26:03:2009 17:54 joining reaction A reaction where the number of atoms in the molecular skeleton increases. reaction carbon-carbon coupling reaction A joining reaction where a bond is formed between two carbon atoms. Perkin reaction An aldol condensation where an aryl aldehyde reacts with an acid anhydride to form a cinnamic acid. ring reaction A reaction in which the number of atoms in any ring changes between the reactant and the products. ring formation reaction A reaction where the product contains a ring that was not in any of the reactants. Diels-Alder reaction A [4+2] cycloaddition reaction where a diene reacts with a compound containing a double or triple bond (a dienophile) to form an unsaturated six-membered ring compound. ene reaction A joining reaction where an alkene with an allylic hydrogen reacts with a compound containing a multiple bond (an enophile) to form a substituted alkene. conjugate addition A joining reaction where a nucleophile adds to the beta-carbon of an alpha,beta-unsaturated system (or an activated carbon-carbon bond). Michael addition A conjugate addition reaction where a carbon nucleophile adds to the beta-carbon of an alpha,beta-unsaturated system (or an activated carbon-carbon bond).\n functional modification A reaction where the number of atoms in the skeleton, and their connectivity, remain the same. functional group modification A reaction in which a functional group undergoes a change that does not affect the number of atoms in (or connectivity of) the skeleton of the molecule. functional group oxidation A functional group modification reaction where a functional group is oxidised. diazotisation A functional group oxidation where an aromatic amine is transformed into an aromatic diazonium salt. Grignard reaction A carbon-carbon coupling reaction where a Grignard reagent reacts with a compound containing an electrophilic carbon atom. A Grignard reagent is a magnesium-stabilised carbon nucleophile. An aldehyde leads to a secondary alcohol, a ketone leads to a tertiary alcohol, an ester leads to a ketone and a nitrile leads to a ketone. Wittig reaction A carbon-carbon coupling reaction where a carbonyl compound reacts with a phosphonium ylide to give an alkene. aldol addition A carbon-carbon coupling reaction where an enol or enolate reacts with a carbonyl compound to form a beta-hydroxy ketone. The name comes from aldehyde + alcohol. aldol condensation An aldol addition where an enol or enolate reacts with a carbonyl compound to form an alpha,beta-unsaturated ketone. 1,3-dipolar cycloaddition A ring formation reaction where a 1,3-dipolar compound reacts with an alkene or alkyne to form a five-membered ring compound. substitution reaction A reaction in which one singly-bonded substituent is replaced by another singly-bonded substituent. aromatic substitution A reaction in which one singly-bonded substituent on an aromatic skeleton is replaced by another singly-bonded substituent. Sandmeyer reaction An aromatic substitution reaction where an aryl diazonium salt reacts with a cuprous halide or pseudohalide to form an aromatic halide or pseudohalide. Gattermann halogenation An aromatic substitution reaction where an aryl diazonium salt reacts with copper powder and hydrochloric acid or hydrobromic acid to form an aromatic chloride or bromide. Koerner-Contardi reaction An aromatic substitution reaction where an aryl diazonium salt reacts with a cupric halide to form an aromatic halide. Heck reaction A carbon-carbon coupling reaction where an organohalide or triflate couples to an alkene, catalysed by palladium. It is stereospecific. rearrangement A reaction which preserves the number of rings and number of skeletal atoms and in which the molecule rearranges so that one or more atoms or groups of atoms move from one atom to another. Beckmann rearrangement A rearrangement where an oxime rearranges to form an amide. Often there is selective migration of one group. [3,3]-sigmatropic rearrangement Cope rearrangement A [3,3]-sigmatropic rearrangement where a 1,5-hexadiene rearranges to form a 1,5-hexadiene. oxy-Cope rearrangement A [3,3]-sigmatropic rearrangement of a 3-hydroxy-1,5-hexadiene rearranges to form a 5,6-unsaturated carbonyl compound. insertion reaction A joining reaction in which one or more atoms are added to the middle of a chain. Baeyer-Villiger oxidation Mannich reaction A carbon-carbon coupling reaction where ammonia or an amine reacts with a non-enolisable aldehyde, often methanal, and an enolisable carbonyl compound to form a beta-amino carbonyl compound. allylic rearrangement A substitution reaction in an allylic system with concomitant migration of the allyl double bond. Mitsunobu reaction A substitution where an alcohol is converted into something else. Typical reagents are a dialkyl azodicarboxylate and a triarylphosphine. The alcohol stereocentre is inverted. Stille coupling A carbon-carbon coupling reaction wehre an organostannane reacts with an organohalide or organotriflate. Reformatsky reaction A carbon-carbon coupling reaction where an aldehyde or amine reacts with a alpha-halo ester and zinc to form a beta-hydroxy ester. functional group reduction A functional group modification reaction where a functional group is reduced. Clemmensen reduction A functional group reduction where an aldehyde or ketone carbonyl group is reduced to a methylene with zinc-mercury amalgam and hydrochloric acid. carbon-carbon homocoupling reaction A joining reaction where a carbon-carbon bond is formed between like moieties. Ullmann reaction A carbon-carbon homocoupling reaction of an aryl halide mediated by copper. addition reaction A reaction in which two or more groups of atoms are added to the molecule, resulting in a change of skeletal bond order. Birch reduction A formal addition reaction