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Acetalization is an organic reaction in which an aldehyde (or a ketone) reacts with an alcohol under acidic conditions to form an acetal, enabling the protection of the carbonyl toward nucleophiles.

The synthesis of a N-acylimidazole is a well-established strategy for activating the carbonyl function of the carboxylic acid toward further transformations. This activation opens access to a variety of derivatives, including ester, amide etc. The reaction involves the activating reagent carbonyldiimidazole (CDI) and a carboxylic acid.

Alcohol dehydration is an elimination reaction in which an alcohol loses a water molecule in the presence of acid to form an alkene.

Tosylation is a reaction in which the hydroxyl group of an alcohol is converted into a tosylate (OTs), by reaction with tosyl chloride (TsCl, 4-methylbenzenesulfonyl chloride) in the presence of a base, typically pyridine or triethylamine.

Carbonyl reduction refers to the conversion of a ketone or aldehyde into the corresponding alcohol by delivery of a hydride to the electrophilic carbonyl carbon.

The aldol reaction is a carbon-carbon bond forming reaction in which two carbonyl compounds (aldehydes, ketones or one of each) react in the presence of a strong base (B) such as sodium hydroxide to form a β-hydroxy carbonyl compound also known as aldol.

Alkene dihydroxylation involving diluted potassium permanganate (KMnO4) as an oxidant converts an alkene into a vicinal diol under cold and basic conditions.

Alkene dihydroxylation using osmium(VIII) tetroxide (OsO4) as the oxidizing agent affords a vicinal diol. Because OsO4 is expensive, it is typically used in catalytic amounts, with N-methylmorpholine N-oxide (NMO) employed in stoechiometric amounts to regenerate the catalyst.

Alkene halogenation is a reaction in which a dihalogen (typically Br2 or Cl2) adds across the double bond of an alkene, yielding a vicinal dihalide, where one halogen atom is added to each carbon of the former double bond.

Alkene hydration is a reaction that converts an alkene into an alcohol by addition of water across the alkene double bond. The transformation is most commonly performed under acidic conditions using a strong acid catalyst and proceeds with Markovnikov regioselectivity.

Alkene hydroboration is a two-step reaction that converts an alkene into an alcohol with anti-Markovnikov regioselectivity. The reaction is typically performed by treating the alkene with borane (BH3) followed by oxidation with hydrogen peroxide (H2O2) in basic medium.

Anti-Markovnikov hydrobromination of alkenes is a reaction in which hydrobromic acid (HBr) adds across the double bond of an alkene, yielding an alkyl bromide. To achieve anti-Markovnikov regioselectivity, the reaction must be carried out in the presence of a radical initiator, typically a peroxide, heat or light. This reaction is only effective with HBr. Radical additions of HCl and HI are not observed under standard conditions because the radical chain propagation steps are thermodynamically unfavorable.

Hydrohalogenation is a reaction in which a hydrogen halide (HX, where X = I, Br, or Cl) adds across the double bond of an alkene, yielding an alkyl halide.

The alkene metathesis is a transition-metal-catalyzed reaction in which two alkenes undergo exchange of their terminal fragments through a sequence of [2+2] cycloaddition and cycloreversion steps. Since its discovery, considerable efforts have been devoted to the development of well-defined ligands, driven by the need to improve activity, selectivity and stereochemical control over the E/Z geometry of the newly formed product.

Oxymercuration-demercuration is a two-step reaction that converts an alkene into a Markovnikov alcohol via an electrophilic addition mechanism, using mercuric acetate Hg(OAc)2 followed by NaBH4 reduction. It is the method of choice for Markovnikov hydration of alkenes when carbocation rearrangements must be avoided.

Halogenation of alkynes is an electrophilic addition reaction in which molecular bromine (Br2) or chlorine (Cl2) adds across the carbon-carbon triple bond. Depending on the amount of halogen employed, the reaction can stop at the dihaloalkene stage or proceed to the fully saturated tetrahalide.

Hydration of alkynes under strongly acidic conditions involves the addition of water across the carbon-carbon triple bond, ultimately yielding a carbonyl compound.

