Thiophenes are aromatic heterocyclic organic compounds containing a five-membered ring with four carbon atoms and one sulfur atom, which are found in various natural substances and synthesized for use in pharmaceuticals and agrochemicals.
Compounds with a 5-membered ring of four carbons and an oxygen. They are aromatic heterocycles. The reduced form is tetrahydrofuran.
A plant genus of the family ASTERACEAE. Members contain a pseudoguaiane sesquiterpene. San-fang-feng is the root of E. grijisii used in DRUGS, CHINESE HERBAL.
Methods used for the chemical synthesis of compounds. Included under this heading are laboratory methods used to synthesize a variety of chemicals and drugs.
A group of compounds that are derivatives of methoxybenzene and contain the general formula R-C7H7O.
The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.
Changing an open-chain hydrocarbon to a closed ring. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
Ring compounds having atoms other than carbon in their nuclei. (Grant & Hackh's Chemical Dictionary, 5th ed)
A chemical element having an atomic weight of 106.4, atomic number of 46, and the symbol Pd. It is a white, ductile metal resembling platinum, and following it in abundance and importance of applications. It is used in dentistry in the form of gold, silver, and copper alloys.
Inorganic or organic compounds that contain sulfur as an integral part of the molecule.
A technology, in which sets of reactions for solution or solid-phase synthesis, is used to create molecular libraries for analysis of compounds on a large scale.
The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.
The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.

Microbial desulfurization of organic sulfur compounds in petroleum. (1/1894)

Sulfur removal from petroleum is important from the standpoint of the global environment because the combustion of sulfur compounds leads to the production of sulfur oxides, which are the source of acid rain. As the regulations for sulfur in fuels become more stringent, the existing chemical desulfurizations are coming inadequate for the "deeper desulfurization" to produce lower-sulfur fuels without new and innovative processes. Biodesulfurization is rising as one of the candidates. Several microorganisms were found to desulfurize dibenzothiophene (DBT), a representative of the organic sulfur compounds in petroleum, forming a sulfur-free compound, 2-hydroxybiphenyl. They are promising as biocatalysts in the microbial desulfurization of petroleum because without assimilation of the carbon content, they remove only sulfur from the heterocyclic compounds which is refractory to conventional chemical desulfurization. Both enzymological and molecular genetic studies are now in progress for the purpose of obtaining improved desulfurization activity of organisms. The genes involved in the sulfur-specific DBT desulfurization were identified and the corresponding enzymes have been investigated. From the practical point of view, it has been proved that the microbial desulfurization proceeds in the presence of high concentrations of hydrocarbons, and more complicated DBT analogs are also desulfurized by the microorganisms. This review outlines the progress in the studies of the microbial desulfurization from the basic and practical point of view.  (+info)

5-HT2B-receptor antagonist LY-272015 is antihypertensive in DOCA-salt-hypertensive rats. (2/1894)

We previously demonstrated a change in the receptors mediating 5-hydroxytryptamine (5-HT)-induced contraction in arteries of deoxycorticosterone acetate (DOCA)-salt-hypertensive rats. Specifically, contraction to 5-HT is mediated primarily by 5-HT2A receptors in arteries from normotensive sham rats and by both 5-HT2A and 5-HT2B receptors in arteries from hypertensive rats. We hypothesized that the 5-HT2B receptor may play a role in maintaining the high blood pressure of DOCA-salt-hypertensive rats, and herein we provide data connecting in vitro and in vivo findings. The endothelium-denuded isolated superior mesenteric artery of DOCA-salt rats displayed a marked increase in maximum contraction to the newly available 5-HT2B-receptor agonist BW-723C86 compared with that of arteries from sham rats, confirming that the 5-HT2B receptor plays a greater role in 5-HT-induced contraction in arteries from DOCA-salt rats. In chronically instrumented rats, the 5-HT2B-receptor antagonist LY-272015 (0.3, 1.0, and 3.0 mg/kg iv at 30-min intervals) was given cumulatively 1 time/wk during 4 wk of continued DOCA-salt treatment. LY-272015 did not reduce blood pressure of the sham-treated rats at any time or dose. However, LY-272015 (1.0 and 3. 0 mg/kg) significantly reduced mean blood pressure in a subgroup of week 3 (-20 mmHg) and week 4 DOCA-salt (-40 mmHg) rats that had extremely high blood pressure (mean arterial blood pressure approximately 200 mmHg). Blockade of 5-HT2B receptors by in vivo administration of LY-272015 (3.0 mg/kg) was verified by observing reduced 5-HT-induced contraction in rat stomach fundus, the tissue from which the 5-HT2B receptor was originally cloned. These data support the novel hypothesis that 5-HT2B-receptor expression is induced during the development of DOCA-salt hypertension and contributes to the maintenance of severe blood pressure elevations.  (+info)