where hydrogen atoms add to an arene to form a dihydroarene. It has a radical mechanism. Claisen condensation A carbon-carbon coupling reaction of an ester and a carbonyl compound to form a beta-keto ester. Knoevenagel condensation A carbon-carbon coupling reaction of an aldehyde and a methylene compound. Friedel-Crafts acylation A carbon-carbon coupling reaction between an arene and a carbonyl compound (usually an acyl halide) to give an aryl ketone. The reaction is usually catalysed by a Lewis acid. Friedel-Crafts alkylation A carbon-carbon coupling reaction between an arene and an alkyl halide/alkene/alcohol (anything that can form a carbocation) to give a substituted arene. The reaction is usually catalysed by a Lewis acid and proceeds by an SN1 mechanism. Oppenauer oxidation An oxidation of a secondary alcohol to a ketone involving an equilibrium between the alcohol and a reagent ketone present in excess, catalysed by a metal alkoxide. Prins reaction A carbon-carbon coupling between formaldehyde and an alkene to give a 1,3-diol or an allylic alcohol. intramolecular Prins reaction A reaction between formaldehyde and an alkene to give a 1,3-dioxane. pinacol rearrangement A rearrangement of a 1,2-diol to give a carbonyl compound, catalysed by acid. Wolff rearrangement A rearrangement of a diazoketone to give a ketene, with the elimination of molecular nitrogen. fused-ring-system formation A reaction in which a fused ring system is present in a product that was not present in any of the reactants. Bischler-Napieralski reaction A cyclodehydration of a beta-phenethylamide to give a 3,4-dihydroisoquinoline. Curtius rearrangement A rearrangement of an acyl azide to give an isocyanate by pyrolysis, with the elimination of molecular nitrogen. Vilsmeier-Haack reaction A formylation of an activated arene with a disubstituted formamide to give an aryl carboxaldehyde. Horner-Wadsworth-Emmons reaction A carbon-carbon coupling reaction between a phosphonate and a carbonyl compound to give an alkene. Horner reaction A joining reaction between a phosphine oxide and a carbonyl compound to give an alkene. Ritter reaction A reaction between an alcohol or alkene and a nitrile to give an amide, catalysed by acid and proceeding by an SN1 mechanism. Pictet-Spengler reaction A condensation-cyclisation of a beta-phenethylamine with an aldehyde to give a tetrahydroisoquinoline. Arbuzov reaction A substitution of an activated alkane with a phosphite to give a phosphonate. Mukaiyama aldol condensation An aldol condensation between an aldehyde or ketone and a silyl enol ether (also known as a ketene silyl acetal) to give a beta-hydroxy carbonyl compound. Skraup reaction A condensation between an aromatic amine and glycerol to give a quinoline. Arndt-Eistert reaction A homologation reaction of a carboxylic acid to give the homologated carboxylic acid. Fischer indole synthesis A cyclisation of an aryl hydrazone of an aldehyde or ketone to give an indole. Dieckmann cyclisation An intramolecular cyclisation of a diester to give a cyclic beta-ketoester. Staudinger reaction A joining of an organic azide and a tertiary phosphine to give a phosphazo compound. Hydrolysis of the phosphazo compound gives the corresponding amine. benzidine rearrangement A rearrangement of a hydrazobenzene to give a diaminobiphenyl compound. semidine rearrangement A rearrangement of a p-substituted hydrazobenzene to give a p-aminodiphenylamine. Dimroth rearrangement A rearrangement of a heterocyclic compound in which endocyclic and exocyclic heteroatoms swap places. chain lengthening Edman degradation A cleaving reaction in which a peptide is treated with phenylisothiocyanate, removing the terminal amino acid group, to form the chain-shortened amine and a phenylthiohydantoin. The latter can be used to identify the terminal amino acid, and the process repeated to enable peptide sequencing. Reimer-Tiemann reaction A formylation reaction between an aromatic compound (for example, phenol, pyrrole or indole) and chloroform (for example, to form an ortho-formyl phenol). cleaving reaction A reaction where atoms are lost from the molecular skeleton. Wurtz reaction A carbon-carbon homocoupling reaction of two molecules of an alkyl halide to give a symmetrical product. benzilic acid rearrangement A rearrangement of a 1,2-diketone to an alpha-hydroxy carboxylic acid. It can also be applied to alpha-keto aldehydes. The first exmaple of this reaction was with benzil (PhC(=O)C(=O)Ph) to form benzilic acid, hence the name. Baylis-Hillman reaction A carbon-carbon coupling of an aldehyde to an activated alkene in the presence of a nucleophilic base to give an an alpha-hydroxyalkylated compound. Darzens reaction A coupling of an aldehyde or ketone with an alpha-halo ester to form an alpha,beta-epoxy ester. Hydrolysis of these products yields aldehydes or ketones by elimination of carbon dioxide. protection reaction A reaction in which a functional group is modified by converting it into a protecting group, in order to make subsequent reactions more selective. Boc protection A protection reaction in which an amine is converted into a tert-butoxycarbonyl compound. Peterson olefination A carbon-carbon coupling reaction in which an alpha-silyl carbanion reacts with an aldehyde or a ketone to give an alkene, proceeding via a beta-hydroxysilane. The stereochemistry of the alkene can be controlled by treating the intermediate with acid or base. Ullmann condensation A coupling reaction in which a phenol is coupled to an aryl halide to give a diaryl ether in the presence of a copper compound. Goldberg reaction A coupling reaction in which an acetanilide is coupled to an aryl halide to give an N-acetyl diaryl amine in the presence of a copper compound. Paterno-Buchi reaction A photochemical cycloaddition between