Hydroboration of alkynes is a two-step reaction that converts an alkyne into a carbonyl compound through anti-Markovnikov addition of water across the carbon-carbon triple bond. The reaction is typically carried out using a bulky borane reagent, such as disiamylborane (Sia2BH) or 9-BBN, followed by oxidation with hydrogen peroxide (H2O2) in basic medium.

Hydrohalogenation of alkynes is an electrophilic addition reaction in which a hydrogen halide (HX, where X = I, Br or Cl) adds across the carbon–carbon triple bond. Depending on the number of equivalents of hydrogen halide employed, the reaction can yield either a vinyl halide or a geminal dihalide.

The alkyne metathesis is a transition-metal-catalyzed reaction in which two alkynes undergo exchange of their terminal fragments through a sequence of [2+2] cycloaddition, isomerization and cycloreversion steps.

Alkyne oxymercuration is a reaction that converts an alkyne into a carbonyl compound through the addition of water across the carbon-carbon triple bond. The reaction is carried out under acidic conditions using a mercury(II) catalyst, typically HgSO4 in aqueous sulfuric acid, and proceeds with Markovnikov regioselectivity.

The reduction of an alkyne into a trans (E)-alkene is achieved via dissolving a metal reductant (typically Na or Li), also called Birch-type reduction of alkynes.

The conversion of an alkyne to a cis (Z)-alkene is achieved via heterogeneous catalytic hydrogenation using a poisoned (i.e. partially deactivated) catalyst, typically Lindlar’s catalyst (Pd deposited on CaCO3 then poisoned with Pb(OAc)2 and quinoline).

The full reduction of an alkyne to an alkane requires the addition of two equivalents of H2 (typically, an excess), breaking both 𝜋 bonds of the triple bond and yielding a saturated product.

The amidation reaction consists of the acylation of an amine by an activated carboxylic acid, forming an amide bond with concomitant departure of the leaving group (LG) introduced during activation. The different manners of activating a carboxylic acid are described in dedicated sheets.

The amide dehydration reaction converts a primary amide into a nitrile using a dehydrating agent (commonly SOCl2, P2O5 or POCl3) and eliminating a molecule of water.

The reduction of an amide to an amine involves formal replacement of the carbonyl oxygen with two hydrogen atoms, converting a C=O into a C–H2 group while retaining the C–N bond. This reaction requires the use of a hydride donor, typically LiAlH4. It is one of the most important methods for C–N bond-forming reductions in synthesis, as amides are readily available from carboxylic acids and amines.

The Appel reaction consists in the conversion of an alcohol function into alkyl halide with inversion of the stereochemistry.

Aromatic halogenation is a reaction in which a hydrogen atom of an aromatic ring is replaced by a halogen atom (typically Cl or Br) in the presence of a Lewis acid (AlCl3, FeBr3, respectively), yielding an aryl halide. Unlike alkene halogenation, which proceeds via electrophilic addition, aromatic halogenation proceeds via electrophilic aromatic substitution (EAS), preserving the aromaticity of the ring.

Aromatic nitration is a reaction in which a hydrogen atom of an aromatic ring is replaced by a nitro group (–NO2), yielding a nitroarene. Like aromatic halogenation, it proceeds via electrophilic aromatic substitution (EAS).

Aromatic sulfonation is a reaction in which a hydrogen atom of an aromatic ring is replaced by a sulfonic group (–SO3H), yielding an aryl sulfonic acid. Like aromatic halogenation, it proceeds via electrophilic aromatic substitution (EAS).

The Baeyer reduction consists of the reduction of nitroarenes (Ar-NO2) into anilines (Ar-NH2) using metal and acid, most classically iron or tin with hydrochloric acid.

The Baeyer–Villiger oxidation is a reaction that converts a ketone (or aldehyde) into an ester (or lactone) by insertion of an oxygen atom into the C–C bond adjacent to the carbonyl, using a peracid (typically, m-CPBA - meta-chloroperbenzoic acid) as oxidant.

