Corey-House reaction

Coupling reaction Corey-House reaction. Preparation of alkanes... 

Pioneering work on the desulphonylation of jS-ketosulphones was carried out by Corey and Chaykovsky - . This reaction was part of a sequence which could be used in the synthesis of ketones, as shown in equation (53). The main thrust of this work was in the use of sulphoxides, but Corey did stress the merits of both sulphones and sulphonamides for different applications of this type of reaction. The method soon found application by Stetter and Hesse for the synthesis of 3-methyl-2,4-dioxa-adamantane , and by House and Larson in an ingenious synthesis of intermediates directed towards the gibberellin skeleton, and also for more standard applications . Other applications of the method have also been madealthough it does suffer from certain limitations in that further alkylation of an a-alkyl- -ketosulphone is a very sluggish, inefficient process. Kurth and O Brien have proposed an alternative, one-pot sequence of reactions (equation 54), carried out at — 78 to — 50°, with yields better than 50%. The major difference between the two routes is that the one-pot process uses the desulphonylation step to generate the enolate anion, whereas in the Corey-House procedure, the desulphonylation with aluminium amalgam is a separate, non-productive step. 

Another transition metal-catalyzed carbon-carbon bond-forming reaction we shall discuss is the Corey—Posner, Whitesides-House reaction. Using this reaction an alkyl halide can be coupled with the alkyl group from a lithium dialkyl cuprate reagent (often called a Gilman reagent). This reaction does not have a catalytic mechanism. 

G.3 THE COREY-POSNER, WHITESIDES-HOUSE REACTION USE OF LITHIUM DIALKYL CUPRATES (GILMAN REAGENTS) IN COUPLING REACTIONS... 

The Corey—Posner, Whitesides—House reaction involves the coupling of a hthium dialkyl-cuprate (called a Gilman reagent) with an alkyl, alkenyl, or aryl halide. The alkyl group of the lithium dialkylcuprate reagent may be primary, secondary, or tertiary. However, the halide with which the Gilman reagent couples must be a primary or cychc secondary alkyl halide if it is not alkenyl or aryl. 

All of the reagents in a Corey-Posner, Whitesides-House reaction are consumed stoichiometrically. The mechanism does not involve a catalyst, as in the other reactions of transition metals that we have studied. 

G.3 The Corey-Posner, Whitesides-House Reaction Use of Lithium Dialkyl Cuprates (Gilman Reagents) in Coupling Reactions... 

The discovery of the Gilman cuprate Me2CuLi [5-8], and House s [6, 7] and Corey s [8] demonstrations of its synthetic potential, produced a major breakthrough in this area of chemistry. A major disadvantage of the application of this type of cuprate reagents in stoichiometric amounts, especially from the point of view of atom economy , is the fact that one equivalent of the (potentially valuable) organic component is usually not used in the reaction and ends up as chemical... 

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