an aldehyde or ketone and an alkene to give an oxetane. Barbier reaction A joining reaction between an aldehyde or ketone and an alkyl halide to give a secondary or tertiary alcohol. acyloin condensation A reductive coupling reaction between two esters to give an acyloin (an alpha-hydroxyketone). Henry reaction A carbon-carbon coupling reaction between a nitroalkane and an aldehyde or ketone to give a beta-hydroxy nitroalkane. Barton reaction The photolytic oxidation of a nitrate ester to give a gamma-nitroalcohol. Negishi coupling A carbon-carbon coupling reaction between an organohalide or organotriflate and an organozinc compound. The reaction is catalysed by palladium or nickel. Meerwein-Ponndorf-Verley reduction A reduction of an aldehyde or ketone to an alcohol involving an equilibrium between the aldehyde or ketone and a reagent alcohol present in excess, catalysed by a metal alkoxide. This reaction is the reverse of the Oppenauer oxidation (RXNO:0000047). Williamson ether synthesis The reaction between an alkyl halide or alkyl sulfate and a metal alkoxide to give an ether. Wittig methylenation A carbon-carbon coupling reaction where a carbonyl compound reacts with a phosphonium ylide to give a terminal alkene. aza-Diels-Alder reaction A Diels-Alder reaction between a diene and an imine or an azadiene and an alkene to give a six-membered nitrogen-containing ring compound. extrusion reaction A cleaving reaction in which a skeletal atom or group of atoms is removed from the middle of a molecule. Ramberg-Backlund reaction The reaction of an alpha-halosulfone to give an alkene, with the extrusion of sulfur dioxide. Fischer-Hepp rearrangement The rearrangement of an aromatic nitrosamine to a para-nitrosoaniline. azo coupling A coupling reaction of a diazonium salt with a phenol or aniline to give an azo compound. imino-Reformatsky reaction A carbon-carbon coupling reaction where an imine reacts with a alpha-halo ester and zinc to form a beta-amino ester. Glaser coupling A coupling reaction between two molecules of a terminal alkyne catalysed by Cu(I) salts. Eglinton reaction A coupling reaction between two molecules of a terminal alkyne using stoichiometric Cu(II) salts. Cadiot-Chodkiewicz coupling A coupling reaction between a terminal alkyne and an alkynyl halide catalysed by Cu(I) salts. Leuckart reaction The reductive amination of ketones or aldehydes with an ammonium formate or formamide to form an amine. Leuckart-Wallach reaction The reductive amination of ketones or aldehydes with an amine and formic acid to form amines. Gabriel synthesis The reaction of primary alkyl halides with sodium or potassium phthalimide, followed by hydrolysis, to give the corresponding primary amine. Ing-Manske procedure The reaction of primary alkyl halides with sodium or potassium phthalimide, followed by treatment with hydrazine, to give the corresponding primary amine. end-of-chain chain shortening A reaction in which a single skeletal atom is removed from the end of a chain. Hunsdiecker reaction The decarboxylation of silver carboxylates with halogens to give organic halides. malonic ester synthesis A carbon-carbon coupling reaction between a dialkyl malonate and an alkyl halide, to give a substituted acetic acid. The base/R'X treatment can be repeated to give a disubstituted product. ring expansion A reaction in which an existing ring is increased in size. Pfitzinger reaction The reaction between isatin and an alpha-methylene carbonyl compound to give a substituted quinoline-4-carboxylic acid. fragmentation reaction A reaction in which the parent molecule breaks up into three or more products. Grob fragmentation The fragmentation of a molecule that takes place when an electron-donating fragment (X) and an electron-accepting fragment (X') are situated at positions 1 and 3 on an aliphatic chain, to give a cationic fragment, a neutral fragment (e.g. an alkene) and an anionic fragment. Michaelis-Arbuzov reaction The alkylation of a trialkyl phosphite with an alkyl halide or acyl halide to give a phosphonate. Brook rearrangement The rearrangement of an alpha-, beta- or gamma-hydroxy silane to give a silyl ether. Nicholas reaction The reaction of a propargylic cation (stabilised with dicobalt octacarbonyl) with a nucleophile to give a substituted alkyne. Nicholas reaction, nucleophilic heteroatom centre The reaction of a propargylic cation (stabilised with dicobalt octacarbonyl) with a hydride or amine or enamine to give a substituted alkyne. Nicholas reaction, nucleophilic carbon centre The reaction of a propargylic cation (stabilised with dicobalt octacarbonyl) with a nucleophilic carbon centre (on e.g. enolates, allyl silanes, ketones, electron-rich aromatics, beta-dicarbonyl compounds) to give a substituted alkyne. Julia olefination A carbon-carbon coupling reaction between a phenyl sulfone and an aldehyde to give a (typically trans) alkene. Sommelet reaction The oxidation of a benzylic halide to give an aldehyde. The reaction uses hexamethylenetetramine. Bouveault-Blanc reaction The reduction of an ester using sodium to give two alcohols. Payne rearrangement A base-catalysed isomerisation of a 2,3-epoxyalcohol, with inversion of configuration at C2. aza-Payne rearrangement A base-catalysed isomerisation of a 2,3-epoxyamine to form a hydroxy aziridine, with inversion of configuration at C2. Baker-Venkataraman rearrangement The base-catalysed rearrangement of an o-acetoxyacetophenone to give a 1,3-diketone. elimination reaction A reaction in which two or more groups of atoms are removed from the molecule, resulting in a change of skeletal bond order. Bamford-Stevens reaction The reaction of a tosylhydrazone of an aldehyde or ketone with a strong base to give an alkene. This generally provides the more-substituted alkene as the thermodynamic