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2-Acetyl-and 2,2'-diacetyl-9,9'spirobifluorene 1 and 2 were studied by cyclic voltammetry in dimethylformamide. The corresponding anion radicals show remarkable persistency in aprotic D M F. The (apparent) standard potentials are P = -1.77 V (SCE) and €" = -1.75 V for the (quasireversible) reduction of 1 and 2 to the anion radicals, respectively. Preparative electrolysis of 1 in DMF-Et,NCIO, (0.1 mol dm-3), with excess acetic acid as proton donor, furnished alcohol 3 and the diastereoisomeric pinacols 5 and 6, which were isolated and characterized. The diastereoisomeric excess, de, as evaluated (NMR) on the electrolyzed solution was only slightly in favour of the ( + ) compound. Spectroscopic properties of compounds 1-6 are, inter alia, the 13C NMR chemical shift for the spiro-carbon at 6 = 65.9 (TMS), and the fragmentation patterns in the mass spectra, with the 100% relative abundance of the molecular-ion M'+ in the case of the aromatic ketones 1 and 2. Some comments on the influence of conformations of 5 and 6 and of the presence of an intramolecular hydrogenbond in some intermediates and products are also presented.Molecules that contain two halves fixed at a 90" angle uiu a 0bonded network, each half bearing an aromatic, conjugated (proconducting) structure are now actively studied. In fact, they may be used as building blocks for molecular electronic based computing instruments, and, generally, for assembling single compounds that function as a self-contained electronic system. For this reason, we decided to study 9,9'-~pirobifluorene,~ its 2acetyl and 2,2'-diacetyl derivative^.^^' Additional interest in Paper 3/02480F

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The electrochemical reduction of ethyl a-bromophenylacetate (1 ) and methyl 2-bromo-2-phenylpropanoate (5) in dry dimethylformamide on a vitreous carbon electrode has been studied. Dimeric products are formed as a consequence of controlled potential electrolysis of ( 1) and ( 5) on a reticulated vitreous carbon electrode. By this route, meso-and DL-diethyl2,3-diphenylsuccinate and -dimethyl 2,3-dimethyl-2,3-diphenylsuccinate are obtained from ester (1) and (5), respectively. A triester is also obtained among the products. The spectral data (n.m.r., mass spectra) show the structure of this triester to be almost certainly MeO2C-CMePh.C6H4.CMeCO2Me-CMePh-C02Me (9). To explain the results, a mechanism is proposed, involving the formation of dimer (10) as an intermediate.