作者:Akio Kamimura、Yuriko Ishihara、Masahiro So、Takahiro Hayashi
DOI:10.1016/j.tetlet.2009.01.132
日期:2009.4
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 Bu3SnH, while the reduction/cyclization ratio was sensitive to the concentration of Bu3SnH. 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 x 10(8) s (1) at 80 degrees C. (C) 2009 Elsevier Ltd. All rights reserved.