| |||
Identifiers | |||
---|---|---|---|
| |||
3D model (JSmol) | |||
605387 | |||
ChEBI |
| ||
ChemSpider |
| ||
PubChem CID |
| ||
CompTox Dashboard (EPA) |
| ||
| |||
| |||
Properties | |||
CH2N2 | |||
Molar mass | 42.041 g·mol−1 | ||
Related compounds | |||
Related compounds | 1H-Diazirine | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
In organic chemistry, diazirines are a class of organic molecules consisting of a carbon bound to two nitrogen atoms, which are double-bonded to each other, forming a cyclopropene-like ring, 3H-diazirine (>CN2). They are isomeric with diazocarbon groups (>C=N=N), and like them can serve as precursors for carbenes by loss of a molecule of dinitrogen. For example, irradiation of diazirines with ultraviolet light leads to carbene insertion into various C−H , N−H, and O−H bonds. [1] Hence, diazirines have grown in popularity as small, photo-reactive, crosslinking reagents. [2] They are often used in photoaffinity labeling studies to observe a variety of interactions, including ligand-receptor, ligand-enzyme, protein-protein, and protein-nucleic acid interactions. [3]
A number of methods exist in the literature for the preparation of diazirines, which begin from a variety of reagents. [4]
Generally, synthetic schemes that begin with ketones (>C=O) involve conversion of the ketone with the desired substituents to diaziridines (>CN2H2). These diaziridines are then subsequently oxidized to form the desired diazirines.
Diaziridines can be prepared from ketones by oximation, followed by tosylation (or mesylation), and then finally by treatment with ammonia (NH3). Generally, oximation reactions are performed by reacting the ketone with hydroxylammonium chloride (NH3OH−Cl+) under heat in the presence of a base such as pyridine. [5] [6] Subsequent tosylation or mesylation of the alpha-substituted oxygen with tosyl or mesyl chloride in the presence of base yields the tosyl or mesyl oxime. [7] The final treatment of the tosyl or mesyl oxime with ammonia produces the diaziridine. [1] [3] [7] [8]
Diaziridines can be also produced directly by the reaction of ketones with ammonia in the presence of an aminating agent such as a monochloramine or hydroxyl amine O-sulfonic acid. [9]
Diaziridines can be oxidized to diazirines by a number of methods. These include oxidation by chromium-based reagents such as the Jones oxidation, [10] oxidation by iodine and triethylamine, [5] oxidation by silver oxide, [11] oxidation by oxalyl chloride, [7] or even electrochemical oxidation on a platinum-titanium anode. [12]
Diazirines can be alternatively formed in a one-pot process using the Graham reaction, starting from amidines. [13] This reaction yields a halogenated diazirine, whose halogen can be displaced by various nucleophilic reagents. [14]
Upon irradiation with UV light, diazirines form reactive carbene species. The carbene may exist in the singlet form, in which the two free electrons occupy the same orbital, or the triplet form, with two unpaired electrons in different orbitals.
The substituents on the diazirine affect which carbene species is generated upon irradiation and subsequent photolytic cleavage. Diazirine substituents that are electron donating in nature can donate electron density to the empty p-orbital of the carbene that will be formed, and hence can stabilize the singlet state. For example, phenyldiazirine produces phenylcarbene in the singlet carbene state [15] whereas 3-chloro-3-[(4-nitrophenyl)methyl]diazirine or trifluoromethylphenyldiazirine produce the respective triplet carbene products. [16] [17]
Electron donating substituents can also encourage photoisomerization to the linear diazo compound [18] , rather than the singlet carbene, and hence these compounds are unfavorable for use in biological assays. [19] On the other hand, trifluoroaryldiazirines in particular show favorable stability and photolytic qualities [19] and are most commonly used in biological applications. [1]
Carbenes produced from diazirines are quickly quenched by reaction with water molecules, [20] and hence yields for photoreactive crosslinking assays are often low. Yet, as this feature minimizes unspecific labeling, it is actually an advantage of using diazirines.
