Acyl Radical Addition Onto Aza‐Baylis–Hillman Adducts: A Stereocontrolled Access to 2,3,5‐trisubstituted Pyrrolidines
Advanced synthesis & catalysis(2017)
摘要
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 reduced using bulky (Me3Si)(3)SiH into the corresponding 2,3,5-pyrrolidine exhibiting a trans-trans relative configuration. In contrast, under these conditions, the N-Boc protecting group was removed, leading to the formation of stable dihydropyrroles, which were then hydrogenated with PtO2, leading to 2,3,5-pyrrolidines having a trans-cis relative configuration. When additional ketone or ester groups were present on the pyrrolidine skeleton, further cyclization led to indolizidinones and pyrrolizidines in good overall yield in 4 steps and two-pot operations.
更多查看译文
关键词
acyl addition,aza-Baylis-Hillman reaction,indolizidines,pyrrolizidines,radicals
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要