A5050099836- Carbohydrate Chemistry and Synthesis
- Crystallization and Solubility Studies
- Chemical Synthesis and Analysis
- X-ray Diffraction in Crystallography
- Chemical Synthesis and Reactions
- Sulfur-Based Synthesis Techniques
- Synthesis and Reactions of Organic Compounds
- Synthesis and Catalytic Reactions
- Natural product bioactivities and synthesis
- Click Chemistry and Applications
- Glycosylation and Glycoproteins Research
- Synthesis and Characterization of Heterocyclic Compounds
- Plant biochemistry and biosynthesis
- Microbial Natural Products and Biosynthesis
- Asymmetric Synthesis and Catalysis
- Synthetic Organic Chemistry Methods
- Synthesis of heterocyclic compounds
- Fluorine in Organic Chemistry
- Chemical Reaction Mechanisms
- Synthesis and Reactivity of Sulfur-Containing Compounds
- Bioactive Compounds and Antitumor Agents
- Organic and Inorganic Chemical Reactions
- Phytochemical compounds biological activities
- Sesquiterpenes and Asteraceae Studies
- Enzyme Catalysis and Immobilization
Riga Technical University
2014-2024
Abstract Novel lupane‐type triterpenoid‐isoxazole conjugates were designed by direct placing of isoxazole linker at C(17) triterpenoid. The suggested synthetic sequence demonstrates successful combination electro‐organic synthesis and conventional approaches. TEMPO‐mediated electrooxidation betulin to betulinal was developed optimized boron‐doped diamond anodes with potassium acetate as inexpensive supporting electrolyte. Betulinal‐derived oxime further selectively electro‐oxidized a...
Abstract The reactions of halides or pseudohalides group I and II metals with carbamate‐protected aziridines azetidines in liquid sulfur dioxide as solvent resulted the efficient ring‐opening these heterocycles. Sulfur dioxide, a highly polar solvent, solubilizes inorganic salts acts mild Lewis acid to accelerate ring‐opening. For this reason, small heterocycles can be used instead corresponding sulfonamides, activities which are well‐established reactions. Thiols also performed well SO 2...
Malignant melanoma is one of the most pressing problems in developing world. New therapeutic agents that might be effective treating malignancies have developed resistance to conventional medications are urgently required. Semisynthesis an essential method for improving biological activity and efficacy natural product precursors. Semisynthetic derivatives compounds valuable sources new drug candidates with a variety pharmacological actions, including anticancer ones. Two novel semisynthetic...
Abstract Synthesis, solubility and cytotoxicity evaluation of anionic phosphonates derived from betulin, betulinic acid, oleanolic acid ursolic is reported. Phosphonate moieties were successfully installed at terpenoid C28 by carboxylic deprotonation/alkylation sequence using (dimethoxyphosphoryl)methyl trifluoromethanesulfonate as alkylation reagent. Also, betulin-derived ether-linked bis-phosphonate obtained characterized. After demethylation in the presence TMSI resulting phosphonic acids...
<i>N</i>-H-Aziridines undergo efficient ring-opening reactions with aromatic and aliphatic thiols in liquid sulfur dioxide as reaction medium. Due to the Lewis acidic nature of SO<sub>2</sub>, these do not require any other catalytic additives. The expected β-alkyl/arylthio-amines (β-amino thioethers) are obtained excellent β-regioselectivity. developed conditions compatible chiral starting materials enantiomeric purity which is conserved corresponding products. This method also useful for...
Liquid SO 2 is a polar solvent that dissolves both covalent and ionic compounds. Sulfur dioxide possesses also Lewis acid properties, including the ability to covalently bind basic fluoride ions in relatively stable fluorosulfite anion (FSO − ). Herein we report application of liquid as promoting for glycosylation with glycosyl fluorides without any external additive. By using various temperature regimes, method applied armed disarmed glucose mannose-derived moderate excellent yields. A...
During the last decade since previous spotlight on same reagent,[1] use of sulfur dioxide increased noticeably. More than 70 articles and patents about are published per year. It is widely used in biological research, synthesis copolymers,[2] radical chemistry,[3] food processing. However, most innovative applications found synthetic organic chemistry as solvent[4] reagent.[5]
Milbemycins are macrolide antibiotics with a broad spectrum of nematocidal, insecticidal, and acaricidal activity. To obtain milbemycin A3/A4 derivatives suitable for chemical conjugation to protein carriers (milbemycin haptens), succinate linker novel 17-atom-long containing terminal carboxylic acid group were attached the core in protecting group-free synthesis. The obtained coupled Potato virus Y-like nanoparticles by activated ester method. reaction products characterized used mice...
Abstract Michael addition reactions of O -nucleophiles to C(3) exocyclic nitromethylene derivative diacetone glucose are reported. The with primary alcohols proceed at ambient temperature in the presence different bases good yields and give products excellent diastereoselectivity. nucleophile occurs from β-face carbohydrate as shown by single crystal X-ray analysis. secondary low while phenolic compounds do not react. Under certain conditions, isomerization starting material is observed.
Copper (II) and indium (III) triflate catalyzes the Rupe rearrangement of propargylic alcohols in liquid sulfur dioxide as reaction medium. 1-Ethynylcyclohexanol 1-(phenylethynyl) cyclohexan-1-ol were used model substrates expected 1-(cyclohex-1-en-1-yl) ethanone 1-(cyclohex-1-en-1-yl)-2-phenylethanone obtained average yields.
The prevalence and severity of skin cancer, specifically malignant melanoma, among Caucasians remains a significant concern. Natural compounds from plants have long been explored as potential anticancer agents. Betulinic acid (BI) has shown promise in its therapeutic properties, including effects. However, limited bioavailability hindered medicinal applications. To address this issue, two recently synthesized semisynthetic derivatives, N-(2,3-indolo-betulinoyl)diglycylglycine (BA1)...
8-Aminoquinoline amides of 3-oxo-olean-12-en-28-oic acid and 3-oxo-urs-12-en-28-oic were obtained characterized by 1H, 13C-NMR single crystal X-ray analysis. The used triterpenoic acids are oxidized forms naturally occurring oleanolic ursolic acids. Such types derivatives known for their anticancer antiviral activities. On the other hand, 8-aminoquinoline frequently transition metal complexation that is applicable both C-H activation processes biological activity studies.
Abstract This provides the first examples of isoxazolyl sugars where azole fragment is attached to C3 carbohydrate through a C—C bond.
The title compound, C13H21NO7 {systematic name: (3aR,5S,6R,6aR)-5-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2,2-dimethyl-6-(nitro-meth-yl)tetra-hydro-furo[2,3-d][1,3]dioxole}, consists of a substituted 2,2-di-methyl-tetra-hydro-furo[2,3-d][1,3]dioxolane skeleton. furan-ose ring A adopts (o)T 4 conformation. fused dioxolane B and the substituent C also have twisted conformations. There are no strong hydrogen bonds in crystal structure: only weak C-H⋯O contacts present, which link mol-ecules to...