The Balz-Schiemann reaction is a reaction in which an aniline is first converted into a diazonium tetrafluoroborate salt by treatment with nitrous acid followed by the addition of tetrafluoroboric acid (HBF4). Thermal decomposition of this intermediate yields the desired fluoroarene.

The Barton–McCombie reaction is a reaction that achieves the deoxygenation of a secondary (or primary) alcohol, converting a C–OH bond into a C–H bond via a xanthate ester intermediate and a radical chain mechanism using a tin hydride reductant.

The Beckmann rearrangement is a reaction in which a ketone (or an aldehyde) is converted into an amide using hydroxylamine under acidic conditions.

The Biginelli reaction is a multicomponent condensation where the final product 3,4-dihydropyrimidin-2(1H)-one is obtained through a sequence of bimolecular steps involving an aryl aldehyde, urea and a β-keto-ester. The reaction proceeds under the catalysis of either a Brønsted or Lewis acid.

The Birch reduction is a reaction that partially reduces aromatic rings to unconjugated 1,4-cyclohexadienes, using dissolved alkali metals in liquid ammonia in the presence of a proton source (typically an alcohol).

The Cannizzaro reaction is a dismutation of two aldehydes lacking α-hydrogen atoms. In the presence of a strong base and heat, one aldehyde molecule is oxidized to a carboxylic acid while the other is reduced to a primary alcohol. When two different aldehydes are used, a mixture of all possible products are obtained.

Carbamates are functional groups containing both an ester-like and an amide-like bond linked through a single carbonyl. They are among the most important protecting groups for amines in synthesis, extensively used in solid phase peptide synthesis.

Carboxylic acids are poor electrophiles in their native form due to the resonance delocalization of the carboxylate that reduces the electrophilicity of the carbonyl carbon. Activation consists of converting the -OH into a better leaving group, generating a more reactive acyl electrophile toward nucleophiles (amines, alcohols, organometallics, etc…). Beyond the existing methods to activate a carboxylic acid, one consists in converting it into an active ester, highly reactive toward nucleophilic attack.

Carboxylic acids are poor electrophiles in their native form due to the resonance delocalization of the carboxylate that reduces the electrophilicity of the carbonyl carbon. Activation consists of converting the -OH into a better leaving group, generating a more reactive acyl electrophile toward nucleophiles (amines, alcohols, organometallics, etc…). Beyond the existing methods to activate a carboxylic acid, one consists in converting it into the corresponding acyl chloride using thionyl chloride (SOCl2).

Carboxylic acids are poor electrophiles in their native form due to the resonance delocalization of the carboxylate that reduces the electrophilicity of the carbonyl carbon. Activation consists of converting the -OH into a better leaving group, generating a more reactive acyl electrophile toward nucleophiles (amines, alcohols, organometallics, etc…). Beyond the existing methods to activate a carboxylic acid, one consists in converting it into an anhydride, highly reactive toward nucleophilic attack.

The reduction of carboxylic acids into the corresponding primary alcohols requires a powerful hydride (typically, LiAlH4), owing to the reduced electrophilicity of the carbonyl carbon caused by resonance donation from the adjacent oxygen atom.

The Claisen condensation is a carbon-carbon bond forming reaction in which two esters (or one ester and a carbonyl) react in the presence of a strong base such as alkoxide or aminide to form a β-keto ester.

The Claisen rearrangement is a [3,3]-sigmatropic rearrangement that converts an allyl vinyl ether (or allyl aryl ether) into a γ,δ-unsaturated carbonyl compound, proceeding through a pericyclic mechanism.

The Clemmensen reduction is a reaction that converts a ketone or aldehyde into the corresponding alkane using zinc/mercury amalgam in concentrated hydrochloric acid. It is one of the two classical methods for the deoxygenation of carbonyl compounds, complementary to the Wolf-Kishner reduction.

The Click reaction, also known as the copper-catalyzed azide-alkyne cycloaddition (CuAAC), is a copper(I)-catalyzed reaction between a terminal alkyne and an organic azide, yielding a 1,4-disubstituted 1,2,3-triazole.

