Bis(pentamethylcyclopentadienyl) ketone (1) reacts at low temperatures
with LiAlH4 to form in good yields (pentamethylcyclopentadienyl)metha
nol (2) and its corresponding intramolecular Diels-Alder product 3 in
a ca. 2:1 ratio. The alcohol 2 is separated from the tetracyclic compo
und 3 by crystallisation at -70 degrees C from hexane/pyridine as pyri
dine adduct. The pyridine-free alcohol 2 is available by repeated diss
olving of the adduct in hexane and removal of the volatile components
in vacuo. The alcohol tends to intramolecular [4 + 2]