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The Crabbé reaction (or Crabbé allene synthesis, Crabbé–Ma allene synthesis) is an organic reaction that converts a terminal alkyne and aldehyde (or, sometimes, a ketone) into an allene in the presence of a soft Lewis acid catalyst (or stoichiometric promoter) and secondary amine.
The coupling of a terminal alkyne and an aromatic ring is the pivotal reaction when talking about applications of the copper-promoted or copper-free Sonogashira reaction. The list of cases where the typical Sonogashira reaction using aryl halides has been employed is large, and choosing illustrative examples is difficult.
The Seyferth–Gilbert homologation is a chemical reaction of an aryl ketone 1 (or aldehyde) with dimethyl (diazomethyl)phosphonate 2 and potassium tert-butoxide to give substituted alkynes 3. [ 1 ] [ 2 ] Dimethyl (diazomethyl)phosphonate 2 is often called the Seyferth–Gilbert reagent .
In organic chemistry, alkynylation is an addition reaction in which a terminal alkyne (−C≡CH) is added to a carbonyl group (C=O) to form an α-alkynyl alcohol (R 2 C(−OH)−C≡C−R). [1] [2] When the acetylide is formed from acetylene (HC≡CH), the reaction gives an α-ethynyl alcohol. This process is often referred to as ethynylation.
Terminal alkynes have the formula RC≡CH, where at least one end of the alkyne is a hydrogen atom. An example is methylacetylene (propyne using IUPAC nomenclature). They are often prepared by alkylation of monosodium acetylide. [4] Terminal alkynes, like acetylene itself, are mildly acidic, with pK a values of around 25.
Carbocupration is a nucleophilic addition of organocopper reagents (R−Cu) to acetylene or terminal alkynes resulting in an alkenylcopper compound (R 2 C=C(R)−Cu). [17] It is a special case of carbometalation and also called the Normant reaction. [18] [19] Catalytic cycle for carbocupration for the synthesis of aldol, Baylis-Hillman type ...
The Cadiot–Chodkiewicz coupling in organic chemistry is a coupling reaction between a terminal alkyne and a haloalkyne catalyzed by a copper(I) salt such as copper(I) bromide and an amine base. [ 1 ] [ 2 ] The reaction product is a 1,3-diyne or di- alkyne .
The Wulff–Dötz reaction (also known as the Dötz reaction or the benzannulation reaction of the Fischer carbene complexes) is the chemical reaction of an aromatic or vinylic alkoxy pentacarbonyl chromium carbene complex with an alkyne and carbon monoxide to give a Cr(CO) 3-coordinated substituted phenol.