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Lactams
A lactam is a cyclic amide, formally derived from an amino alkanoic acid. The term is a portmanteau of the words ''lactone'' + ''amide''. Nomenclature Greek prefixes in alphabetical order indicate ring size: * α-Lactam (3-atom rings) * β-Lactam (4-atom rings) * γ-Lactam (5-atom rings) * δ-Lactam (6-atom rings) * ε-Lactam (7-atom rings) This ring-size nomenclature stems from the fact that a hydrolyzed α-Lactam leads to an α-amino acid and a β-Lactam to a β-amino acid, ''etc''. Synthesis General synthetic methods exist for the organic synthesis of lactams. Beckmann rearrangement Lactams form by the acid-catalyzed rearrangement of oximes in the Beckmann rearrangement. Schmidt reaction Lactams form from cyclic ketones and hydrazoic acid in the Schmidt reaction. Cyclization of amino acids Lactams can be formed from cyclisation of amino acids via the coupling between an amine and a carboxylic acid within the same molecule. Lactamization is most efficient in this wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactams General Formulae V
A lactam is a Cyclic compound, cyclic amide, formally derived from an amino alkanoic acid. The term is a portmanteau of the words ''lactone'' + ''amide''. Nomenclature Greek prefixes in alphabetical order indicate ring size: * α-Lactam (3-atom rings) * β-Lactam (4-atom rings) * 2-Pyrrolidone, γ-Lactam (5-atom rings) * 2-Piperidinone, δ-Lactam (6-atom rings) * Caprolactam, ε-Lactam (7-atom rings) This ring-size nomenclature stems from the fact that a hydrolysis, hydrolyzed α-Lactam leads to an α-amino acid and a β-Lactam to a β-amino acid, ''etc''. Synthesis General synthetic methods exist for the organic synthesis of lactams. Beckmann rearrangement Lactams form by the Acid catalysis, acid-catalyzed Rearrangement reaction, rearrangement of oximes in the Beckmann rearrangement. Schmidt reaction Lactams form from cyclic ketones and hydrazoic acid in the Schmidt reaction. Cyclization of amino acids Lactams can be formed from cyclisation of amino acids via the coupling bet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
β-Lactam
A beta-lactam (β-lactam) ring is a four-membered lactam. A ''lactam'' is a cyclic amide, and ''beta''-lactams are named so because the nitrogen atom is attached to the Β carbon, β-carbon atom relative to the carbonyl. The simplest β-lactam possible is 2-azetidinone. β-lactams are significant structural units of medicines as manifested in many Beta-lactam antibiotic, β-lactam antibiotics Up to 1970, most β-lactam research was concerned with the penicillin and cephalosporin groups, but since then, a wide variety of structures have been described. Clinical significance The β-lactam ring is part of the core structure of several antibiotic families, the principal ones being the penicillins, cephalosporins, carbapenems, and monobactams, which are, therefore, also called β-lactam antibiotics. Nearly all of these antibiotics work by inhibiting bacterial cell wall biosynthesis. This has a lethal effect on bacteria, although any given bacteria population will typically contain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schmidt Reaction
In organic chemistry, the Schmidt reaction is an organic reaction in which an azide reacts with a carbonyl derivative, usually an aldehyde, ketone, or carboxylic acid, under acidic conditions to give an amine or amide, with expulsion of nitrogen. It is named after Karl Friedrich Schmidt (1887–1971), who first reported it in 1924 by successfully converting benzophenone and hydrazoic acid to benzanilide. The intramolecular reaction was not reported until 1991 but has become important in the synthesis of natural products. The reaction is effective with carboxylic acids to give amines (above), and with ketones to give amides (below). Reaction mechanism The reaction is closely related to the Curtius rearrangement except that in this reaction the acyl azide is produced by reaction of the carboxylic acid with hydrazoic acid via the protonated carboxylic acid, in a process akin to a Fischer esterification. An alternative, involving the formation of an acylium ion, becomes more i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Reaction
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, Mechanistic Organic Photochemistry, photochemical reactions and organic redox reaction, 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 c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beckmann Rearrangement
The Beckmann rearrangement, named after the German chemist Ernst Otto Beckmann (1853–1923), is a rearrangement of an oxime functional group to substituted amides. The rearrangement has also been successfully performed on haloimines and nitrones. Cyclic oximes and haloimines yield lactams. The Beckmann rearrangement is often catalyzed by acid; however, other reagents have been known to promote the rearrangement. These include tosyl chloride, thionyl chloride, phosphorus pentachloride, phosphorus pentoxide, triethylamine, sodium hydroxide, trimethylsilyl iodide among others. The Beckmann fragmentation is another reaction that often competes with the rearrangement, though careful selection of promoting reagent and solvent conditions can favor the formation of one over the other, sometimes giving almost exclusively one product. The rearrangement occurs stereospecifically for ketoximes and N-chloro/N-fluoro imines, with the migrating group being anti-periplanar to the leaving gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleophilic Abstraction
