Self-assembled hexameric capsule: A highly -selective O-glycosylation reaction enabled via proton wire mechanism

A simple methodology has been developed for the synthesis of highly beta-selective O-glycosylation scaffolds of wider substrate scope under mild conditions using a self-assembled hexameric capsule. The reaction conditions are compatible with a wide range of functional groups. Extensive control experiments and theoretical studies established that the reaction takes place inside the capsule cavity. The substrates are activated via a proton wire as seen in some enzymes, and the reactions follow an S(N)2 pathway through a loose transition state. The advantages of this methodology are selectivity, high yields and scalability; the catalyst is readily recovered and reused. The methodology was adapted to the synthesis of mesomorphic glycosides and anti-tumour agents in short synthetic routes.