Spirocyclohexa-2,5-dienes were shown to rearrange at -40 degrees C, when treated with 1 equiv of LDA. Alkyl halides and aldehydes then reacted with the resulting phenanthridinone lithium enolate intermediates, with distinct regioselectivities and high diastereocontrol, to afford functionalized dearomatized phenanthridinones which were elaborated further. A mechanistic scheme involving a diisopropylamine-mediated
aldehydes. Interestingly, alkylation and hydroxyalkylation occurred with different regiocontrol. DFT calculations were performed that rationalize the observed skeleton rearrangement, emphasizing the role of LDA/diisopropylamine in this rearrangement. The proposed mechanism thus relies on a thermodynamically driven diisopropylamine‐mediated proton transfer with the cleavage of the diene–amide CO bond
介绍了螺环己基2,5-二烯恶吲哚的制备和功能化。标题化合物的螺环核心是通过SmI 2介导的芳基碘代苯甲酰胺的环化反应而安装的。然后用CF 3 CO 3 H进行环氧化,并显示出高水平的非对映异构控制:该试剂接近二烯部分合成酰胺基上的氢键很可能是由于酰胺的CO键和过酸氢之间存在氢键所致。然后检查了螺环己基2,5-二烯恶吲哚的碳负离子官能化,从而将应变的螺环系统空前地重排为脱芳香族化的菲啶酮。在-40°C下用二异丙基氨基化锂(LDA)处理后,二烯重排以提供一个菲啶酮锂烯醇盐中间体,该中间体被亲电子试剂(包括卤代烷和醛)捕获。有趣的是,在不同的区域控制下发生烷基化和羟烷基化。进行DFT计算以合理化观察到的骨架重排,强调LDA /二异丙胺在这种重排中的作用。