School of Chemistry, University of Hyderabad, Hyderabad 500046, India.
Molecules. 2023 Jun 27;28(13):5014. doi: 10.3390/molecules28135014.
In this study, we report the synthesis of unsubstituted 1,2-benzothiazines through a redox-neutral Rh(III)-catalyzed C-H activation and [4+2]-annulation of S-aryl sulfoximines with vinylene carbonate. Notably, the introduction of an N-protected amino acid ligand significantly enhances the reaction rate. The key aspect of this redox-neutral process is the utilization of vinylene carbonate as an oxidizing acetylene surrogate and an efficient vinylene transfer agent. This vinylene carbonate enables the cyclization with the sulfoximine motifs, successfully forming a diverse array of 1,2-benzothiazine derivatives in moderate to good yields. Importantly, this study highlights the potential of Rh(III)-catalyzed C-H activation and [4+2]-annulation reactions for the synthesis of optically pure 1,2-benzothiazines with high enantiomeric purity.
在这项研究中，我们报告了通过氧化还原中性 Rh(III)催化的 C-H 活化和 S-芳基亚磺酰胺与乙烯基碳酸酯的 [4+2]-环加成反应合成未取代的 1,2-苯并噻嗪。值得注意的是，引入 N-保护氨基酸配体可显著提高反应速率。该氧化还原中性过程的关键方面是利用乙烯基碳酸酯作为氧化乙炔替代物和有效的乙烯基转移试剂。这种乙烯基碳酸酯能够与亚磺酰胺基元环化，成功地以中等至良好的收率形成多种 1,2-苯并噻嗪衍生物。重要的是，这项研究强调了 Rh(III)催化的 C-H 活化和 [4+2]-环加成反应在合成具有高对映体纯度的光学纯 1,2-苯并噻嗪方面的潜力。
