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Elias James "E.J." Corey is an American organic chemist. In 1990, he won the Nobel Prize in Chemistry "for his development of the theory and methodology of organic synthesis", specifically retrosynthetic analysis. Regarded by many as one of the greatest living chemists, he has developed numerous synthetic reagents, methodologies and total syntheses and has advanced the science of organic synthesis considerably.
An allyl group is a substituent with the structural formula H2C=CH−CH2R, where R is the rest of the molecule. It consists of a methylene bridge (−CH2−) attached to a vinyl group (−CH=CH2). The name is derived from the Latin word for garlic, Allium sativum. In 1844, Theodor Wertheim isolated an allyl derivative from garlic oil and named it "Schwefelallyl". The term allyl applies to many compounds related to H2C=CH−CH2, some of which are of practical or of everyday importance, for example, allyl chloride.
A sigmatropic reaction in organic chemistry is a pericyclic reaction wherein the net result is one σ-bond is changed to another σ-bond in an uncatalyzed intramolecular reaction. The name sigmatropic is the result of a compounding of the long-established sigma designation from single carbon–carbon bonds and the Greek word tropos, meaning turn. In this type of rearrangement reaction, a substituent moves from one part of a π-bonded system to another part in an intramolecular reaction with simultaneous rearrangement of the π system. True sigmatropic reactions are usually uncatalyzed, although Lewis acid catalysis is possible. Sigmatropic reactions often have transition-metal catalysts that form intermediates in analogous reactions. The most well-known of the sigmatropic rearrangements are the [3,3] Cope rearrangement, Claisen rearrangement, Carroll rearrangement, and the Fischer indole synthesis.
In stereochemistry, asymmetric induction describes the preferential formation in a chemical reaction of one enantiomer or diastereoisomer over the other as a result of the influence of a chiral feature present in the substrate, reagent, catalyst or environment. Asymmetric induction is a key element in asymmetric synthesis.
Schwartz's reagent is the common name for the organozirconium compound with the formula (C5H5)2ZrHCl, sometimes called zirconocene hydrochloride or zirconocene chloride hydride, and is named after Jeffrey Schwartz, a chemistry professor at Princeton University. This metallocene is used in organic synthesis for various transformations of alkenes and alkynes.
The Schmidt reaction is an organic reaction in which an azide reacts with a carbonyl derivative, usually a aldehyde, ketone, or carboxylic acid, under acidic conditions to give an amine or amide, with expulsion of nitrogen. It is named after Karl Friedrich Schmidt (1887–1971), who first reported it in 1924 by successfully converting benzophenone and hydrazoic acid to benzanilide. Surprisingly, the intramolecular reaction was not reported until 1991 but has become important in the synthesis of natural products.
The Meyers synthesis is an organic synthesis for the preparation of unsymmetrical aldehydes via hydrolysis of an oxazine. The reaction is named after the American chemist Albert Meyers.
Richard Frederick Heck was an American chemist noted for the discovery and development of the Heck reaction, which uses palladium to catalyze organic chemical reactions that couple aryl halides with alkenes. The analgesic naproxen is an example of a compound that is prepared industrially using the Heck reaction.
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Strychnine total synthesis in chemistry describes the total synthesis of the complex biomolecule strychnine. The first reported method by the group of Robert Burns Woodward in 1954 is considered a classic in this research field.
The Rothemund reaction is a condensation/oxidation process that converts four pyrroles and four aldehydes into a porphyrin. It is based on work by Paul Rothemund, who first reported it in 1936. The method underpin more modern synthesis such as those described by Adler and Longo and by Lindsey. The Rothemund reactions is common in university teaching labs.
The Saegusa–Ito oxidation is a chemical reaction used in organic chemistry. It was discovered in 1978 by Takeo Saegusa and Yoshihiko Ito as a method to introduce α-β unsaturation in carbonyl compounds. The reaction as originally reported involved formation of a silyl enol ether followed by treatment with palladium(II) acetate and benzoquinone to yield the corresponding enone. The original publication noted its utility for regeneration of unsaturation following 1,4-addition with nucleophiles such as organocuprates.
Hydrogen-bond catalysis is a type of organocatalysis that relies on use of hydrogen bonding interactions to accelerate and control organic reactions. In biological systems, hydrogen bonding plays a key role in many enzymatic reactions, both in orienting the substrate molecules and lowering barriers to reaction. However, chemists have only recently attempted to harness the power of using hydrogen bonds to perform catalysis, and the field is relatively undeveloped compared to research in Lewis acid catalysis.
