MULTINUCLEAR FERROCENES .V. ALLYLIC OXIDATION OF 1-FERROCENYLCYCLOPENTENE

Allylic oxidations of 1-ferrocenylcyclopentene (3) by selenium dioxide, chromium trioxide, mercuric acetate, and lead tetraacetate have been studied with the view toward development of a suitable entry into the syntheses of new multinuclear ferrocenes. All oxidations were attended by fairly high degrees of decomposition, and products were obtained in low yields. In all cases oxidation was shown to take place exclusively α to the side of the double bond bearing the ferrocenyl group. Thus, 2-ferrocenyl-2-cyclopenten-1-one (5), 2-ferrocenyl-3-acetoxy-1-cyclopentene (7), and 2-ferrocenyl-3-ethoxy-1-cyclopentene (8) were the oxidation products. While the unsaturated ketone (5) underwent unexpected conjugate hydride addition with sodium borohydride to give the saturated alcohol, 2-ferrocenyl-1-cyclopentanol (9); the unsaturated alcohol, 2-ferrocenyl-2-cyclopenten-1-ol (6), obtained from hydrolysis of 7, was not reduced upon similar treatment with sodium borohydride. © 1968, American Chemical Society. All rights reserved.