The conversion of an alcohol into an alkyl halide by substitution of the hydroxyl group is one of the most fundamental reactions in organic synthesis. Because the hydroxyl group is a poor leaving group, it must first be activated before a nucleophilic substitution by a halide (Br- or Cl-) can occur. Three common methods are described below.

The Cope rearrangement is a [3,3]-sigmatropic rearrangement that converts a 1,5-diene into another 1,5-diene through a pericyclic mechanism. It is the all-carbon analog of the Claisen rearrangement, differing only in the absence of a heteroatom in the reacting framework.

The Corriu-Tamao-Kumada coupling is a palladium or nickel catalyzed reaction, where an organic halide (aryl, vinyl or alkyle halide) (R1-X, where X = I, Br or Cl) reacts with a Grignard reagent (R2-MgY, where Y = Br or Cl) to create a new C-C bond.

The Curtius rearrangement is a thermal [1,2]-migration that converts an acyl azide into an isocyanate with loss of dinitrogen. The isocyanate intermediate can then be trapped by various nucleophiles such as water, alcohols, thiols or amines, giving amines, carbamates, thiocarbamates or ureas respectively.

Dehydrohalogenation is an elimination reaction in which a haloalkane loses a hydrohalic acid molecule (HX, where X = I, Br or Cl) to form an alkene.

Dess-Martin oxidation is a reaction in which an alcohol is oxidized to an aldehyde (or ketone for secondary alcohol). One of the main advantages of this reaction is its mild and selective nature: the oxidation can be carefully controlled, preventing further oxidation of primary alcohols to carboxylic acid.

Dieckmann condensation is an intramolecular reaction between a diester and a base, leading to a cyclic β-keto ester.

The Diels-Alder reaction is a [4+2] cycloaddition between a conjugated diene (4𝜋 electrons) and a dienophile (2𝜋 electrons), forming a cyclohexene ring in a single concerted step.

Enolate alkylation is a reaction in which the final product depends critically on the reaction conditions. Using a weak base at room temperature affords the thermodynamic alkylation product. In contrast, a strong base at low temperature results in the formation of the kinetic alkylation product.

One way to synthesize an epoxide is to react an alkene with a peroxycarboxylic acid (commonly, the meta-chloroperbenzoïc acid (m-CPBA) is used). This reaction proceeds with retention of the initial alkene configuration.

The reduction of esters into the corresponding primary alcohols requires a powerful hydride (typically, LiAlH4), owing to the reduced electrophilicity of the carbonyl carbon caused by resonance donation from the adjacent oxygen atom.

The reduction of an ester to an aldehyde is most commonly achieved using DIBAL-H (diisobutylaluminum hydride) under carefully controlled conditions, typically at −78 °C. The selectivity of this transformation relies on the formation of a stable, aluminum-coordinated intermediate that prevents over-reduction.

The Fischer esterification is a synthetic method used to prepare esters from a carboxylic acid and an alcohol under acidic catalysis. Because the reaction is an equilibrium process, several strategies can be employed to shift the equilibrium toward ester formation, such as continuous removal of water using a Dean-Stark apparatus.

One of the most well-known method to obtain indoles is the Fischer indole synthesis. Under acidic conditions, a carbonyl compound reacts with a phenylhydrazine to obtain the desired indol.

Diazonium salts are versatile intermediates used in several organic reactions such as Sandmeyer reaction or azo compounds synthesis (azobenzene). One of the most common methods for preparing a diazonium salt is the reaction of aniline with sodium nitrite in acidic conditions.

Radical halogenation is a reaction that introduces a halogen atom (Cl or Br) onto a saturated carbon of an alkane via a free radical chain mechanism, using molecular halogen (Cl2 or Br2) activated by light (hν) or heat (Δ).

Friedel-Crafts acylation is an electrophilic aromatic substitution reaction catalyzed by a Lewis acid, in which an acyl chloride reacts with an aromatic compound to form an aromatic carbonyl.