Diazirines are often used as photoreactive crosslinking reagents, as the reactive carbenes they form upon irradiation with UV light can insert into C-H, N-H, and O-H bonds. This results in proximity dependent labeling of other species with the diazirine containing compound.
Diazirines are often preferred to other photoreactive crosslinking reagents due to their smaller size, longer irradiation wavelength, short period of irradiation required, and stability in the presence of various nucleophiles, and in both acidic and basic conditions. [21] Benzophenones, which form reactive triplet carbonyl species upon irradiation, often require long periods of irradiation which can result in non-specific labeling, and moreover are often inert to various polar solvents. [22] Aryl azides require a low wavelength of irradiation, which can damage the biological macromolecules under investigation.
Diazirines are widely used in receptor labeling studies. This is because diazirine-containing analogs of various ligands can be synthesized and incubated with their respective receptors, and then subsequently exposed to light to produce reactive carbenes. The carbene will covalently bond to residues in the binding site of the receptor. The carbene compound may include a bioorthogonal tag or handle by which the protein of interest can be isolated. The protein can then be digested and sequenced by mass spectrometry in order to identify which residues the carbene containing ligand is bound to, and hence the identity of the binding site in the receptor.
Examples of diazirines used in receptor labeling studies include:
In a manner analogous to receptor labeling, diazirine containing compounds that are analogs of natural substrates have also been used to identify binding pockets of enzymes. Examples include:
Diazirines have been used in photoaffinity labeling experiments involving nucleic acids as well. Examples include:
Diazirines have also been used to study protein lipid interactions, for example the interaction of various sphingolipids with proteins in vivo. [30]
Benzophenone is a naturally occurring organic compound with the formula (C6H5)2CO, generally abbreviated Ph2CO. Benzophenone has been found in some fungi, fruits and plants, including grapes. It is a white solid with a low melting point and rose-like odor that is soluble in organic solvents. Benzophenone is the simplest diaromatic ketone. It is a widely used building block in organic chemistry, being the parent diarylketone.
In chemistry and biology, a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural polymers.
In organic chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is R−:C−R' or R=C: where the R represents substituents or hydrogen atoms.
Chemoselectivity is the preferential reaction of a chemical reagent with one of two or more different functional groups.
A transition metal carbene complex is an organometallic compound featuring a divalent carbon ligand, itself also called a carbene. Carbene complexes have been synthesized from most transition metals and f-block metals, using many different synthetic routes such as nucleophilic addition and alpha-hydrogen abstraction. The term carbene ligand is a formalism since many are not directly derived from carbenes and most are much less reactive than lone carbenes. Described often as =CR2, carbene ligands are intermediate between alkyls (−CR3) and carbynes (≡CR). Many different carbene-based reagents such as Tebbe's reagent are used in synthesis. They also feature in catalytic reactions, especially alkene metathesis, and are of value in both industrial heterogeneous and in homogeneous catalysis for laboratory- and industrial-scale preparation of fine chemicals.
The Baeyer–Villiger oxidation is an organic reaction that forms an ester from a ketone or a lactone from a cyclic ketone, using peroxyacids or peroxides as the oxidant. The reaction is named after Adolf von Baeyer and Victor Villiger who first reported the reaction in 1899.
Affinity labels are a class of enzyme inhibitors that covalently bind to their target causing its inactivation. The hallmark of an affinity label is the use of a targeting moiety to specifically and reversibly deliver a weakly reactive group to the enzyme that irreversibly binds to an amino acid residue. The targeting portion of the label often resembles the enzyme's natural substrate so that a similar mode of noncovalent binding is used prior to the covalent linkage. Their usefulness in medicine can be limited by the specificity of the first noncovalent binding step whereas indiscriminate action can be utilized for purposes such as affinity labeling - a technique for the validation of substrate-specific binding of compounds.
Organoselenium chemistry is the science exploring the properties and reactivity of organoselenium compounds, chemical compounds containing carbon-to-selenium chemical bonds. Selenium belongs with oxygen and sulfur to the group 16 elements or chalcogens, and similarities in chemistry are to be expected. Organoselenium compounds are found at trace levels in ambient waters, soils and sediments.
In organic chemistry, umpolung or polarity inversion 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.
