| Abstract
| - 1,2,4,5-Benzenetetracarbonitrile (TCB) is irradiated in thepresence of adamantane (1) and someof its derivatives. The singlet excited state of TCB is a strongoxidant, and there is various evidence,including time-resolved spectroscopy, to prove that SET from the alkaneto TCB1* takes place andyields the corresponding radical ions. The adamantane radicalcation deprotonates from thebridgehead position, and the resulting radical couples withTCB-•. Deprotonation via theradicalcation occurs with a number of substituted adamantanes and remains theexclusive or predominating reaction also with derivatives containing a potential electrofugalgroup, such as one of thefollowing carbocations: t-Bu, CH2OMe,CH2OH (notable here is that C−H deprotonation ismoreefficient than O−H deprotonation). A carboxy group is lost moreefficiently than a proton, however.In contrast, detaching of such cations is the main process whenthe radical cations of substitutedadamantanes is produced anodically. This different behavior isexplained on the basis ofthermochemical calculation and of the different environmentsexperienced by the radical cation inthe two cases, viz reaction from the solvated radical cation in thefirst case and from the substrateadsorbed on the anode in the latter one. 1-Methoxyadamantanedeprotonates from the methylgroup, a reaction explained by the different structure of the radicalcation. On the other hand, theradical NO3•, conveniently produced byphotolysis of cerium(IV) ammonium nitrate, reacts byhydrogen abstraction with selective attack at the bridgehead positionand little interference bysubstituents and thus offers a useful way for the selective oxidativefunctionalization of adamantanes.
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