Unusual temperature dependence of enantioselectivity in asymmetric reductions by chiral NADH models.
[reaction: see text] Unusual stereoselectivity changes, i.e., enhancement and inversion of enantioselectivity with increasing temperature, were observed in the asymmetric reduction of methyl benzoylformate with chiral 1,4-dihydropyridines possessing amino acid residues as ligating chiral auxiliaries. The differential activation parameters, DeltaDeltaH(S-R) and DeltaDeltaS(S-R), obtained from the Eyring plots demonstrate that the entropy term controls the enantiodifferentiating step, accounting for the observed unique temperature dependencies.
Saito
Ryota
R
Department of Materials and Life Science, Seikei University, Musashino, Japan. rsaito@st.seikei.ac.jp
Naruse
Shoichiro
S
Takano
Koji
K
Fukuda
Keiko
K
Katoh
Akira
A
Inoue
Yoshihisa
Y