10.1021/ja070516j
The research focuses on the enantioselective Tsuji allylation reaction, which is a method used in organometallic chemistry to synthesize enantioenriched quaternary stereocenters without the need for stoichiometric chiral reagents. The purpose of the study is to understand and optimize the reaction mechanism that leads to high enantioselectivity, particularly using (S)-t-Bu-phosphinooxazoline (PHOX) ligands. The researchers conducted quantum chemistry calculations to investigate possible mechanisms and found evidence supporting an inner-sphere mechanism, which is lower in energy than the external attack mechanism previously thought to be dominant. This discovery contradicts previous results involving soft enolate nucleophiles and prochiral allyl fragments, and suggests that high enantioselectivity can be achieved without prochiral allyl fragments. The chemicals used in the process include Pd(0) complexes, enol carbonates, ketone enolates, and the PHOX ligand, which are key to the formation of the allylated products with high yields and enantiomeric excess.