product. Shapiro reaction The reaction of a tosylhydrazone of an aldehyde or ketone with an alkyllithium or Grignard reagent to give an alkene. This generally provides the less-substituted alkene as the kinetic product. Doebner reaction The reaction between an aromatic amine, an aldehyde and pyruvic acid to give a quinoline 4-carboxylic acid (cinchoninic acid). Balz-Schiemann reaction The conversion of an aromatic amine to the corresponding fluoride via the diazonium fluoroborate. Kolbe electrolysis The decarboxylation and coupling of a carboxylate or mixture of carboxylates to give a dimer. Ugi reaction Reaction of a ketone or aldehyde, amine, isocyanide and carboxylic acid to form a bisamide. Wacker-Tsuji oxidation The oxidation of a terminal alkene or ethene to a methyl ketone or acetaldehyde, catalysed by PdCl2 and CuCl2, and using molecular oxygen as the oxidant. Wacker process The oxidation of ethene to acetaldehyde, catalysed by PdCl2 and CuCl2, and using molecular oxygen as the oxidant. Monsanto process The reaction of formaldehyde with methanol to form acetic acid, catalysed by a rhodium complex. Cativa process The reaction of formaldehyde with methanol to form acetic acid, catalysed by an iridium complex. Barton-McCombie deoxygenation The deoxygenation of an alcohol to the corresponding alkane using a thiochloroformate. It proceeds by a radical mechanism. Barton decarboxylation The decarboxylation of a carboxylic acid to the lower homologue alkane using a pyridine thione. The reaction proceeeds by a radical mechanism. Rosenmund reduction The hydrogenolysis of an acyl halide to the corresponding aldehyde (FG reduction), catalysed by palladium-on-barium sulfate. Sonogashira coupling A carbon-carbon coupling reaction where a terminal alkyne reacts with an aryl halide to give an aryl alkyne. It is catalysed by palladium. benzoin condensation A reaction between two aromatic aldehydes to give a benzoin (an alpha-hydroxyketone). Gattermann reaction The formylation of an arene with hydrogen cyanide to give an aryl aldehyde or ketone. Suzuki-Miyaura coupling The coupling of a boronic acid or boronic ester with an unsaturated halide, triflate or sulfonate catalysed by a palladium(0) complex. Sharpless asymmetric epoxidation The epoxidation of an allylic alcohol to give a beta,gamma-epoxy alcohol, with control of absolute stereochemistry at the two new stereocentres. The oxidising agent is tert-butyl hydroperoxide, and the catalyst is a complex of titanium salt and optically active diethyl tartrate. Sharpless asymmetric dihydroxylation The dihydroxylation of an alkene to give an alpha,beta-diol, with control of absolute stereochemistry at the two new stereocentres. The oxidising agent is osmium tetroxide, which is used catalytically with a stoichiometric oxidant and a chiral ligand. The reagents are available commercially as AD-mix. Sharpless asymmetric aminohydroxylation The aminohydroxylation of an alkene to give a beta-amino alcohol, with control of absolute stereochemistry at the two new stereocentres. The oxidising agent is an oxygen-containing osmium species and/or an amino derivative which can be used catalytically with a stoichiometric oxidant and a chiral ligand. Kumada coupling A cross-coupling reaction between a Grignard reagent and an activated (aryl or vinyl) halide or triflate. The reaction is catalysed by a palladium or nickel catalyst. Barbier-Wieland degradation The degradation of a carboxylic acid to its next lower homologous carboxylic acid. Corey-Fuchs reaction A homologation reaction of an aldehyde to yield a terminal alkyne. The reagents are tetrabromomethane, triphenylphosphine, butyllithium and water. Emde degradation A reduction of a quaternary ammonium salt containing at least one unsaturated substituent, to give a tertiary amine. Claisen rearrangement The [3,3]-sigmatropic rearrangement of an allyl vinyl ether to give a gamma,delta-unsaturated carbonyl compound. Ireland-Claisen rearrangement The enolisation and subsequent [3,3]-sigmatropic rearrangement of an allylic acetate to give a gamma,delta-unsaturated carboxylic acid. joining with rearrangement Bellus-Claisen rearrangement The coupling and subsequent [3,3]-sigmatropic rearrangement of an allylic ether or allylic thioether or allylic amine and a ketene to give the corresponding gamma,delta-unsaturated carbonyl compound. Eschenmoser-Claisen rearrangement The coupling and subsequent [3,3]-sigmatropic rearrangement of an allylic alcohol and alpha,alpha-dialkoxy ethylamine to give a gamma,delta-unsaturated dialkyl amide. Johnson-Claisen rearrangement The coupling and subsequent [3,3]-sigmatropic rearrangement of an allylic alcohol and trimethyl orthoacetate to give a gamma,delta-unsaturated alkyl ester. Swern oxidation The oxidation of a primary alcohol or secondary alcohol to an aldehyde or ketone respectively. Does not work with allylic or benzylic alcohols. Finkelstein reaction The conversion of an alkyl chloride, alkyl bromide or alkyl sulfonate ester to an alkyl iodide by SN2 substitution. The reaction relies upon the equilibrium being pushed to completion by the precipitation. Lossen rearrangement The derivatisation (for example with tosyl chloride) and subsequent rearrangement of a hydroxamic acid to give an isocyanate. Nef reaction The conversion of a primary nitroalkane or secondary nitroalkane to an aldehyde or ketone, respectively. Japp-Klingemann reaction The reaction of a doubly activated methylene compound that has at least one carbonyl substituent with an aryl azide to give a hydrazone. Usually there is concomitant cleaving and oxidation of one of the carbonyl substituents. Doebner-Miller reaction The formation of a quinoline from a primary aromatic amine and an alpha,beta-unsaturated carbonyl compound. Fmoc protection The protection of