Metathesis‐Based Stapling of a Pyridine–Acetylene–Phenol Oligomer Having Alkenyl Side Chains after Intermolecular Templation by Native Saccharides

• Published in: European journal of organic chemistry 2018-06, Vol.2018 (24), p.3131-3138
• Main Authors: Abe, Hajime, Sato, Chihiro, Ohishi, Yuki, Inouye, Masahiko
• Format: Article
• Language: English
• Subjects: Acetylene; Carbohydrates; Chains; Chirality; Cotton; Glucosides; Helical structures; Hexoses; Host–guest systems; Metathesis; Phenols; Racemization; Template synthesis
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201800531

A nonameric (pyridine–acetylene–phenol–acetylene)4–pyridine oligomer formed a helical structure by intermolecular templation with a hexose such as d‐glucose associated by the means of solid–liquid extraction. Subsequent treatment by 2nd generation Grubbs catalyst stapled the helix by double‐cross‐linking among four 3‐butenyloxy side chains on the pyridine units. The stapling never proceeded without the templation. The resulting double‐bridged helix could be asymmetrized to show typical Cotton effects, not only by the strong binding with octyl hexosides in a DCE solution but also by the solid–liquid extraction of native hexoses into an organic phase. A chiral memory effect of the double‐bridged helix was studied by guest exchange using equimolar d‐ and l‐glucosides, and the half‐time of racemization of the helix was estimated to be 1 min. A nonameric (pyridine–acetylene–phenol–acetylene)4–pyridine oligomer formed a helical structure by intermolecular templation with a hexose associated by solid–liquid extraction. Treatment by 2nd generation Grubbs catalyst stapled the helix by double‐cross‐linking among four 3‐butenyloxy side chains on the pyridine units. A chiral memory effect of the double‐bridged helix was investigated.