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1.
Adv Sci (Weinh) ; 11(33): e2403158, 2024 Sep.
Article in English | MEDLINE | ID: mdl-38953329

ABSTRACT

In situ cancer vaccination is an attractive strategy that stimulates protective antitumor immunity. Cytotoxic T lymphocytes (CTLs) are major mediators of the adaptive immune defenses, with critical roles in antitumor immune response and establishing immune memory, and are consequently extremely important for in situ vaccines to generate systemic and lasting antitumor efficacy. However, the dense extracellular matrix and hypoxia in solid tumors severely impede the infiltration and function of CTLs, ultimately compromising the efficacy of in situ cancer vaccines. To address this issue, a robust in situ cancer vaccine, Au@MnO2 nanoparticles (AMOPs), based on a gold nanoparticle core coated with a manganese dioxide shell is developed. The AMOPs modulated the unfavorable tumor microenvironment (TME) to restore CTLs infiltration and function and efficiently induced immunogenic cell death. The Mn2+-mediated stimulator of the interferon genes pathway can be activated to further augment the therapeutic efficacy of the AMOPs. Thus, the AMOPs vaccine successfully elicited long-lasting antitumor immunity to considerably inhibit primary, recurrent, and metastatic tumors. This study not only highlights the importance of revitalizing CTLs efficacy against solid tumors but also makes progress toward overcoming TME barriers for sustained antitumor immunity.


Subject(s)
Cancer Vaccines , Gold , Immunotherapy , T-Lymphocytes, Cytotoxic , Tumor Microenvironment , Animals , T-Lymphocytes, Cytotoxic/immunology , Cancer Vaccines/immunology , Immunotherapy/methods , Mice , Tumor Microenvironment/immunology , Gold/chemistry , Disease Models, Animal , Manganese Compounds/chemistry , Neoplasms/immunology , Neoplasms/therapy , Metal Nanoparticles/chemistry , Metal Nanoparticles/therapeutic use , Oxides/chemistry , Humans , Cell Line, Tumor , Light
2.
Sci Rep ; 14(1): 16980, 2024 07 23.
Article in English | MEDLINE | ID: mdl-39043795

ABSTRACT

Musk is an important animal product, but the musk secretion mechanism of forest musk deer (Moschus berezovskii) is still unclear. The musk synthesis process in forest musk deer is extremely complex, and many raw materials are directly or indirectly derived from forest musk deer blood. In this study, metabolomics was used to analyze the blood of forest musk deer in secretory and non-secretory phases for the first time, aim at explaining the secretion mechanism from the perspective of blood metabolism. We found that P450-related, choline-related, axonal regeneration and other pathways and related metabolites were significantly enriched during the musk secretion of forest musk deer. These pathways and metabolites related to P450 and choline in blood may have important implications for the mechanism of musk secretion in forest musk deer, because blood components were closely related to musk components and could provide raw materials for musk synthesis in musk gland cells.


Subject(s)
Deer , Fatty Acids, Monounsaturated , Metabolome , Animals , Deer/blood , Deer/metabolism , Fatty Acids, Monounsaturated/blood , Fatty Acids, Monounsaturated/metabolism , Metabolomics/methods , Forests
3.
Free Radic Biol Med ; 212: 477-492, 2024 02 20.
Article in English | MEDLINE | ID: mdl-38190924

ABSTRACT

Forkhead box O3a (FOXO3a)-mediated mitochondrial dysfunction plays a pivotal effect on cardiac hypertrophy and heart failure (HF). However, the role and underlying mechanisms of FOXO3a, regulated by breviscapine (BRE), on mitochondrial function in HF therapy remain unclear. This study reveals that BRE-induced nuclear translocation of FOXO3a facilitates mitofusin-1 (MFN-1)-dependent mitochondrial fusion in cardiac hypertrophy and HF. BRE effectively promotes cardiac function and ameliorates cardiac remodeling in pressure overload-induced mice. In addition, BRE mitigates phenylephrine (PE)-induced cardiac hypertrophy in cardiomyocytes and fibrosis remodeling in fibroblasts by inhibiting ROS production and promoting mitochondrial fusion, respectively. Transcriptomics analysis underscores the close association between the FOXO pathway and the protective effect of BRE against HF, with FOXO3a emerging as a potential target of BRE. BRE potentiates the nuclear translocation of FOXO3a by attenuating its phosphorylation, other than its acetylation in cardiac hypertrophy. Mechanistically, over-expression of FOXO3a significantly inhibits cardiac hypertrophy and mitochondrial injury by promoting MFN-1-mediated mitochondrial fusion. Furthermore, BRE demonstrates its ability to substantially curb cardiac hypertrophy, reduce mitochondrial ROS production, and enhance MFN-1-mediated mitochondrial fusion through a FOXO3a-dependent mechanism. In conclusion, nuclear FOXO3a translocation induced by BRE presents a successful therapeutic avenue for addressing cardiac hypertrophy and HF through promoting MFN-1-dependent mitochondrial fusion.


