Mechanistic study of 7-endo selective radical cyclization of the aryl radical

Mechanistic studies on the novel 7-endo selective radical cyclization were carried out. The reaction afforded three products, 7-endo product, 6-exo product, and reduced product. The distribution of these products was estimated by GC analyses. The 7-endo/6-exo selectivity was almost constant against...

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Bibliographic Details
Published in:Tetrahedron letters 2009-04, Vol.50 (15), p.1727-1730
Main Authors: Kamimura, Akio, Ishihara, Yuriko, So, Masahiro, Hayashi, Takahiro
Format: Article
Language:English
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Summary:Mechanistic studies on the novel 7-endo selective radical cyclization were carried out. The reaction afforded three products, 7-endo product, 6-exo product, and reduced product. The distribution of these products was estimated by GC analyses. The 7-endo/6-exo selectivity was almost constant against variation in the concentration of Bu 3SnH, while the reduction/cyclization ratio was sensitive to the concentration of Bu 3SnH. The reduction/cyclization ratio was mainly affected by the rotational isomeric ratio of the cyclization precursor. Kinetic analyses indicated that the cyclization process should be irreversible, and the rate constant of 7-endo/6-exo radical cyclization was estimated to be about 3.3 × 10 8 s −1 at 80 °C.
ISSN:0040-4039
1873-3581
DOI:10.1016/j.tetlet.2009.01.132