The aza-Baylis–Hillman reaction or aza-BH reaction in organic chemistry is a variation of the Baylis–Hillman reaction and describes the reaction of an electron deficient alkene, usually an α,β-unsaturated carbonyl compound, with an imine in the presence of a nucleophile. The reaction product is an allylic amine. The reaction can be carried out in enantiomeric excess of up to 90% with the aid of bifunctional chiral BINOL and phosphinyl BINOL compounds, for example in the reaction of n-(4-chloro-benzylidene)-benzenesulfonamide with methyl vinyl ketone (MVK) in cyclopentyl methyl ether and toluene at -15°C.
In chemistry, transfer hydrogenation is a chemical reaction involving the addition of hydrogen to a compound from a source other than molecular H2. It is applied in laboratory and industrial organic synthesis to saturate organic compounds and reduce ketones to alcohols, and imines to amines. It avoids the need for high-pressure molecular H2 used in conventional hydrogenation. Transfer hydrogenation usually occurs at mild temperature and pressure conditions using organic or organometallic catalysts, many of which are chiral, allowing efficient asymmetric synthesis. It uses hydrogen donor compounds such as formic acid, isopropanol or dihydroanthracene, dehydrogenating them to CO2, acetone, or anthracene respectively. Often, the donor molecules also function as solvents for the reaction. A large scale application of transfer hydrogenation is coal liquefaction using "donor solvents" such as tetralin.
In organic chemistry, organocatalysis is a form of catalysis in which the rate of a chemical reaction is increased by an organic catalyst. This "organocatalyst" consists of carbon, hydrogen, sulfur and other nonmetal elements found in organic compounds. Because of their similarity in composition and description, they are often mistaken as a misnomer for enzymes due to their comparable effects on reaction rates and forms of catalysis involved.
A carbometallation is any reaction where a carbon-metal bond reacts with a carbon-carbon π-bond to produce a new carbon-carbon σ-bond and a carbon-metal σ-bond. The resulting carbon-metal bond can undergo further carbometallation reactions or it can be reacted with a variety of electrophiles including halogenating reagents, carbonyls, oxygen, and inorganic salts to produce different organometallic reagents. Carbometallations can be performed on alkynes and alkenes to form products with high geometric purity or enantioselectivity, respectively. Some metals prefer to give the anti-addition product with high selectivity and some yield the syn-addition product. The outcome of syn and anti- addition products is determined by the mechanism of the carbometallation.
Bis(oxazoline) ligands (often abbreviated BOX ligands) are a class of privileged chiral ligands containing two oxazoline rings. They are typically C2‑symmetric and exist in a wide variety of forms; with structures based around CH2 or pyridine linkers being particularly common (often generalised BOX and PyBOX respectively). The coordination complexes of bis(oxazoline) ligands are used in asymmetric catalysis. These ligands are examples of C2-symmetric ligands.
A frustrated Lewis pair (FLP) is a compound or mixture containing a Lewis acid and a Lewis base that, because of steric hindrance, cannot combine to form a classical adduct. Many kinds of FLPs have been devised, and many simple substrates exhibit activation.
Asymmetric hydrogenation is a chemical reaction that adds two atoms of hydrogen to a target (substrate) molecule with three-dimensional spatial selectivity. Critically, this selectivity does not come from the target molecule itself, but from other reagents or catalysts present in the reaction. This allows spatial information to transfer from one molecule to the target, forming the product as a single enantiomer. The chiral information is most commonly contained in a catalyst and, in this case, the information in a single molecule of catalyst may be transferred to many substrate molecules, amplifying the amount of chiral information present. Similar processes occur in nature, where a chiral molecule like an enzyme can catalyse the introduction of a chiral centre to give a product as a single enantiomer, such as amino acids, that a cell needs to function. By imitating this process, chemists can generate many novel synthetic molecules that interact with biological systems in specific ways, leading to new pharmaceutical agents and agrochemicals. The importance of asymmetric hydrogenation in both academia and industry contributed to two of its pioneers — William Standish Knowles and Ryōji Noyori — being collectively awarded one half of the 2001 Nobel Prize in Chemistry.
Organogold chemistry is the study of compounds containing gold–carbon bonds. They are studied in academic research, but have not received widespread use otherwise. The dominant oxidation states for organogold compounds are I with coordination number 2 and a linear molecular geometry and III with CN = 4 and a square planar molecular geometry.
In organic chemistry, the Baylis–Hillman, Morita–Baylis–Hillman, or MBH reaction is a carbon-carbon bond-forming reaction between an activated alkene and a carbon electrophile in the presence of a nucleophilic catalyst, such as a tertiary amine or phosphine. The product is densely functionalized, joining the alkene at the α-position to a reduced form of the electrophile.
