The Fischer indole synthesis uses a protic or Lewis acid catalyst to convert a phenylhydrazine and an aldehyde or ketone to an indole. The phenylhydrazine makes an iminium ion with the carbonyl compound, which tautomerizes to the ene-hydrazine. A [3,3]-sigmatropic rearrangement disrupts the aromatic ring, but a subsequent proton transfer...

The Fischer esterification uses a catalytic acid to convert a carboxylic acid and alcohol to an ester. Protonation of the carbonyl oxygen activates the carboxylic acid to nucleophilic attack by the alcohol, producing a tetrahedral intermediate with two hydroxyl groups. Ester formation occurs when a proton is transferred to one...

The Beckmann rearrangement involves the use of a strong acid to rearrange an oxime (aldoxime or ketoxime) to an amide. First the oxime hydroxyl group receives a proton from the acid, forming a leaving group. A [1,2]-shift of the R group, which is anti to the leaving group, then promotes...

The Buchwald-Hartwig cross-coupling reaction (Buchwald-Hartwig Amination) uses catalytic palladium and a strong base in stoichiometric amounts to make an aryl amine from an aryl halide and a 1° or 2° amine. Oxidative addition of the aryl halide to the Pd(0) catalyst occurs first, followed by amine coordination to the Pd(II)...

The Jones oxidation uses chromium trioxide (CrO3), acid, water, and acetone to convert 1° or 2° alcohols into carboxylic acids or ketones respectively. Chromic acid is first prepared by dissolving CrO3 or Cr2O72- in acid: the monomeric form (HCrO4-) dominating in dilute solutions versus the dimeric form (HCr2O7-) dominating in...

The Knoevenagel condensation uses a catalytic base such as piperidine to convert an aldehyde or ketone and an activated methylene compound to a α,β-unsaturated dicarbonyl or related compound. The base deprotonates the methylene compound, creating a resonance stabilized enolate, which reacts with an iminium ion made from the carbonyl compound...