Friedel-Crafts alkylation is an electrophilic aromatic substitution reaction catalyzed by a Lewis acid, in which an alkyl chloride reacts with an aromatic compound to form an alkyl-substituted aromatic.

Gabriel synthesis is a useful method for synthesizing primary amines, avoiding the over-alkylation issues typically encountered with direct alkylation. It involves phthalimide, an alkyl halide, hydrazine and a suitable base.

The Gattermann-Koch reaction is an electrophilic aromatic substitution reaction in which an aromatic compound reacts with carbon monoxide and hydrochloric acid in the presence of a Lewis acid, typically aluminium chloride, to give a benzaldehyde.

The formation of Grignard reagent involves the reaction between an organic halide (RX, where R = alkyl or aryl, and X = Br or Cl) and magnesium. Due to the high reactivity of the resulting Grignard reagent toward moisture and oxygen, the reaction must be performed under strictly anhydrous and inert conditions.

The Grignard reaction is a versatile method to form a new carbon-carbon bonds. It involves a nucleophilic organomagnesium halide reagent, known as Grignard reagent and of a general formula R-MgX where R is an organic group and X is a halogen (either Br or Cl). This reagent reacts with an electrophilic carbonyl compound via a nucleophilic addition, yielding a new carbon-carbon bond, after acidic aqueous workup.

The Grignard reaction is a versatile method for forming new carbon-carbon bonds. It involves a nucleophilic organomagnesium halide reagent, known as Grignard reagent and of a general formula R-MgX where R is an organic group and X is a halogen (either Br or Cl). This reagent acts as a nucleophile in the presence of an epoxide, affording an alcohol.

The Grignard reaction is a versatile method for forming new carbon-carbon bonds. It involves a nucleophilic organomagnesium halide reagent, known as Grignard reagent and of a general formula R-MgX where R is an organic group and X is a halogen (either Br or Cl). This reagent reacts with a Weinreb amide to afford a ketone without repeating the Grignard reaction.

The haloform reaction is a reaction in which a methylketone derivative is converted into a carboxylic acid through successive halogenations by a dihalogen molecule (X2, where X = I, Br or Cl) in a basic aqueous medium.

The Hartwig-Buchwald coupling is a palladium-catalyzed reaction used to form new C-N bonds by coupling an amine (primary or secondary) with an aryl halide (Ar-X, where X = I, Br or Cl) in the presence of a base.

The Hiyama coupling is a palladium-catalyzed cross-coupling reaction in which an aryl, or vinyl halide (R1-X, where X = I, Br, Cl) reacts with an organosilane in the presence of a fluoride source or a base to form a new C-C bond.

Hofmann elimination is a reaction in which a primary amine undergoes successive alkylation steps followed by treatment with silver oxide, and subsequent E2 elimination to afford an alkene. Unlike Zaitsev’s rule which favours the more substituted alkene, the Hofmann elimination selectively produces the less substituted alkene.

The Hofmann rearrangement converts a primary amide into its corresponding primary amine, one carbon shorter, using bromine and a base. Carbon dioxide and water are released as by-products in the process.

The HWE reaction is a phosphonate-based olefination of aldehydes and ketones, closely related to the Wittig reaction but using a stabilized phosphonate carbanion instead of a phosphorus ylide. It is one of the most widely used methods for the stereoselective synthesis of (E)-alkenes.

Hydroformylation is a transition metal-catalyzed reaction in which an alkene reacts with a gas mixture of carbon monoxide and dihydrogen to yield an aldehyde.

Imine formation involves the condensation of an aldehyde or a ketone with a primary amine, under Brønsted acid catalysis.

The Jones oxidation is a chromium(VI)-based oxidation reaction used to convert primary alcohols into carboxylic acids and secondary alcohols into ketones using Jones reagent, which is prepared from chromium trioxide (CrO3) and sulfuric acid in aqueous acetone.

The Julia-Kocienscki olefination is a reaction that converts a heteroaryl sulfone (benzothiazolyl sulfone or 1-phenyl-1H-tetrazolyl sulfone) and an aldehyde (or ketone) into an alkene. It is one of the most powerful methods for selective alkene synthesis.

