exo-Selective asymmetric Diels-Alder reaction catalyzed by diamine salts as organocatalysts.
An organocatalyst formed from a binaphthyl-substituted diamine and trifluoromethanesulfonic acid exhibited unprecedented levels of exo selectivity in the Diels-Alder reaction of alpha,beta-unsaturated aldehydes with cyclopentadiene. A novel axially chiral diamine was also designed as an organocatalyst for an asymmetric variant of this reaction, in which the desired cycloadducts were formed with high diastereo- and enantioselectivities. The highest diastereoselectivity observed was greater than 20:1 in favor of the exo cycloadduct in the asymmetric Diels-Alder reaction of crotonaldehyde with cyclopentadiene.
Kano
Taichi
T
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
Tanaka
Youhei
Y
Maruoka
Keiji
K