Synthesis of Bicyclic <i>N</i>-Heterocycles via Photoredox Cycloaddition of Imino-Alkynes and Imino-Alkenes
作者:Hyeonji Oh、Bokyeong Ryou、Jinhwi Park、Minju Kim、Jun-Ho Choi、Cheol-Min Park
DOI:10.1021/acscatal.1c03919
日期:2021.11.5
we report the synthesis of pyrrolizidinones based on intramolecular imine-alkyne [2 + 2] cycloaddition under visible light photocatalysis. This redox-neutral reaction involves formal imine-alkyne metathesis followed by redox-mediated annulation with concomitant rearrangement. In contrast, the use of imino-alkenes provides dihyro-1,4-oxazines via an alternative [4 + 2] cycloaddition pathway. The proposed
环加成反应在原子和步骤经济性方面为构建各种碳环和杂环提供了巨大的优势。虽然最近基于敏化可见光光催化的发展允许通过亚胺-烯烃 [2 + 2] 环加成反应合成氮杂环丁烷,但在可见光光催化下亚胺-炔烃 [2 + 2] 环加成反应尚未见报道。在这方面,我们报告了在可见光光催化下基于分子内亚胺-炔 [2 + 2] 环加成反应的吡咯里西酮的合成。这种氧化还原中性反应涉及正式的亚胺-炔烃复分解,然后是氧化还原介导的环化和伴随的重排。相比之下,亚氨基烯烃的使用通过替代的 [4 + 2] 环加成途径提供二氢-1,4-恶嗪。