Reductive Transformations, 19(2) Electron‐Transfer‐Induced Dimerization of β‐Alkylstyrenes and the Structures of the Resulting 1,4‐Dilithiobutanes(1)

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Abstract
Upon reaction with lithium β‐alkylstyrenes undergo dimerization of the resulting radical anions with the formation of 2,3‐dialkyl‐1,4‐dilithio‐1,4‐diphenyl butanes 1–8. The structure and the dynamic behavior of these dilithium organyls are investigated by cryoscopic measurements and 1H‐, 13C‐, and 6Li‐NMR spectroscopy at different temperatures. The butane chain adopts a cisoid conformation; the two benzyl subunits chelate one lithium cation while the other is solvent‐separated from the hydrocarbon frame. Depending on the size of the alkyl substituents and the reaction temperature, the dimerization of the radical anions with the formation of two stereogenic centers can proceed diastereoselectively.