On the use of deuterium isotope effects in chemical synthesis

The decreased kinetic acidity of deuterium relative to hydrogen can be used to gain an advantage in the reductive cyclization of an alkenyllithium species onto a ketone. The intermediate alkenyllithium can add to the carbonyl or abstract an α-proton, giving rise to two products. The yield of the cyclized product can be increased, and the formation of the uncyclized by-product can be suppressed, by replacing the acidic protons with deuterons prior to cyclization.