Beschreibung:
<jats:title>Abstract</jats:title><jats:p>(<jats:italic>Z)</jats:italic>‐2‐(2‐Methylphenyl)‐1,2‐diphenylvinyllithium <jats:bold>(1)</jats:bold> isomerizes in THF solution to give 1‐[2‐(lithiomethyl)phenyl]‐1,2‐diphenylethene <jats:bold>(2)</jats:bold>. Although <jats:bold>2</jats:bold> cannot be observed directly in this case, its intermediacy becomes evident from the independent preparation by metallation of 1‐[2‐(ethoxymethyl)phenyl]‐ <jats:bold>(5)</jats:bold> and 1‐(2‐methylphenyl)‐1,2‐diphenylethene <jats:bold>(7)</jats:bold>, with formation of the same sequential products from all three sources. <jats:bold>2</jats:bold> cyclizes by reversible attack on the <jats:italic>syn</jats:italic>‐phenyl group to give a cyclohexadienide anion <jats:bold>3</jats:bold> containing a seven‐membered ring. <jats:bold>3</jats:bold> exhibits <jats:sup>1</jats:sup>H NMR coalescence phenomena and rearranges under thermodynamic control to the 1,2‐diphenyl‐1‐indanide anion <jats:bold>10</jats:bold>.</jats:p>