Photochemistry of 1-Isopropylcycloalkyl Aryl Ketones: Ring Size Effects, Medium Effects, and Asymmetric Induction
作者:Wujiong Xia、John R. Scheffer、Mark Botoshansky、Menahem Kaftory
DOI:10.1021/ol050104k
日期:2005.3.1
solid state. Based on X-ray crystallography, these differences in reactivity are attributed to an unusually large distance for 1,4-hydroxybiradical cyclization in the solid state for the n = 0 and 2 ring systems, which leads to predominant reverse hydrogen transfer (rht). Enantiomeric excesses of up to 99% can be achieved in the case of the n = 1 system through the use of the solid-state ionic chiral
[反应:请参见文本]上面显示的n = 0、1和2个酮在溶液中经历杨光环化,但是只有n = 1个类似物以这种方式在固态下反应。根据X射线晶体学,这些反应性差异归因于n = 0和2环系统固态1,4-羟基双自由基环化的距离异常大,这导致主要的反向氢转移(rht)。在n = 1的情况下,通过使用不对称合成的固态离子手性辅助方法,可以实现高达99%的对映体过量。