참고문헌 (12)

1. # NO3 Radicals in Synthesis, part 4; for part 3 see ref.4 

2. 10.1002/9783527615230 1. D. P. Curran, N. A. Porter and B. Giese, Stereochemistry of Radical Reactions, VCH, Weinheim, New York, Basel, Cambridge, Tokyo, 1996. 

   

3. 2. A recent compilation is given in: T. Linker and M. Schmittel, Radikale und Radikalionen in der Organischen Synthese, Wiley-VCH, Weinheim, New York, Chichester, Brisbane, Singapore, Toronto, 1998. 

4. 10.1016/S0040-4020(99)00564-5 3. U. Wille and L. Lietzau, Tetrahedron, 1999, 55, 10119. 

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5. 10.1016/S0040-4020(99)00663-8 4. U. Wille and L. Lietzau, Tetrahedron, 1999, 55, 11465. 

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6. 5. The stereochemistry in the tetrahydrofurans (5) significantly depends on the size (ring members n = 5-7) and the stereochemistry of the anellated ring and also on the substitution pattern of the ether side chain; see ref.4. 

7. 10.1002/jlac.199719970117 6. This solvent system was empirically found to give the best results in the reaction of NO3· with medium sized cycloalkynes and cycloalkynones (see: U. Wille, and C. Plath, Liebigs Ann./Recueil, 1997, 111). Water is required for the cathodic reduction process. The role of ether is not clear, but it may be assumed that the ether solvates the reaction products and protects them, at least in part, from reactions occurring directly at the electrode surfaces. 

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8. 7. For the sake of clarity the hydrogen atoms are omitted. 

9. 8. Significantly higher yields ( > 70%) were obtained by NO3·-induced cyclization of medium sized cycloalkynes and cycloalkynones in the electrochemical cell. This may be due to the strong transannular interactions in these strained carbocycles, because the reactive vinyl radical intermediate obtained after addition of NO3· to the C≡C triple bond is effectively trapped by a very fast, entropically favored tranannular reaction; see ref.6 

10. 9. The assumption of an interfering oxidation step at the stage of the vinyl radical is supported by the finding that alkynyl ethers, in which the cycloalkyl ring is replaced by an aromatic ring, yield 1,2-diketones as exclusive products upon treatment with electrogenerated NO3·. In this reaction a vinyl radical in a benzylic position is intermediately formed, which should be easily oxidized under the applied electrochemical conditions; L. Lietzau, Ph.D. Thesis, Universität Kiel, 2000; U. Wille, manuscript in preparation. 

11. 10.1039/c39870001246 10. E. Baciocchi, T. Del Giacco, S. M. Murgia and G. V. Sebastiani, J. Chem. Soc., Chem. Commun., 1987, 1246; and cited literature. 

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12. 11. CAN: E0 (Ce4+/Ce3+) = 1.61 V vs. NHE; Handbook of Chemistry and Physics, 63rd ed., CRC Press, Boca Raton, Florida, 1982, D-162.