Acyl Radical Addition onto Aza-Baylis-Hillman Adducts: A Stereocontrolled Access to 2,3,5-Trisubstituted Pyrrolidines
作者:Simon Grélaud、Jonathan Lusseau、Stéphane Massip、Yannick Landais
DOI:10.1002/adsc.201700362
日期:2017.7.17
Free‐radical addition of acyl radicals to chiral aza‐Baylis–Hillman adducts was shown to afford the corresponding 1,4‐amino ketones in good yields and good 1,2‐stereocontrol. These ketones were then elaborated further using conditions varying as a function of the nature of the N‐protecting group. Robust N–Ts protection thus allowed the formation, under acidic conditions, of a cyclic iminium which was
自由基在手性氮杂-Baylis-Hillman加合物上的自由基自由基加成反应可提供相应的1,4-氨基酮,收率高,1,2-立体控制良好。然后使用根据N保护基的性质而变化的条件进一步修饰这些酮。因此,在酸性条件下,稳健的N-Ts保护可以形成环状亚胺,使用大体积(Me 3 Si)3 SiH可以将其还原成相应的2,3,5-吡咯烷,表现出反-反相对构型。相反,在这些条件下,N-Boc保护基被除去,导致形成稳定的二氢吡咯,然后将其与PtO 2氢化,生成具有3,3,5-吡咯烷酮的反式相对配置。当吡咯烷骨架上存在其他酮或酯基团时,进一步的环化将导致吲哚并二酮和吡咯烷核苷在4步和两锅操作中具有良好的总收率。