In organic chemistry, benzyl is the substituent or molecular fragment possessing the structure R−CH2−C6H5. Benzyl features a benzene ring attached to a methylene group group.
The Robinson annulation is a chemical reaction used in organic chemistry for ring formation. It was discovered by Robert Robinson in 1935 as a method to create a six membered ring by forming three new carbon–carbon bonds. The method uses a ketone and a methyl vinyl ketone to form an α,β-unsaturated ketone in a cyclohexane ring by a Michael addition followed by an aldol condensation. This procedure is one of the key methods to form fused ring systems.
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. Ihsan Ullah Khand (1935-1980) discovered the reaction around 1970, while working as a postdoctoral associate with Peter Ludwig Pauson (1925–2013) at the University of Strathclyde in Glasgow. Pauson and Khand's initial findings were intermolecular in nature, but starting a decade after the reaction's discovery, many intramolecular examples have been highlighted in both synthesis and methodology reports. This reaction was originally mediated by stoichiometric amounts of dicobalt octacarbonyl, but newer versions are both more efficient, enhancing reactivity and yield via utilizing different chiral auxiliaries for stereo induction, main group transition-metals, and additives.
The Nenitzescu indole synthesis is a chemical reaction that forms 5-hydroxyindole derivatives from benzoquinone and β-aminocrotonic esters.
The Baker–Venkataraman rearrangement is the chemical reaction of 2-acetoxyacetophenones with base to form 1,3-diketones.
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.
The Hunsdiecker reaction is a name reaction in organic chemistry whereby silver salts of carboxylic acids react with a halogen to produce an organic halide. It is an example of both a decarboxylation and a halogenation reaction as the product has one fewer carbon atoms than the starting material and a halogen atom is introduced its place. A catalytic approach has been developed.
Pivalic acid, also known as neovaleric 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. It is an isomer of valeric acid, the other two isomers of it are 2-Methylbutanoic acid and 3-Methylbutanoic acid.
Rebeccamycin (NSC 655649) is a weak topoisomerase I inhibitor isolated from Nocardia sp. It is structurally similar to staurosporine, but does not show any inhibitory activity against protein kinases. It shows significant antitumor properties in vitro (IC50=480nM against mouse B16 melanoma cells and IC50=500nM against P388 leukemia cells). It is an antineoplastic antibiotic and an intercalating agent.
Methylecgonidine is a chemical intermediate derived from ecgonine or cocaine.
The Krapcho decarboxylation is the chemical reaction of esters with halide anions. The ester must contain an electron-withdrawing group in the beta position, such as β-ketoesters, malonic esters, α-cyanoesters, or α-sulfonylesters. It works best with methyl esters, since methyl groups are more susceptible to SN2-reaction than are larger alkyl ester substituents, such as ethyl or propyl groups. The byproducts of this decarbomethoxylation are chloromethane and CO2. They are lost as gases, which helps drive the reaction.
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.
Michael E. Jung is a Professor of Chemistry in the Department of Chemistry and Biochemistry at the University of California at Los Angeles.
Sparsomycin is a compound, initially discovered as a metabolite of the bacterium Streptomyces sparsogenes, which binds to the 50S ribosomal subunit and inhibits protein synthesis through peptidyl transferase inhibition. As it binds to the 50S ribosomal subunit, it induces translocation on the 30S subunit. It is a nucleotide analogue. It was also formerly thought to be a possible anti-tumor agent, but interest in this drug was later discarded after it was discovered that it resulted in retinopathy and as a tool to study protein synthesis; it is not specific for bacterial ribosomes and so not usable as an antibiotic.
Peter Wipf is the distinguished university professor of chemistry at the University of Pittsburgh. His research interests focus on the total synthesis of natural products, the discovery of new transformations of strained molecules, and the development of new pharmaceuticals. He is a Fellow of the Royal Society of Chemistry (RSC), the American Association for the Advancement of Science (AAAS), and the American Chemical Society (ACS).
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.
Mark S. Cushman is an American chemist, whose primary research is in the area of medicinal chemistry. He completed his pre-pharmacy studies at Fresno State College (now California State University, Fresno) in 1965. He then attended the University of California San Francisco (as a University of California Regents Scholar), earning a Pharm.D. in 1969 and a Ph.D. in Medicinal Chemistry in 1973. Thereafter, he performed postdoctoral training in the laboratory of George Büchi, Ph.D., at the Massachusetts Institute of Technology (MIT). There, his research focused on the discovery and development of new synthetic methodologies, and the isolation and structural characterization of mycotoxins from Aspergillus niger. In 1975, he joined the Department of Medicinal Chemistry and Molecular Pharmacology (at the time, Department of Medicinal Chemistry and Pharmacognosy) at Purdue University. From 1983 to 1984, Prof. Cushman was a Senior Fulbright Scholar at Munich Technical University working in the laboratory of Professor Adelbert Bacher. His sabbatical work dealt with the design and synthesis of probes to elucidate key aspects of the biosynthesis of riboflavin (vitamin B2). Currently he holds the rank of Distinguished Professor Emeritus of Medicinal Chemistry at Purdue University. He has mentored 40 graduate students, 59 postdoctoral researchers, and 5 visiting scholars. He has published 348 papers and holds 41 patents. His work has ~17,000 citations with an h-index of 69. His most cited papers had 471, 403, and 299 citations as of August 2021. He has made seminal contributions to the fields of synthetic and medicinal chemistry including the development of new synthetic methodologies, the synthesis of natural products, and the preparation of antivirals, antibacterials, and anticancer agents, and mechanism probes to understand the function of over thirty macromolecular targets. One of his main scientific contributions is the development of the indenoisoquinolines, molecules that inhibit the action of toposiomerase I (Top1) and stabilize the G-quadruplex in the Myc promoter. Three indenoisoquinolines designed and synthesized by his research group at Purdue University [indotecan (LMP 400), indimitecan (LMP 776), and LMP 744] demonstrated potent anticancer activity in vivo and have completed phase I clinical trials at the National Institutes of Health.
Fascaplysin is a marine alkaloid based on 12H-pyrido[1–2-a:3,4-b′]diindole ring system. It was first isolated as a red pigment from the marine sponge Fascaplysinopsis bergquist collected in the South Pacific near Fiji in 1988. Fascaplysin possesses a broad range of in vitro biological activities including analgesic, antimicrobial, antifungal, antiviral, antimalarial, anti-angiogenic, and antiproliferative activity against numerous cancer cell lines.
The Babler oxidation, also known as the Babler-Dauben oxidation, is an organic reaction for the oxidative transposition of tertiary allylic alcohols to enones using pyridinium chlorochromate (PCC):
Hafnium(IV) triflate or hafnium trifluoromethansulfonate is an inorganic substance with the idealized formula Hf(OSO2CF3)4, also written as Hf(OTf)4. Hafnium triflate is used as an impure mixture as a catalyst. Hafnium (IV) has an ionic radius of intermediate range (Al < Ti < Hf < Zr < Sc < Ln) and has an oxophilic hard character typical of group IV metals. This solid is a stronger Lewis acid than its typical precursor hafnium tetrachloride, HfCl4, because of the strong electron-withdrawing nature of the four triflate groups, which makes it a great Lewis acid and has many uses including as a great catalyst at low Lewis acid loadings for electrophilic aromatic substitution and nucleophilic substitution reactions.
