Iron-Ligand Coordination in Tandem Radical Cyclizations: Synthesis of Benzo[b]thiophenes by a One-pot Reaction of Iron 1,3-Diketone Complexes with 2-Thiosalicylic Acids
作者:Sharon Lai-Fung Chan、Kam-Hung Low、Chen Yang、Samantha Hui-Fung Cheung、Chi-Ming Che
DOI:10.1002/chem.201100377
日期:2011.4.18
Iron—the mediator: 1,3‐Diketone ligands coordinated to iron undergo unprecedented tandem reactions with 2‐thiosalicylic acids to give 2‐substituted 3‐hydroxylbenzo[b]thiophenes in up to 98 % yield. A similar reaction with 2‐mercaptonicotinic acid gave a thieno[2,3‐b]pyridine derivative in 72 % yield (see scheme). A mechanism involving redox transformation and tandem radical cyclization of the coordinated
铁—介体:与铁配位的1,3-二酮配体与2-硫代水杨酸进行空前的串联反应,生成2-取代的3-羟基苯并[ b ]噻吩,收率高达98%。与2-巯基烟碱酸的类似反应得到噻吩并[2,3- b ]吡啶衍生物,产率为72%(参见方案)。提出了涉及配体的氧化还原转化和串联自由基环化的机理。