an amine (often a peptide) as its 9H-fluoren-9-ylmethoxycarbonyl derivative. Paal-Knorr synthesis The cyclisation of a 1,4-dicarbonyl compound to give a five-membered aromatic ring compound. Paal-Knorr furan synthesis The cyclisation of a 1,4-dicarbonyl compound with an acid catalyst to give a pyrrole. Paal-Knorr thiophene synthesis The cyclisation of a 1,4-dicarbonyl compound with phosphorus pentasulfide to give a five-membered aromatic ring compound. Paal-Knorr pyrrole synthesis The cyclisation of a 1,4-dicarbonyl compound with an amine to give a five-membered aromatic ring compound. Schotten-Baumann reaction The coupling of an alcohol or amine with an acyl chloride to give an ester or amide. A two-phase solvent system is often used, to enable the acid generated during the reaction to be neutralised by the aqueous base, while the starting materials and products remain in the organic phase. Hofmann elimination The elimination of a methylated amine from an alkyl amine to form an alkene. The reaction proceeds via the quaternary ammonium salt. Fischer-Speier esterification The esterification of a carboxylic acid with an alcohol. Various Lewis acids or Bronsted acids may be used as catalyst. Weerman reaction The degradation of an alpha-hydroxy amide or an alpha,beta-unsaturated amide to the lower homologue aldehyde, especially in carbohydrate chemistry. The process proceeds via Hofmann degradation. Dakin reaction The reaction of ortho- or para-phenolic (or ortho- or para-anilinic) aldehydes or ketones with hydrogen peroxide to form bisphenols (or hydroxy anilines) and carboxylic acids. Schmidt rearrangement, carboxylic acid The reaction of a carboxylic acid with hydrazoic acid to give the lower homologue amine, with the loss of the terminal carbon atom. Schmidt rearrangement, ketone The reaction of a ketone with hydrazoic acid with the insertion of an NH group between the carbonyl carbon and one of the R groups to form an amide. Schmidt rearrangement, tertiary alcohol The reaction of a tertiary alcohol with hydrazoic acid with rearrangement to form an imide. Schmidt rearrangement, alkene The reaction of an alkene with hydrazoic acid with rearrangement to form an imide. Sommelet-Hauser rearrangement The [2,3]-sigmatropic rearrangement of a benzyl quaternary ammonium salt to form an aniline. Dakin-West reaction The reaction of an amino acid with an acid anhydride to give an alpha-acylamido ketone. The reaction proceeds via the mixed anhydride and an oxazolone; the product is always racemic. Beckmann fragmentation The cleavage of an oxime to the corresponding nitrile and an alkyl halide. This reaction is related to the Beckmann rearrangement, and occurs when the R group that is anti to the oxime hydroxyl is quaternary. Kharasch reaction The transfer of a hydrogen or halogen atom from a haloalkane to an alkene, giving the chain-extended halogenated alkane. Kharasch-Sosnovsky reaction The allylic oxidation of an alkene with a peroxy ester or a peroxide to give the corresponding allylic alcohol derivative. The catalyst is a copper compound. Elbs persulfate oxidation, phenol variant The oxidation of a phenol to give a (predominantly para) diphenol using potassium persulfate. Elbs persulfate oxidation, tolyl variant The oxidation of a methyl-substituted aromatic compound to the corresponding benzaldehyde using potassium persulfate. Boyland-Sims oxidation The oxidation of an aromatic amine to give a (predominantly ortho) amino aryl sulfate using potassium persulfate followed by hydrolysis to yield the corresponding aminophenol. Kolbe-Schmitt reaction The (predominantly ortho) carboxylation of a phenoxide. Perkow reaction The reaction between an alpha-halocarbonyl compound and a trialkyl phosphite to give an enol phosphate. Pfitzner-Moffatt oxidation The oxidation of a primary or secondary alcohol to the corresponding aldehyde or ketone respectively using dimethyl sulfoxide, 1,3-dicyclohexylcarbodiimide and acid. The reaction proceeds via an alkoxysulfonium ylide. Willgerodt reaction The conversion of an aryl alkyl ketone to an amide and/or an ammonium salt of a carboxylic acid using ammonium polysulfide. The carbonyl group of the product is always at the end of the alkyl chain. Willgerodt-Kindler reaction The conversion of an aryl alkyl ketone to an amide using sulfur and dry ammonia or a primary or secondary amine. The amide carbonyl group is always at the end of the alkyl chain. Tishchenko reaction The formation of an ester from two aldehydes via a disproportionation process using a metal alkoxide to oxidise one aldehyde and reduce the other. Zimmermann reaction The reaction between a methylene ketone and a polynitro aromatic compound. Neber rearrangement The rearrangement of the sulfonic ester of a ketoxime in base to give an alpha-amino ketone. Nozaki-Hiyama-Kishi reaction A coupling reaction of an aldehyde to an allyl, vinyl or aryl halide or triflate in the presence of chromium(II). It is catalysed by nickel. Buchwald-Hartwig amination A reaction in which an aryl halide or aryl triflate reacts with a primary or secondary amine in the presence of base to give a secondary or tertiary amine. It is catalysed by a palladium catalyst. Hiyama coupling A carbon-carbon coupling reaction where an organosilane reacts with an organic halide or triflate. It is catalysed by a palladium or nickel complex. Stevens rearrangement The 1,2-rearrangement of an alpha-methylene ammonium salt or alpha-methylene sulfonium salt to an amine or sulfide in the presence of strong base. Stevens rearrangement, ammonium The 1,2-rearrangement of an alpha-methylene ammonium salt to an amine in the presence of strong base. Stevens rearrangement, sulfonium The 1,2-rearrangement of an alpha-methylene sulfonium salt to a sulfide in the presence of strong base. aza-Cope rearrangement A [3,3]-sigmatropic rearrangement where an aza-1,5-hexadiene rearranges to form an aza-1,5-hexadiene. 