Chiroptical Assignment of the Anomeric Configuration of 4-(α,β-D-lyxopyranosyl)- and 4-(α,β-D-lyxofuranosyl)-2-phenyl-2H-1,2,3-Triazole C-Nucleoside Anomeric Pairs: Extension of the CD Triazole Rule

The circular dichroism of the anomeric 4-(α,β-D-lyxopyranosyl)- and 4-(α,β-D-lyxofuranosyl)-2-phenyl-2H-1,2,3-triazole C-nucleoside analogs obtained by acid-catalyzed dehydrative cyclization of 4-(D-galacto-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole analog was studied. A correlation between the sign of the Cotton effect at the maximal UV absorption and the absolute configuration of the anomeric carbon atom was obtained and used for their anomeric configuration assignment. This correlation supports the CD triazole rule for anomeric assignment and is in accord with the assignment obtained by NMR spectral studies.