In chemistry, a ketone is a functional group with the structure R2C=O, where R can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond). The simplest ketone is acetone (R = R' = methyl), with the formula CH3C(O)CH3. Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids (e.g., testosterone), and the solvent acetone.
In organic chemistry, an aldehyde is an organic compound containing a functional group with the structure R−CH=O. The functional group itself can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are common and play important roles in the technology and biological spheres.
The aldol reaction is a means of forming carbon–carbon bonds in organic chemistry. Discovered independently by the Russian chemist Alexander Borodin in 1869 and by the French chemist Charles-Adolphe Wurtz in 1872, the reaction combines two carbonyl compounds to form a new β-hydroxy carbonyl compound. These products are known as aldols, from the aldehyde + alcohol, a structural motif seen in many of the products. Aldol structural units are found in many important molecules, whether naturally occurring or synthetic. For example, the aldol reaction has been used in the large-scale production of the commodity chemical pentaerythritol and the synthesis of the heart disease drug Lipitor.
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates.
Organolithium reagents are organometallic compounds that contain carbon–lithium bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.
Enolates are organic anions derived from the deprotonation of carbonyl compounds. Rarely isolated, they are widely used as reagents in the synthesis of organic compounds.
Dess–Martin periodinane (DMP) is a chemical reagent used in the Dess–Martin oxidation, oxidizing primary alcohols to aldehydes and secondary alcohols to ketones. This periodinane has several advantages over chromium- and DMSO-based oxidants that include milder conditions, shorter reaction times, higher yields, simplified workups, high chemoselectivity, tolerance of sensitive functional groups, and a long shelf life. However, use on an industrial scale is made difficult by its cost and its potentially explosive nature. It is named after the American chemists Daniel Benjamin Dess and James Cullen Martin who developed the reagent in 1983. It is based on IBX, but due to the acetate groups attached to the central iodine atom, DMP is much more reactive than IBX and is much more soluble in organic solvents.
n-Butyllithium C4H9Li (abbreviated n-BuLi) is an organolithium reagent. It is widely used as a polymerization initiator in the production of elastomers such as polybutadiene or styrene-butadiene-styrene (SBS). Also, it is broadly employed as a strong base (superbase) in the synthesis of organic compounds as in the pharmaceutical industry.
Organic reductions or organic oxidations or organic redox reactions are redox reactions that take place with organic compounds. In organic chemistry oxidations and reductions are different from ordinary redox reactions, because many reactions carry the name but do not actually involve electron transfer in the electrochemical sense of the word. Instead the relevant criterion for organic oxidation is gain of oxygen and/or loss of hydrogen, respectively.
Nucleophilic acyl substitution describe a class of substitution reactions involving nucleophiles and acyl compounds. In this type of reaction, a nucleophile – such as an alcohol, amine, or enolate – displaces the leaving group of an acyl derivative – such as an acid halide, anhydride, or ester. The resulting product is a carbonyl-containing compound in which the nucleophile has taken the place of the leaving group present in the original acyl derivative. Because acyl derivatives react with a wide variety of nucleophiles, and because the product can depend on the particular type of acyl derivative and nucleophile involved, nucleophilic acyl substitution reactions can be used to synthesize a variety of different products.
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 Holton Taxol total synthesis, published by Robert A. Holton and his group at Florida State University in 1994, was the first total synthesis of Taxol.
The Corey–Kim oxidation is an oxidation reaction used to synthesise aldehydes and ketones from primary and secondary alcohols. It is named for American chemist and Nobel Laureate Elias James Corey and Korean-American chemist Choung Un Kim.
Umpolung or polarity inversion in organic chemistry 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.
Oppenauer oxidation, named after Rupert Viktor Oppenauer, is a gentle method for selectively oxidizing secondary alcohols to ketones.
Selenoxide elimination is a method for the chemical synthesis of alkenes from selenoxides. It is most commonly used to synthesize α,β-unsaturated carbonyl compounds from the corresponding saturated analogues. It is mechanistically related to the Cope reaction.
tert-Butanesulfinamide is an organosulfur compound and a member of the class of sulfinamides. Both enantiomeric forms are commercially available and are used in asymmetric synthesis as chiral auxiliaries, often as chiral ammonia equivalents for the synthesis of amines. tert-Butanesulfinamide and the associated synthetic methodology was introduced in 1997 by Jonathan A. Ellman et al.
Oxidation with chromium(VI) complexes involves the conversion of alcohols to carbonyl compounds or more highly oxidized products through the action of molecular chromium(VI) oxides and salts. The principal reagents are Collins reagent, PDC, and PCC. These reagents represent improvements over inorganic chromium(VI) reagents such as Jones reagent.
Organocerium compounds are chemical compounds that contain one or more chemical bond between carbon and cerium. Organocerium chemistry is the corresponding science exploring properties, structure and reactivity of these compounds. In general, organocerium compounds are not isolable, and are rather studied in solution via their reactions with other species. There are notable exceptions, such as the Cp*3Ce(III) complex shown at right, but they are relatively rare. Complexes involving cerium of various oxidation states are known: though lanthanides are most stable in the +3 state, complexes of cerium(IV) have been reported. These latter compounds have found less widespread use due to their oxidizing nature, and the majority of literature regarding organometallic cerium complexes involves the +3 oxidation state. In particular, organocerium compounds have been developed extensively as non-basic carbon nucleophiles in organic synthesis. Because cerium is relatively non-toxic, they serve as an "environmentally friendly" alternative to other organometallic reagents. Several reviews detailing these applications have been published.
Alpha-substitution reactions occur at the position next to the carbonyl group, the α-position, and involve the substitution of an α hydrogen atom by an electrophile, E, through either an enol or enolate ion intermediate.
