In organic chemistry, benzyl is the substituent or molecular fragment possessing the structure C6H5CH2–. Benzyl features a benzene ring attached to a CH2 group.
The Pauson–Khand reaction is a chemical reaction described as a [2+2+1] cycloaddition between an alkyne, an alkene and carbon monoxide to form a α,β-cyclopentenone. The reaction was discovered by Ihsan Ullah Khand (1935-1980), who was working as a postdoctoral associate with Peter Ludwig Pauson (1925–2013) at the University of Strathclyde in Glasgow. The seminal report dates back to 1970, however a detailed follow up was reported in 1973. Initial findings by Pauson and Khand were intermolecular in nature, however many intramolecular examples have been highlighted in both synthesis and methodology reports, starting a decade later from reaction discovery. This reaction was originally mediated by stoichiometric amounts of dicobalt octacarbonyl, but newer versions are both more efficient and catalytic utilizing different chiral auxiliaries for stereo induction, main group transition-metals, and additives to enhance rate of reactivity and yield. For a more extensive review on PKR, refer to Torres' book.
In chemistry, a phosphaalkyne is an organophosphorus compound containing a triple bond between phosphorus and carbon with the general formula R-C≡P. Phosphaalkynes are the heavier congeners of nitriles, though, due to the similar electronegativities of phosphorus and carbon, possess reactivity patterns reminiscent of alkynes. Due to their high reactivity, phosphaalkynes are not found naturally on earth, but the simplest phosphaalkyne, phosphaethyne (H-C≡P) has been observed in the interstellar medium.
Lawesson's reagent, or LR, is a chemical compound used in organic synthesis as a thiation agent. Lawesson's reagent was first made popular by Sven-Olov Lawesson, who did not, however, invent it. Lawesson's reagent was first made in 1956 during a systematic study of the reactions of arenes with P4S10.
The Reformatsky reaction is an organic reaction which condenses aldehydes or ketones with α-halo esters using metallic zinc to form β-hydroxy-esters:
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.
Palladium on carbon, often referred to as Pd/C, is a form of palladium used as a catalyst. The metal is supported on activated carbon to maximize its surface area and activity.
Pivalic acid is a carboxylic acid with a molecular formula of (CH3)3CCO2H. This colourless, odiferous organic compound is solid at room temperature. A common abbreviation for the pivalyl or pivaloyl group (t-BuC(O)) is Piv and for pivalic acid (t-BuC(O)OH) is PivOH.
The Wurtz–Fittig reaction is the chemical reaction of aryl halides with alkyl halides and sodium metal in the presence of dry ether to give substituted aromatic compounds. Charles Adolphe Wurtz reported what is now known as the Wurtz reaction in 1855, involving the formation of a new carbon-carbon bond by coupling two alkyl halides. Work by Wilhelm Rudolph Fittig in the 1860s extended the approach to the coupling of an alkyl halide with an aryl halide. This modification of the Wurtz reaction is considered a separate process and is named for both scientists.
A carbometalation 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. Carbometalations 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 carbometalation.
Organobismuth chemistry is the chemistry of organometallic compounds containing a carbon to bismuth chemical bond. Applications are few. The main bismuth oxidation states are Bi(III) and Bi(V) as in all higher group 15 elements. The energy of a bond to carbon in this group decreases in the order P > As > Sb > Bi. The first reported use of bismuth in organic chemistry was in oxidation of alcohols by Challenger in 1934 (using Ph3Bi(OH)2). Knowledge about methylated species of bismuth in environmental and biological media is limited.
Electrophilic amination is a chemical process involving the formation of a carbon–nitrogen bond through the reaction of a nucleophilic carbanion with an electrophilic source of nitrogen.
Diphenyldichloromethane is an organic compound with the formula (C6H5)2CCl2. It is a colorless solid that is used as a precursor to other organic compounds.
David Markham Lemal is the Albert W. Smith Professor of Chemistry Emeritus and Research Professor of Chemistry at Dartmouth College. He received an A.B. degree (summa) from Amherst College in 1955 and a Ph.D. in Chemistry from Harvard University in 1959. At Harvard he worked with R. B. Woodward on deoxy sugars and a synthesis of the alkaloid yohimbine.
MoOPH, also known as oxodiperoxymolybdenum(pyridine)-(hexamethylphosphoric triamide), is a reagent used in organic synthesis. It contains a molybdenum(VI) center with multiple oxygen ligands, coordinated with pyridine and HMPA ligands. It is an electrophilic source of oxygen that reacts with enolates and related structures, and thus can be used for alpha-hydroxylation of carbonyl-containing compounds. Other reagents used for alpha-hydroxylation via enol or enolate structures include Davis oxaziridine, oxygen, and various peroxyacids. This reagent was first utilized by Edwin Vedejs as an efficient alpha-hydroxylating agent in 1974 and an effective preparative procedure was later published in 1978.
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 organic chemistry, the Fujiwara–Moritani reaction is a type of cross coupling reaction where an aromatic C-H bond is directly coupled to an olefinic C-H bond, generating a new C-C bond. This reaction is performed in the presence of a transition metal, typically palladium. The reaction was discovered by Yuzo Fujiwara and Ichiro Moritani in 1967. An external oxidant is required to this reaction to be run catalytically. Thus, this reaction can be classified as a C-H activation reaction, an oxidative Heck reaction, and a C-H olefination. Surprisingly, the Fujiwara–Moritani reaction was discovered before the Heck reaction.
The Mizoroki−Heck coupling of aryl halides and alkenes to form C(sp2)–C(sp2) bonds has become a staple transformation in organic synthesis, owing to its broad functional group compatibility and varied scope. In stark contrast, the palladium-catalyzed reductive Heck reaction has received considerably less attention, despite the fact that early reports of this reaction date back almost half a century. From the perspective of retrosynthetic logic, this transformation is highly enabling because it can forge alkyl–aryl linkages from widely available alkenes, rather than from the less accessible and/or more expensive alkyl halide or organometallic C(sp3) synthons that are needed in a classical aryl/alkyl cross-coupling.
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, the Davis oxidation or Davis' oxaziridine oxidation refers to oxidations involving the use of the Davis reagent or other similar oxaziridine reagents. This reaction mainly refers to the generation of α-hydroxy carbonyl compounds (acyloins) from ketones or esters. The reaction is carried out in a basic environment to generate the corresponding enolate from the ketone or ester. This reaction has been shown to work for amides.
