Laboratory of Sustainable Synthesis, Department of Chemistry, SRM Institute of Science and Technology, Kattankulatur, 603 203, Chengalpet (Dt), Tamilnadu, India.
School of Chemistry, University of Hyderabad, P.O. Central University, 500046, Hyderabad, India.
Chem Asian J. 2022 Nov 16;17(22):e202200878. doi: 10.1002/asia.202200878. Epub 2022 Sep 22.
Herein, visible light mediated organophoto redox catalysed simple and convenient method for the α-benzylation and α-oxygenation of tertiary amines is demonstrated. Synthesis of novel thiophenol based donor acceptor organophotoredox catalysts 4 a-4 d were investigated along with commercial catalyst 4-CzIPN (4 e). A diverse biologically active α-benzylated tetrahydroisoquinolines and natural products such as (±)-Norlaudanosine, (±)-laudanosine and (±)-xylopinine have been synthesized under the optimized conditions in yields ranging from from 62-91%. Exploitation of synthesized α-benzylated compound using present phtoredox catalyzed conditions gave rise to dehydyrogenative benzylic oxidation product under oxygen atmosphere which is known to display biologically and structurally important properties. Also, various N-protected tertiary amines were found to be suitable for the α-oxygenation reactions using catalyst 4 e and resulted in good yields (61-85%).
本文展示了一种可见光介导的有机光氧化还原催化的简便方法，用于叔胺的α-苄基化和α-氧化。还研究了新型基于噻吩酚的给体-受体有机光氧化还原催化剂 4a-4d 以及商业催化剂 4-CzIPN（4e）。在优化条件下，从 62-91%的收率合成了多种具有生物活性的α-苄基化四氢异喹啉和天然产物，如（±）-诺劳丹宁、（±）劳丹宁和（±）-木菠萝碱。利用本光氧化还原催化条件下合成的α-苄基化合物进行的开发，在氧气气氛下产生了已知具有生物和结构重要性的脱氢苄基氧化产物。此外，还发现各种 N-保护的叔胺适用于使用催化剂 4e 的α-氧化反应，并得到了良好的收率（61-85%）。
