The Castro–Stephens coupling is a cross coupling reaction between a copper(I) acetylide and an aryl halide forming a disubstituted alkyne and a copper(I) halide.
The reaction was discovered in 1963 by University of California, Riverside chemists Castro and Stephens and is used as a tool in the organic synthesis of organic compounds.
The reaction has similarities with the much older Rosenmund–von Braun synthesis (1916) between aryl halides and copper(I) cyanide and was itself modified in 1973 with as the Sonogashira coupling by adding a palladium catalyst and preparing the organocopper compound in situ, allowing copper to also be used catalytically.
A typical reaction is the coupling of iodobenzene with the copper acetylide of phenylacetylene in refluxing pyridine to diphenylacetylene:
Unlike the Sonogashira coupling, the Castro–Stephens coupling can produce heterocyclic compounds when a nucleophilic group is ortho to the aryl halide, although this typically requires use of DMF as solvent.
Darzens reaction
The Darzens reaction (also known as the Darzens condensation or glycidic ester condensation) is the chemical reaction of a ketone or aldehyde with an α-haloester in the presence of base to form an α,β-epoxy ester, also called a "glycidic ester". This reaction was discovered by the organic chemist Auguste George Darzens in 1904.
The reaction was discovered in 1963 by University of California, Riverside chemists Castro and Stephens[1][2] and is used as a tool in the organic synthesis of organic compounds. The reaction has similarities with the much older Rosenmund–von Braun synthesis (1916) between aryl halides and copper(I) cyanide and was itself modified in 1973 with as the Sonogashira coupling by adding a palladium catalyst and preparing the organocopper compound in situ, allowing copper to also be used catalytically.
A typical reaction is the coupling of iodobenzene with the copper acetylide of phenylacetylene in refluxing pyridine to diphenylacetylene: