Stabilized Chiral Organic Material Containing BINAP Oxide Units as a Heterogeneous Asymmetric Organocatalyst for Allylation of Aldehydes

Abstract

Condensation of BINAPO-(PhCHO) 2 and 1,3,5tris(4-aminophenyl)benzene (TAPB) results in a new imine-based chiral organic material (COM) that can be further postfunctionalized through reductive transformation of imine linkers to amines. While the imine-based material does not show the necessary stability to be used as a heterogeneous catalyst, the reduced amine-linked framework can be efficiently employed in asymmetric allylation of different aromatic aldehydes. Yields and enantiomeric excesses found are comparable to those observed for the molecular BINAP oxide catalyst, but importantly, the aminebased material also permits its recyclability.

Chiral Porous Organic Frameworks: Synthesis, Chiroptical Properties, and Asymmetric Organocatalytic Applications

“…Phosphine oxides offer an additional organocatalytic platform for asymmetric catalysis as a result of their high nucleophilicity, which enables their function as Lewis bases. As an example of the application of this concept in heterogeneous asymmetric organocatalysis, Mas-Ballesté and coworkers have recently designed a chiral organic material (COM) based on (R)-BINAP Oxide [88]. This material was successfully applied in the allylation reaction of aromatic aldehydes with allyltrichlorosilane (Scheme 17), leading to yields and enantiomeric excesses competing with those reported previously in literature for the molecular (R)-BINAP Oxide catalyst (54% yield and 42% ee for benzaldehyde allylation).…”