Subject(s)
Flavonoids , Heart Failure , Mitochondrial Dynamics , Mice , Animals , Reactive Oxygen Species/metabolism , Cardiomegaly/chemically induced , Cardiomegaly/drug therapy , Cardiomegaly/genetics , Myocytes, Cardiac/metabolism , Heart Failure/pathology
4.
J Pharm Biomed Anal ; 231: 115400, 2023 Jul 05.
Article in English | MEDLINE | ID: mdl-37099978

ABSTRACT

The absorbed prototypes and metabolites of traditional Chinese medicines (TCMs) serves an important part in pharmacological action and clinical effects. However, the comprehensive characterization of which is facing actual or possible rigorous challenges due to the lack of data mining methods and the complexity of metabolite samples. Yindan Xinnaotong soft capsule (YDXNT), a typical traditional Chinese medicine prescription consisting of extracts from 8 herbal medicines, is widely used for the treatment of angina pectoris and ischemic stroke in the clinic. This study established a systematic data mining strategy based on ultra-high performance liquid chromatography tandem quadrupole-time-of-fight mass spectrometry (UHPLC-Q-TOF MS) for comprehensive metabolite profiling of YDXNT in rat plasma after oral administration. The multi-level feature ion filtration strategy was primarily conducted through the full scan MS data of plasma samples. All potential metabolites were rapidly fileted out from the endogenous background interference based on the background subtract and the chemical type specifically mass defect filter (MDF) windows including flavonoids, ginkgolides, phenolic acids, saponins, and tanshinones. As the MDF windows of certain types were overlapped, the screened-out potential metabolites were deeply characterized and identified according to their retention times (RT), integrating neutral loss filtering (NLF), diagnostic fragment ions filtering (DFIF), and further confirmed by reference standards. Thus, a total of 122 compounds, consisting of 29 prototype components (16 confirmed with reference standards) and 93 metabolites had been identified. This study provides a rapid and robust metabolite profiling method for researching complicated traditional Chinese medicine prescriptions.


Subject(s)
Drugs, Chinese Herbal , Rats , Animals , Drugs, Chinese Herbal/chemistry , Tandem Mass Spectrometry/methods , Medicine, Chinese Traditional , Reference Standards , Administration, Oral , Chromatography, High Pressure Liquid/methods
5.
J Am Chem Soc ; 145(16): 9233-9241, 2023 Apr 26.
Article in English | MEDLINE | ID: mdl-37043290

ABSTRACT

A new strategy focusing on the last-stage asymmetric assembly of the ring D, which inherently possesses the densest part of stereogenic centers and functional groups in the A/B/C/D ring system of (-)-cephalotaxine, has been developed, in which a novel Rh-catalyzed asymmetric (2 + 3) annulation of tertiary enamides with enoldiazoacetates is designed and explored for enantioselective construction of the crucial cyclopentane ring D bearing a unique spirocyclic aza-quaternary stereocenter. Based on the expeditious access of chiral functionalized building block with the tetracyclic A/B/C/D ring system, a concise enantioselective total synthesis of (-)-cephalotaxine starting from readily available homopiperonyl alcohol has been achieved in nine steps with only two column chromatography purifications. Following the tactical introduction of the Meinwald rearrangement, enantioselective divergent syntheses of (-)-cephalotine B with an additional C3-O-C11 oxo-bridged bond (14 steps), (-)-fortuneicyclidin B with an unprecedented C3-C10 bond (14 steps), and its 2-epimer (-)-fortuneicyclidin A (16 steps) have been also accomplished for the first time.

