Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one methine group (=CH−) 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.
Demethylation is the chemical process resulting in the removal of a methyl group (CH3) from a molecule. A common way of demethylation is the replacement of a methyl group by a hydrogen atom, resulting in a net loss of one carbon and two hydrogen atoms.
In organosulfur chemistry, a sulfonate is a salt or ester of a sulfonic acid. It contains the functional group R−S(=O)2−O−, where R is an organic group. Sulfonates are the conjugate bases of sulfonic acids. Sulfonates are generally stable in water, non-oxidizing, and colorless. Many useful compounds and even some biochemicals feature sulfonates.
Terpyridine is a heterocyclic compound derived from pyridine. It is a white solid that is soluble in most organic solvents. The compound is mainly used as a ligand in coordination chemistry.
In organic chemistry, the Mannich reaction is a three-component organic reaction that involves the amino alkylation of an acidic proton next to a carbonyl functional group by formaldehyde and a primary or secondary amine or ammonia. The final product is a β-amino-carbonyl compound also known as a Mannich base. Reactions between aldimines and α-methylene carbonyls are also considered Mannich reactions because these imines form between amines and aldehydes. The reaction is named after Carl Mannich.
Aromatization is a chemical reaction in which an aromatic system is formed from a single nonaromatic precursor. Typically aromatization is achieved by dehydrogenation of existing cyclic compounds, illustrated by the conversion of cyclohexane into benzene. Aromatization includes the formation of heterocyclic systems.
Hantzsch ester refers to an organic compound with the formula HN(MeC=C(CO2Et))2CH2 where Me = methyl (CH3) and Et = ethyl (C2H5). It is a colorless solid. The compound is an example of a 1,4-dihydropyridine. It is named after Arthur Rudolf Hantzsch who described its synthesis in 1881. The compound is a hydride donor, e.g., for reduction of imines to amines. It is a synthetic analogue of NADH, a naturally occurring dihydropyridine.
2-Pyridone is an organic compound with the formula C
5H
4NH(O). It is a colourless solid. It is well known to form hydrogen bonded dimers and it is also a classic case of a compound that exists as tautomers.
The Sarett oxidation is an organic reaction that oxidizes primary and secondary alcohols to aldehydes and ketones, respectively, using chromium trioxide and pyridine. Unlike the similar Jones oxidation, the Sarett oxidation will not further oxidize primary alcohols to their carboxylic acid form, neither will it affect carbon-carbon double bonds. Use of the original Sarett oxidation has become largely antiquated however, in favor of other modified oxidation techniques. The unadulterated reaction is still occasionally used in teaching settings and in small scale laboratory research.
A carbon–nitrogen bond is a covalent bond between carbon and nitrogen and is one of the most abundant bonds in organic chemistry and biochemistry.
The Chichibabin pyridine synthesis is a method for synthesizing pyridine rings. The reaction involves the condensation reaction of aldehydes, ketones, α,β-Unsaturated carbonyl compounds, or any combination of the above, with ammonia. It was reported by Aleksei Chichibabin in 1924. Methyl-substituted pyridines, which show widespread uses among multiple fields of applied chemistry, are prepared by this methodology.
Pozanicline is a drug developed by Abbott, that has nootropic and neuroprotective effects. Animal studies suggested it useful for the treatment of ADHD and subsequent human trials have shown ABT-089 to be effective for this application. It binds with high affinity subtype-selective to the α4β2 nicotinic acetylcholine receptors and has partial agonism to the α6β2 subtype, but not the α7 and α3β4 subtypes familiar to nicotine. It has particularly low tendency to cause side effects compared to other drugs in the class, making it an exciting candidate for clinical development.
2-Methyl-6-(phenylethynyl)pyridine (MPEP) is a research drug which was one of the first compounds found to act as a selective antagonist for the metabotropic glutamate receptor subtype mGluR5. After being originally patented as a liquid crystal for LCDs, it was developed by the pharmaceutical company Novartis in the late 1990s. It was found to produce neuroprotective effects following acute brain injury in animal studies, although it was unclear whether these results were purely from mGluR5 blockade as it also acts as a weak NMDA antagonist, and as a positive allosteric modulator of another subtype mGlu4, and there is also evidence for a functional interaction between mGluR5 and NMDA receptors in the same populations of neurons. It was also shown to produce antidepressant and anxiolytic effects in animals, and to reduce the effects of morphine withdrawal, most likely due to direct interaction between mGluR5 and the μ-opioid receptor.
3-( ethynyl)pyridine (MTEP) is a research drug that was developed by Merck & Co. as a selective allosteric antagonist of the metabotropic glutamate receptor subtype mGluR5. Identified through structure-activity relationship studies on an older mGluR5 antagonist MPEP, MTEP has subsequently itself acted as a lead compound for newer and even more improved drugs.
The Parikh–Doering oxidation is an oxidation reaction that transforms primary and secondary alcohols into aldehydes and ketones, respectively. The procedure uses dimethyl sulfoxide (DMSO) as the oxidant and the solvent, activated by the sulfur trioxide pyridine complex (SO3•C5H5N) in the presence of triethylamine or diisopropylethylamine as base. Dichloromethane is frequently used as a cosolvent for the reaction.
RTI(-4229)-274, or 2β-( methyl)-3α-(4-fluorophenyl)nortropane is a phenyltropane homologue of paroxetine developed by the group led by F Ivy Carroll in the 1990s.
A-84543 is a drug developed by Abbott, which acts as an agonist at neural nicotinic acetylcholine receptors with high selectivity for the α4β2 subtype. It is widely used in scientific research into the structure and function of this receptor subtype and has been the lead compound for the development of a large family of related derivatives.
2-Chloropyridine is an organohalide with the formula C5H4ClN. It is a colorless liquid that is mainly used to generate fungicides and insecticides in industry. It also serves to generate antihistamines and antiarrythymics for pharmaceutical purposes.
The Kröhnke pyridine synthesis is reaction in organic synthesis between α-pyridinium methyl ketone salts and α, β-unsaturated carbonyl compounds used to generate highly functionalized pyridines. Pyridines occur widely in natural and synthetic products, so there is wide interest in routes for their synthesis. The method is named after Fritz Kröhnke.
In homogeneous catalysis, MACHO catalysts are metal complexes containing MACHO ligands, which are of the type HN(CH2CH2PR2)2, where R is typically phenyl or isopropyl. Complexes with ruthenium(II) and iridium(III) have received much attention for their ability to hydrogenate polar bonds such as those in esters and even carbon dioxide. The catalysts appear to operate via intermediates where the amine proton and the hydride ligand both interact with the substrate. The Ru-MACHO catalyst have been commercialized for the synthesis of 1,2-propanediol from bio-derived methyl lactate.
