping chloride ion and an efficient method of the synthesis of d-annulated pentacyclic steroids based on this reaction was proposed. The structures of the synthesized pentacyclic steroids were determined by NMR and X-ray diffraction. It was found that the reaction affords a single diastereomer, but the latter can crystallize as two conformers depending on the structure. Antiproliferative activity of synthesized compounds was evaluated against two breast cancer cell lines: MCF-7 and MDA-MB-231. All tested compounds showed relatively high antiproliferative activity. The synthetic potential of the protocol developed was illustrated by the gram-scale experiment.

Design, Synthesis, and Biological Evaluation of Two Series of Novel A-Ring Fused Steroidal Pyrazines as Potential Anticancer Agents

BACKGROUND

Increasingly, different heterocyclic systems have been introduced into the steroid nucleus to significantly enhance the antitumor activities of steroid molecules. However, in this study, few literature precedents describing the pyrazine heterocyclic-condensed modification to an A-ring of steroid monomers were found, although the pyrazine group is thought to be essential for the potent anticancer activity of clinically relevant drugs and natural steroid dimers.

METHODS AND RESULTS

Two series of novel A-ring fused steroidal pyrazines were designed and efficiently synthesized from commercially available progesterone via key α-ketoenol intermediates. Through a cell counting kit-8 cytotoxic assay of 36 derivatives for three tumor cells, 14 compounds displayed significant antiproliferative activity compared to 5-fluorouracil, especially for human prostatic tumor cells (PC-3) in vitro. Further mechanistic studies indicated that the most active compound, 12n (IC₅₀, 0.93 μM; SI, 28.71), could induce the cell apoptosis of PC-3 cells in a dose-dependent manner and cause cell cycle arrest in the G2/M phase. The molecular docking study suggested that compound 12n fitted the active sites of cytochrome P450 17A1 (6CIZ) well.

CONCLUSIONS

12n might serve as a promising lead compound for the development of novel anticancer drugs. This facile ring-closing strategy may provide a novel and promising avenue for the cycloaddition reaction of the steroidal skeleton through α-ketoenol intermediates.

Synthesis of new steroidal quinolines with antitumor properties

The incorporation of the heterocycles into the steroid nucleus has been recognized as a useful strategy to develop new steroidal agents for disease treatment. Representative examples are abiraterone and galeterone, which are presently used in clinic for the treatment of advanced prostate cancers. Herein we have developed the first Al₂O₃/KF-promoted pfitzinger reactions for the synthesis of new steroidal quinolines. These new steroidal quinolines showed moderate to good antiproliferative activity against several human lung cancer cells. Of these compounds, compound 2f exhibited the best potency toward the tested three lung cancer cells with IC₅₀ values <10 μM. Mechanistic studies showed that compound 2f concentration-dependently inhibited colony formation, morphological changes, apoptosis, and migration of A549 cells. To conclude, compound 2f could be used as a hit compound for developing steroid-based anti-lung cancer agents.

Synthesis and Evaluation of Pyrimidine Steroids as Antiproliferative Agents

A small and focused library of steroidal non-fused and fused pyrimidines was prepared from pregnenolone acetate and diosgenin, respectively. The key step was the cycloaddition reaction of nitrogen-containing 1,3-binucleophiles with the steroidal α,β-unsaturated ketone. Urea, thiourea and guanidine reacted in a similar manner and afforded the steroidal pyrimidines in good yields. The antiproliferative tests against human tumor cell lines gave GI₅₀ values in the micromolar range and had no effect on healthy fibroblasts. Additional experiments indicated that the compounds did not act as P-glycoprotein substrates, thus avoiding the rise of drug resistance. The fused steroidal pyrimidinethione was selected as drug lead for further testing due to its strong antiproliferative activities within the low micromolar range.

Design, synthesis and biological evaluation of new steroidal β-triazoly enones as potent antiproliferative agents

β-Triazoly enones are biologically interesting scaffolds, incorporation of such scaffolds into the steroid nucleus may generate new bioactive steroids and further enrich structural types of steroids. In this work, a series of new steroidal β-triazoly enones were synthesized based on click chemistry and Claisen-Schmidt condensation reaction and further evaluated for their antiproliferative activity against a panel of cancer cells. Most of these compounds showed better potency against PC-3 and MGC-803 cells. Particularly, compound 5a inhibited PC-3 and MGC-803 cells potently with the IC₅₀ values of 1.61 and 1.16 μM, respectively, and was less toxic toward GES-1 with an IC₅₀ value of 20.72 μM. Further mechanistic studies showed that compound 5a inhibited migration and invasion of MGC-803 and PC-3 dose-dependently. Treatment with compound 5a varied mRNA levels and protein expression of EMT markers in both cells. Collectively, the steroidal β-triazoly enones could be potentially utilized to develop new anticancer agents with the ability of inhibiting cell migration and invasion.

