Development of catalytic asymmetric synthesis of indanones via an enantioselective 1,1-carbene migratory insertion/carbopalladation cascade is achieved. In this enantioselective reaction, the in situ generated enantioenriched unstable η3-benzyl Pd species is trapped by an intramolecular olefin to access chiral indanone scaffolds at room temperature with yields up to 96% and e.r. up to 96:4. This methodology is unique in the generation of carbenes from N-tosylhydrazones at room temperature and tolerance for diverse functional groups with catalyst loading as low as 3 mol % and ligand loading of 9 mol %. The catalytic system is found to exhibit asymmetric amplification, giving insight into the structure of the active catalytic species and the catalytic cycle involved. Also, a photokinetic study of the isomerization of the pendant alkene in the synthesized indanone core is reported.
Nair et al. (Fri,) studied this question.