1380114-64-6Relevant articles and documents
New lithium phosphonium diylides: A methylene and a cyclopentadienyl moiety as ylidic coordination sites
Lichtenberg, Crispin,Hillesheim, Nina S.,Elfferding, Michael,Oelkers, Benjamin,Sundermeyer, Joerg
, p. 4259 - 4266 (2012)
A set of lithium phosphonium diylides Li[CH2-PR 2-CpX] (9-12; CpX = C5Me 4, C5H3tBu, R = Ph, Me) is presented. Two of the lithium complexes were characterized by means of single-crystal X-ray analysis, revealing a dimeric head-to-tail arrangement in the solid state. The coordination behavior of 9-12 in the liquid phase is solvent dependent. These lithium phosphonium diylides exist as contact ion pairs in benzene and as solvent-separated ion pairs in THF solutions. Phosphonium salts [H 3C-PR2-CpXH)]+I- (1-4) are starting materials for the syntheses of the title compounds and exist as mixtures of isomers due to [1,5]-prototropic rearrangements. The dynamic behavior in solution has been investigated. Two different routes allow access to title compounds 9-12. Reactions of 1-4 with 2 equiv of nBuLi give 9-12 in a one-pot synthesis. In an alternative two-step route, dehydrodehalogenation of 1-4 with KH gives the corresponding phosphonium ylides 5-8. Two of these phosphonium ylides were characterized by single-crystal X-ray analysis. In one case two different conformers were obtained.
