Acid-catalyzed dehydrative cyclization of 4-(D-galacto -pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole. synthesis and anomeric configuration of D-lyxo-C-nucleoside analogs

Studies on saccharide benzimidazoles: 2-(β-D-gulofuranosyl)benzimidazole and 2-(β-D-glucofuranosyl)benzimidazole C-nucleoside analogs; synthesis, anomeric configuration and antifouling potency

A series of acyclic 2-(D-gulo-) and 2-(D-gluco-)benzimidazole C-nucloside analogs have been prepared by condensation of o-phenylenediamine dihydrochloride derivatives with D-gulonic acid-γ-lactone and D-gluconic acid-γ-lactone, separately. Acid catalyzed dehydrative cyclization of the acyclic benzimidazole C-nucleoside afforded the corresponding 2-(β-D-gulo-) and 2-(β-D-gluco-)furanosyl benzimidazole C-nucleoside analogs. The structure and the anomeric configuration of C-nucleoside analogs obtained were determined by periodate oxidation, ¹H NMR, UV and circular dichroism (CD) spectroscopy. The antifouling property of C-nucleoside analogs has been studied using antibacterial biofilm test. 2-(D-gulo-) and 2-(D-gluco-)benzimidazole analogs were useful for inhibiting marine bacterial growth and did not cause any bad effect to the surrounding seawater.

Homo-C-nucleoside analogs IV. Synthesis of 4-(2,5-anhydro-D-altro-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole homo-C-nucleoside. CD assignment of the absolute configuration of the carbon bridge

Dehydrative cyclization of 4-(D-altro-pentitol-1-yl)2-phenyl-2H-1,2,3-triazole in basic medium with one moler equivalent of p-toluene sulfonyl chloride in pyridine solution gave the homo-C-nucleoside 4-(2,5-anhydro-D-altro-1-yl)-2-phenyl-2H-1,2,3-triazole. The structure and anomeric configuration was determined by acylation, nuclear magnetic resonance (NMR), and mass spectroscopy. The stereochemistry at the carbon bridge of homo-C-nucleoside 2-phenyl-2H-1,2,3-triazoles was determined by circular dichroism (CD) spectroscopy.

Homo-C-nucleoside analogs III. Studies on the base-catalyzed dehydrative cyclization of 4-(d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole

Treatment of 4-(d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole with one molar equivalent of 2,4,6-triisopropylbenzenesulfonyl chloride (TIBSCl) in pyridine solution afforded the homo-C-nucleoside analog; 4-(2,5-anhydro-d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole in 54% yield and 4-(α-d-arabinopyranosyl)-2-phenyl-2H1,2,3-triazole analog in 3% yield. The 4-(5-O-triisopropylbenzenesulfonyl)-d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole analog was isolated as an intermediate and identified as its tetra-O-acetyl derivative. The 4-(5-chloro-5-deoxy-d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole analog was isolated as a byproduct. The structure and anomeric configuration of the products were determined by acylation, NMR spectroscopy, and mass spectrometry.

Circular dichroism as a reliable tool for anomeric assignment of glycosyl-2-phenyl-2H-1,2,3-triazoleC-nucleoside analogs. A rule for prediction of their anomeric configuration

The circular dichroism (CD) of a series of acyclic C-nucleoside analogs; 4-(pentahydroxypentyl-1-yl)-2-phenyl-2H-1,2,3-triazoles [1-5] and 4-(D-glycero-D-gulo)-2-phenyl-2H-1,2,3-triazole 6, are reported. A correlation between the sign of the Cotton effect at the maximal UV absorption and the absolute configuration of the carbon atom alpha- to the triazole base moiety is reported. The CD of anomeric 4-(alpha,beta-D-arabinofuranosyl)- and 4-(alpha,beta-D-arabinopyranosyl)-2-phenyl-2H-1,2,3-triazole C-nucleosides are reported. The assignment of the anomeric configuration of C-glycosyl-2-phenyl-2H-1,2,3-triazoles from their CD spectra was found to be a simple method that relies on comparison of the sign of the Cotton effect at the maximal UV absorption and the absolute configuration of the anomeric carbon atom. A correlation between the anomeric configuration and the sign of the Cotton effect at the maximal UV absorption is deduced and generalized as a rule for prediction of the anomeric configuration of C-glycosyl-2-phenyl-2H-1,2,3-triazoles. Nuclear Overhauser effect and 13C NMR spectra supported the CD assignment rule.

Studies on the dehydrative cyclization of epimeric 4-(L-xylo and L-lyxo-tetritol-1-yl)-2-phenyl-2H-1,2,3-triazoles. Circular dichroism and NMR assignment of the formed anomericC-nucleoside L-threofuranosyl triazole analogs

Dehydrative cyclization of epimeric 4-(L-xylo- and L-lyxo-tetritol-1-yl)-2-phenyl-2H-1,2,3-triazoles afforded the anomeric alpha and beta-L-threofuranosyl analogs. The anomeric configuration of the formed anomeric C-nucleoside analogs was determined by circular dichroism and NMR spectroscopy.