Barrelene is a bicyclic organic compound with chemical formula C8H8 and systematic name bicyclo[2.2.2]octa-2,5,7-triene. First synthesized and described by Howard Zimmerman in 1960, the name derives from the resemblance to a barrel, with the staves being three ethylene units attached to two methine groups. It is the formal Diels–Alder adduct of benzene and acetylene. Due to its unusual molecular geometry, the compound is of considerable interest to theoretical chemists.
The Negishi coupling is a widely employed transition metal catalyzed cross-coupling reaction. The reaction couples organic halides or triflates with organozinc compounds, forming carbon-carbon bonds (C-C) in the process. A palladium (0) species is generally utilized as the catalyst, though nickel is sometimes used. A variety of nickel catalysts in either Ni0 or NiII oxidation state can be employed in Negishi cross couplings such as Ni(PPh3)4, Ni(acac)2, Ni(COD)2 etc.
Organocopper chemistry is the study of the physical properties, reactions, and synthesis of organocopper compounds, which are organometallic compounds containing a carbon to copper chemical bond. They are reagents in organic chemistry.
In genetics, crosslinking of DNA occurs when various exogenous or endogenous agents react with two nucleotides of DNA, forming a covalent linkage between them. This crosslink can occur within the same strand (intrastrand) or between opposite strands of double-stranded DNA (interstrand). These adducts interfere with cellular metabolism, such as DNA replication and transcription, triggering cell death. These crosslinks can, however, be repaired through excision or recombination pathways.
Organoruthenium chemistry is the chemistry of organometallic compounds containing a carbon to ruthenium chemical bond. Several organoruthenium catalysts are of commercial interest and organoruthenium compounds have been considered for cancer therapy. The chemistry has some stoichiometric similarities with organoiron chemistry, as iron is directly above ruthenium in group 8 of the periodic table. The most important reagents for the introduction of ruthenium are ruthenium(III) chloride and triruthenium dodecacarbonyl.
In organic chemistry, carbonyl reduction is the conversion of any carbonyl group, usually to an alcohol. It is a common transformation that is practiced in many ways. Ketones, aldehydes, carboxylic acids, esters, amides, and acid halides - some of the most pervasive functional groups, -comprise carbonyl compounds. Carboxylic acids, esters, and acid halides can be reduced to either aldehydes or a step further to primary alcohols, depending on the strength of the reducing agent. Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation, the alcohol group can be further reduced and removed altogether by replacement with H.
An insertion reaction is a chemical reaction where one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.:
Photoaffinity labeling is a chemoproteomics technique used to attach "labels" to the active site of a large molecule, especially a protein. The "label" attaches to the molecule loosely and reversibly, and has an inactive site which can be converted using photolysis into a highly reactive form, which causes the label to bind more permanently to the large molecule via a covalent bond. The technique was first described in the 1970s. Molecules that have been used as labels in this process are often analogs of complex molecules, in which certain functional groups are replaced with a photoreactive group, such as an azide, a diazirine or a benzophenone.
l-Photo-leucine is a synthetic derivative of the l-leucine amino acid that is used as its natural analog and is characterized for having photo-reactivity, which makes it suitable for observing and characterizing protein-protein interactions (PPI). When a protein containing this amino acid (A) is exposed to ultraviolet light while interacting with another protein (B), the complex formed from these two proteins (AB) remains attached and can be isolated for study.
Gallium monoiodide is an inorganic gallium compound with the formula GaI or Ga4I4. It is a pale green solid and mixed valent gallium compound, which can contain gallium in the 0, +1, +2, and +3 oxidation states. It is used as a pathway for many gallium-based products. Unlike the gallium(I) halides first crystallographically characterized, gallium monoiodide has a more facile synthesis allowing a synthetic route to many low-valent gallium compounds.
In organic chemistry, the Graham reaction is an oxidation reaction that converts an amidine into a diazirine using a hypohalite reagent. The halide of the hypohalite oxidant, or another similar anionic additive to the reaction, is retained as a substituent on the diazirine product. The reaction was first reported in 1965. Various reaction mechanisms have been proposed.