Key Role of Ti(IV) in the Selective Radical−Radical Cross-Coupling Mediated by the Ingold-Fischer Effect
作者:Raffaele Spaccini、Nadia Pastori、Angelo Clerici、Carlo Punta、Ombretta Porta
DOI:10.1021/ja807613q
日期:2008.12.31
We report an innovative approach for the selective synthesis of polyfunctional derivatives by cross-combination of different radicals generated under mild conditions. The coordinating effect of Ti(IV) plays a key role in the reaction mechanism: due to its chelating action on the hydroxyl groups, it promotes the homolytic C-C bond cleavage of alpha,beta-dihydroxy ketones by enhancing the captodative
我们报告了一种通过在温和条件下产生的不同自由基的交叉组合选择性合成多功能衍生物的创新方法。Ti(IV) 的配位作用在反应机理中起关键作用:由于其对羟基的螯合作用,它通过增强捕获效应和随后的稳定性来促进 α,β-二羟基酮的均裂 CC 键断裂相应的α-羟基-α-羰基自由基。当这些自由基在化学计量的 TiCl(4) 和 2,2'-偶氮双异丁腈 (AIBN) 的存在下产生时,作为 α-氰基异丙基自由基的来源,选择性自由基-自由基交叉偶联是观察到,以高产率提供相应的β-羟基腈。