The Knoevenagel condensation involves active methylene compounds, such as a β-dicarbonyl or a malonitrile, reacting with a ketone or an aldehyde. This reaction is typically catalyzed by an amine base, such as piperidine or pyridine.

The Knorr pyrazole synthesis is a reaction that yields a pyrazole ring by condensation of a 1,3-dicarbonyl compound (β-ketoester, β-diketone or malonaldehyde derivatives) with a hydrazine (R–NH–NH2), forming a five-membered aromatic nitrogen heterocycle.

The Kolbe reaction is a reaction in which a phenol is first converted into its phenoxide salt by treatment with a base, then reacts with pressurized carbon dioxide at elevated temperature, to give salicylic acid as the final product.

The Mannich reaction is a multicomponent reaction that combines an aldehyde or a ketone, formaldehyde and a secondary amine to form a β-aminoketone, also called Mannich base.

The Michael addition is a reaction involving, on one hand, soft nucleophiles according to the Hard and Soft Acids and Bases (HSAB) principle, known as Michael donors. Typically, Michael donors are stabilized carbanions such as enolate compounds (malonates, β-ketoesters), or soft nucleophiles such as thiols, etc. On the other hand, Michael acceptors are soft electrophiles bearing an electron-withdrawing group conjugated to a C=C double bond, like α,β-unsaturated carbonyl compounds (ketones, aldehydes, esters, etc.).

The Mitsunobu reaction consists in the conversion of primary or secondary alcohols into another nucleophilic functional group with inversion of the stereochemistry.

The Mizoroki-Heck coupling engages an aryl or vinyl halide (R1-X, where X = I, Br or Cl) and an activated alkene in a palladium-catalyzed reaction, in the presence of a base.

The Murai coupling is a directed C-H activation reaction in which a carbonyl group bore by an aryl compound acts as a directing group to coordinate a ruthenium catalyst and facilitate selective ortho C-H functionalization, enabling the alkylation of aromatic substrate with an alkene.

Negishi reaction is a palladium or nickel catalyzed cross-coupling reaction between an aryl halide, vinyl halide or alkyl halide (R1-X, where X = I, Br or Cl) and an organozinc (R2-ZnY, where Y = I, Br or Cl).

Nitrile hydrolysis consists in the reaction of a nitrile (R–C≡N) with water under acidic or basic conditions, leading sequentially to an amide and then to a carboxylic acid. It is one of the most fundamental methods for converting a nitrile into a carboxylic acid or amide, and can be stopped at either stage depending on conditions.

Nitrile reduction consists in the conversion of a nitrile (R–C≡N) into a primary amine by formal addition of two equivalents of H2 across the C≡N triple bond. It is one of the most direct and atom-efficient routes to primary amines in organic synthesis.

The catalytic hydrogenation of a nitroarene is one of the most common methods for the synthesis of anilines. The reaction is typically carried out using molecular hydrogen (H2) in the presence of a metal catalyst such as palladium on carbon (Pd/C), platinum (Pt), Raney nickel, or rhodium (Rh).

The Nozaki-Hiyama-Kishi reaction is a nickel catalyzed reaction in which a vinyl halide (RX, where X = I or Br) couples with an aldehyde, in the presence of an excess of chromium(II) dichloride, to afford an allylic alcohol.

Nucleophilic aromatic substitution (NAS) is a reaction in which a nucleophile replaces a leaving group on an aromatic ring. Unlike nucleophilic substitution at aliphatic carbon atoms, aromatic systems do not generally undergo direct SN2 displacement because the carbon bearing the leaving group is part of a planar sp2-hybridized system. Instead, the reaction proceeds through an addition–elimination mechanism.

A nucleophilic substitution is a reaction in which a nucleophile displaces a leaving group (LG) attached to a sp3 carbon. Two nucleophilic substitution mechanisms exist, SN1 and SN2, differing in whether bond-breaking and bond-forming occur simultaneously or sequentially.