Cleavage of the HER2 ectodomain is a pervanadate-activable process that is inhibited by the tissue inhibitor of metalloproteases-1 in breast cancer cells. (3/1894)

HER2/neu, a Mr 185,000 tyrosine kinase receptor that is overexpressed in breast cancer, undergoes proteolytic cleavage of its extracellular domain (ECD). In contrast with other membrane-bound proteins, including growth factor receptors, that are cleaved by a common machinery system, we show that HER2 cleavage is a slow process and is not activated by protein kinase C. Pervanadate, a general inhibitor of protein-tyrosine phosphatases, induces a rapid and potent shedding of HER2 ECD. The shedding of HER2 ECD is inhibited by the broad-spectrum metalloprotease inhibitors EDTA, TAPI-2, and batimastat. The tissue inhibitor of metalloproteases-1; an inhibitor of matrix metalloproteases that does not inhibit cleavage by the general protein kinase C-dependent shedding machinery, also inhibited HER2 ECD shedding, whereas tissue inhibitor of metalloproteases-2 did not. These data suggest that HER2 cleavage is a process regulated by an as-yet-unidentified distinct protease.  (+info)

Phase I study of intrapleural batimastat (BB-94), a matrix metalloproteinase inhibitor, in the treatment of malignant pleural effusions. (4/1894)

Tumor cells and associated stromal cells secrete matrix metalloproteinases (MMPs), contributing to invasion, angiogenesis, and metastasis. Batimastat (BB-94) is a broad-spectrum MMP inhibitor that causes resolution of ascites and/or tumor growth delay in animal models of breast, ovarian, and colorectal cancer. We recruited 18 patients with cytologically positive malignant pleural effusions into a Phase I study of intrapleural BB-94. Three patients received single doses of BB-94 at each dose level: 15, 30, 60, 105, 135, and 300 mg/m2. Two patients were retreated with a second course at 60 and 105 mg/m2. BB-94 was detectable in plasma 1 h after intrapleural administration, and peak levels of 20-200 ng/ml occurred after 4 h to 1 week. BB-94 persisted in the plasma for up to 12 weeks, at levels exceeding the IC50s for target MMPs. Peak values were higher, and persistence in the plasma was longer after higher doses of BB-94. The treatment was well tolerated. Toxic effects included low-grade fever for 24-48 h (6 of 18 patients, 33%) and reversible asymptomatic elevation of liver enzymes (8 patients, 44%). Toxicity seemed unrelated to BB-94 dose or plasma levels. Sixteen patients evaluable for response required significantly fewer pleural aspirations in the 3 months after BB-94 compared with the 3 months before. Seven patients (44%) required no further pleural aspiration until death/last follow-up. After 1 month, patients treated with 60-300 mg/m2 BB-94 had significantly better dyspnea scores, indicating improved exercise tolerance, compared with baseline scores the day after BB-94. The maximum tolerated intrapleural dose remains to be defined, but it is clear that intrapleural BB-94 is well tolerated, with evidence of local activity.  (+info)

Limited anti-inflammatory efficacy of cyclo-oxygenase-2 inhibition in carrageenan-airpouch inflammation. (5/1894)

1. Cyclo-oxygenase-2 (COX-2) is expressed at sites of inflammation and is believed to be the major source of inflammation-associated prostaglandin synthesis. Selective inhibition of COX-2 has been suggested to produce anti-inflammatory effects with reduced toxicity in the gastrointestinal tract. We examined the extent to which suppression of COX-2 led to inhibition of various components of inflammation in the carrageenan-airpouch model in the rat. 2. Indomethacin (> or =0.3 mg kg(-1)), nimesulide (> or =3 mg kg(-1)) and the selective COX-2 inhibitor, SC-58125 (> or =0.3 mg kg(-1)), significantly suppressed the production of prostaglandin E2 at the site of inflammation. At higher doses, indomethacin (> or =1 mg kg(-1)) and nimesulide (30 mg kg(-1)), but not SC-58125 (up to 10 mg kg(-1)), significantly inhibited COX-1 activity (as measured by whole blood thromboxane synthesis). 3. All three test drugs significantly reduced the volume of exudate in the airpouch, but only at doses greater than those required for substantial (>90%) suppression of COX-2 activity. Similarly, reduction of leukocyte infiltration was only observed with the doses of indomethacin and nimesulide that caused significant suppression of COX-1 activity. 4. SC-58125 did not significantly affect leukocyte infiltration into the airpouch at any dose tested (up to 10 mg kg(-1)). A second selective COX-2 inhibitor, Dup-697, was also found to suppress exudate PGE2 levels without significant effects on leukocyte infiltration. 5. These results indicate that selective inhibition of COX-2 results in profound suppression of PGE2 synthesis in the carrageenan-airpouch, but does not affect leukocyte infiltration. Exudate volume was only reduced with the highly selective COX-2 inhibitor when a dose far above that necessary for suppression of COX-2 activity was used. Inhibition of leukocyte infiltration was observed with indomethacin and nimesulide, but only at doses that inhibited both COX-1 and COX-2.  (+info)

