Samarium(II) Iodide (SmI₂)-Mediated Reductive Ring-Opening of Cyclopropanecarboxylates for Site-Selective Deuteration

Herein, we report a SmI₂-mediated reductive ring-opening deuteration of cyclopropanes bearing carboxylate ester substituents. This method enables the regioselective synthesis of α,γ-dideuterated esters with high deuterium incorporation efficiency. By increasing the stoichiometry of SmI₂/Et₃N/D₂O, the reaction proceeds through a sequential pathway: initial cyclopropane ring-opening followed by ester reduction, yielding α,α,β,δ-tetradeuterated alcohols as the final products. Remarkably, near-quantitative deuterium labeling (>99% D) was achieved in all cases. Furthermore, the strategy was extended to carboxylic acid and amide-substituted cyclopropanes, demonstrating its broad applicability for accessing diverse deuterated molecules. This work significantly expands the toolbox for deuterium-labeled compound synthesis, particularly offering a novel route to tetradeuterated alcohols.