Polylithiumorganic compounds. Part 29: C,C Bond cleavage of phenyl substituted and strained carbocycles using lithium metal

Non-Deprotonating Methodologies for Organolithium Reagents Starting from Non-Halogenated Materials. Part 2: Transmetallation and Addition to Multiple Bonds

“…This intermediate 250 gave S E producing compounds 251 or 252 depending on the electrophiles: whereas a sterically non-hindered carbonylic compound produced exclusively the regioisomer 251, a bulky ketone or a silyl reagent produced the isomer 252. Employing ultrasounds for the lithium activation instead of an electron carrier led to the formation of the same intermediates, but the dimerisation product 253 was the only product observed (Scheme 65) [156]. Similarly, 1,1-diphenylcyclopropane gave reductive ring opening under DTBB catalysed lithiation, and the subsequent reaction with several electrophiles produced mixtures of mono-and disubstituted diphenylpropanes [155].…”

“…D 2 O, Bu t CHO, Me 2 CO, Et 2 CO, Pr n 2 CO, Pr i 2 CO, Bu t 2 CO, Ph 2 CO, (CH 2 ) 5 CO, 2-adamantanone, CH 2 =CMeCH 2 Cl, Me 3 SiCl, Me 3 SiCH 2 Cl] allowed the regioselective preparation of the corresponding 1,3-difunctionalised-2-(diphenylmethylene)propane derivatives 255 [157]. Phenylspiropentane and 1,1-diphenylspiropentane reacted with lithium generating, after ring opening and rearrangement, the corresponding dilithium derivative 256, together with the organolithium 257 resulting from a lithium hydride elimination [156]. Additionally, the reductive ring opening of various bicyclobutanes with lithium metal was also studied.…”

Recent developments in homobimetallic reagents and catalysts for organic synthesis

“…As shown in Chart 1, cleavage always occurred at the carbon-carbon bond next to the phenyl group [38].…”

Reductive Lithiation and Multilithiated Compounds in Synthesis

“…Although the reductive metallation of phenyl-and 1,1-diphenylsubstituted cyclopropanes led to the formation of relatively unstable diorganometals affording, upon trapping with electrophiles, relatively complex reaction mixtures [27,28], better results were reported in the reductive lithiation of 2,2-diphenylmethylenecyclopropane, 27 [29]. This cyclopropane derivative underwent a highly regioselective cleavage reaction, leading to the formation of a mixture of dianionic intermediates, 28 and 29, as evidenced by quenching the reaction mixture with H 2 O or D 2 O.…”