Steroidal dimer by001 inhibits proliferation and migration of esophageal cancer cells via multiple mechanisms

OBJECTIVE

To investigate the potential inhibitory effects of structurally novel steroidal dimer by001 in esophageal cancer in vitro.

METHODS

The cytotoxicity of by001 on esophageal, gastric, neuroblastoma and prostate cancer cells was examined MTT assay and colony formation assay. By001 induced apoptosis and production of intracellular reactive oxygen species on esophageal cancer cells Ec109, TE-1 and human normal gastric epithelial cells GES-1 was detected by flow cytometry. The effect of by001 on mitochondrial membrane potential was detected by fluorescence microscope through JC-1 staining. The level of intracellular reactive oxygen species was measured by fluorescence microscope and flow cytometry via DCFH-DA staining. The effect of by001 on members of Bcl-2 family, Fas, LC3, PARP and caspases was determined by Western blot. The effect of by001 on migration was measured by transwell assay.

RESULTS

By001 effectively inhibited proliferation of esophageal, gastric, neuroblastoma and prostate cancer cells in a time- and concentration-dependent manner in vitro. By001 reduced the number and the size of colonies at low micromolar concentrations, elevated cellular ROS levels and caused mitochondrial dysfunction in esophageal cancer cells. Molecular mechanistic studies showed that by001 triggered apoptosis through regulating members of Bcl-2 family and Fas.

CONCLUSIONS

These findings suggested that by001 may inhibited proliferation of esophageal cancer cells through mitochondria and death receptor-mediated apoptotic pathways, autophagy induction, as well as suppressed migration of esophageal cancer cells.

3-Dialkylamino-1,2,4-triazoles via ZnII-Catalyzed Acyl Hydrazide-Dialkylcyanamide Coupling

Zinc(II)-catalyzed (10 mol % ZnCl₂) coupling of acyl hydrazides and dialkylcyanamides in ethanol leads to 3-dialkylamino-1,2,4-triazoles (76-99%; 17 examples). This reaction represents a novel, straightforward, and high-yielding approach to practically important 3-NR₂-1,2,4-triazoles, which utilizes commercially available and/or easily generated substrates. Seventeen new 3-NR₂-1,2,4-triazoles were characterized by HRESI⁺-MS and IR, ¹H, and ¹³C{¹H} NMR spectroscopies and five species additionally by single-crystal X-ray diffraction (XRD). The Zn^II-catalyzed reaction proceeds via initial generation of the [Zn{RC(=O)NHNH₂}₃](ZnCl₄) complexes (exemplified by isolation of the complex with R = Ph, 76%; characterized by HRESI⁺-MS, IR, CP-MAS TOSS ¹³C{¹H} NMR, and XRD). Electronic effects of substituents at the acyl hydrazide moiety do not significantly affect the reaction rate and the yield of the target triazoles, whereas the steric hindrances reduce the reaction rate without affecting the yield of the heterocycles.

Discovery of 5,6-diaryl-1,2,4-triazines hybrids as potential apoptosis inducers

A series of 5,6-diaryl-1,2,4-triazines hybrids bearing a 1,2,3-triazole linker were synthesized by molecular hybridization strategy and evaluated for antiproliferative activity against three selected cancer cell lines (MGC-803, EC-109 and PC-3). The first structure-activity relationship (SAR) for these 5,6-diaryl-1,2,4-triazines is explored in this report with evaluation of 15 variants of the structural class. Among these chemical derivatives, 3-(((1-(4-fluorobenzyl)-1H-1,2,3-triazol-4-yl)methyl)thio)-5,6-diphenyl-1,2,4-triazine (11E) showed the more potent inhibitory effect against three cell lines than 5-Fu. Cellular mechanism studies in MGC-803 cells elucidated 11E inhibited colony formation and arrested cell cycle at G2/M phase. Furthermore, compound 11E caused morphological changes, decreased mitochondrial membrane potential, and induced apoptosis through the apoptosis-related proteins in MGC-803 cells. It was the first time, to our knowledge, that 5,6-diaryl-1,2,4-triazines bearing a 1,2,3-triazole linker were used as potential apoptosis inducers.

