Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
J Am Chem Soc. 2009 Oct 28;131(42):15492-500. doi: 10.1021/ja9066282.
Radical cyclizations (Bu(3)SnH, Et(3)B/air, rt) of racemic alpha-halo-ortho-alkenyl anilides provide 3,4-dihydroquinolin-2-ones in high yield. Cyclizations of enantioenriched precursors occur in similarly high yields and with transfer of axial chirality to the new stereocenter of the products with exceptionally high fidelity (often >95%). Single and tandem cyclizations of alpha-halo-ortho-alkenyl anilides bearing an additional substituent on the alpha-carbon occur with high chirality transfer and high diastereoselectivity. Straightforward models are proposed to interpret both the chirality transfer and diastereoselectivity aspects. These first examples of an approach for axial chiral transfer from a reactive species in the amide to an acceptor suggest broad potential for extension both within and beyond radical reactions.
通过立体选择性自由基环化反应（Bu(3)SnH，Et(3)B/空气，室温），可以高收率地得到外消旋的α-卤代-邻烯基苯胺衍生物的 3,4-二氢喹啉-2-酮。通过对映体富集的前体进行环化反应，可以以类似的高收率得到产物，并且新的立体中心的轴手性转移具有极高的保真度（通常>95%）。带有额外取代基的α-卤代-邻烯基苯胺衍生物的单环化和串联环化反应，具有高的手性转移和高的非对映选择性。提出了简单的模型来解释手性转移和非对映选择性的两个方面。这些首例从酰胺中的反应性物种到受体的轴手性转移方法的实例表明，这种方法在自由基反应内外都具有广泛的扩展潜力。
