Ruthenium-catalyzed selective α-deuteration of aliphatic nitrites using D2O

Selective catalytic alpha-deuteration of aliphatic nitriles using deuterium oxide as a deuterium source is reported. A PNP-ruthenium pincer complex catalyzed the alpha-deuteration of aliphatic nitrites including acetonitrile. Efficient deuteration occurred with a low catalyst load (0.2 to 0.5 mol%) and under mild conditions. A [2+2] cycloadduct formation from nitrile functionality and a deprotonated catalytic intermediate, followed by an imine-enamine tautomerization and a H/D exchange between the enamine intermediate and deuterium oxide leading to the selective deuteration at the alpha-position of the nitrile, is proposed as a plausible reaction mechanism.