Surmounting Byproduct Inhibition in an Intermolecular Catalytic Asymmetric Alkene Bromoesterification Reaction as Revealed by Kinetic Profiling

Kinetic profiling has shown that a (DHQD)₂PHAL-catalyzed intermolecular asymmetric alkene bromoesterification reaction is inhibited by primary amides, imides, hydantoins, and secondary cyclic amides, which are byproducts of common stoichiometric bromenium ion sources. Two approaches to resolving the inhibition are presented, enabling the (DHQD)₂PHAL loading to be dropped from 10 to 1 mol % while maintaining high bromoester conversions in 8 h or less. Iterative post-reaction recrystallizations enabled a homochiral bromonaphthoate ester to be synthesized using only 1 mol % (DHQD)₂PHAL.