Organocuprates, reaction with acid chlorides

In addition to their reactions with acid chlorides, epoxides, and a,P-unsaturated carbonyl compounds (Sections 20.13-20.15), organocuprate reagents (R2CuLi) also react with organic halides R X to form coupling products R-R that contain a new C-C bond. Only one R group of the organocuprate is transferred to form the product, while the other becomes part of RCu, a reaction by-product. 

Organocuprates also react with acid chlorides to form a ketone. When 126 reacts with benzoyl chloride, for example, the product is 128. This reaction is a preferred method for the conversion of carboxylic acids to ketones. A reaction sequence that begins with 3-methylpentanoic acid first forms the acid chloride via reaction with thionyl chloride (Section 20.3.1), and subsequent reaction with lithium diethyl cuprate leads to the ketone 129. 

The reaction of tert-alkyl Grignard reagents with carboxylic acid chlorides in the presence of a copper catalyst provides ieri-alkyl ketones in substantially lower yields than those reported here.4,14 The simplicity and mildness of experimental conditions and isolation procedure, the diversity of substrate structural type, and the functional group selectivity of these mixed organocuprate reagents render them very useful for conversion of carboxylic acid chlorides to the corresponding secondary and tertiary alkyl ketones.15... 

B Reaction of an acid chloride with an organocuprate reagent... 

Acid chlorides react readily with organocuprates to give ketones. The reaction is chemoselective for the acid chloride and no addition to functional groups such as ketones, esters or nitriles takes place. For example, addition of lithium dibutylcuprate to the acid chloride 172 gave the ketone 173 (1.174). 

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