β-Substituted organoalkaline tri- and tetra-anions; preparation, stability, and reactivity

Abstract

New β,γ-, β,β′-disubstituted organometallic trianions of the type C(Ȳ)C(Ȳ′)(8) and C(Ȳ)C(Ȳ′)(18)(Y = or ≠ Y′= O, PhN), β-substituted organodimetallic trianions of the type C(Ph)(25) with alkali-metal cations (Li, Na, and K), and a lithiated tetra-anion of the type C(Ph)C(Ph)(32) are obtained from the corresponding substituted organomercury(II) compounds via low-temperature mercury-alkali metal transmetallation. The starting organomercurials can be obtained by solvomercuriation from suitable unsaturated systems. These polyanion derivatives are stable species only at temperatures in the range –78 to –100°C; at higher temperatures rapid decomposition takes place via either a β-elimination process or proton abstraction from the reaction media. The new polyanionic compounds are characterized by transformation into their deuterio derivatives with deuterium oxide at low temperature. The thermal decomposition of these organometallic intermediates is also reported. The reactivity of the lithiated trianion derived from isopropylaniline (25a) with different agents (ethyl bromide, dimethyl bisulphide, and trimethylchlorosilane) in a successive or simultaneous way is studied; this process occurs in a regioselective manner.