Photoredox radical conjugate addition of dithiane-2-carboxylate promoted by an iridium(<scp>iii</scp>) phenyl-tetrazole complex: a formal radical methylation of Michael acceptors
作者:Andrea Gualandi、Elia Matteucci、Filippo Monti、Andrea Baschieri、Nicola Armaroli、Letizia Sambri、Pier Giorgio Cozzi
DOI:10.1039/c6sc03374a
日期:——
2′-bipyridine) is shown to be a versatile catalyst for a new photocatalytic Michael reaction. Under light irradiation in the presence of 2, a dithiane 2-carboxylic acid, obtained by simple hydrolysis of a commercially available ethyl ester, generates a 1,3-dithiane radical capable of performing addition to a variety of Michael acceptors (e.g., unsaturated ketones, esters, amides and malonates). This broad
易于获得的铱(III)苯基-四唑络合物([Ir(ptrz)2(t Bu-bpy)] +,2 ; Hptrz = 2-甲基-5-苯基-四唑; t Bu-bpy = 4,4' -二叔丁基-2,2'-联吡啶被证明是一种新的光催化迈克尔反应的多用途催化剂。在2的存在下,在光照射下,通过简单水解可商购的乙酯获得的二噻吩2-羧酸会生成1,3-二噻吩基,该自由基能够加成至多种Michael受体(例如,,不饱和酮,酯,酰胺和丙二酸酯)。这种高产率的宽范围反应是难以捉摸的甲基的正式光-氧化还原加成,并且获得的加合物可以是多种功能化产物的起始原料。催化剂2的激发态氧化电势允许仅由α-杂取代的羧酸盐选择性地形成自由基。这种金属配合物的化学修饰可以调节电化学性能,从而为新的高度选择性的催化光氧化反应开辟了道路。