Synthesis of 1,1'-Biindenes and 3,3'-Biindenes

Article abstract of DOI:10.1055/s-1987-27892

1,1'-Biindenes 2, conveniently prepared from indenyllithiums by treatment with copper(II) chloride, are quantitatively isomerized to the corresponding 3,3'-biindenes 3 by heating in triethylamine/pyridine.Both d,l and meso isomers of 2 react to form 3; the rate of reaction of the meso form, however, is substantially faster.