Effects of angiogenesis inhibitors on multistage carcinogenesis in mice. (6/1894)

Solid tumors depend on angiogenesis for their growth. In a transgenic mouse model of pancreatic islet cell carcinogenesis (RIP1-Tag2), an angiogenic switch occurs in premalignant lesions, and angiogenesis persists during progression to expansive solid tumors and invasive carcinomas. RIP1-Tag2 mice were treated so as to compare the effects of four angiogenesis inhibitors at three distinct stages of disease progression. AGM-1470, angiostatin, BB-94, and endostatin each produced distinct efficacy profiles in trials aimed at preventing the angiogenic switch in premalignant lesions, intervening in the rapid expansion of small tumors, or inducing the regression of large end-stage cancers. Thus, anti-angiogenic drugs may prove most efficacious when they are targeted to specific stages of cancer.  (+info)

Marked suppression of T cells by a benzothiophene derivative in patients with human T-lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis. (7/1894)

In a search for new anti-autoimmune agents that selectively suppress activation of autoreactive T cells, one such agent, 5-methyl-3-(1-methylethoxy)benzo[b]thiophene-2-carboxamide (CI-959-A), was found to be effective. This compound, which is known to suppress tumor necrosis factor alpha (TNF-alpha)-induced CD54 expression, inhibited the primary proliferative response of the T cell to antigen (Ag)-presenting cells (APCs) including allogenic dendritic cells (DCs), autologous Epstein-Barr virus-infected B cells, and human T lymphotropic virus type I (HTLV-I)-infected T cells. Autoreactive T cells from patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) spontaneously proliferate in vitro, and their activation is reported to be associated with CD54 expression. The spontaneous proliferation of T cells from patients with HAM/TSP was entirely blocked by CI-959-A. However, in this study, the T-cell proliferation in 15 patients with HAM/TSP was found to depend more extensively on major histocompatibility complex (MHC) class II and CD86 than on CD54 Ags. Since most important APCs for the development of HAM/TSP are DCs and HTLV-I-infected T cells, the effect of CI-959-A on DC generation and on the expression of surface molecules on activated T cells is examined. CI-959-A suppressed recombinant granulocyte-macrophage colony stimulating factor (GM-CSF)- and recombinant interleukin-4-dependent differentiation of DCs from monocytes and inhibited the expression of CD54 and, more extensively, MHC class II and CD86 Ags. CI-959-A showed little toxicity toward lymphoma or HTLV-I-infected T-cell lines or toward monocytes and cultured DCs. These results suggest that CI-959-A might be a potent anti-HAM/TSP agent.  (+info)

Dorzolamide effect on ocular blood flow. (8/1894)

PURPOSE: To evaluate the effect of dorzolamide on ocular blood flow in normal and glaucomatous eyes. METHODS: Twenty-six eyes with documented open-angle glaucoma of 26 patients and 13 normal control eyes of 8 age-matched subjects were included in this study. All eyes underwent color Doppler imaging for measuring peak-systolic velocity, end-diastolic velocity, and resistance index in the ophthalmic and central retinal arteries and the maximal and minimal velocities in the central retinal vein. Eyes were grouped in control and initial and advanced glaucoma categories. Measurements were made in all groups before and after application of topical dorzolamide. Intragroup comparisons between baseline and dorzolamide conditions were made using paired Student's t-test. Intergroup comparisons under baseline conditions between normal and glaucomatous eyes were made by using the one-way ANOVA test. Statistical significance was set at P < 0.05. RESULTS: The peak-systolic velocity of the central retinal artery in glaucomatous eyes and the end-diastolic velocity of the ophthalmic and central retinal arteries in all groups were significantly higher after application of dorzolamide. The minimal velocity of the central retinal vein showed significantly higher values after dorzolamide, whereas the maximal velocity remained unchanged. The peak-systolic velocity of the ophthalmic artery in all groups and the peak-systolic velocity of the central retinal artery in normal eyes also remained unchanged. The resistance index was significantly lower in the ophthalmic and central retinal arteries in all groups after dorzolamide. The intraocular pressure was significantly reduced in all groups after dorzolamide. Under baseline conditions normal control eyes and glaucomatous eyes showed differences in various measurements. Peak-systolic velocity was significantly lower in glaucomatous eyes than in normal control eyes with the exception of the ophthalmic artery in the initial glaucoma group. End-diastolic velocity was lower in glaucomatous eyes than in control eyes in both arteries. Maximal and minimal velocities of the central retinal vein were lower in glaucomatous eyes than in normal control eyes. Resistance index was higher in glaucomatous eyes than in normal control eyes in the ophthalmic artery but not in the central retinal artery. CONCLUSIONS: Most hemodynamic parameters of intraocular and periocular vessels improve after application of topical dorzolamide in both normal control and glaucomatous eyes. Dorzolamide should be regarded as a useful drug for treatment of glaucoma not only because it reduces intraocular pressure but also because it improves the ocular blood supply.  (+info)

