An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates.
Tropinone is an alkaloid, famously synthesised in 1917 by Robert Robinson as a synthetic precursor to atropine, a scarce commodity during World War I. Tropinone and the alkaloids cocaine and atropine all share the same tropane core structure. Its corresponding conjugate acid at pH 7.3 major species is known as tropiniumone.
In organic chemistry, the Mannich reaction is a three-component organic reaction that involves the amino alkylation of an acidic proton next to a carbonyl functional group by formaldehyde and a primary or secondary amine or ammonia. The final product is a β-amino-carbonyl compound also known as a Mannich base. Reactions between aldimines and α-methylene carbonyls are also considered Mannich reactions because these imines form between amines and aldehydes. The reaction is named after Carl Mannich.
The Mitsunobu reaction is an organic reaction that converts an alcohol into a variety of functional groups, such as an ester, using triphenylphosphine and an azodicarboxylate such as diethyl azodicarboxylate (DEAD) or diisopropyl azodicarboxylate (DIAD). Although DEAD and DIAD are most commonly used, there are a variety of other azodicarboxylates available which facilitate an easier workup and/or purification and in some cases, facilitate the use of more basic nucleophiles. It was discovered by Oyo Mitsunobu (1934–2003). In a typical protocol, one dissolves the alcohol, the carboxylic acid, and triphenylphosphine in tetrahydrofuran or other suitable solvent, cool to 0 °C using an ice-bath, slowly add the DEAD dissolved in THF, then stir at room temperature for several hours. The alcohol reacts with the phosphine to create a good leaving group then undergoes an inversion of stereochemistry in classic SN2 fashion as the nucleophile displaces it. A common side-product is produced when the azodicarboxylate displaces the leaving group instead of the desired nucleophile. This happens if the nucleophile is not acidic enough or is not nucleophilic enough due to steric or electronic constraints. A variation of this reaction utilizing a nitrogen nucleophile is known as a Fukuyama–Mitsunobu.
In organic chemistry, Madelung synthesis is a chemical reaction that produces indoles by the intramolecular cyclization of N-phenylamides using strong base at high temperature. The Madelung synthesis was reported in 1912 by Walter Madelung, when he observed that 2-phenylindole was synthesized using N-benzoyl-o-toluidine and two equivalents of sodium ethoxide in a heated, airless reaction. Common reaction conditions include use of sodium or potassium alkoxide as base in hexane or tetrahydrofuran solvents, at temperatures ranging between 200–400 °C. A hydrolysis step is also required in the synthesis. The Madelung synthesis is important because it is one of few known reactions that produce indoles from a base-catalyzed thermal cyclization of N-acyl-o-toluidines.
2-Iodoxybenzoic acid (IBX) is an organic compound used in organic synthesis as an oxidizing agent. This periodinane is especially suited to oxidize alcohols to aldehydes. IBX is prepared from 2-iodobenzoic acid, potassium bromate, and sulfuric acid. Frigerio and co-workers have also demonstrated, in 1999 that potassium bromate may be replaced by commercially available Oxone. One of the main drawbacks of IBX is its limited solubility; IBX is insoluble in many common organic solvents. In the past, it was believed that IBX was shock sensitive, but it was later proposed that samples of IBX were shock sensitive due to the residual potassium bromate left from its preparation. Commercial IBX is stabilized by carboxylic acids such as benzoic acid and isophthalic acid.
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 metal 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.
Methylecgonidine is a chemical intermediate derived from ecgonine or cocaine.
Larry E. Overman is Distinguished Professor of Chemistry at the University of California, Irvine. He was born in Chicago in 1943. Overman obtained a B.A. degree from Earlham College in 1965, and he completed his Ph.D. in chemistry from the University of Wisconsin–Madison in 1969, under Howard Whitlock Jr. Professor Overman is a member of the United States National Academy of Sciences and the American Academy of Arts and Sciences. He was the recipient of the Arthur C. Cope Award in 2003, and he was awarded the Tetrahedron Prize for Creativity in Organic Chemistry for 2008.