6.
Article in English | MEDLINE | ID: mdl-36906956

ABSTRACT

Yindan Xinnaotong soft capsule (YDXNT) is a commonly used Chinese herbal preparation for the clinical treatment of coronary disease. However, there is a lack of pharmacokinetic studies on YDXNT, and its active ingredients and their mechanism in the treatment of cardiovascular diseases (CVD) are still unclear. In this study, 15 absorbed ingredients in rat plasma after oral administration of YDXNT were quickly identified based on liquid chromatography tandem quadrupole time-of-flight mass spectrometry (LC-QTOF MS), and then a sensitive and accurate quantitative method based on ultra-high performance liquid chromatography tandem triple quadrupole mass spectrometry (UHPLC-QQQ MS) was established and validated for simultaneous determination of the 15 ingredients of YDXNT in rat plasma, which was then applied to the pharmacokinetic study. Different types of compounds showed various pharmacokinetic characteristics, for instance, ginkgolides with higher maximum plasma concentration (Cmax), flavonoids presenting concentration-time curve with double peaks, phenolic acids with shorter time to reach maximum plasma concentration (Tmax), saponins with long elimination half-life (t1/2) and tanshinones showing fluctuant plasma concentration. Then the measured analytes were regarded as effective compounds and their potential targets and mechanism of action were predicted by constructing and analyzing the compound-target network of YDXNT and CVD. Those potential active compounds of YDXNT interacted with targets such as MAPK1 and MAPK8, and molecular docking showed that the binding free energies of 12 ingredients with MAPK1 were less than -5.0 kcal/mol, indicating that YDXNT intervened in the MAPK signaling pathway to display its therapeutic effect on CVD.


Subject(s)
Cardiovascular Diseases , Drugs, Chinese Herbal , Animals , Rats , Capsules , Cardiovascular Diseases/drug therapy , Chromatography, High Pressure Liquid/methods , Chromatography, Liquid , Drugs, Chinese Herbal/chemistry , Molecular Docking Simulation , Tandem Mass Spectrometry/methods
7.
Cereb Cortex ; 33(8): 4977-4989, 2023 04 04.
Article in English | MEDLINE | ID: mdl-36227200

ABSTRACT

Autism is often comorbid with other psychiatric disorders. We have previously shown that Dip2a knockout (KO) induces autism-like behaviors in mice. However, the role of Dip2a in other psychiatric disorders remains unclear. In this paper, we revealed that Dip2a KO mice had comorbid anxiety. Dip2a KO led to a reduction in the dendritic length of cortical and hippocampal excitatory neurons. Molecular mechanism studies suggested that AMPK was overactivated and suppressed the mTOR cascade, contributing to defects in dendritic morphology. Deletion of Dip2a in adult-born hippocampal neurons (Dip2a conditional knockout (cKO)) increased susceptibility to anxiety upon acute stress exposure. Application of (2R,6R)-hydroxynorketamine (HNK), an inhibitor of mTOR, rescued anxiety-like behaviors in Dip2a KO and Dip2a cKO mice. In addition, 6 weeks of high-fat diet intake alleviated AMPK-mTOR signaling and attenuated the severity of anxiety in both Dip2a KO mice and Dip2a cKO mice. Taken together, these results reveal an unrecognized function of DIP2A in anxiety pathophysiology via regulation of AMPK-mTOR signaling.


Subject(s)
AMP-Activated Protein Kinases , Signal Transduction , Mice , Animals , Mice, Knockout , TOR Serine-Threonine Kinases/metabolism , Anxiety/genetics , Nuclear Proteins
8.
J Am Chem Soc ; 145(1): 311-321, 2023 01 11.
Article in English | MEDLINE | ID: mdl-36538760

ABSTRACT

A unified strategy toward asymmetric divergent syntheses of nine C8-ethano-bridged diterpenoids A1-A9 (candol A, powerol, sicanadiol, epi-candol A, atisirene, ent-atisan-16α-ol, 4-decarboxy-4-methyl-GA12, trachinol, and ent-beyerane) has been developed based on late-stage transformations of common synthons having ent-kaurane and ent-trachylobane cores. The expeditious assembly of crucial advanced ent-kaurane- and ent-trachylobane-type building blocks is strategically explored through a regioselective and diastereoselective Fe-mediated hydrogen atom transfer (HAT) 6-exo-trig cyclization of the alkene/enone and 3-exo-trig cyclization of the alkene/ketone, showing the multi-reactivity of densely functionalized polycyclic substrates with πC═C and πC═O systems in HAT-initiated reactions. Following the rapid construction of five major structural skeletons (ent-kaurane-, ent-atisane-, ent-beyerane-, ent-trachylobane-, and ent-gibberellane-type), nine C8-ethano-bridged diterpenoids A1-A9 could be accessed in the longest linear 8 to 11 steps starting from readily available chiral γ-cyclogeraniol 1 and known chiral γ-substituted cyclohexenone 2, in which enantioselective total syntheses of candol A (A1, 8 steps), powerol (A2, 9 steps), sicanadiol (A3, 10 steps), epi-candol A (A4, 8 steps), ent-atisan-16α-ol (A6, 11 steps), and trachinol (A8, 10 steps) are achieved for the first time.


