996-83-8Relevant academic research and scientific papers
Synthetic Implications of the Reactions of Alkali-Metal Pentadienyls with Organic Electrophiles and Comments on the Nature of "Organopotassiums" Derived Using Lochmann's Base.
Paget, Walter E.,Smith, Keith,Hutchings, Michael G.,Martin, Gary E.
, p. 327 - 341 (2007/10/02)
Pentadienyl anions derived by metallation of penta-1,4-diene with n-butyl-lithium, or of penta-1,3-diene with n-butyl-lithium - potassium tert-butoxide, react with electrophiles to produce mixtures of E- and Z-5-substituted penta-1,3-dienes and 3-substituted penta-1,4-dienes.The proportions depend, amongst other things, upon the nature of the electrophile.For simple aldehydes and ketones, for example, the proportions can vary, under otherwise identical conditions, from entirely 5-substituted product (as an E/Z mixture) with benzophenone, to predominantly (64percent) 3-substituted product with acetone.Reaction with bromocyclopentane produces almost entirely the 3-substituted product.The synthetic implications of these results are discussed.The reactions of the anions generated by the two different methods are very similar, which has prompted a discussion of the nature of the reagents, often described as organopotassiums, which are derived using Lochmann's base.