Nucleophilic abstraction is a type of an organometallic reaction which can be defined as a nucleophilic attack on a ligand which causes part or all of the original ligand to be removed from the metal along with the nucleophile.Spessard, Gary; Miessler, Gary (2010).''Organometallic Chemistry: Second Edition''. pp. 285-289 Alkyl abstraction While nucleophilic abstraction of an alkyl group is relatively uncommon, there are examples of this type of reaction. In order for this reaction to be favorable, the metal must first be oxidized because reduced metals are often poor leaving groups. The oxidation of the metal causes the M-C bond to weaken, which allows for the nucleophilic abstraction to occur. G.M. Whitesides and D.J. Boschetto use the halogens Br2 and I2 as M-C cleaving agents in the following example of nucleophilic abstraction. It is important to note that the product of this reaction is inverted with respect to the stereochemical center attached to the metal. There ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Acyl Derivatives
Linearity is the property of a mathematical relationship (''function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear relationship of voltage and current in an electrical conductor (Ohm's law), and the relationship of mass and weight. By contrast, more complicated relationships are ''nonlinear''. Generalized for functions in more than one dimension, linearity means the property of a function of being compatible with addition and scaling, also known as the superposition principle. The word linear comes from Latin ''linearis'', "pertaining to or resembling a line". In mathematics In mathematics, a linear map or linear function ''f''(''x'') is a function that satisfies the two properties: * Additivity: . * Homogeneity of degree 1: for all α. These properties are known as the superposition principle. In this definition, ''x'' is not necessarily a real nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intramolecular Reaction
Intramolecular in chemistry describes a process or characteristic limited within the structure of a single molecule, a property or phenomenon limited to the extent of a single molecule. Examples * intramolecular hydride transfer (transfer of a hydride ion from one part to another within the same molecule) * intramolecular hydrogen bond (a hydrogen bond formed between two functional groups of the same molecule) *cyclization of ω-haloalkylamines and alcohols to form the corresponding saturated nitrogen and oxygen heterocycles, respectively (an SN2 reaction within the same molecule) In intramolecular organic reactions, two reaction sites are contained within a single molecule. This creates a very high effective concentration (resulting in high reaction rates), and, therefore, many intramolecular reactions that would not occur as an intermolecular reaction between two compounds take place. Examples of intramolecular reactions are the Smiles rearrangement, the Dieckmann condensation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PyAOP
PyAOP ((7-Azabenzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate) is a coupling reagent used in solid phase peptide synthesis. It is a derivative of the HOAt family of coupling reagents. It is preferred over HATU, because it does not side react at the N-terminus of the peptide. Compared to the HOBt derivates, PyAOP (and HOAt in general) are more reactive due to the additional nitrogen. See also * HOAt reagent * HOBt reagent * BOP reagent * PyBOP PyBOP (benzotriazol-1-yloxytripyrrolidinophosphonium hexafluorophosphate) is a peptide coupling reagent used in solid phase peptide synthesis. It is used as a substitute for the BOP reagent - avoiding the formation of the carcinogenic waste product ... References Hexafluorophosphates Peptide coupling reagents Triazolopyridines Reagents for biochemistry Quaternary phosphonium compounds {{Organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HATU
HATU (1- is(dimethylamino)methylene1H-1,2,3-triazolo ,5-byridinium 3-oxide hexafluorophosphate, Hexafluorophosphate Azabenzotriazole Tetramethyl Uronium) is a reagent used in peptide coupling chemistry to generate an active ester from a carboxylic acid. HATU is used along with Hünig's base (''N,N''-diisopropylethylamine, DIPEA), or triethylamine to form amide bonds. Typically DMF is used as solvent, although other polar aprotic solvents can also be used. History HATU was first reported by Louis A. Carpino in 1993 as an efficient means of preparing active esters derived from 1-hydroxy-7-azabenzotriazole (HOAt). HATU can exist as either the uronium salt (''O-''form) or the less reactive iminium salt (''N''-form). HATU was initially reported as the O-form using the original preparation reported by Carpino; however, X-ray crystallographic and NMR studies revealed the true structure of HATU to be the less reactive guanidinium isomer. It is, however, possible to obtain the uronium i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboxylic Acid
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion. Examples and nomenclature Carboxylic acids are commonly identified by their trivial names. They at oftentimes have the suffix ''-ic acid''. IUPAC-recommended names also exist; in this system, carboxylic acids have an ''-oic acid'' suffix. For example, butyric acid (C3H7CO2H) is butanoic acid by IUPAC guidelines. For nomenclature of complex molecules containing a carboxylic acid, the carboxyl can be considered position one of the parent chain even if there are other substituents, such as 3-chloropropanoic acid. Alternately, it can be named as a "carboxy" or "carboxylic acid" substituent on another ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group (these may respectively be called alkylamines and arylamines; amines in which both types of substituent are attached to one nitrogen atom may be called alkylarylamines). Important amines include amino acids, biogenic amines, trimethylamine, and aniline; Inorganic derivatives of ammonia are also called amines, such as monochloramine (). The substituent is called an amino group. Compounds with a nitrogen atom attached to a carbonyl group, thus having the structure , are called amides and have different chemical properties from amines. Classification of amines Amines can be classified according to the nature and number of substituents on nitrogen. Aliphatic amines contain only H and alkyl substituents. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
