Enantioselective Catalytic α-Alkylation of Aldehydes via an S N 1 Pathway

Primary aminothiourea derivatives are shown to catalyze enantioselective alkylation of alpha-arylpriopionaldehdyes with diarylbromomethane. Evidence for a stepwise, S(N)1 mechanism in the substitution reaction induced by anion binding to the catalyst is provided by catalyst structure-activity studies, kinetic isotope effects, linear free-energy relationship studies, and competition experiments.