Thiophenes are organic compounds that contain a heterocyclic ring made up of four carbon atoms and one sulfur atom. The structure of thiophene is similar to benzene, with the benzene ring being replaced by a thiophene ring. Thiophenes are aromatic compounds, which means they have a stable, planar ring structure and delocalized electrons.

Thiophenes can be found in various natural sources such as coal tar, crude oil, and some foods like onions and garlic. They also occur in certain medications, dyes, and pesticides. Some thiophene derivatives have been synthesized and studied for their potential therapeutic uses, including anti-inflammatory, antiviral, and antitumor activities.

In the medical field, thiophenes are used in some pharmaceuticals as building blocks to create drugs with various therapeutic effects. For example, tipepidine, a cough suppressant, contains a thiophene ring. Additionally, some anesthetics and antipsychotic medications also contain thiophene moieties.

It is important to note that while thiophenes themselves are not typically considered medical terms, they play a role in the chemistry of various pharmaceuticals and other medical-related compounds.

Furans are not a medical term, but a class of organic compounds that contain a four-membered ring with four atoms, usually carbon and oxygen. They can be found in some foods and have been used in the production of certain industrial chemicals. Some furan derivatives have been identified as potentially toxic or carcinogenic, but the effects of exposure to these substances depend on various factors such as the level and duration of exposure.

In a medical context, furans may be mentioned in relation to environmental exposures, food safety, or occupational health. For example, some studies have suggested that high levels of exposure to certain furan compounds may increase the risk of liver damage or cancer. However, more research is needed to fully understand the potential health effects of these substances.

It's worth noting that furans are not a specific medical condition or diagnosis, but rather a class of chemical compounds with potential health implications. If you have concerns about exposure to furans or other environmental chemicals, it's best to consult with a healthcare professional for personalized advice and recommendations.

Echinops plants, also known as globe thistles, are a genus of prickly, herbaceous plants that belong to the family Asteraceae. The name Echinops comes from the Greek words echinos (hedgehog) and ops (face), which refers to the spiky appearance of the plant's flowers.

Globe thistles are native to Europe, Asia, and eastern Africa, and they typically grow in dry, rocky habitats. The plants can reach heights of up to 4 feet (1.2 meters) and have deeply lobed, gray-green leaves that are covered in stiff hairs.

The most distinctive feature of Echinops plants is their large, round flower heads, which are composed of numerous small florets that are surrounded by spiky bracts. The flowers can be blue, purple, or white and appear in the summer and fall.

Echinops plants have been used in traditional medicine for their anti-inflammatory and diuretic properties. However, it's important to note that some parts of the plant, particularly the spines, can be irritating to the skin and mucous membranes, so they should be handled with care.

Synthetic chemistry techniques refer to the methods and processes used in the laboratory to synthesize or create new chemical compounds or molecules. This can involve a wide range of procedures, including various types of reactions, separations, purifications, and characterizations. The goal of synthetic chemistry is often to produce a specific compound with desired properties, such as a drug molecule with therapeutic activity or a materials compound with unique physical or chemical characteristics. Synthetic chemists use their knowledge of organic, inorganic, physical, and analytical chemistry to design and execute efficient and effective syntheses, and they may employ automation, computational modeling, and other advanced tools to aid in their work.

Anisoles are organic compounds that consist of a phenyl ring (a benzene ring with a hydroxyl group replaced by a hydrogen atom) attached to a methoxy group (-O-CH3). The molecular formula for anisole is C6H5OCH3. Anisoles are aromatic ethers and can be found in various natural sources, including anise plants and some essential oils. They have a wide range of applications, including as solvents, flavoring agents, and intermediates in the synthesis of other chemicals.

