In chemistry a divergent synthesis is a strategy with the aim to improve the efficiency of chemical synthesis. It is often an alternative to convergent synthesis or linear synthesis.
In one strategy divergent synthesis aims to generate a library of chemical compounds by first reacting a molecule with a set of reactants. The next generation of compounds is generated by further reactions with each compound in generation 1. This methodology quickly diverges to large numbers of new compounds
An entire library of new chemical compounds, for instance saccharides, can be screened for desirable properties. In another strategy divergent synthesis starts from a molecule as a central core from which successive generations of building blocks are added. A good example is the divergent synthesis of dendrimers, for example, where in each generation a new monomer reacts to the growing surface of the sphere.
Diversity oriented synthesis or DOS is a strategy for quick access to molecule libraries with an emphasis on skeletal diversity. [1] In one such application a Petasis reaction product (1) is functionalized with propargyl bromide leading to a starting compound (2) having 5 functional groups. [2] This molecule can be subjected to a range of reagents yielding unique molecular skeletons in one generation. [3]
A ketene is an organic compound of the form R′R″C=C=O, where R and R' are two arbitrary monovalent chemical groups. The name may also refer to the specific compound ethenone H2C=C=O, the simplest ketene.
Combinatorial chemistry comprises chemical synthetic methods that make it possible to prepare a large number of compounds in a single process. These compound libraries can be made as mixtures, sets of individual compounds or chemical structures generated by computer software. Combinatorial chemistry can be used for the synthesis of small molecules and for peptides.
Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes it from semisynthesis. Syntheses may sometimes conclude at a precursor with further known synthetic pathways to a target molecule, in which case it is known as a formal synthesis. Total synthesis target molecules can be natural products, medicinally-important active ingredients, known intermediates, or molecules of theoretical interest. Total synthesis targets can also be organometallic or inorganic, though these are rarely encountered. Total synthesis projects often require a wide diversity of reactions and reagents, and subsequently requires broad chemical knowledge and training to be successful.
The 1,3-dipolar cycloaddition is a chemical reaction between a 1,3-dipole and a dipolarophile to form a five-membered ring. The earliest 1,3-dipolar cycloadditions were described in the late 19th century to the early 20th century, following the discovery of 1,3-dipoles. Mechanistic investigation and synthetic application were established in the 1960s, primarily through the work of Rolf Huisgen. Hence, the reaction is sometimes referred to as the Huisgen cycloaddition. 1,3-dipolar cycloaddition is an important route to the regio- and stereoselective synthesis of five-membered heterocycles and their ring-opened acyclic derivatives. The dipolarophile is typically an alkene or alkyne, but can be other pi systems. When the dipolarophile is an alkyne, aromatic rings are generally produced.
Retrosynthetic analysis is a technique for solving problems in the planning of organic syntheses. This is achieved by transforming a target molecule into simpler precursor structures regardless of any potential reactivity/interaction with reagents. Each precursor material is examined using the same method. This procedure is repeated until simple or commercially available structures are reached. These simpler/commercially available compounds can be used to form a synthesis of the target molecule. E.J. Corey formalized this concept in his book The Logic of Chemical Synthesis.
In chemistry, a multi-component reaction, sometimes referred to as a "Multi-component Assembly Process", is a chemical reaction where three or more compounds react to form a single product. By definition, multicomponent reactions are those reactions whereby more than two reactants combine in a sequential manner to give highly selective products that retain majority of the atoms of the starting material.
The Ugi reaction is a multi-component reaction in organic chemistry involving a ketone or aldehyde, an amine, an isocyanide and a carboxylic acid to form a bis-amide. The reaction is named after Ivar Karl Ugi, who first reported this reaction in 1959.
The Petasis reaction is the multi-component reaction of an amine, a carbonyl, and a vinyl- or aryl-boronic acid to form substituted amines.
Umpolung or polarity inversion in organic chemistry is the chemical modification of a functional group with the aim of the reversal of polarity of that group. This modification allows secondary reactions of this functional group that would otherwise not be possible. The concept was introduced by D. Seebach and E.J. Corey. Polarity analysis during retrosynthetic analysis tells a chemist when umpolung tactics are required to synthesize a target molecule.
Stuart L. Schreiber is a scientist at Harvard University and co-Founder of the Broad Institute. He has been active in chemical biology, especially the use of small molecules as probes of biology and medicine. Small molecules are the molecules of life most associated with dynamic information flow; these work in concert with the macromolecules that are the basis for inherited information flow.
Organozinc compounds in organic chemistry contain carbon to zinc chemical bonds. Organozinc chemistry is the science of organozinc compounds describing their physical properties, synthesis and reactions.
