A Pyrene‐Linked Cavity within a β‐Barrel Protein Promotes an Asymmetric Diels–Alder Reaction. Issue 44 (31st August 2017) - Himiyama, Tomoki
Abstract: A unique π‐expanded reaction cavity tethering a polycyclic moiety which provides a platform for substrate binding was constructed within the robust β‐barrel structure of nitrobindin (NB). NB variants with cavities of different sizes and shapes are coupled with N ‐(1‐pyrenyl)maleimide (Pyr ) to prepare a series of NB‐Pyr conjugates. The orientation of the pyrene moiety is fixed within the cavity by the coupling reaction. The fluorescent quenching analysis of NB‐Pyr indicates that azachalcone (aza ), which is a dienophile for a Diels–Alder (DA) reaction, is efficiently incorporated within the pyrene‐linked reaction cavity by the aromatic interaction. The DA reaction between aza and cyclopentadiene proceeds within the reaction cavity of NB‐Pyr in the presence of Cu II ion in high yield and high enantio‐ and regioselectivity. Abstract : Selectivity by the barrel‐load : A reaction cavity with a tethered polycyclic pyrene moiety, which acts as a platform to provide aromatic interactions, is constructed within the rigid scaffold of the β‐barrel nitrobindin protein. An asymmetric Diels–Alder reaction between azachalcone and cyclopentadiene proceeds within the reaction cavity of the pyrene‐linked nitrobindin with high stereoselectivity.