72952-73-9Relevant articles and documents
Pentadienyl type lithium and potassium species: The regioselectivity of their reactions with electrophiles
Schlosser,Zellner,Leroux
, p. 1830 - 1836 (2007/10/03)
Seven structurally distinct pentadienyl type lithium and potassium compounds were screened against a variety of electrophiles in order to assess the regioselectivity of the trapping reactions. Organoborates and analogs thereof (fluorodimethoxyborane) proved to be perfectly regioreliable attacking only unsubstituted terminal positions and thus providing, after oxidation, exclusively primary allylic alcohols. 2,4-Pentadienyllithiums or -potassiums, that carry a methyl group at the 1- or 3-position, exhibit the same extreme regioselectivity towards halotrialkylsilanes or carbon dioxide. Although the unsubstituted parent compounds combine with such electrophiles still preferentially at the terminal position, considerable proportions of branched products are concomitantly formed as well (1/3-attack ratios ranging from 2:1 to >20:1). Hydroxyalkylating and alkylating reagents such as formaldehyde, oxirane or butyl iodide invariably afford regioisomeric mixtures generally varying in composition between 3:1 and 1:3. The condensation reaction with halotrialkylsilanes appears to follow a concerted (SN2-like) rather than an addition/elimination (ate complex-mediated) mechanism.
SYNTHESE NEUER ORGANOELEMENTSUBSTITUIERTER PENTADIENE (1)
Kauffmann, Thomas,Gaydoul, Klaus-Ruediger
, p. 4067 - 4070 (2007/10/02)
By applying four different methods twelve new organoelement substituted pentadienes have been prepared.They contain one or two organoelement groups. - Pentadienyllithium (2) reacted with Cl-SPh, Br-SePh, Cl-PPh2, and Cl-AsPh2 (lone pair at the element) ex
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.
