TOPOSPECIFIC REACTIONS OF A [5.5.5.5]FENESTRADIENE WITH [FE-2(CO)(9)]

N,N-Dimethylformamide dimethyl acetal transforms an allylic OH group, which is part of a tetracyclic hydrocarbon in a unique elimination rea ction into a [5.5.5.5]fenestradiene (2b --> 4). In topologically selec tive reactions of this diene 3 with [Fe-2(CO)(9)], the [Fe(CO)(4)(eta( 2)-diene)] and the (Fe(CO)(3)(eta(4)-diene)] complexes 8 and 9, respec tively, are formed by complexation on one side of the diene moiety, wh ereas complexation on the other side leads to a [Fe(CO)(2)(Cp)] comple x 10.