In chemistry, a boranylium ion is an inorganic cation with the chemical formula BR+
2, where R represents a non-specific substituent. Being electron-deficient, boranylium ions form adducts with Lewis bases. Boranylium ions have historical names that depend on the number of coordinated ligands:
Trifluoromethylation in organic chemistry describes any organic reaction that introduces a trifluoromethyl group in an organic compound. Trifluoromethylated compounds are of some importance in pharmaceutical industry and agrochemicals. Several notable pharmaceutical compounds have a trifluoromethyl group incorporated: fluoxetine, mefloquine, Leflunomide, nulitamide, dutasteride, bicalutamide, aprepitant, celecoxib, fipronil, fluazinam, penthiopyrad, picoxystrobin, fluridone, norflurazon, sorafenib and triflurazin. A relevant agrochemical is trifluralin. The development of synthetic methods for adding trifluoromethyl groups to chemical compounds is actively pursued in academic research.
Hydrogen-bond catalysis is a type of organocatalysis that relies on use of hydrogen bonding interactions to accelerate and control organic reactions. In biological systems, hydrogen bonding plays a key role in many enzymatic reactions, both in orienting the substrate molecules and lowering barriers to reaction. The field is relatively undeveloped compared to research in Lewis acid catalysis.
Asymmetric ion-pairing catalysis in chemistry is a type of asymmetric catalysis taking place specifically with charged intermediates or charged reagents. In one type of catalysis ion-pairing exists with a charged and chiral catalyst. The charged catalyst can be cationic or anionic. Catalysis by anionic catalysts is also called asymmetric counteranion-directed catalysis. In the other variation of asymmetric ion-pairing catalysis called anion or cation binding, the chiral catalyst is neutral but binds in a noncovalent way to an intermediate ion pair. Asymmetric ion-pairing catalysis is distinct from other covalent types of catalysis such as Lewis acid catalysis and Bronsted acid catalysis. It is one of several strategies in enantioselective synthesis and of some relevance to academic research.
Photoredox catalysis is a branch of photochemistry that uses single-electron transfer. Photoredox catalysts are generally drawn from three classes of materials: transition-metal complexes, organic dyes, and semiconductors. While organic photoredox catalysts were dominant throughout the 1990s and early 2000s, soluble transition-metal complexes are more commonly used today.
Cycloisomerization is any isomerization in which the cyclic isomer of the substrate is produced in the reaction coordinate. The greatest advantage of cycloisomerization reactions is its atom economical nature, by design nothing is wasted, as every atom in the starting material is present in the product. In most cases these reactions are mediated by a transition metal catalyst, in few cases organocatalysts and rarely do they occur under thermal conditions. These cyclizations are able to be performed with excellent levels of selectivity in numerous cases and have transformed cycloisomerization into a powerful tool for unique and complex molecular construction. Cycloisomerization is a very broad topic in organic synthesis and many reactions that would be categorized as such exist. Two basic classes of these reactions are intramolecular Michael addition and Intramolecular Diels–Alder reactions. Under the umbrella of cycloisomerization, enyne and related olefin cycloisomerizations are the most widely used and studied reactions.
Cobalt(II)–porphyrin catalysis is a process in which a Co(II) porphyrin complex acts as a catalyst, inducing and accelerating a chemical reaction.
In organic chemistry, the Roskamp reaction is a name reaction describing the reaction between α-diazoesters (such as ethyl diazoacetate) and aldehydes to form β-ketoesters, often utilizing various Lewis acids (such as BF3, SnCl2, and GeCl2) as catalysts. The reaction is notable for its mild reaction conditions and selectivity.
F. Dean Toste is the Gerald E. K. Branch Distinguished Professor of Chemistry at the University of California, Berkeley and faculty scientist at the chemical sciences division of Lawrence Berkeley National Lab. He is a prominent figure in the field of organic chemistry and is best known for his contributions to gold chemistry and asymmetric ion-pairing catalysis. Toste was elected a member of the National Academy of Sciences in 2020, and a member of the American Academy of Arts and Sciences in 2018.
In organic chemistry, chiral phosphoric acids are esters of phosphoric acid H3PO4 that have chiral backbones. Well known examples include cyclic diesters derived from the BINOL and TADDOL motifs. These compounds are used in asymmetric catalysis as chiral Brønsted acids and/or hydrogen-bond donors. The conjugate bases are also used in generating chiral ion pairs.
T.V. (Babu) RajanBabu is an organic chemist who holds the position of Distinguished Professor of Chemistry in the College of Arts and Sciences at the Ohio State University. His laboratory traditionally focuses on developing transition metal-catalyzed reactions. RajanBabu is known for helping develop the Nugent-RajanBabu reagent, a chemical reagent used in synthetic organic chemistry as a single electron reductant.