Molecular structure, in the context of biochemistry and molecular biology, refers to the arrangement and organization of atoms and chemical bonds within a molecule. It describes the three-dimensional layout of the constituent elements, including their spatial relationships, bond lengths, and angles. Understanding molecular structure is crucial for elucidating the functions and reactivities of biological macromolecules such as proteins, nucleic acids, lipids, and carbohydrates. Various experimental techniques, like X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and cryo-electron microscopy (cryo-EM), are employed to determine molecular structures at atomic resolution, providing valuable insights into their biological roles and potential therapeutic targets.

Cyclization is a chemical process that involves forming a cyclic structure or ring-shaped molecule from a linear or open-chain compound. In the context of medicinal chemistry and drug design, cyclization reactions are often used to synthesize complex molecules, including drugs, by creating rings or fused ring systems within the molecule's structure.

Cyclization can occur through various mechanisms, such as intramolecular nucleophilic substitution, electrophilic addition, or radical reactions. The resulting cyclized compounds may exhibit different chemical and biological properties compared to their linear precursors, making them valuable targets for drug discovery and development.

In some cases, the cyclization process can lead to the formation of stereocenters within the molecule, which can impact its three-dimensional shape and how it interacts with biological targets. Therefore, controlling the stereochemistry during cyclization reactions is crucial in medicinal chemistry to optimize the desired biological activity.

Overall, cyclization plays a significant role in the design and synthesis of many pharmaceutical compounds, enabling the creation of complex structures that can interact specifically with biological targets for therapeutic purposes.

Heterocyclic compounds are organic compounds that contain at least one atom within the ring structure, other than carbon, such as nitrogen, oxygen, sulfur or phosphorus. These compounds make up a large class of naturally occurring and synthetic materials, including many drugs, pigments, vitamins, and antibiotics. The presence of the heteroatom in the ring can have significant effects on the physical and chemical properties of the compound, such as its reactivity, stability, and bonding characteristics. Examples of heterocyclic compounds include pyridine, pyrimidine, and furan.

I'm sorry for the confusion, but "Palladium" is not a medical term. It is a chemical element with symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. It's used in various applications, including jewelry, dental work, electronics, and chemical reactions. If you have any medical terms you would like me to define, please let me know!

Sulfur compounds refer to chemical substances that contain sulfur atoms. Sulfur can form bonds with many other elements, including carbon, hydrogen, oxygen, and nitrogen, among others. As a result, there is a wide variety of sulfur compounds with different structures and properties. Some common examples of sulfur compounds include hydrogen sulfide (H2S), sulfur dioxide (SO2), and sulfonic acids (R-SO3H).

In the medical field, sulfur compounds have various applications. For instance, some are used as drugs or drug precursors, while others are used in the production of medical devices or as disinfectants. Sulfur-containing amino acids, such as methionine and cysteine, are essential components of proteins and play crucial roles in many biological processes.

However, some sulfur compounds can also be harmful to human health. For example, exposure to high levels of hydrogen sulfide or sulfur dioxide can cause respiratory problems, while certain organosulfur compounds found in crude oil and coal tar have been linked to an increased risk of cancer. Therefore, it is essential to handle and dispose of sulfur compounds properly to minimize potential health hazards.

Combinatorial chemistry techniques are a group of methods used in the field of chemistry to synthesize and optimize large libraries of chemical compounds in a rapid and efficient manner. These techniques involve the systematic combination of different building blocks, or reagents, in various arrangements to generate a diverse array of molecules. This approach allows chemists to quickly explore a wide chemical space and identify potential lead compounds for drug discovery, materials science, and other applications.

There are several common combinatorial chemistry techniques, including:

1. **Split-Pool Synthesis:** In this method, a large collection of starting materials is divided into smaller groups, and each group undergoes a series of chemical reactions with different reagents. The resulting products from each group are then pooled together and redistributed for additional rounds of reactions. This process creates a vast number of unique compounds through the iterative combination of building blocks.
2. **Parallel Synthesis:** In parallel synthesis, multiple reactions are carried out simultaneously in separate reaction vessels. Each vessel contains a distinct set of starting materials and reagents, allowing for the efficient generation of a series of related compounds. This method is particularly useful when exploring structure-activity relationships (SAR) or optimizing lead compounds.
3. **Encoded Libraries:** To facilitate the rapid identification of active compounds within large libraries, encoded library techniques incorporate unique tags or barcodes into each molecule. These tags allow for the simultaneous synthesis and screening of compounds, as the identity of an active compound can be determined by decoding its corresponding tag.
4. **DNA-Encoded Libraries (DELs):** DELs are a specific type of encoded library that uses DNA molecules to encode and track chemical compounds. In this approach, each unique compound is linked to a distinct DNA sequence, enabling the rapid identification of active compounds through DNA sequencing techniques.
5. **Solid-Phase Synthesis:** This technique involves the attachment of starting materials to a solid support, such as beads or resins, allowing for the stepwise addition of reagents and building blocks. The solid support facilitates easy separation, purification, and screening of compounds, making it an ideal method for combinatorial chemistry applications.