Synthesis of monomeric and dimeric steroids containing [1,2,4]triazolo[1,5-a]pyrimidines

The synthesis of several monomeric and dimeric steroidal [1,2,4]triazolo[1,5-a]pyrimidines (TPs) derived from steroids are described. These derivatives were prepared from α,β-unsaturated carbonyl compounds through a Claisen Schmidt condensation and rearrangement of the spiro moiety followed by a cycloaddition with 3-amino-1,2,4-triazole. The antiproliferative activity of compounds 7, 13-15 was tested against human cancer cells; several IG₅₀ values were below 10μM.

Structurally novel steroidal spirooxindole by241 potently inhibits tumor growth mainly through ROS-mediated mechanisms

Cancer cells always have increased ROS levels, thus making them more vulnerable to persistent endogenous oxidative stress. The biochemical difference between cancer and normal cells could be exploited to achieve selective cancer cell killing by exogenous ROS-producing agents. Herein we described a structurally novel steroidal spirooxindole by241 and its anticancer efficacy. By241 exhibited potent inhibition against human cancer cells and less toxic to normal cells. By241 concentration-dependently induced apoptosis of MGC-803 and EC9706 cells, accompanied with the mitochondrial dysfunction and increased ROS levels. NAC can completely restore the decreased cell viability of MGC-803 cells caused by by241, suggesting ROS-mediated mechanisms. The expression levels of proteins involved in the mitochondrion-related pathways were detected, showing increased expression of proapoptotic proteins and decreased expression of anti-apoptotic proteins, and activation of caspases-9/-3, but without activating caspase-8 expression. Pretreatment with Z-VAD-FMK partially rescued by241-induced apoptosis of MGC-803 cells. Additionally, by241 inhibited mTOR, activated p53 and its downstream proteins, cleaved MDM2 and PI3K/AKT as well as NF-κB signaling pathway. In vivo experiments showed that by241 did not have significant acute oral toxicity and exerted good anticancer efficacy against MGC-803 bearing mice models. Therefore, by241 may serve as a lead for further development for cancer therapy.

Multicomponent assembly of novel antiproliferative steroidal dihydropyridinyl spirooxindoles

Multicomponent assembly of steroidal dihydropyridinyl spirooxindoles from pregnenolone, isatins, malononitrile, and ammonium acetate is described, which involves the formation of two C-C bonds, two C-N bonds, and an all-carbon quaternary stereogenic center in a single operation. MTT assays showed that some of these compounds had moderate to excellent cytotoxicity against the tested cancer cell lines and were more potent than 5-FU. Particularly, compound 5o represented excellent inhibitory effect toward EC-109 (IC50=0.3 μM), being about 33-fold more potent than 5-FU.

Efficient three-component one-pot synthesis of steroidal polysubstituted anilines

An efficient and practical base-promoted cascade reaction has been developed to access steroidal polysubstituted anilines from simple precursors. The protocol reported herein achieved the formation of a benzene ring as well as three continuous C-C bonds in a single operation. The reaction mechanism was proposed on the basis of the key intermediate obtained. Besides, this method could be potentially employed for the synthesis of biphenyl compounds. The adjacent amine and nitrile groups existed in the final products have the potential for late stage functionalization, which would provide efficient access to steroidal compound collections with structural diversity and complexity.

Efficient synthesis of novel antiproliferative steroidal spirooxindoles via the [3+2] cycloaddition reactions of azomethine ylides

A series of novel steroidal spirooxindoles 3a-h were synthesized from pregnenolone in a high regioselective manner using the 1,3-dipolar cycloaddition as the key step. This protocol resulted in the formation of two C-C bonds, one C-N bond and the creation of one pyrrolidine ring and three contiguous stereocenters in a single operation. Biological evaluation showed that these synthesized steroidal spirooxindoles exhibited moderate to good antiproliferative activity against the tested cell lines and some of them were more potent than 5-FU. Among them, compounds 3e and 3f displayed the best antiproliferative activity against MCF-7 cells with the IC50 values of 4.0 and 3.9μM, respectively. Flow cytometry analysis demonstrated that compound 3d caused the cellular apoptosis and cell cycle arrest at G2/M phase in a concentration-dependent manner. Docking results indicated that compound 3d fitted well into the MDM2 active site 1RV1 by interacting with Lys94 and Thr101 residues.