Efficient activation of thioglycosides with N-(p-methylphenylthio)-ε-caprolactam-TMSOTf

N-(p-Methylphenylthio)-ε-caprolactam (1) in combination with trimethylsilyl trifluoromethanesulfonate (TMSOTf) provides an efficient thiophilic promoter system, capable of activating different thioglycosides. Both 'armed' and 'disarmed' thioglycosyl donors were activated for glycosidic bond formation. Notably, this reagent combination works well in reactivity-based one-pot oligosaccharide assembly strategy.

Synthesis of glycal-based chiral benzimidazoles by VO(acac)2-CeCl3 combo catalyst and their self-aggregated nanostructured materials

VO(acac)(2)-CeCl(3) combo catalyst has been developed for chemoselective cyclocondensation cum oxidation under mild reaction conditions toward synthesis of a new class of optically pure compounds, 2-(2'-C-3',4',6'-tri-O-benzyl/methyl-glycal)-1H-benzimidazoles. It involves an operationally simple synthetic protocol efficient for the syntheses of a wide range of chiral benzimidazoles in high yields without formation of undesired 1,2-disubstituted and pseudoglycal byproducts. Vanadium(V) is found as active oxidant for the chemical processes which is investigated by UV absorption spectroscopy. Highly ordered one-dimensional low molecular mass organic nanostructured materials are fabricated by nanocrystallization of the chiral nanoscale building blocks. Theoretical calculation by the B3LYP/6-31G** level of theory of the glycal-based chiral benzimidazoles shows out of planar geometry of the 1H-anthra[1,2-d]imidazole-6,11-dione moiety, which is responsible for the strong self-aggregation to generate ultralong nanostructured materials. We have also found nice agreement between the theoretical results with the experimental observation in 2D-NOESY experiments. The photophysical property of the solid nanostructured materials is also reported.

Crystal or Low Molecular Mass Organogel Based on Sugar-Derived Chiral Pyrano[2,3-b]naphtho[1,2-e]pyrans

[structure: see text] 2-C-Acetoxymethyl glycal derivatives reacted with beta-naphthol in the presence of InCl(3) (30 mol %) to give chiral pyrano[2,3-b]naphtho[1,2-e]pyrans in good to excellent yields via stereoselective Ferrier rearrangement-tandem cyclization. The major glucose-derived product exhibited crystal packing with C-H...O and C-H...pi (arene) interactions and the major galactose-derived product, a low molecular mass organogelator (LMOG), formed a rare type of micro tubular gel assembly in n-hexane.