exo-selective asymmetric Diels-Alder reaction catalyzed by diamine salts as organocatalysts.
[reaction: see text] A novel binaphthyl-based diamine (R)-2 was designed and synthesized. A protonic acid-(R)-2 salt catalyst has the advantage of exhibiting unprecedented high exo selectivity in the asymmetric Diels-Alder reaction of alpha,beta-unsaturated aldehydes. For instance, the reaction between cinnamaldehyde and cyclopentadiene in the presence of 12 mol % of binaphthyl-based diamine (R)-2 and 10 mol % of p-TsOH.H(2)O in alpha,alpha,alpha-trifluorotoluene at -20 degrees C gave the corresponding exo cycloadduct with 92% ee as a major diastereomer (exo/endo = 13/1).
Kano
Taichi
T
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Japan.
Tanaka
Youhei
Y
Maruoka
Keiji
K