2-aza-Cope rearrangement The rearrangement of a 2-aza-1,5-hexadiene to form an imine. 3-aza-Cope rearrangement The rearrangement of a 3-aza-1,5-hexadiene to form a delta,epsilon-unsaturated imine. 1-aza-Cope rearrangement The rearrangement of a delta,epsilon-unsaturated imine to form a 3-aza-1,5-hexadiene. Steglich rearrangement The rearrangement of an oxazolyl carbonate to a C-carboxyazlactone. ring rearrangement A reaction in which the number of rings in a molecule stays the same but the connectivity of the atoms in at least one ring changes. deprotection reaction A reaction in which a protecting group is modified by converting it into a functional group. multiple-bond metathesis A joining reaction in which two carbon-carbon multiple bonds are redistributed among two fragments. The reaction is typically catalysed by a metal carbenoid, and proceeds via two four-membered intermediates (metallacyclobutanes). The reaction is driven by release of a low-MW alkene. ring breaking A reaction where the product has fewer rings than the reactants. ring contraction A reaction in which an existing ring is reduced in size. Strecker reaction An addition reaction between a carbonyl compound, an inorganic cyanide and an ammonium salt, followed by hydrolysis, to give an alpha-amino carboxylic acid. aromatic Claisen rearrangement The [3,3]-sigmatropic rearrangement, and subsequent re-aromatisation, of an allyl aryl ether to give an ortho-allyl phenol. Nazarov cyclisation The acid-catalysed cyclisation of a divinylketone to give a cyclopentenone. Fleming-Tamao oxidation The stereospecific oxidation of a (phenyldimethylsilyl)alkane to the corresponding alcohol using bromine, usually generated in situ from potassium bromide and peracetic acid. Tamao oxidation The stereospecific oxidation of (halosilyl)alkane to the corresponding alcohol using potassium fluoride and hydrogen peroxide. Sakurai reaction, aldehyde or ketone A carbon-carbon coupling reaction in which an aldehyde or ketone reacts with allyltrimethylsilane to form a homoallylic alcohol. Sakurai reaction, enone A carbon-carbon coupling reaction in which an enone reacts with allyltrimethylsilane to form a delta,epsilon-unsaturated carbonyl compound. Sakurai reaction, acid chloride A carbon-carbon coupling reaction in which an acid chloride reacts with allyltrimethylsilane to form a gamma,delta-unsaturated ketone. Sakurai reaction, acetal or ketal A carbon-carbon coupling reaction in which an acetal or ketal reacts with allyltrimethylsilane to form a homoallylic ether. Sakurai reaction, iminium salt A carbon-carbon coupling reaction in which an iminium salt reacts with allyltrimethylsilane to form a homoallylic amine. Sakurai reaction, epoxide A ring-breaking reaction in which an epoxide reacts with allyltrimethylsilane to form a hydroxy alkene. Cannizzaro reaction The disproportionation of a non-enolisable aldehyde to the corresponding carboxylic acid salt and alcohol. The reaction is base-catalysed. crossed Cannizzaro reaction The reaction between two different non-enolisable aldehydes to give a carboxylic acid salt and an alcohol. The reaction is base-catalysed. Pummerer rearrangement The conversion of a sulfoxide with an alpha-hydrogen to an alpha-subtituted thioether. The reaction is usually performed with an acid anhydride or acyl halide. Polonovski reaction The reaction of a tertiary amine oxide with an anhydride or acyl chloride to give an N,N-disubstituted acetamide and an aldehyde. Polonovski-Potier reaction The reaction of a tertiary amine oxide with trifluoroacetic anhydride to give an N,N-disubstituted acetamide and an aldehyde. Menshutkin reaction The alkylation of a tertiary amine with an alkyl halide to the corresponding ammonium salt. Strecker degradation The deamination and decarboxylation of amino acids to imines and then to aldehydes or ketones, in the presence of a carbonyl compound (especially an alpha,beta-dicarbonyl compound or a reducing sugar such as glucose). The reaction is involved in the generation of meat aromas/flavours in cooking. Wohl-Ziegler bromination The allylic or benzylic bromination of hydrocarbons using an N-bromoimide and a radical initiator, to give an allylic or benzylic bromide. Wolff-Kishner reduction The reduction of an aldehyde or ketone to the corresponding methylene compound, using hydrazine hydrate and a base. Wolff-Kishner reduction, Huang-Minlon modification The reduction of an aldehyde or ketone to the corresponding methylene compound, using hydrazine hydrate and a base in refluxing ethylene glycol. Zemplen transesterification The reduction of an ester to the corresponding alcohol, using sodium methoxide in dry methanol. Ferrier rearrangement The rearrangement of an O-alkenyl acetal to give the corresponding beta-alkoxy carbonyl compound. aza-Ferrier rearrangement The rearrangement of an O-alkenyl hemiaminal ether to give the corresponding beta-amino carbonyl compound. aza-ene reaction A joining reaction where an N=C system with an allylic hydrogen reacts with a compound containing a multiple bond (an enophile) to form a substituted alkene. Petasis reaction The alkylation of an amine with a boronic acid and an aldehyde to give a substituted amine. Achmatowicz rearrangement A rearrangement of a furfuryl alcohol derivative to a dihydropyranone, from which monosaccharides may be synthesised. aza-Achmatowicz rearrangement A rearrangement of a furfuryl amine derivative to a tetrahydropyridinone. aza-Henry reaction A carbon-carbon coupling reaction between a nitroalkane and an imine to give a beta-amino nitroalkane. Biginelli reaction A three-component coupling of a beta-keto ester, an aldehyde and urea to give a 3,4-dihydropyrimidinone. Blaise