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PET oxidation of PhSe-SePh and R-CH2-Se-R' generates an electrophilic selenium and carbocationic species, respectively. Similarly, one-electron reductive activations of R-CH2-Se-R' and R3-Si-SePh produces alkyl and alkyl silyl radicals, respectively. The possible structure of the reactive electrophilic selenium species is discussed and the fragmentation of -C-Se]*+ is found to be nucleophilic-assisted. These mechanistically interesting studies have been shown to be useful in initiating various synthetic reactions.

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Vicinal quaternary and tertiary stereocenters of the 5,10b‐phenanthridine skeleton 1 are constructed simultaneously in one step by the [3+2]‐cycloaddition of non‐stabilized azomethine ylide 9, generated by sequential double desilylation of 10 utilizing silver(I) fluoride as a one‐electron oxidant. The regio‐ as well as stereochemical origin of this cycloaddition reaction is explained through a favorable transition state 9″. The strategy is successfully applied for the total synthesis of the biologically active alkaloids (±)‐maritidine (1a), (±)‐crinine (1b), and their analogues (1d, 1e, and 1f).

PET activation of cyclic t-amines, utilizing 9, 10-dicyanonaphthalene (DCN) as light absorbing electron acceptor in aqueous acetonitrile solution, leads to the generation of iminium cation intermediate involving electron -proton -electron (E-P-E) transfer sequence. Iminium cation generation is found to be highly regiospecific and depends upon the kinetic acidity which is subject to the stereoelectronic factor of the α -C-H proton of the unymmetrical t-amines. Tetrahydro-1, 3-oxazines (6) are synthesized in complete regio-and stereoselective manner from the PET activation of the substrates of type 4. Nucleophilic alkylation of 6 by alkyl Grignard reagents provides cis-α, α'-dialkyl cyclic amines (8). Similarly, chiral perhydropyrido[2,1-b][1, 3, 4]-oxadiazinone (11) is synthesized as a precursor for the synthesis of optically active α-alkyl piperidines. Both enantiomers of hemlock alkaloid coniine (13) are also synthesized. Furthermore, to broaden the scope of these reactions, precursor 16 is designed for the synthesis of various α -amino acids and their N-alkyl derivatives.