Glycosyl-Templated Chiral Helix Stapling of Ethynylpyridine Oligomers by Alkene Metathesis between Inter-Pitch Side Chains

• Published in: Chemistry : a European journal 2015-06, Vol.21 (26), p.9405-9413
• Main Authors: Abe, Hajime, Kayamori, Fumihiro, Inouye, Masahiko
• Format: Article
• Language: English
• Subjects: Chemistry; chirality; Circular Dichroism; Decomposition reactions; glycosides; Glycosides - chemical synthesis; Glycosides - chemistry; Heating; Helical; helical structures; Helicity; Hydrogen Bonding; hydrogen bonds; Metathesis; Molecular Structure; Olefins; Oligomers; Pyridines - chemical synthesis; Pyridines - chemistry; Solvents; Solvents - chemistry; Stereoisomerism; template synthesis
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201501102

Ethynylpyridine polymers and oligomers consisting of 4‐substituted pyridine rings linked by acetylene bonds at the 2‐ and 6‐positions have been investigated. Ethynylpyridine oligomers covalently linked with a glycosyl chiral template form chiral helical complexes by intramolecular hydrogen bonding, in which the chirality of the template is translated to the helix. With a view to fixation of the chiral architecture, D/L‐galactosyl‐ and D/L‐mannosyl‐linked ethynylpyridine oligomers have been developed with 4‐(3‐butenyloxy)pyridine units having alkene side chains. The helical structures are successfully stapled by alkene metathesis of the side chains. Subsequent removal of the chiral templates by acidolysis produces template‐free stapled oligomers. The chiral, template‐free, stapled oligomers show chiral helicity, which is resistant to polar solvents and heating. Stapling makes more happen: Ethynylpyridine oligomers have been prepared as helical structures by using a chiral template. These structures can be stapled by alkene metathesis of the side chains (see figure). Subsequent removal of the chiral template by acidolysis produces template‐free stapled helical oligomers, which are resistant to polar solvents and heating.