The oxidative cleavage of alkene using a concentrated solution of potassium permanganate at high temperature, leads to the formation of ketone or carboxylic acid depending on the nature of the initial alkene. During this reaction, a C-C bond is oxidatively cleaved, resulting in the formation of two separated carbonyl products.

The oxidative cleavage of alkynes using potassium permanganate (KMnO4) is a reaction during which an alkyne is oxidized by KMnO4 to afford, depending on the reaction medium, either an α-diketone or a carboxylic acid as the desired product.

First, the lone pair of one hydroxyl group attacks firstly the iodine atom of periodate to form an iodinate ester intermediate. After proton transfer, the second hydroxyl group undergoes the same reaction, closing the five-membered cyclic ester. The cyclic intermediate then undergoes cycloreversion, in which the C-C bond is cleaved heterolytically, yielding two carbonyl compounds and releasing iodate with water.

Ozonolysis of alkene is a reaction in which a carbon-carbon double bond is oxidatively cleaved by ozone, leading to two carbonyl products. Depending on the treatment conditions, the products can be ketones, aldehydes or carboxylic acids.

Ozonolysis of alkyne is a reaction between an alkyne and ozone that leads to different products, depending both workup conditions and the substitution pattern of the alkyne. With neutral workup, carboxylic acids or carbon dioxide can be obtained. Under reductive workup, diketone or α-ketoaldehyde can be produced.

The Pauson-Khand coupling is a formal [2+2+1] cycloaddition involving a binuclear cobalt complex, an alkyne, an alkene and carbon monoxide to synthesize an α,β-unsaturated cyclopentanone.

The Petasis reaction is a three-component reaction that couples an aldehyde (or ketone), an amine, and a boronic acid to produce a substituted amine.

Reductive amination is a reaction that converts a ketone or an aldehyde into an amine through condensation with a primary or secondary amine, followed by reduction of the resulting iminium ion.

The Sandmeyer reaction is a reaction in which a primary aromatic amine (aniline) is converted into a functionalized aryl (Ar-X, where X = Cl, Br, CN, etc.) through two sequential steps : the formation of a diazonium salt followed by a copper(I)-catalyzed step.

The saponification reaction consists of the hydrolysis of an ester to form the corresponding carboxylate salt (soap) and an alcohol using a strong base such as sodium hydroxide or potassium hydroxide.

The Schotten-Baumann reaction is a synthetic method for the preparation of amides from a secondary or primary amine and an acyl chloride, carried out in a biphasic basic aqueous medium.

The Sharpless alkene dihydroxylation is a reaction in which an alkene is converted into a vicinal diol with high enantiomeric excess, using a pre-formulated mixture known as AD-mix. This mixture contains four components: osmium(VIII) tetroxide (OsO4) as catalyst, a chiral alkaloid ligand, potassium ferricyanide (K3Fe(CN)6) as a stoichiometric co-oxidant and potassium carbonate as a base to maintain slightly basic conditions.

This reaction involves the epoxidation of an allylic alcohol by tert-butyl hydroperoxide, catalysed by a titanium(IV) isopropoxide complex in the presence of a chiral auxiliary, diethyl tartrate (DET).

The Simmons-Smith cyclopropanation is a reaction in which an alkene is converted into a cyclopropane upon treatment with diiodomethane and zinc.

Sonogashira reaction is a palladium-catalyzed cross-coupling reaction between an aryl halide or vinyl halide (R1-X, where X = I, Br or Cl) and a terminal alkyne.

The Staudinger reaction is a reaction between an azide and a phosphine that yields an iminophosphorane with loss of dinitrogen (N2). It is one of the most important reactions in bioorthogonal chemistry and serves as a key method for the reduction of azides to amines as well as for chemoselective ligation in chemical biology.

The Steglich esterification is a reaction that forms an ester from a carboxylic acid and an alcohol, using dicyclohexylcarbodiimide (DCC) and a catalytic amount of dimethylaminopyridine (DMAP).

Stille reaction is a palladium-catalyzed cross-coupling reaction between an aryl halide, vinyl halide or alkyl halide (R1-X, where X = I, Br or Cl) and an organostannane.

