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Boger Pyridine Synthesis
The Boger pyridine synthesis is a cycloaddition approach to the formation of pyridines named after its inventor Dale L. Boger, who first reported it in 1981. The reaction is a form of inverse-electron demand Diels-Alder reaction in which an enamine reacts with a 1,2,4-triazine to form the pyridine nucleus. The reaction is especially useful for accessing pyridines that would be difficult or impossible to access via other methods and has been used in the total synthesis Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes ... of several complicated natural products. Mechanism The enamine is generally generated ''in situ'' from catalytic amine (such as pyrrolidine) and a ketone. The enamine then reacts as the dienophile with a 1,2,4-triazine. The initial adduct then expels nitrogen, and the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycloaddition
In organic chemistry, a cycloaddition is a chemical reaction in which "two or more Unsaturated hydrocarbon, unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the Multiplicity (chemistry)#Molecules, bond multiplicity". The resulting reaction is a cyclization reaction. Many but not all cycloadditions are Concerted reaction, concerted and thus pericyclic. Nonconcerted cycloadditions are not pericyclic. As a class of addition reaction, cycloadditions permit carbon–carbon bond formation without the use of a nucleophile or electrophile. Cycloadditions can be described using two systems of notation. An older but still common notation is based on the size of linear arrangements of atoms in the reactants. It uses parentheses: where the variables are the numbers of linear atoms in each reactant. The product is a cycle of size . In this system, the standard Diels-Alder reaction is a (4 + 2)-cyc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow, due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. As of 2016, it is synthesized on the scale of about 20,000 tons per year worldwide. Properties Physical properties The molecular electric dipole moment is 2.2 debyes. Pyridine is diamagnetic and has a diamagnetic susceptibility of −48.7 × 10−6 cm3·mol−1. The standard enthalpy of formation is 100.2 kJ·mol−1 in the liquid phase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dale L
Dale or dales may refer to: Locations * Dale (landform), an open valley * Dale (place name element) Geography ;Australia * The Dales (Christmas Island), in the Indian Ocean ;Canada * Dale, Ontario ;Ethiopia *Dale (woreda), district ;Norway *Dale, Fjaler, the administrative centre of Fjaler municipality, Vestland county *Dale, Sel, a village in Sel municipality in Innlandet county * Dale, Vaksdal, the administrative centre of Vaksdal municipality, Vestland county * Dale, Vaksdal, the administrative bop on the head * Dale Church (Fjaler), a church in Fjaler municipality, Vestland county *Dale Church (Luster), a church in Luster municipality, Vestland county *Dale Church (Vaksdal), a church in Vaksdal municipality, Vestland county *Dale Church (also known as Norddal Church), a church in Fjord municipality, Møre og Romsdal county ;Poland *Dale, Lesser Poland Voivodeship (south Poland) ;Sweden *The Dales, English exonym for Dalarna province ;United Kingdom *Dale, Cumbria, a haml ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Electron-demand Diels–Alder Reaction
The inverse electron demand Diels–Alder reaction, or DAINV or IEDDA is an organic chemical reaction, in which two new chemical bonds and a six-membered ring are formed. It is related to the Diels–Alder reaction, but unlike the Diels–Alder (or DA) reaction, the DAINV is a cycloaddition between an electron-rich dienophile and an electron-poor diene. During a DAINV reaction, three pi-bonds are broken, and two sigma bonds and one new pi-bond are formed. A prototypical DAINV reaction is shown on the right. DAINV reactions often involve heteroatoms, and can be used to form heterocyclic compounds. This makes the DAINV reaction particularly useful in natural product syntheses, where the target compounds often contain heterocycles. Recently, the DAINV reaction has been used to synthesize a drug transport system which targets prostate cancer. History The Diels–Alder reaction was first reported in 1928 by Otto Diels and Kurt Alder; they were awarded the Nobel Prize in chemistr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enamine
