Reactions of Organolithiums with Carbonyl Compounds

Reaction of the ultrasonically generated alkyllithiums with carbonyl compounds provides an extremely facile route to secondary and tertiary alcohols in a lithium-mediated Barbier-type reaction. 

Furthermore, the commonly observed side reactions, such as reduction and enolization, were minimal. The reaction also proceeded cleanly with allylic, vinylic and even benzylic halides, where Wurtz coupling normally predominates. 

Optimising the reaction conditions showed that didthyl ether was a better solvent than THF, as recommended by Luche in his original publication. Furthermore, the presence of 2% sodium in the lithium sand gave better results than those obtained using commercial lithium wire of varying purity. 

In the examples given, the cyclization proceeded with retention of configuration at the centres indicated. This includes the synthesis of the highly strained tra 5-fused system, although competing dehydrobromination reduced the yield to 44 %. 

Araki and Butsugan have recently described the lithium-mediated allyla-tion of carbonyls by means of an allylic phosphate anion [91]. 

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