Easy access to modified cyclodextrins by an intramolecular radical approach

A simple methodology to modify the primary face of cyclodextrins (CDs) is described. The 6I-O-yl radical of α-, β-, and γ-CD abstracts regioselectively the H5II, located in the adjacent D-glucose unit, by an intramolecular 1,8-hydrogen atom transfer reaction through a geometrically restricted nine-membered transition state to give a stable 1,3,5-trioxocane ring. The reaction has been extended to 1,4-diols of α-and β-CD to give the corresponding bis-trioxocanes. The bi-alkoxyl radical generated from 6I-IV-diol-α-CD under oxidative conditions led to a stable crystalline bis-1,3,5-trioxocane with a guest n-hexane molecule where the primary face is severely distorted toward a narrower elliptical shape.

D. Alvarez-Dorta, E. I. Leon, A. R. Kennedy, A. Martin, I. Perez-Martin, E. Suarez, Angew Chem Int Ed Engl 2015, 54, 3674-3678. DOI: 10.1002/anie.201412300.

Uni bern 2017/02