Asymmetric protonation of enolic species: dramatic increase in the selectivity with temperature and unexpected Eyring diagram

TLDR: In this article, the palladium-induced cleavage of β-ketosters and enol carbonates derived from α-alkylated 1-indanones and 1-tetralones in the presence of (+)- endo-2-hydroxy- endo -3-aminobornane led to (R )- α -alkylation of indanone and tetralones with a large increase in the enantioselectiviy (up to 38-40%) when the reaction temperature was raised from 21 to 45-70°C

Abstract: The palladium-induced cleavage of β-ketosters and enol carbonates derived from α-alkylated 1-indanones and 1-tetralones in the presence of (+)- endo -2-hydroxy- endo -3-aminobornane led to ( R )- α -alkylated indanones and tetralones with a large increase in the enantioselectiviy (up to 38–40%) when the reaction temperature was raised from 21 to 45–70°C. Thus, enantiopure 2-methyl-1-indanone was obtained at 52°C. More than one inversion temperature has appeared in plotting the corresponding Eyring diagrams.