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.
Rearrangements, especially those that can participate in cascade reactions, such as the aza-Cope rearrangements, are of high practical as well as conceptual importance in organic chemistry, due to their ability to quickly build structural complexity out of simple starting materials. The aza-Cope rearrangements are examples of heteroatom versions of the Cope rearrangement, which is a [3,3]-sigmatropic rearrangement that shifts single and double bonds between two allylic components. In accordance with the Woodward-Hoffman rules, thermal aza-Cope rearrangements proceed suprafacially. Aza-Cope rearrangements are generally classified by the position of the nitrogen in the molecule :
In organic chemistry, carbonyl allylation describes methods for adding an allyl anion to an aldehyde or ketone to produce a homoallylic alcohol. The carbonyl allylation was first reported in 1876 by Alexander Zaitsev and employed an allylzinc reagent.
The asymmetric addition of alkynylzinc compounds to aldehydes is an example of a Nef synthesis, a chemical reaction whereby a chiral propargyl alcohol is prepared from a terminal alkyne and an aldehyde. This alkynylation reaction is enantioselective and involves an alkynylzinc reagent rather than the sodium acetylide used by John Ulric Nef in his 1899 report of the synthetic approach. Propargyl alcohols are versatile precursors for the chirally-selective synthesis of natural products and pharmaceutical agents, making this asymmetric addition reaction of alkynylzinc compounds useful. For example, Erick Carreira used this approach in a total synthesis of the marine natural product leucascandrolide A, a bioactive metabolite of the calcareous sponge Leucascandra caveolata with cytotoxic and antifungal properties isolated in 1996.
The Krische allylation involves the enantioselective iridium-catalyzed addition of an allyl group to an aldehyde or an alcohol, resulting in the formation of a secondary homoallylic alcohol. The mechanism of the Krische allylation involves primary alcohol dehydrogenation or, when using aldehyde reactants, hydrogen transfer from 2-propanol. Unlike other allylation methods, the Krische allylation avoids the use of preformed allyl metal reagents and enables the direct conversion of primary alcohols to secondary homoallylic alcohols.
In organic chemistry, an ynone is a compound containing a ketone function and a C≡C triple bond. Many ynones are α,β-ynones, where the carbonyl and alkyne groups are conjugated. Capillin is a naturally occurring example. Some ynones are not conjugated.
Rick L. Danheiser is an American organic chemist and is the Arthur C. Cope Professor of Chemistry at the Massachusetts Institute of Technology and Chair of the MIT Faculty. His research involves the invention of new methods for the synthesis of complex organic compounds. Danheiser is known for the Danheiser annulation and Danheiser benzannulation reactions.
References
- ↑ Total synthesis of (+)-calyculin A. J. Am. Chem. Soc.1992, 114, 9434-9453 doi : 10.1021/ja00050a024
- ↑ Asymmetric Synthesis of the Squalene Synthase Inhibitor Zaragozic Acid C. J. Am. Chem. Soc.1994, 116, 12111-12112 doi : 10.1021/ja00105a085
- ↑ ""ACS Cope Award"". Archived from the original on 2016-03-04. Retrieved 2015-04-06.
- ↑ Mark Van Doren Award for Teaching. http://www.columbia.edu/cu/vpas/about/recognition.html#2
- ↑ An Approach to the Synthesis of CP-263,114: A Remarkably Facile Silyloxy-Cope Rearrangement. J. Am. Chem. Soc.1999, 121, 890-891. doi : 10.1021/ja983609x
- ↑ Total Synthesis of Leucascandrolide A. J. Am. Chem. Soc.2000, 122, 12894-12895. doi : 10.1021/ja003593m
- ↑ Formal Total Synthesis of Mycoticin A. J. Am. Chem. Soc.2001, 123, 341-342. doi : 10.1021/ja0035102
- ↑ Total Synthesis of Dolabelide D. J. Am. Chem. Soc.2006, 128, 2796-2797. doi : 10.1021/ja058692k
- ↑ Origins of Stereoselectivity in Strain-Release Allylations. Angew. Chem. Int. Ed.2004, 44, 938-941. doi : 10.1002/anie.200462130