Suga Takuya, Takahashi Yuuki, Miki Chinatsu, Ukaji Yutaka
Division of Material Chemistry, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa, 920-1192, Japan.
Angew Chem Int Ed Engl. 2022 Mar 1;61(10):e202112533. doi: 10.1002/anie.202112533. Epub 2022 Jan 24.
Low-valent Ti-mediated homolytic C-O bond cleavage offers unified access to carbon radicals from ubiquitous non-activated tertiary, secondary, and even primary alcohols. In contrast to the representative Ti reagents, which were ineffective for this purpose, "TiCl (cat)"/Zn (cat=catecholate) was found to be specifically active. This method was applied to the addition reactions of radicals to alkenes and exhibited high generality and yields. More than 50 combinations were examined. The excellent cost-efficiency and accessibility of "TiCl (cat)"/Zn further enhance its applicability. Control experiments proved the presence of a carbon radical intermediate and excluded the pathway via alkyl chlorides. Further mechanistic study indicated that the 1 : 2 complex of alkoxide (R-O ) and Ti is an active species in the C-O cleavage.
低价钛介导的均裂C-O键裂解为从普遍存在的未活化叔醇、仲醇甚至伯醇获取碳自由基提供了统一的途径。与为此目的无效的代表性钛试剂相比,发现“TiCl (cat)”/Zn(cat = 儿茶酚盐)具有特殊的活性。该方法应用于自由基与烯烃的加成反应,具有很高的通用性和产率。研究了50多种组合。“TiCl (cat)”/Zn出色的成本效益和可及性进一步提高了其适用性。对照实验证明了碳自由基中间体的存在,并排除了通过烷基氯的途径。进一步的机理研究表明,醇盐(R-O )与Ti的1:2配合物是C-O裂解中的活性物种。