Subject(s)
Diterpenes, Kaurane , Diterpenes
9.
Org Lett ; 24(37): 6851-6856, 2022 09 23.
Article in English | MEDLINE | ID: mdl-36103354

ABSTRACT

Triacylamines with Cs symmetry have been explored in asymmetric organocatalysis, leading to the development of a novel catalytic enantioselective desymmetrization of prochiral triacylamines by methanolysis under the catalysis of chiral pseudopeptidic guanidine-guanidinium salt having a weakly coordinating anion. This organocatalytic methodology provides an effective approach to the synthetically useful chiral imide-esters with a 1,5-dicarbonyl moiety, and its synthetic potential has been manifested in the asymmetric synthesis of two GABA analogue drugs, (R)-Baclofen·HCl and (S)-Pregabalin.


Subject(s)
Baclofen , Esters , Catalysis , Guanidine , Imides , Pregabalin , Stereoisomerism
10.
Chem Commun (Camb) ; 58(62): 8710-8713, 2022 Aug 02.
Article in English | MEDLINE | ID: mdl-35833607

ABSTRACT

The unique reactivity of indolyl-substituted p-QMs as a new type of two-carbon synthon has been explored for the first time in a novel iron(III)-catalyzed tandem annulation. This (2+2) annulation/retro-4π electrocyclization/imino-Nazarov cyclization cascade reaction is characterized by an unusual structural reconstruction of indolyl-substituted p-QMs, leading to an expeditious assembly of synthetically important functionalized cyclopenta[b]indoles.


Subject(s)
Indoles , Iron , Catalysis , Cyclization , Indolequinones , Indoles/chemistry
11.
Front Oncol ; 12: 1079402, 2022.
Article in English | MEDLINE | ID: mdl-36686788

ABSTRACT

Background: N6-methyladenosine (m6A) RNA regulators play important roles in cancers, but their functions and mechanism have not been demonstrated clearly in gastric cancer (GC). Methods: In this study, the GC samples with clinical information and RNA transcriptome were downloaded from The Cancer Genome Atlas database. The different expression genes were compared by the absolute value and median ± standard deviation. Samples with complete information were randomly divided into a training dataset and a test dataset. The differential expression genes (DEGs) between ALKBH5-low and ALKBH5-high subgroups were identified in the training dataset and constructed a risk model by Cox and least absolute shrinkage and selection operator regression. The model was testified in test datasets, overall survival (OS) was compared with the Kaplan-Meier method, and immune cell infiltration was calculated by the CIBERSORT algorithm in the low-risk and high-risk subgroups based on the model. The protein levels of ALKBH5 were detected with immunohistochemistry. The relative expression of messenger-ribonucleic acid (mRNA) was detected with quantitative polymerase chain reaction. Results: ALKBH5 was the only regulator whose expression was lower in tumor samples than that in normal samples. The low expression of ALKBH5 led to the poor OS of GC patients and seemed to be an independent protective factor. The model based on ALKBH5-regulated genes was validated in both datasets (training/test) and displayed a potential capacity to predict a clinical prognosis. Gene Ontology analysis implied that the DEGs were involved in the immune response; CIBERSORT results indicated that ALKBH5 and its related genes could alter the immune microenvironment of GC. The protein levels of ALKBH5 were verified as lowly expressed in GC tissues. SLC7A2 and CGB3 were downregulated with ALKBH5 knockdown. Conclusions: In this study, we found that ALKBH5 might be a suppressor of GC; ALKBH5 and its related genes were latent biomarkers and immunotherapy targets.

12.
Org Lett ; 23(22): 8905-8909, 2021 Nov 19.
Article in English | MEDLINE | ID: mdl-34756037

ABSTRACT

A novel strategy based on Cu-catalyzed (4+1) cascade annulation of terminal alkynes as one-carbon synthons with 2-(tosylmethyl)anilines has been developed for the expeditious synthesis of 2,3-disubstituted indoles, in which in situ generations of aza-o-quinone methides and alkynyl-copper(I) species are involved. This annulation provides an effective method for the assembly of synthetically and structurally interesting 2,3-disubstituted indoles.