Strecker reaction is a reaction where an aldehyde is condensed in presence of cyanide salt and ammonia in an aqueous acid medium, to give an α-amino acid.

The Suzuki-Miyaura coupling is a palladium-catalyzed cross-coupling reaction that involves an organoboron compound, a base (NaOH, K2CO3...) and an organic halide (R1-X, where R = aryl, vinyl or alkyl, and X = I, Br or Cl) to form a new carbon-carbon bond.

The Swern oxidation is a reaction in which a primary or secondary alcohol is converted into an aldehyde or ketone, respectively, using oxalyl chloride (COCl)2 and dimethylsulfoxide (DMSO) as the oxidizing system, in the presence of a base (typically triethylamine, Et3N).

The Takai olefination is a reaction that converts an aldehyde into a vinyl halide, specifically a (E)-vinyl iodide (or bromide), using CHI3 (iodoform) or CHBr3 (bromoform) in the presence of CrCl2. It is one of the most reliable and stereoselective methods for the synthesis of building blocks for cross-coupling chemistry.

The treatment of toluene derivatives with potassium permanganate under basic conditions leads to the synthesis of benzoic acid derivatives. A strict prerequisite for this reaction is the presence of at least one hydrogen atom attached to the benzylic position.

Transesterification is a reaction in which a new ester is obtained by reacting an alcohol with an ester precursor. The reaction is often performed with a large excess of the incoming alcohol, which can conveniently serve as the solvent. This reaction finds numerous industrial applications, most notably in biodiesel production, in which fatty acid methyl esters are obtained by reacting vegetable oils with methanol, releasing glycerol as a by-product.

The Tsuji-Trost reaction is a palladium-catalyzed allylic substitution involving an allylic substrate bearing a leaving group (such as halide, acetate…) and a nucleophile (soft or hard), enabling the formation of a new carbon-carbon or carbon-heteroatom bond.

The Ugi reaction is a multicomponent reaction that combines an aldehyde (or a ketone), an amine, a carboxylic acid and an isocyanide to form a bis-amide.

Ullmann reaction is a biaryl coupling reaction promoted by copper. This reaction typically requires very high temperatures (around 200 °C), which constitutes one of its main limitations compared to modern transition-metal-catalyzed cross-coupling reactions.

The Vilsmeier–Haack reaction is an electrophilic aromatic formylation that introduces an aldehyde group (–CHO) onto an electron-rich aromatic or heteroaromatic ring, using a combination of DMF and phosphorus oxychloride (POCl3) as formylating agent.

Wagner-Meerwein rearrangement is an acid-catalyzed reaction in which a molecule undergoes dehydration, generating a new alkene. A key feature of this rearrangement is the 1,2-alkyl (or aryl, hydride ...) shift step which leads to a more substituted and stabilized carbocation.

Weinreb amides are synthesized from an activated carboxylic acid derivative by a reaction with the reagent N,O-dimethylhydroxylamine (DMHA). These compounds are widely used in reactions implying organomagnesium (Grignard) reagents, allowing the controlled formation of alkyl-substituted ketones.

The Weinreb amide reduction is a reaction that converts a Weinreb amide into an aldehyde using a reductant, most commonly LiAlH4 or DIBAL-H. It is one of the most reliable and chemoselective methods for the partial reduction of an amide to an aldehyde without over-reduction to the corresponding amine.

The Williamson reaction allows the synthesis of an ether from an alcohol (R1-OH, where R1 = alkyl or aryl) and an alkyl derivative bearing a good leaving group (R2-X, where X = I, Br, Cl or OTs), under basic conditions.

The Wittig reaction converts a ketone (or aldehyde) into an alkene by reaction with a phosphorus ylide, with concomitant formation of triphenylphosphine oxide (Ph3P=O) as by-product. It is one of the most powerful and widely used methods for the stereoselective synthesis of alkenes with complete control over the position of the double bond.

The Wolff-Kishner reaction enables the reduction of ketones or aldehydes into alkanes using hydrazine and a strong base such as potassium hydroxide.

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