Combinatorial chemistry techniques have revolutionized drug discovery and development by enabling the rapid synthesis, screening, and optimization of large libraries of chemical compounds. These methods continue to play a crucial role in modern medicinal chemistry and materials science research.

A Structure-Activity Relationship (SAR) in the context of medicinal chemistry and pharmacology refers to the relationship between the chemical structure of a drug or molecule and its biological activity or effect on a target protein, cell, or organism. SAR studies aim to identify patterns and correlations between structural features of a compound and its ability to interact with a specific biological target, leading to a desired therapeutic response or undesired side effects.

By analyzing the SAR, researchers can optimize the chemical structure of lead compounds to enhance their potency, selectivity, safety, and pharmacokinetic properties, ultimately guiding the design and development of novel drugs with improved efficacy and reduced toxicity.

Stereoisomerism is a type of isomerism (structural arrangement of atoms) in which molecules have the same molecular formula and sequence of bonded atoms, but differ in the three-dimensional orientation of their atoms in space. This occurs when the molecule contains asymmetric carbon atoms or other rigid structures that prevent free rotation, leading to distinct spatial arrangements of groups of atoms around a central point. Stereoisomers can have different chemical and physical properties, such as optical activity, boiling points, and reactivities, due to differences in their shape and the way they interact with other molecules.

There are two main types of stereoisomerism: enantiomers (mirror-image isomers) and diastereomers (non-mirror-image isomers). Enantiomers are pairs of stereoisomers that are mirror images of each other, but cannot be superimposed on one another. Diastereomers, on the other hand, are non-mirror-image stereoisomers that have different physical and chemical properties.

Stereoisomerism is an important concept in chemistry and biology, as it can affect the biological activity of molecules, such as drugs and natural products. For example, some enantiomers of a drug may be active, while others are inactive or even toxic. Therefore, understanding stereoisomerism is crucial for designing and synthesizing effective and safe drugs.

Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst, which remains unchanged at the end of the reaction. A catalyst lowers the activation energy required for the reaction to occur, thereby allowing the reaction to proceed more quickly and efficiently. This can be particularly important in biological systems, where enzymes act as catalysts to speed up metabolic reactions that are essential for life.