reaction The coupling of an alpha-bromo ester with a nitrile to give a beta-ketoester, in the presence of zinc. Katritzky pyrylium-pyridinium method The substitution of an amine with a nucleophile using a pyrylium salt. metalla-aza-Claisen rearrangement The rearrangement of a 3-aza-4-metalla-1,5-hexadiene to form a delta,epsilon-unsaturated metallaimine. Bergman cyclisation The cyclisation of an ene-diyne to give a biradical. The biradical usually aromatises. nitro-Michael reaction A conjugate addition reaction where a carbon nucleophile adds to an alpha,beta-unsaturated nitro compound. Noyori asymmetric hydrogenation, alkene The homogeneous asymmetric catalytic hydrogenation of a C=C double bond using a ruthenium(II) BINAP catalyst. Noyori asymmetric hydrogenation, carbonyl The homogeneous asymmetric catalytic hydrogenation of a carbonyl bond using a ruthenium(II) BINAP catalyst. Passerini reaction The reaction between an isonitrile, a carboxylic acid and aldehyde or ketone to give an alpha-acyloxy amide. ring-closing metathesis A joining reaction in which two carbon-carbon double bonds in the same molecule are redistributed to give a cycloalkene. It is typically catalysed by a metal carbenoid, and proceeds via two four-membered intermediates (metallacyclobutanes). The reaction is driven by release of a low-MW alkene. polymerisation reaction A joining reaction in which a large number of monomers react together to produce a polymer consisting of repeating units. ring-opening metathesis polymerisation A joining reaction in which two carbon-carbon double bonds are redistributed among two fragments, i.e. two alkenes. It is typically catalysed by a metal carbenoid, and proceeds via two four-membered intermediates (metallacyclobutanes). The reaction is driven by release of ring strain in the cycloalkene. Carroll rearrangement An adaptation of the Claisen rearrangement that transforms a beta-keto allyl ester into a gamma,delta-allyl ketone. It uses base and high temperature or milder conditions with a ruthenium or palladium complex as catalyst. Bose-Mitsunobu reaction A Mitsunobu reaction, where an alcohol is converted to something else with inversion at the stereocentre, using diphenylphosphoryl azide. Fritsch-Buttenberg-Wiechell rearrangement The rearrangement of a 2-bromoalkene into an alkyne, mediated by strong base. Stork-Wittig olefination A carbon-carbon coupling reaction where an aldehyde reacts with a phosphonium salt to give a Z-iodoalkene. The reaction is mediated by sodium or potassium hexamethyldisilazide. Cadogan carbazole synthesis The reduction of a 2-nitrobiaryl compound to give a carbazole. Cadogan coupling The arylation of an arylamine mediated by isopentyl nitrite. MacDonald condensation The reaction between a 1,9-diformyldipyrromethane and a dipyrromethane to give a porphodimethene. Zweifel diene synthesis The carbon-carbon homocoupling reaction of a pair of alkyne molecules using a borane and iodine. The reaction proceeds via a borane intermediate. Dess-Martin oxidation The oxidation of a primary alcohol to an aldehyde or a secondary alcohol to a ketone using the Dess-Martin periodinane. Criegee oxidation The oxidative cleavage of an alpha,beta-diol using lead tetraacetate to give the corresponding carbonyl compounds. Simmons-Smith reaction A ring formation reaction where an alkene reacts with a dihalomethane in the presence of a metal atom or metal complexes to form a cyclopropane. The traditional reaction uses a zinc-copper couple and diiodomethane. Wittig rearrangement Any of a family of sigmatropic rearrangements that involve the migration of a group on an electronegative atom (O or N) to a carbon atom. [1,2]-Wittig rearrangement A base-mediated 1,2-sigmatropic rearrangement of an ether to give an alcohol. [2,3]-Wittig rearrangement A base-mediated 2,3-sigmatropic rearrangement of an allyl ether to give a homoallylic alcohol. [1,2]-aza-Wittig rearrangement A base-mediated 1,2-sigmatropic rearrangement of a tertiary amine to give a secondary amine. [2,3]-aza-Wittig rearrangement A base-mediated 2,3-sigmatropic rearrangement of an activated tertiary allyl amine, to give a secondary homoallylic amine. aza-Baylis-Hillman reaction A carbon-carbon coupling of an imine to an activated alkene in the presence of a nucleophilic base to give an allylic amine. aza-Wittig reaction A carbon-carbon coupling reaction where a carbonyl compound reacts with a phosphazene to give an imine. Fenton reaction, carboxylic acid variant Either (a) the oxidation of an alpha-hydroxy carboxylic acid with Fenton's reagent (hydrogen peroxide and iron salts) to give an alpha-keto carboxylic acid, or (b) the reaction between the species in Fenton's reagent. Fenton reaction, diol variant The oxidation of a 1,2-glycol with Fenton's reagent (hydrogen peroxide and iron salts) to give an alpha-hydroxy aldehyde. Hantzsch pyridine synthesis A ring-forming reaction between two equivalents of a beta-ketoester, an aldehyde and ammonia (or an ammonium salt), to give a dihydropyridine. The dihydropyridine can be oxidised to a pyridine using an oxidising agent. alkyne-azide click reaction A [3+2] cycloaddition reaction between an azide and an alkyne to give a 1,2,3-triazole, needing only heat to proceed. copper(I)-catalyzed azide-alkyne cycloaddition A [3+2] cycloaddition reaction between an azide and an alkyne to give a 1,2,3-triazole as a single regioisomer. Commonly described as a variant of the (uncatalyzed) alkyne-azide click reaction, the mechanism of reaction is different, and thus formally it is not a 1,3-dipolar cycloaddition. Fischer-Tropsch process A process in which carbon monoxide and hydrogen ('syngas') are converted into various liquid hydrocarbons. hydroformylation The reaction of hydrogen and carbon monoxide with an alkene, to