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates. : The word "enamine" is derived from the affix ''en''-, used as the suffix of alkene, and the root ''amine''. This can be compared with enol, which is a functional group containing both alkene (''en''-) and alcohol (-''ol''). Enamines are considered to be nitrogen analogs of enols. If one of the nitrogen substituents is a hydrogen atom, H, it is the tautomeric form of an imine. This usually will rearrange to the imine; however there are several exceptions (such as aniline). The enamine-imine tautomerism may be considered analogous to the keto-enol tautomerism. In both cases, a hydrogen atom switches its location between the heteroatom (oxygen or nitrogen) and the second carbon atom. Enamines are both good nucleophiles and good bases. Their behavior as carbon-based nucleophiles is explained with reference to the following reson ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triazine
Triazines are a class of nitrogen-containing heterocycles. The parent molecules' molecular formula is . They exist in three isomeric forms, 1,3,5-triazines being common. Structure The triazines have planar six-membered benzene-like ring but with three carbons replaced by nitrogens. The three isomers of triazine are distinguished by the positions of their nitrogen atoms, and are referred to as 1,2,3-triazine, 1,2,4-triazine, and 1,3,5-triazine. Other aromatic nitrogen heterocycles are pyridines with one ring nitrogen atom, diazines with 2 nitrogen atoms in the ring, triazoles with 3 nitrogens in a 5 membered ring, and tetrazines with 4 ring nitrogen atoms. Uses Melamine A well known triazine is melamine (2,4,6-triamino-1,3,5-triazine). With three amino substituents, melamine is a precursor to commercial resins. Guanamines are closely related to melamine, except with one amino substituent replaced by an organic group. This difference is exploited in the use of guanamines t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Total Synthesis
Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes it from semisynthesis. Syntheses may sometimes conclude at a precursor with further known synthetic pathways to a target molecule, in which case it is known as a formal synthesis. Total synthesis target molecules can be natural products, medicinally-important active ingredients, known intermediates, or molecules of theoretical interest. Total synthesis targets can also be organometallic or inorganic, though these are rarely encountered. Total synthesis projects often require a wide diversity of reactions and reagents, and subsequently requires broad chemical knowledge and training to be successful. Often, the aim is to discover a new route of synthesis for a target molecule for which there already exist known routes. Sometimes, however, no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyridine Forming Reactions
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow, due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. As of 2016, it is synthesized on the scale of about 20,000 tons per year worldwide. Properties Physical properties The molecular electric dipole moment is 2.2 debyes. Pyridine is diamagnetic and has a diamagnetic susceptibility of −48.7 × 10−6 cm3·mol−1. The standard enthalpy of formation is 100.2 kJ·mol−1 in the liquid ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterocycle Forming Reactions
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different chemical element, elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of these heterocycles. Examples of heterocyclic compounds include all of the nucleic acids, the majority of drugs, most biomass (cellulose and related materials), and many natural and synthetic dyes. More than half of known compounds are heterocycles. 59% of US FDA-approved drugs contain nitrogen heterocycles. Classification The study of heterocyclic chemistry focuses especially on unsaturated derivatives, and the preponderance of work and applications involves unstrained 5- and 6-membered rings. Included are pyridine, thiophene, pyrrole, and furan. Another large class of heterocycles refers to those fused to benzene rings. For example, the fused benzene derivatives of pyridine, thiophene, pyrrole, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Reactions
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis, organic reactions are used in the construction of new organic molecules. The production of many man-made chemicals such as drugs, plastics, food additives, fabrics depend on organic reactions. The oldest organic reactions are combustion of organic fuels and saponification of fats to make soap. Modern organic chemistry starts with the Wöhler synthesis in 1828. In the history of the Nobel Prize in Chemistry awards have been given for the invention of specific organic reactions such as the Grignard reaction in 1912, the Diels-Alder reaction in 1950, the Wittig reaction in 1979 and olefin metathesis in 2005. Classifications Organic chemistry has a strong tradition of naming a specific reac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
