Photoinduced Pd-catalyzed bisfunctionalization of butadienes with a readily available organic halide and a nucleophile represents an emerging and attractive method to assemble versatile alkenes bearing various functional groups at the allylic position. However, enantiocontrol and/or diastereocontrol in the C-C or C-X bond-formation step have not been solved due to the open-shell process. Herein, we present a cascade asymmetric dearomatization reaction of indoles via photoexcited Pd-catalyzed 1,2-biscarbonfunctionalization of 1,3-butadienes, wherein asymmetric control on both the nucleophile and electrophile part is achieved for the first time in photoinduced bisfunctionalization of butadienes. This method delivers structurally novel chiral spiroindolenines bearing two contiguous stereogenic centers with high diastereomeric ratios (up to >20:1 dr) and good to excellent enantiomeric ratios (up to 97:3 er). Experimental and computational studies of the mechanism have confirmed a radical pathway involving excited-state palladium catalysis. The alignment and non-covalent interactions between the substrate and the catalyst were found to be essential for stereocontrol.

中文翻译：

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通过光诱导 Pd 催化丁二烯 1,2-双官能化实现吲哚的催化不对称级联脱芳构化

光诱导的 Pd 催化丁二烯与易于获得的有机卤化物和亲核试剂的双官能化代表了一种新兴且有吸引力的方法，用于组装在烯丙基位置带有各种官能团的多功能烯烃。然而，由于开壳过程，CC或CX键形成步骤中的对映控制和/或非对映控制尚未得到解决。在此，我们提出了通过光激发Pd催化1,3-丁二烯的1,2-双碳官能化进行的吲哚级联不对称脱芳构化反应，其中在丁二烯的光诱导双官能化中首次实现了对亲核试剂和亲电试剂部分的不对称控制。该方法可提供结构新颖的手性螺吲哚，其具有两个连续的立体中心，具有高非对映体比率（高达 >20:1 dr）和良好至优异的对映体比率（高达 97:3 er）。该机制的实验和计算研究已经证实了涉及激发态钯催化的激进途径。发现底物和催化剂之间的排列和非共价相互作用对于立体控制至关重要。