A5011880323- Synthetic Organic Chemistry Methods
- Asymmetric Synthesis and Catalysis
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Marine Sponges and Natural Products
- Microbial Natural Products and Biosynthesis
- Chemical Synthesis and Analysis
- Chemical synthesis and alkaloids
- Synthesis and Catalytic Reactions
- Cyclopropane Reaction Mechanisms
- Traditional and Medicinal Uses of Annonaceae
- Carbohydrate Chemistry and Synthesis
- Oxidative Organic Chemistry Reactions
- Crystallography and molecular interactions
- PI3K/AKT/mTOR signaling in cancer
- Chemical Synthesis and Reactions
- Marine Toxins and Detection Methods
- RNA and protein synthesis mechanisms
- Advanced Synthetic Organic Chemistry
- Biochemical and Molecular Research
- RNA Research and Splicing
- Asymmetric Hydrogenation and Catalysis
- Synthesis of β-Lactam Compounds
- Coordination Chemistry and Organometallics
- Cancer Treatment and Pharmacology
Baylor University
2016-2025
Texas A&M University
2012-2023
The University of Texas at El Paso
2023
Texas State University
2019
University of Naples Federico II
2019
Mitchell Institute
2014-2015
Tecnológico de Monterrey
2012
Illinois State University
2011
Welch Foundation
2011
University of Montana
2010
Stress granules are aggregates of small ribosomal subunits, mRNA, and numerous associated RNA-binding proteins that include several translation initiation factors. granule assembly occurs in the cytoplasm higher eukaryotic cells under a wide variety stress conditions, including heat shock, UV irradiation, hypoxia, exposure to arsenite. Thus far, unifying principle factor 2alpha phosphorylation prior formation has been observed from majority experimental evidence. Pateamine A, natural product...
Quickly emerging complexity characterizes the asymmetric, nucleophile-catalyzed aldol lactonization (NCAL) process with keto acid substrates and subsequent topology-altering reactions. The utility of chiral cyclic isothiourea catalysts as nucleophilic promoters (Lewis bases) for desymmetrization reactions through scaleable NCAL processes is demonstrated (see picture; HBTM=homobenzotetramisole). Detailed facts importance to specialist readers are published "Supporting Information". Such...
α,β-Unsaturated acylammonium salts, generated in situ from commodity acid chlorides and a chiral isothiourea organocatalyst, comprise new versatile family of dienophiles for the venerable Diels-Alder (DA) cycloaddition. Their reactivity is unveiled through highly diastereo- enantioselective Diels-Alder/lactonization organocascade that generates cis- trans-fused bicyclic γ- δ-lactones bearing up to four contiguous stereocenters. Moreover, first examples DA-initiated, stereodivergent...
Significance We developed reagents and approaches to pull down ribosome-associated RNAs from Cre-labeled cells. show that this strategy is useful probe cell type-specific gene expression the extent of transcript binding ribosomes.
The asymmetric synthesis of the potent immunosuppressive agent (−)-pateamine A isolated from marine sponge Mycale sp. is described. key strategy employed in was a β-lactam-based macrocyclization to form 19-membered dilactone macrolide. confirms relative and absolute stereochemistry as 3R,5S,10S,24S sets stage for studies into mechanism action pateamine A. Other findings made course described herein include following: (1) Stille coupling can be competitive with π-allyl formation, (2) SmI2...
4-Alkylidene-beta-lactones (hetero ketene dimers) and alpha-amino acids are useful precursors for total syntheses of the beta-lactone-containing proteasome inhibitors salinosporamide A, cinnabaramide derivatives. A key step is a nucleophile-promoted, bis-cyclization keto that simultaneously generates gamma-lactam beta-lactone these natural products. This reaction sequence may have implications biosynthesis
Dyotropic processes involving unprecedented 1,2-acyl migrations provide access to novel spirocyclic, bridged keto-gamma-lactones from a series of fused, tricyclic-beta-lactones, available via biscyclization ketoacids including new asymmetric variant. In addition, spirocyclic bis-gamma-lactone was generated dyotropic process 1,2-beta-lactone/sigma-lactone interchange. Overall, this sequence provides simple, two-step for conversion diketoacids complex spiro[5.n]alkanes bearing contiguous...
The exploration of b-lactone reactivity and transformations has continued since the first synthesis these strained heterocycles by Einhorn in 1883.The principal modes b-lactones include nucleophilic addition resulting either acyl C2-O1 or alkyl C4-O1 cleavage, rearrangement leading to ring expansion, decarboxylation, electrophilic reactions enolates.Recent advances asymmetric led further developments area novel significantly increased applications natural product total synthesis.The latter...
The intramolecular, nucleophile-catalyzed, aldol lactonization (NCAL) process merges catalytic, asymmetric carbocycle synthesis with β-lactone synthesis. application of modified Mukaiyama reagents to this led greatly improved conversion and efficiency (70−82% yield) shorter reaction times no diminution enantioselectivity (91−98% ee). was extended several new aldehyde−acid substrates leading bicyclic-β-lactones. This methodology uniquely provides β-lactone-fused cyclopentanes cyclohexanes...
Abstract We report here that des-methyl, des-amino pateamine A (DMDA-PatA), a structurally simplified analogue of the marine natural product A, has potent antiproliferative activity against wide variety human cancer cell lines while showing relatively low cytotoxicity nonproliferating, quiescent fibroblasts. DMDA-PatA retains almost full in vitro potency P-glycoprotein-overexpressing MES-SA/Dx5-Rx1 uterine sarcoma cells are significantly resistant to paclitaxel, suggesting is not substrate...
A full account of concise, enantioselective syntheses the anticancer agent (-)-salinosporamide and derivatives, including (-)-homosalinosporamide, that was inspired by biosynthetic considerations is described. The brevity synthetic strategy stems from a key bis-cyclization β-keto tertiary amide, which retains optical purity enabled A(1,3)-strain rendering slow epimerization relative to rate bis-cyclization. Optimization studies bis-cyclization, through byproduct isolation characterization,...
Abstract Triptolide is a key component of the traditional Chinese medicinal plant Thunder God Vine and has potent anticancer immunosuppressive activities. It an irreversible inhibitor eukaryotic transcription through covalent modification XPB, subunit general factor TFIIH. Cys342 XPB was identified as residue that undergoes by 12,13‐epoxide group triptolide. Mutation to threonine conferred resistance triptolide on mutant protein. Replacement endogenous wild‐type with Cys342Thr in HEK293T...
Dyotropic rearrangements of fused, tricyclic β-lactones are described that proceed via unprecedented stereospecific, 1,2-acyl migrations delivering bridged, spiro-γ-butyrolactones. A unique example this dyotropic process involves a fused bis-lactone possessing both β- and δ-lactone moieties which enabled rapid access to the core structures curcumanolide curcumalactone. Our current mechanistic understanding latter process, based on computational studies, is also described. Other key...
The first total synthesis of the marine toxin (−)-gymnodimine (1) has been accomplished in a convergent manner. A highly diastereo- and enantioselective exo-Diels–Alder reaction catalyzed by bis-oxazoline Cu(II) catalyst enabled rapid assembly spirocyclic core gymnodimine. preparation tetrahydrofuran fragment utilized chiral auxiliary based anti-aldol reaction. Two major fragments, spirolactam 56 55, were then coupled through an efficient Nozaki–Hiyama–Kishi An unconventional, ambient...