Ketyl-Type Radicals from Cyclic and Acyclic Esters are Stabilized by SmI2(H2O)n: The Role of SmI2(H2O)n in Post-Electron Transfer Steps

摘要: Mechanistic details pertaining to the SmI2–H2O-mediated reduction and reductive coupling of 6-membered lactones, first class simple unactivated carboxylic acid derivatives that had long been thought lie outside reducing range SmI2, have elucidated. Our results provide new experimental evidence water enables productive electron transfer from Sm(II) by stabilization radical anion intermediate rather than solely promoting as originally proposed. Notably, these studies suggest all reactions involving generation ketyl-type radicals with SmI2 occur under a unified mechanism based on thermodynamic control second step, thus providing blueprint for development broad novel chemoselective transformations via open-shell pathways.