The Se/Li exchange by elemental lithium or better alkyllithiums on selenides and functionalized selenides offers easy access to α-selenoalkyllithiums and allyl- and benzyl-lithiums, which are otherwise difficult to synthesize. These compounds are found to be particularly nucleophilic toward carbonyl compounds for the former, and alkyl halides, epoxides (by substitution), olefins and heterosubstituted carbon-carbon double bonds for the latter. These reactions allow the synthesis of olefins, epoxides, and ring-enlarged carbonyl compounds in processes related to the reaction of phosphorus-, sulfur ylides, and the pinacolic rearrangement which are able to achieve the same transformations but not with highly hindered or enolizable carbonyl compounds.Benzyllithium derivatives allow the synthesis of aryl alkanes and aryl cycloalkanes by formal geminal dialkylation of the carbonyl group of aromatic aldehydes and ketones or aryl, alkylation of the carbonyl group of alkyl aldehydes and ketones. It allows the synthesis of particularly hindered quaternary benzylic carbons and, if the second alkylation implies the addition of benzyllithiums across a carbon-carbon double bond, the formation of two adjacent quaternary carbons. © 2014 Elsevier Ltd. All rights reserved.
|titre||Comprehensive Organic Synthesis II (Second Edition)|
|rédacteurs en chef||Paul Knochel|
|Lieu de publication||Amsterdam|
|Editeur||Pergamon, Elsevier Science Ltd|
|Nombre de pages||101|
|Etat de la publication||Publié - 2014|