The Stieglitz rearrangement is a rearrangement reaction in organic chemistry which is named after the American chemist Julius Stieglitz (1867–1937) and was first investigated by him and Paul Nicholas Leech in 1913. It describes the 1,2-rearrangement of trityl amine derivatives to triaryl imines. It is comparable to a Beckmann rearrangement which also involves a substitution at a nitrogen atom through a carbon to nitrogen shift. As an example, triaryl hydroxylamines can undergo a Stieglitz rearrangement by dehydration and the shift of a phenyl group after activation with phosphorus pentachloride to yield the respective triaryl imine, a Schiff base.
The biosynthesis of cocaine has long attracted the attention of biochemists and organic chemists. This interest is partly motivated by the strong physiological effects of cocaine, but a further incentive was the unusual bicyclic structure of the molecule. The biosynthesis can be viewed as occurring in two phases, one phase leading to the N-methylpyrrolinium ring, which is preserved in the final product. The second phase incorporates a C4 unit with formation of the bicyclic tropane core.
Indole is an aromatic, heterocyclic, organic compound with the formula C8H7N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole is widely distributed in the natural environment and can be produced by a variety of bacteria. As an intercellular signal molecule, indole regulates various aspects of bacterial physiology, including spore formation, plasmid stability, resistance to drugs, biofilm formation, and virulence. The amino acid tryptophan is an indole derivative and the precursor of the neurotransmitter serotonin.
In organic chemistry, keto acids or ketoacids are organic compounds that contain a carboxylic acid group and a ketone group. In several cases, the keto group is hydrated. The alpha-keto acids are especially important in biology as they are involved in the Krebs citric acid cycle and in glycolysis.
Torreyanic acid is a dimeric quinone first isolated and by Lee et al. in 1996 from an endophyte, Pestalotiopsis microspora. This endophyte is likely the cause of the decline of Florida torreya, an endangered species that is related to the taxol-producing Taxus brevifolia. The natural product was found to be cytotoxic against 25 different human cancer cell lines with an average IC50 value of 9.4 µg/mL, ranging from 3.5 (NEC) to 45 (A549) µg/mL. Torreyanic acid was found to be 5-10 times more potent in cell lines sensitive to protein kinase C (PKC) agonists, 12-o-tetradecanoyl phorbol-13-acetate (TPA), and was shown to cause cell death via apoptosis. Torreyanic acid also promoted G1 arrest of G0 synchronized cells at 1-5 µg/mL levels, depending on the cell line. It has been proposed that the eukaryotic translation initiation factor EIF-4a is a potential biochemical target for the natural compound.
Akuammicine is a monoterpene indole alkaloid of the Vinca sub-group. It is found in the Apocynaceae family of plants including Picralima nitida, Vinca minor and the Aspidosperma.
Biomimetic synthesis is an area of organic chemical synthesis that is specifically biologically inspired. The term encompasses both the testing of a "biogenetic hypothesis" through execution of a series of reactions designed to parallel the proposed biosynthesis, as well as programs of study where a synthetic reaction or reactions aimed at a desired synthetic goal are designed to mimic one or more known enzymic transformations of an established biosynthetic pathway. The earliest generally cited example of a biomimetic synthesis is Sir Robert Robinson's organic synthesis of the alkaloid tropinone.
Erysodienone is a key precursor in the biosynthesis of many Erythrina-produced alkaloids. Early work was done by Derek Barton and co-workers to illustrate the biosynthetic pathways towards erythrina alkaloids. It was demonstrated that erysodienone could be synthesized from simple starting materials by a similar approach as its biosynthetic pathway, which led to the development of the biomimetic synthesis of erysodienone.
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.
The Criegee oxidation is a glycol cleavage reaction in which vicinal diols are oxidized to form ketones and aldehydes using lead tetraacetate. It is analogous to the Malaprade reaction, but uses a milder oxidant. This oxidation was discovered by Rudolf Criegee and coworkers and first reported in 1931 using ethylene glycol as the substrate.
Bis(cyclopentadienyl)titanium(III) chloride, also known as the Nugent–RajanBabu reagent, is the organotitanium compound which exists as a dimer with the formula [(C5H5)2TiCl]2. It is an air sensitive green solid. The complex finds specialized use in synthetic organic chemistry as a single electron reductant.
