[1.1]FERROCENOPHANES IN SOLUTION - ANTI OR SYN ISOMERS

Carbon-bridged [1.1]ferrocenophanes have generally been assumed to hav e syn structures, since anti isomers have been considered to be too st rained. The recent discovery that such compounds may crystallize as an ti isomers raises the question of whether the compounds prefer anti or syn conformations in solution. The synthesis of beta-acetyl-[1.1]ferr ocenophane (1) and its investigation by H-1,H-1-NOESY are reported. Co mpound 1 was found to be a rapidly equilibrating mixture of syn isomer s in CDCl3 at 22 degrees C.