give an aldehyde, catalysed by a rhodium or cobalt catalyst. The process is equivalent to the formal addition of the H-C bond of formaldehyde across the double bond of an alkene. retro-Diels-Alder reaction The reverse of a [4+2] cycloaddition reaction, in which an unsaturated six-membered ring compound fragments to give a diene and a compound containing a double or triple bond (a dienophile). retro-aldol addition Stork-Crabtree hydrogenation A hydrogenation in which a metal-ligating group distant from the reacting alkene directs the attack of hydrogen, giving preferentially one stereoisomer of the product. Aufbau reaction The insertion of alkenes (usually ethene) into the Al-C bond of an aluminium alkyl, to give a long-chain aluminium alkyl that can go on to react again, or can decompose into the corresponding terminal alkene. The addition of transition metals results in reliable production of high molecular weight polymers. hydroalumination The reaction of an aluminium alkyl with an alkene, to give an intermediate aluminium species that can give various products after work-up. hydrovinylation The reaction of two alkenes to give an elongated alkene, employing a transition-metal-based catalyst. 1,4-hydrovinylation The reaction of a 1,3-diene with an alkene to give a 1,4-diene, usually employing a cobalt-based catalyst (see Hilt and Luers, Synthesis, 2002, 609). alkene metathesis A joining reaction in which two carbon-carbon double bonds are redistributed among two fragments, i.e. two alkenes. It is typically catalysed by a metal carbenoid, and proceeds via two four-membered intermediates (metallacyclobutanes). The reaction is driven by release of a low-MW alkene. alkyne metathesis A joining reaction in which two carbon-carbon triple bonds are redistributed among two fragments, i.e. two alkynes. It is catalysed by a metal carbenoid, and proceeds via two four-membered intermediates (metallacyclobutenes). The reaction is driven by release of a low-MW alkyne. enyne metathesis A joining reaction in which a carbon-carbon double bond and a carbon-carbon triple bond are redistributed among two fragments, i.e. an alkene and an alkyne. It is typically catalysed by a metal carbenoid, and proceeds via two four-membered intermediates (metallacyclobutenes). As a low-MW alkene is not released, the reaction is usually driven by formation of a ring. ring-closing enyne metathesis A joining reaction in which a carbon-carbon double bond and a carbon-carbon triple bond in the same molecule are redistributed to give a alkene-substituted cycloalkene. It is typically catalysed by a metal carbenoid, and proceeds via two four-membered intermediates (metallacyclobutanes). The reaction is driven by formation of the ring. ring-opening metathesis A ring-breaking reaction in which two carbon-carbon double bonds are redistributed among two fragments, i.e. an alkene and a cycloalkene. It is typically catalysed by a metal carbenoid, and proceeds via two four-membered intermediates (metallacyclobutanes). The reaction is driven by release of ring strain in the cycloalkene. Luche reaction A carbon-carbon coupling reaction where an aldehyde or ketone reacts with an allyl halide and zinc to give a homoallylic alcohol. Not to be confused with the Luche reduction (the chemoselective reduction of an enone to an allylic alcohol). Luche reduction The chemoselective reduction of an enone to give an allylic alcohol, using sodium borohydride and an lanthanoid chloride, typically cerium chloride. Not to be confused with the Luche reaction (the coupling of an aldehyde or ketone with an allyl halide). Lindgren oxidation The oxidation of an aldehyde to a carboxylic acid with chlorite. Rosenmund-von Braun reaction A carbon-carbon coupling reaction where an aryl halide reacts with cuprous cyanide to give an aryl nitrile. Woehler reaction The formation of urea from ammonium cyanate. Ammonium cyanate is unstable, and so is formed in situ from either (a) cyanic acid and ammonia, (b) a metal cyanate and an ammonium salt, or (c) a metal cyanate and ammonia. hydrosilylation The addition of a hydrosilane across the double bond of an alkene or alkyne to give a more substituted silane. Addition to an aldehyde or ketone produces a silyl ether. hydroamination The addition of the N-H bond of an amine across a double bond of an alkene or alkyne, to give a more substituted amine. hydroboration The addition of a boron hydride across a double bond of an alkene or alkyne. The boron usually adds to the less substituted carbon. hydroboration-oxidation The formal addition of water across a double bond of an alkene or alkyne by formation of an organoborane and in situ oxidation, typically with basic peroxide. The product is usually the less substituted alcohol. hydrometallation The reaction of any of a number of metal hydride species with an alkene or alkyne, to give an intermediate organometal species that can give various products after work-up. hydrozirconation The reaction of a organozirconium hydride with an alkene or alkyne, to give an intermediate zirconium species that can give various products after work-up. The zirconium reagent used is typically Schwartz's reagent, Cp2ZrHCl. hydrostannylation The reaction of a organotin hydride with an alkene or alkyne, to give an intermediate tin species that can give various products after work-up. hydrotelluration The reaction of a organotellurium hydride with an alkyne, to give a (usually (Z)-configured) vinyltellurium species. Fetizon oxidation The oxidation of a primary alcohol to an aldehyde or a secondary alcohol to a ketone using Fetizon's reagent. Vorbrueggen condensation The substitution of an acylated sugar with a silylated base to give a nucleoside. thiol-ene reaction The addition of a thiol across the double bond of an alkene to give a thioether.