OXIDATIVE FUNCTIONALIZATION OF ADAMANTANE AND SOME OF ITS DERIVATIVESIN SOLUTION

1,2,4,5-Benzenetetracarbonitrile (TCB) is irradiated in the presence o f adamantane (1) and some of its derivatives. The singlet excited stat e of TCB is a strong oxidant, and there is various evidence, including time-resolved spectroscopy, to prove that SET from the alkane to TCB1 takes place and yields the corresponding radical ions. The adamantan e radical cation deprotonates from the bridgehead position, and the re sulting radical couples with TCB-.. Deprotonation via the radical cati on occurs with a number of substituted adamantanes and remains the exc lusive or predominating reaction also with derivatives containing a po tential electrofugal group, such as one of the following carbocations: t-Bu, CH(2)OMe, CH2OH (notable here is that C-H deprotonation is more efficient than O-H deprotonation). A carboxy group is lost more effic iently than a proton, however. In contrast, detaching of such cations is the main process when the radical cations of substituted adamantane s is produced anodically. This different behavior is explained on the basis of thermochemical calculation and of the different environments experienced by the radical cation in the two cases, viz reaction from the solvated radical cation in the first case and from the substrate a dsorbed on the anode in the latter one. 1-Methoxyadamantane deprotonat es from the methyl group, a reaction explained by the different struct ure of the radical cation. On the other hand, the radical NO3., conven iently produced by photolysis of cerium(IV) ammonium nitrate, reacts b y hydrogen abstraction with selective attack at the bridgehead positio n and little interference by substituents and thus offers a useful way for the selective oxidative functionalization of adamantanes.