Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one of the most important branches of organic chemistry. There are several main areas of research within the general area of organic synthesis: total synthesis, semisynthesis, and methodology.
Enantioselective synthesis, also called asymmetric synthesis, is a form of chemical synthesis. It is defined by IUPAC as "a chemical reaction in which one or more new elements of chirality are formed in a substrate molecule and which produces the stereoisomeric products in unequal amounts."
William Standish Knowles was an American chemist. He was born in Taunton, Massachusetts. Knowles was one of the recipients of the 2001 Nobel Prize in Chemistry. He split half the prize with Ryōji Noyori for their work in asymmetric synthesis, specifically for his work in hydrogenation reactions. The other half was awarded to K. Barry Sharpless for his work in oxidation reactions.
Nucleophilic conjugate addition is a type of organic reaction. Ordinary nucleophilic additions or 1,2-nucleophilic additions deal mostly with additions to carbonyl compounds. Simple alkene compounds do not show 1,2 reactivity due to lack of polarity, unless the alkene is activated with special substituents. With α,β-unsaturated carbonyl compounds such as cyclohexenone it can be deduced from resonance structures that the β position is an electrophilic site which can react with a nucleophile. The negative charge in these structures is stored as an alkoxide anion. Such a nucleophilic addition is called a nucleophilic conjugate addition or 1,4-nucleophilic addition. The most important active alkenes are the aforementioned conjugated carbonyls and acrylonitriles.
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.
Hydrosilylation, also called catalytic hydrosilation, describes the addition of Si-H bonds across unsaturated bonds. Ordinarily the reaction is conducted catalytically and usually the substrates are unsaturated organic compounds. Alkenes and alkynes give alkyl and vinyl silanes; aldehydes and ketones give silyl ethers. Hydrosilylation has been called the "most important application of platinum in homogeneous catalysis."
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.
Cyclooctadiene rhodium chloride dimer is the organorhodium compound with the formula Rh2Cl2(C8H12)2, commonly abbreviated [RhCl(COD)]2 or Rh2Cl2(COD)2. This yellow-orange, air-stable compound is a widely used precursor to homogeneous catalysts.
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.
1,2-Diphenyl-1,2-ethylenediamine, DPEN, is an organic compound with the formula H2NCHPhCHPhNH2, where Ph is phenyl (C6H5). DPEN exists as three stereoisomers: meso and two enantiomers S,S- and R,R-. The chiral diastereomers are used in asymmetric hydrogenation. Both diastereomers are bidentate ligands.
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 awarded one half of the 2001 Nobel Prize in Chemistry.
DuPhos is a class of organophosphorus compound that are used ligands for asymmetric synthesis. The name DuPhos is derived from (1) the chemical company that sponsored the research leading to this ligand's invention, DuPont and (2) the compound is a diphosphine ligand type. Specifically it is classified as a C2-symmetric ligand, consisting of two phospholanes rings affixed to a benzene ring.
Within the area of organocatalysis, (thio)urea organocatalysis describes the use of ureas and thioureas to accelerate and stereochemically alter organic transformations. The effects arise through hydrogen-bonding interactions between the substrate and the (thio)urea. Unlike classical catalysts, these organocatalysts interact by non-covalent interactions, especially hydrogen bonding. The scope of these small-molecule H-bond donors termed (thio)urea organocatalysis covers both non-stereoselective and stereoselective applications.
Organorhodium chemistry is the chemistry of organometallic compounds containing a rhodium-carbon chemical bond, and the study of rhodium and rhodium compounds as catalysts in organic reactions.
Phanephos is an organophosphorus compound with the chemical formula (C2H4)2(C6H3PPh2)2 (Ph = C6H5). It is a white solid that is soluble in organic solvents. It is an example of a chiral C2-symmetric diphosphine ligand used in asymmetric hydrogenation. Many substituents have been introduced in place of the phenyl groups, e.g., i-Pr, C6H11, etc and a variety of chiral diphosphine ligands have been reported in asymmetric catalysis since the 1960s.
DIOP is an organophosphorus compound that is used as a chiral ligand in asymmetric catalysis. It is a white solid that is soluble in organic solvents.
Bernard Lucas Feringa is a Dutch synthetic organic chemist, specializing in molecular nanotechnology and homogeneous catalysis. He is the Jacobus van 't Hoff Distinguished Professor of Molecular Sciences, at the Stratingh Institute for Chemistry, University of Groningen, Netherlands, and an Academy Professor of the Royal Netherlands Academy of Arts and Sciences. He was awarded the 2016 Nobel Prize in Chemistry, together with Sir J. Fraser Stoddart and Jean-Pierre Sauvage, "for the design and synthesis of molecular machines".
Ugi’s amine is a chemical compound named for the chemist who first reported its synthesis in 1970, Ivar Ugi. It is a ferrocene derivative. Since its first report, Ugi’s amine has found extensive use as the synthetic precursor to a large number of metal ligands that bear planar chirality. These ligands have since found extensive use in a variety of catalytic reactions. The compound may exist in either the 1S or 1R isomer, both of which have synthetic utility and are commercially available. Most notably, it is the synthetic precursor to the Josiphos class of ligands.
In homogeneous catalysis, C2-symmetric ligands refer to ligands that lack mirror symmetry but have C2 symmetry. Such ligands are usually bidentate and are valuable in catalysis. The C2 symmetry of ligands limits the number of possible reaction pathways and thereby increases enantioselectivity, relative to asymmetrical analogues. C2-symmetric ligands are a subset of chiral ligands. Chiral ligands, including C2-symmetric ligands, combine with metals or other groups to form chiral catalysts. These catalysts engage in enantioselective chemical synthesis, in which chirality in the catalyst yields chirality in the reaction product.
P-Chiral phosphines are organophosphorus compounds of the formula PRR′R″, where R, R′, R″ = H, alkyl, aryl, etc. They are a subset of chiral phosphines, a broader class of compounds where the stereogenic center can reside at sites other than phosphorus. P-chirality exploits the high barrier for inversion of phosphines, which ensures that enantiomers of PRR'R" do not racemize readily. The inversion barrier is relatively insensitive to substituents for triorganophosphines. By contrast, most amines of the type NRR′R″ undergo rapid pyramidal inversion.
![Structure of [Rh(DIPAMP)(cod)] by X-ray crystallography. IBOZABcationDownC2.png](http://upload.wikimedia.org/wikipedia/commons/thumb/3/33/IBOZABcationDownC2.png/220px-IBOZABcationDownC2.png)