The first catalytic asymmetric allylation of imines with the tetraallylsilane-TBAF-MeOH system, using the chiral bis-pi-allylpalladium complex.
The asymmetric allylation of imines with use of catalytic transition metals with chiral ligands should be a new frontier of the enantioselective C-C bond formation. So far allyltrimethylsilane, allyltrichlorosilane, and allyltrimethoxysilane have been commonly employed with use of either silane activators or dual silane-imine activators. However, tetraallylsilane is untouched in the allylation of aldimines. The first allylation of aldimines with the tetraallylsilane-TBAF-MeOH system with use of the bis-pi-allylpalladium catalyst under catalytic, non-Lewis acid, essentially neutral and very mild reaction conditions has been achieved. The reaction is triggered by dual activation/promotion by TBAF and MeOH in which the fluoride anion activates the C-Si bond cleavage and MeOH promotes the facile protonation of intermediate palladium amide. Thus, the synthesis of chiral homoallylamines is achieved in a shorter reaction time and higher yields and enantioselectivities through an efficient, general, and reproducible allylation protocol for imines.
Fernandes
Rodney A
RA
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
Yamamoto
Yoshinori
Y