13.
Membranes (Basel) ; 11(11)2021 Nov 22.
Article in English | MEDLINE | ID: mdl-34832133

ABSTRACT

This study in-situ modified a commercial nanofiltration membrane, NF90, through the concentration-polymerization-enhanced radical graft polarization method by applying two agents of 3-sulfopropyl methacrylate potassium salt (SPM) and 2-hydroxyethyl methacrylate (HEMA) with different dosages. Surface characterization revealed that the modified membranes became rougher and more hydrophilic compared with the pristine membrane. The modified membranes exhibited considerably enhanced separation performance with 5.8-19.6% higher NaCl rejection and 17.2-19.9% higher pharmaceuticals and personal care products (PPCPs) rejection than the pristine membrane. When treating the feedwater with high silica concentration, the modified membranes exhibited relatively less flux decline with high percentage of reversible fouling, especially the ones modified using a lower monomer concentration (0.01 M SPM and 0.01 M HEMA). Moreover, membrane modification enhanced the PPCP rejection (1.3-5.4%) after silica fouling by mitigating foulant deposition on the membrane surface. The fouling mechanism was confirmed to be intermediate blocking of membrane pores. Therefore, the in-situ modification technique with a low monomer concentration proved to be effective for mitigating silica fouling and improving PPCP rejection, which can be easily performed and cost-effective in practical application.

14.
Org Lett ; 23(15): 5885-5890, 2021 08 06.
Article in English | MEDLINE | ID: mdl-34279973

ABSTRACT

A new tandem annulation of p-quinone methides (p-QMs) with ynamides is described. This cascade reaction features a unique combination of (2 + 2) annulation, retro-4π electrocyclization, and imino-Nazarov cyclization, wherein vinyl p-quinone methides (p-VQMs) as one of the key intermediates have been identified chemically. Significantly, an unusual structural reconstruction of p-QMs involving the cleavage of the C5-C6 bond and the late-stage formation of the C4-C6 bond is involved, leading to a methodology development for the construction of functionalized aminoindenes.

15.
Org Lett ; 23(3): 745-750, 2021 Feb 05.
Article in English | MEDLINE | ID: mdl-33475379

ABSTRACT

An unprecedented asymmetric catalytic (4 + 2) annulation reaction of aryl-substituted γ-methylidene-δ-valerolactones (GMDVs) with isatin-derived para-quinone methides (p-QMs) has been developed under the catalysis of palladium(0) and (S,S,S)-(-)-Xyl-SKP, offering a new approach for the diastereo- and enantioselective synthesis of chiral cyclohexadienone-fused cyclohexyl spirooxindoles. Significantly, three highly congested contiguous tetrasubstituted carbon atoms embedded in bispirocyclic skeleton, of which two are vicinal quaternary stereogenic centers, are forged in an effective and selective manner (up to 99% yield, up to 95% ee, >20/1 dr). The current reaction represents the first exploration of enantioselective catalytic (4 + 2) annulation forming the six-membered carbocycles in the chemistry of both GMDVs and p-QMs.

16.
Org Lett ; 22(11): 4171-4175, 2020 06 05.
Article in English | MEDLINE | ID: mdl-32433889

ABSTRACT

A novel asymmetric catalytic (2+3) annulation of p-quinone methides with CN-substituted trimethylenemethane is described under palladium catalysis, providing an alternative approach for the enantioselective construction of highly functionalized chiral spirocyclopentyl p-dienones. Driven by the significant improvement in the reactivity and enantioselectivity, a novel type of non-C2-symmetric phosphoramidite ligand from the chirality-matched combination of (S)-BINOL and sterically demanding amine derived from l-hydroxyproline is evolved and explored for the protocol presented here.

17.
Chemistry ; 26(17): 3803-3809, 2020 Mar 23.
Article in English | MEDLINE | ID: mdl-31830333

ABSTRACT

Palladium-catalyzed asymmetric [4+5] annulation of ortho-quinone methides (o-QMs) with substituted vinylethylene carbonates (VECs) is described for the first time, giving a novel enantioselective approach to chiral nine-membered benzoheterocycles. Based on this designed [4+5] annulation, an unprecedented silica gel-promoted tandem rearrangement reaction featuring a unique asymmetric aromatic Claisen rearrangement is explored at room temperature, offering a new method for asymmetric construction of all-carbon quaternary stereocenters embedded in chiral functionalized homoallylic alcohols.

