In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.
In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups. The nitro group is one of the most common explosophores used globally. The nitro group is also strongly electron-withdrawing. Because of this property, C−H bonds alpha (adjacent) to the nitro group can be acidic. For similar reasons, the presence of nitro groups in aromatic compounds retards electrophilic aromatic substitution but facilitates nucleophilic aromatic substitution. Nitro groups are rarely found in nature. They are almost invariably produced by nitration reactions starting with nitric acid.
The Fischer indole synthesis is a chemical reaction that produces the aromatic heterocycle indole from a (substituted) phenylhydrazine and an aldehyde or ketone under acidic conditions. The reaction was discovered in 1883 by Emil Fischer. Today antimigraine drugs of the triptan class are often synthesized by this method.
A sigmatropic reaction in organic chemistry is a pericyclic reaction wherein the net result is one σ-bond is changed to another σ-bond in an uncatalyzed intramolecular reaction. The name sigmatropic is the result of a compounding of the long-established sigma designation from single carbon–carbon bonds and the Greek word tropos, meaning turn. In this type of rearrangement reaction, a substituent moves from one part of a π-bonded system to another part in an intramolecular reaction with simultaneous rearrangement of the π system. True sigmatropic reactions are usually uncatalyzed, although Lewis acid catalysis is possible. Sigmatropic reactions often have transition-metal catalysts that form intermediates in analogous reactions. The most well-known of the sigmatropic rearrangements are the [3,3] Cope rearrangement, Claisen rearrangement, Carroll rearrangement, and the Fischer indole synthesis.
The Claisen rearrangement is a powerful carbon–carbon bond-forming chemical reaction discovered by Rainer Ludwig Claisen. The heating of an allyl vinyl ether will initiate a [3,3]-sigmatropic rearrangement to give a γ,δ-unsaturated carbonyl, driven by exergonically favored carbonyl CO bond formation.
The Leimgruber–Batcho indole synthesis is a series of organic reactions that produce indoles from o-nitrotoluenes 1. The first step is the formation of an enamine 2 using N,N-dimethylformamide dimethyl acetal and pyrrolidine. The desired indole 3 is then formed in a second step by reductive cyclisation.
The Reissert indole synthesis is a series of chemical reactions designed to synthesize indole or substituted-indoles from ortho-nitrotoluene 1 and diethyl oxalate 2.
The Larock indole synthesis is a heteroannulation reaction that uses palladium as a catalyst to synthesize indoles from an ortho-iodoaniline and a disubstituted alkyne. It is also known as Larock heteroannulation. The reaction is extremely versatile and can be used to produce varying types of indoles. Larock indole synthesis was first proposed by Richard C. Larock in 1991 at Iowa State University.
The von Richter reaction, also named von Richter rearrangement, is a name reaction in the organic chemistry. It is named after Victor von Richter, who discovered this reaction in year 1871. It is the reaction of aromatic nitro compounds with potassium cyanide in aqueous ethanol to give the product of cine substitution by a carboxyl group. Although it is not generally synthetically useful due to the low chemical yield and formation of numerous side products, its mechanism was of considerable interest, eluding chemists for almost 100 years before the currently accepted one was proposed.
The Weinreb–Nahm ketone synthesis is a chemical reaction used in organic chemistry to make carbon–carbon bonds. It was discovered in 1981 by Steven M. Weinreb and Steven Nahm as a method to synthesize ketones. The original reaction involved two subsequent nucleophilic acyl substitutions: the conversion of an acid chloride with N,O-Dimethylhydroxylamine, to form a Weinreb–Nahm amide, and subsequent treatment of this species with an organometallic reagent such as a Grignard reagent or organolithium reagent. Nahm and Weinreb also reported the synthesis of aldehydes by reduction of the amide with an excess of lithium aluminum hydride.
In organic chemistry, nitroso refers to a functional group in which the nitric oxide group is attached to an organic moiety. As such, various nitroso groups can be categorized as C-nitroso compounds, S-nitroso compounds, N-nitroso compounds, and O-nitroso compounds.
A Grignard reagent or Grignard compound is a chemical compound with the general formula R−Mg−X, where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride Cl−Mg−CH3 and phenylmagnesium bromide (C6H5)−Mg−Br. They are a subclass of the organomagnesium compounds.
The Kulinkovich reaction describes the organic synthesis of cyclopropanols via reaction of esters with dialkyldialkoxytitanium reagents, generated in situ from Grignard reagents bearing hydrogen in beta-position and titanium(IV) alkoxides such as titanium isopropoxide. This reaction was first reported by Oleg Kulinkovich and coworkers in 1989.
The Baeyer–Emmerling indole synthesis is a method for synthesizing indole from a (substituted) ortho-nitrocinnamic acid and iron powder in strongly basic solution. This reaction was discovered by Adolf von Baeyer and Adolph Emmerling in 1869.
Indole is an aromatic heterocyclic organic compound with the formula C8H7N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole is widely distributed in the natural environment and can be produced by a variety of bacteria. As an intercellular signal molecule, indole regulates various aspects of bacterial physiology, including spore formation, plasmid stability, resistance to drugs, biofilm formation, and virulence. The amino acid tryptophan is an indole derivative and the precursor of the neurotransmitter serotonin.
Reactions of organocopper reagents involve species containing copper-carbon bonds acting as nucleophiles in the presence of organic electrophiles. Organocopper reagents are now commonly used in organic synthesis as mild, selective nucleophiles for substitution and conjugate addition reactions.
Nitroethylene (also known as nitroethene) is a liquid organic compound with the formula C2H3NO2. It is the simplest nitroalkene, which are unsaturated carbon chains with at least one double bond and a NO2 functional group. Nitroethylene serves as a useful intermediate in the production of various other chemicals.
The Cadogan–Sundberg indole synthesis, or simply Cadogan indole synthesis, is a name reaction in organic chemistry that allows for the generation of indoles from o-nitrostyrenes with the use of trialkyl phosphites, such as triethyl phosphite.
Chlorine-free germanium processing are methods of germanium activation to form useful germanium precursors in a more energy efficient and environmentally friendly way compared to traditional synthetic routes. Germanium tetrachloride is a valuable intermediate for the synthesis of many germanium complexes. Normal synthesis of it involves an energy-intensive dehydration of germanium oxide, , with hydrogen chloride, Due to the environmental and safety impact of non-recyclable, high energy reactions with , an alternative synthesis of a shelf-stable germanium intermediate precursor without chlorine is of interest. In 2017, a synthesis of organogermanes, without using chloride species was reported, allowing for a much more environmentally friendly and low energy synthesis using , , and even selectively activating germanium in the presence of zinc oxide, resulting in products that are bench stable and solid.