Fullerene chemistry is a field of organic chemistry devoted to the chemical properties of fullerenes. Research in this field is driven by the need to functionalize fullerenes and tune their properties. For example, fullerene is notoriously insoluble and adding a suitable group can enhance solubility. By adding a polymerizable group, a fullerene polymer can be obtained. Functionalized fullerenes are divided into two classes: exohedral fullerenes with substituents outside the cage and endohedral fullerenes with trapped molecules inside the cage.
A boronic acid is a compound related to boric acid in which one of the three hydroxyl groups is replaced by an alkyl or aryl group. As a compound containing a carbon–boron bond, members of this class thus belong to the larger class of organoboranes. Boronic acids act as Lewis acids. Their unique feature is that they are capable of forming reversible covalent complexes with sugars, amino acids, hydroxamic acids, etc.. The pKa of a boronic acid is ~9, but they can form tetrahedral boronate complexes with pKa ~7. They are occasionally used in the area of molecular recognition to bind to saccharides for fluorescent detection or selective transport of saccharides across membranes.
The Achmatowicz reaction, also known as the Achmatowicz rearrangement, is an organic synthesis in which a furan is converted to a dihydropyran. In the original publication by the Polish Chemist Osman Achmatowicz Jr. in 1971 furfuryl alcohol is reacted with bromine in methanol to 2,5-dimethoxy-2,5-dihydrofuran which rearranges to the dihydropyran with dilute sulfuric acid. Additional reaction steps, alcohol protection with methyl orthoformate and boron trifluoride) and then ketone reduction with sodium borohydride produce an intermediate from which many monosaccharides can be synthesised.
DNA-encoded chemical libraries (DEL) is a technology for the synthesis and screening on unprecedented scale of collections of small molecule compounds. DEL is used in medicinal chemistry to bridge the fields of combinatorial chemistry and molecular biology. The aim of DEL technology is to accelerate the drug discovery process and in particular early phase discovery activities such as target validation and hit identification.
Dynamic combinatorial chemistry (DCC); also known as constitutional dynamic chemistry (CDC) is a method to the generation of new molecules formed by reversible reaction of simple building blocks under thermodynamic control. The library of these reversibly interconverting building blocks is called a dynamic combinatorial library (DCL). All constituents in a DCL are in equilibrium, and their distribution is determined by their thermodynamic stability within the DCL. The interconversion of these building blocks may involve covalent or non-covalent interactions. When a DCL is exposed to an external influence, the equilibrium shifts and those components that interact with the external influence are stabilised and amplified, allowing more of the active compound to be formed.
Metal-catalyzed C–H borylation reactions are transition metal catalyzed organic reactions that produce an organoboron compound through functionalization of aliphatic and aromatic C–H bonds and are therefore useful reactions for carbon–hydrogen bond activation. Metal-catalyzed C–H borylation reactions utilize transition metals to directly convert a C–H bond into a C–B bond. This route can be advantageous compared to traditional borylation reactions by making use of cheap and abundant hydrocarbon starting material, limiting prefunctionalized organic compounds, reducing toxic byproducts, and streamlining the synthesis of biologically important molecules. Boronic acids, and boronic esters are common boryl groups incorporated into organic molecules through borylation reactions. Boronic acids are trivalent boron-containing organic compounds that possess one alkyl substituent and two hydroxyl groups. Similarly, boronic esters possess one alkyl substituent and two ester groups. Boronic acids and esters are classified depending on the type of carbon group (R) directly bonded to boron, for example alkyl-, alkenyl-, alkynyl-, and aryl-boronic esters. The most common type of starting materials that incorporate boronic esters into organic compounds for transition metal catalyzed borylation reactions have the general formula (RO)2B-B(OR)2. For example, bis(pinacolato)diboron (B2Pin2), and bis(catecholato)diborane (B2Cat2) are common boron sources of this general formula.
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 Dr. Fritz Kröhnke.
The thiol-ene reaction is an organic reaction between a thiol and an alkene to form a thioether. This reaction was first reported in 1905, but it gained prominence in the late 1990s and early 2000s for its feasibility and wide range of applications. This reaction is accepted as a click chemistry reaction given the reactions’ high yield, stereoselectivity, high rate, and thermodynamic driving force.
Building block is a term in chemistry which is used to describe a virtual molecular fragment or a real chemical compound the molecules of which possess reactive functional groups. Building blocks are used for bottom-up modular assembly of molecular architectures: nano-particles, metal-organic frameworks, organic molecular constructs, supra-molecular complexes. Using building blocks ensures strict control of what a final compound or a (supra)molecular construct will be.