18.
J Cell Biochem ; 120(10): 17573-17583, 2019 10.
Article in English | MEDLINE | ID: mdl-31111550

ABSTRACT

Non-small cell lung cancer (NSCLC) is still an unresolved source of tumor-related death internationally. Current studies have discovered that microRNAs (miRNAs) are associated with diverse cancers development, including NSCLC. Our paper focused on the functional character of miR-4286 in NSCLC. miR-4286 level in 68 cases of NSCLC tissues, matched neighboring nontumor tissues and different cancer cell lines were inspected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The connection concerning miR-4286 expression and clinicopathological features of patients with NSCLC were further determined. After knockdown or overexpression of miR-4286, cell viability, cell cycle, and/or apoptotic cells were examined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry assay, respectively. Moreover, the cell cycle- and apoptosis-related proteins were estimated by qRT-PCR and Western blot. In comparison with the matched nontumor tissues, miR-4286 was significantly enhanced in lung malignancy tissues and different cell lines. miR-4286 expression was related with the tumor-node-metastasis stage, lymphatic metastasis, and distant metastasis. Cell viability was ominously weakened by suppression of miR-4286 in A549 cells, whereas was statistically upregulated by overexpression of miR-4286 in NCI-H1299 cells. Additionally, we detected that suppression of miR-4286 tempted cell cycle arrest in G1 stage and fortified apoptosis in A549 cells. Runx3 was recognized as one target gene of miR-4286, and the impacts of suppression of miR-4286 on cell viability and apoptosis were through regulation of Runt-related transcription factor 3. Our study suggests that miR-4286 overexpression represents a tumor promoter role in NSCLC cells.


Subject(s)
Carcinoma, Non-Small-Cell Lung/genetics , Core Binding Factor Alpha 3 Subunit/genetics , MicroRNAs/genetics , Prognosis , A549 Cells , Adult , Aged , Apoptosis/genetics , Biomarkers, Tumor/genetics , Carcinoma, Non-Small-Cell Lung/epidemiology , Carcinoma, Non-Small-Cell Lung/pathology , Cell Cycle Checkpoints/genetics , Cell Line, Tumor , Cell Movement/genetics , Cell Proliferation/genetics , Disease-Free Survival , Female , Gene Expression Regulation, Neoplastic/genetics , Humans , Lymphatic Metastasis , Male , Middle Aged , Neoplasm Invasiveness/genetics , Neoplasm Invasiveness/pathology
19.
Org Lett ; 19(11): 2965-2968, 2017 06 02.
Article in English | MEDLINE | ID: mdl-28514154

ABSTRACT

A novel Au-catalyzed [2 + 3] annulation reaction of enamides with propargyl esters has been developed, providing a new method for expeditious assembly of synthetically useful functionalized 1-azaspiro[4.4]nonane building blocks. Based on this key annulation, strategic installation of the pivotal azaspirocyclic core, followed by constructing the benzazepine unit via Witkop cyclization, led to the divergent total syntheses of cephalotaxine and cephalezomine H.

20.
J Am Chem Soc ; 139(12): 4282-4285, 2017 03 29.
Article in English | MEDLINE | ID: mdl-28252292

ABSTRACT

The first total syntheses of Lycopodium alkaloids palhinine A, palhinine D, and their C3-epimers have been divergently achieved through the use of a connective transform to access a pivotal hexacyclic isoxazolidine precursor. A microwave-assisted regio- and stereoselective intramolecular nitrone-alkene cycloaddition was tactically orchestrated as a key step to install the crucial 10-oxa-1-azabicyclo[5.2.1]decane moiety embedded in the conformationally rigid isotwistane framework, demonstrating the feasibility of constructing the highly strained medium-sized ring by introduction of an oxygen bridging linker to relieve the transannular strain in the polycyclic scaffold. Subsequent N-O bond cleavage provided the synthetically challenging nine-membered azonane ring system bearing the requisite C3 hydroxyl group. Late-stage transformations featuring a chemo- and stereoselective reduction of the pentacyclic ß-diketone secured the availability of our target molecules.


Subject(s)
Alkaloids/chemical synthesis , Alkaloids/chemistry , Molecular Structure
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