Corey-House-Posner-Whitesides reaction
The Corey–House synthesis (also called the Corey–Posner–Whitesides–House reaction and other permutations) is an organic reaction that involves the reaction of a lithium diorganylcuprate (R2CuLi) with an organyl (pseudo)halide (R'X) to form a new alkane, as well as an ill-defined organocopper species and lithium halide as byproducts.
In principle, a carbanion equivalent such as an organolithium or Grignard reagent can react directly (without copper) with an alkyl halide in a nucleophilic substitution reaction to form a new carbon–carbon bond. However, aside from the use of metal acetylides as nucleophiles, such a process rarely works well in practice due to metal–halogen exchange and/or the formation of large amounts of reduction or elimination side-products. As a solution to this problem, the Corey–House reaction constitutes a general and high yielding method for the joining of two alkyl groups or an alkyl group and an aryl group.
The scope of the Corey-House synthesis is exceptionally broad, and a range of lithium diorganylcuprates (R2CuLi, R = 1°, 2°, or 3° alkyl, aryl, or alkenyl) and organyl (pseudo) halides (RX, R = methyl, benzylic, allylic, 1°, or cyclic 2° alkyl, aryl, or alkenyl and X = Br, I, OTs, or OTf; X = Cl is marginal) will undergo coupling as the nucleophilic and electrophilic coupling partners, respectively. The reaction usually takes place at room temperature or below in an ethereal solvent. Due to the wide range of applicable coupling partners, functional group tolerance, and operational simplicity, the Corey–House synthesis is a powerful and practical tool for the synthesis of complex organic molecules. However, as limitations, hindered (2° or 3°) alkyl halides are generally unsuccessful or low-yielding substrates for the Corey-House synthesis. Furthermore, alkynylcuprates are generally inert under usual coupling conditions. The forging of aryl-aryl bonds is also inefficient and much more effectively achieved using palladium catalysis.
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