Oxidation can occur both at sulfur, giving a thiophene S-oxide, as well as at the 2,3-double bond, giving the thiophene 2,3- ... Oxidation of thiophenes may be relevant to the metabolic activation of various thiophene-containing drugs, such as tienilic ... Thiophenes undergo hydrogenolysis to form hydrocarbons and hydrogen sulfide. Thus, thiophene itself is converted to butane and ... Desulfurization of thiophene with Raney nickel affords butane. When coupled with the easy 2,5-difunctionalization of thiophene ...
Benzo[c]thiophene is an organic compound with the chemical formula C8H6S. The similarly named Benzo[b]thiophene is an isomer ... Benzo[b]thiophene is more stable and far more commonly encountered. Cava, Michael P.; Lakshmikantham, M. V. (1975). " ... "Nonclassical Condensed Thiophenes". Accounts of Chemical Research. 8 (4): 139-44. doi:10.1021/ar50088a005. v t e (Articles with ... thiophenes, Simple aromatic rings, All stub articles, Heterocyclic compound stubs). ...
The Fiesselmann thiophene synthesis is a name reaction in organic chemistry that allows for the generation of 3-hydroxy-2- ... Ram, Vishnu J.; Goel, Atul; Shukla, P. K.; Kapil, A. (1997-12-16). "Synthesis of thiophenes and thieno[3,2-c]pyran-4-ones as ... Nicolaou used the conditions of the Fiesselmann thiophene synthesis to show potential DNA cleaving properties of golfomycin A, ... Gronowitz, Salo (1991-01-01). Chemistry of Heterocyclic Compounds: Thiophene and Its Derivatives, Part Four, Volume 44. ...
It can be prepared from thiophene by the Vilsmeier reaction. Alternatively, it is prepared from chloromethylation of thiophene ... Thiophene-2-carboxaldehyde is an organosulfur compound with the formula C4H3SCHO. It is one of two isomeric ... Jonathan Swanston (2006). "Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/ ...
Together with thiophene-3-acetic acid, it is one of two isomeric thiophene acetic acids. It is prepared from 2-acetylthiophene ... Swanston, Jonathan (2006). "Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/ ... Thiophene-2-acetic acid is the organosulfur compound with the formula HO2CCH2C4H3S. ...
It is one of two monocarboxylic acids of thiophene, the other being thiophene-3-carboxylic acid. Copper(I) thiophene-2- ... Thiophene-2-carboxylic acid has been widely studied as a substrate in coupling reactions and olefinations. E. Campaigne, ... Swanston, Jonathan (2006). "Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/ ... It can be prepared by the oxidation of thiophene-2-carboxaldehyde or, more practically, 2-acetylthiophene. Upon treatment with ...
It is one of two isomers of thiophene acetic acid, the other being thiophene-2-acetic acid. Thiophene-3-acetic acid has ... Thiophene-3-acetic acid is an organosulfur compound with the formula HO2CCH2C4H3S. It is a white solid. ... Thiophenes, Acetic acids, All stub articles, Organic compound stubs). ...
... or CuTC is a coordination complex derived from copper and thiophene-2-carboxylic acid. It is ... Copper(I) thiophene-2-carboxylate at Sigma-Aldrich NIOSH Pocket Guide to Chemical Hazards. "#0150". National Institute for ... Thiophenes, Copper(I) compounds, Reagents for organic chemistry). ...
Other names in common use include thiophene-2-carboxyl-CoA dehydrogenase, thiophene-2-carboxyl-CoA hydroxylase, and thiophene-2 ... In enzymology, a thiophene-2-carbonyl-CoA monooxygenase (EC 1.14.99.35) is an enzyme that catalyzes the chemical reaction ... nov., a thiophene-2-carboxylate-metabolizing bacterium from activated sludge". Arch. Microbiol. 169 (4): 293-302. doi:10.1007/ ... The systematic name of this enzyme class is thiophene-2-carbonyl-CoA, hydrogen-donor:oxygen oxidoreductase. ...
Three constitutional isomers have been synthesized: thieno[3,2-b]thiophene, thieno[2,3-b]thiophene, and thieno[3,4-b]thiophene ... Thieno[2,3-b]thiophene CAS RN 250-84-0 b.p. 102 °C at 16 mmHg colorless oil. Thieno[3,4-b]thiophene CAS RN 250-65-7 m.p. 7.0- ... Thieno[2,3-b]thiophene was the first member of the series to be isolated. It was obtained in very low yield upon heating citric ... In organic chemistry, thienothiophene is any of several compounds consisting of two fused thiophene rings. They have the ...
... and Complete Characterization of Thiophene S-Oxide Dimers and Evidence for Thiophene S-Oxide as an Intermediate in Thiophene ... "Evidence for thiophene-S-oxide as a primary reactive metabolite of thiophene in vivo: formation of a dihydrothiophene sulfoxide ... Thiopropamine is a stimulant drug which is an analogue of amphetamine where the phenyl ring has been replaced by thiophene. It ... Campaigne E, McCarthy WC (September 1954). "3-Substituted Thiophenes. VIII. 3-Thienylalkylamines". Journal of the American ...
In addition to benzo[b]thiophene, a second isomer is known: benzo[c]thiophene. Benzothiophene finds use in research as a ... thiophenes, and Thieno[3,2-b]thiophenes". Organic Letters. American Chemical Society (ACS). 13 (15): 4100-4103. doi:10.1021/ ... Cava, Michael P.; Lakshmikantham, M. V. (1975). "Nonclassical Condensed Thiophenes". Accounts of Chemical Research. 8 (4): 139- ... thiophenes". The Journal of Organic Chemistry. American Chemical Society (ACS). 76 (18): 7546-7550. doi:10.1021/jo201081v. ISSN ...
Swanston, Jonathan (2006). "Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/ ... Thiophenes, All stub articles, Gastrointestinal system drug stubs, Livestock stubs). ...
Unlike 2-bromothiophene, the 3-bromo isomer cannot be prepared directly from thiophene. It can be prepared by debromination of ... 2-Bromothiophene Jonathan Swanston (2006). "Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. ... 2,3,5-tribromothiophene, which is obtained by bromination of thiophene. ... Thiophenes, Bromoarenes, All stub articles, Organohalide stubs). ...
Swanston, Jonathan (2006). "Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/ ... J.; Nord, F. F. (1949). "Thiophene Series. V. Wolff-Kishner Reductions". Journal of Organic Chemistry. 14: 638-42. doi:10.1021/ ... It can be produced by Wolff-Kishner reduction of thiophene-2-carboxaldehyde. Its commercial synthesis involvess vapor-phase ...
The compound is a derivative of thiophene-2-acetic acid. Hameed TK, Robinson JL (July 2002). "Review of the use of ... 128-. ISBN 978-0-19-953484-5. International Drug Names: Cefalotin Swanston, Jonathan (2006). "Thiophene". Ullmann's ... Thiophenes, Acetate esters, All stub articles, Antibiotic stubs). ...
Swanston, Jonathan (2006). "Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/ ...
Unlike 3-bromothiophene, the 2-bromo isomer is prepared directly by partial bromination of thiophene. It is a precursor to ... The LD50 is low, 200 - 250 mg/kg (oral, rat). Jonathan Swanston (2006). "Thiophene". Ullmann's Encyclopedia of Industrial ... Thiophenes, Bromoarenes, All stub articles, Organohalide stubs). ...
It is the saturated analog of thiophene. It is a volatile, colorless liquid with an intensely unpleasant odor. It is also known ... Tetrahydrofuran Thiophene Armarego WF, Chai CL (2003). "Purification of Organic Chemicals". Purification of Laboratory ... "Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a26_793.pub2. Uson R, ...
"Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a26_793.pub2. F.A.Cotton ...
By synthesizing thiophene and selenophene analogues, it was found that there was a reduction in the optical band gap as a ... Compared to thiophenes, tellurophenes have been found to have lower optical band gaps, significantly lower LUMO levels, and ... MIDA-capped thiophene, selenophene, and tellurophenes were synthesized through Stille coupling. Crystal structures of DPT-MIDA ... By replacing the pinacolboronate esters with thiophenes, there was no luminescence, indicating that both Te(II) and BPin played ...
It is of commercial interest as a precursor to both thiophene-2-carboxylic acid and thiophene-2-acetic acid. It is prepared by ... Swanston, Jonathan (2006). "Thiophene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/ ... the reaction of thiophene with acetyl chloride in the presence of stannic chloride. "2-Acetylthiophene". pubchem.ncbi.nlm.nih. ...
Liu, Y.; Ye, M.; Guo, H. Z.; Zhao, Y. Y.; Guo, D. A. (2002). "New thiophenes from Echinops grijisii". Journal of Asian Natural ... In the most common isomer of terthiophene, two thienyl groups are connected via their 2 positions to a central thiophene, also ... It is an oligomer of the heterocycle thiophene, a shorter oligomer is dithienyl, and the parent polymer is polythiophene. ...
"Palladium-Catalyzed Multiple Arylation of Thiophenes". Journal of the American Chemical Society. 124 (19): 5286-5287. doi: ... in multiple reactions including the amination of a range of aryl halides and triflates as well as the arylation of thiophenes. ...
Urban, S.; Beiring, B.; Ortega, N.; Paul, D.; Glorius, F. (2012). "Asymmetric Hydrogenation of Thiophenes and Benzothiophenes ... The asymmetric hydrogenation of thiophenes and benzothiophenes No heterogeneous catalyst has been commercialized for asymmetric ... of compounds where sulfur is part of the initial unsaturated pi-bonding system so far appears to be limited to thiophenes and ...
Heinz, J.; Schulze-Makuch, D. (2020). "Thiophenes on Mars: biotic or abiotic origin?". Astrobiology. 20 (4): 552-561. Bibcode: ...
Polymerization of thiophene can be effected by a solution of ferric chloride in acetonitrile. The kinetics of thiophene ... and urethanes Thiophenes with chiral substituents at the 3 position have been polymerized. Such chiral PTs in principle could ... SCE, whereas unsubstituted thiophene requires an additional 0.2 V. Steric hindrance resulting from branching at the α-carbon of ... Poly(3-(perfluorooctyl)thiophene)s is soluble in supercritical carbon dioxide Oligothiophenes capped at both ends with ...
As for thiophene, electrophiles tend to attack at the carbon positions next to the chalcogen. Such reactions are slower than ... Hartough, H. D. (2009). Thiophene and Its Derivatives. John Wiley & Sons. ISBN 9780470188026. Eicher, Theophil; Hauptmann, ... that of furan, but faster than thiophene. International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic ...
Thiophene, a sulfur analog. Simple aromatic rings Varsol, a petroleum distillate with a boiling range of 150-200 °C. Frederick ...
With 1,4-diketones the reagent forms thiophenes. It is also used to deoxygenate sulfoxides. The use of P4S10 has been displaced ...

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