Precision Deuteration Using Cu-Catalyzed Transfer Hydrodeuteration to Access Small Molecules Deuterated at the Benzylic Position

A highly regio- and chemoselective Cu-catalyzed aryl
alkyne transfer
hydrodeuteration to access a diverse scope of aryl alkanes precisely
deuterated at the benzylic position is described. The reaction benefits
from a high degree of regiocontrol in the alkyne hydrocupration step,
leading to the highest selectivities reported to date for an alkyne
transfer hydrodeuteration reaction. Only trace isotopic impurities
are formed under this protocol, and analysis of an isolated product
by molecular rotational resonance spectroscopy confirms that high
isotopic purity products can be generated from readily accessible
aryl alkyne substrates.