Resolution and Determination of the Absolute Configuration of a Twisted Bis-Lactam Analogue of Tröger's Base: A Comparative Spectroscopic and Computational Study.

The first reported twisted bis-lactam, a racemic Tröger's base (TB) analogue (2), was resolved into its enantiomers on a chiral stationary phase HPLC column. The absolute configuration of (+)-2 was determined to be (R,R)-2 by comparing experimental and calculated vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra. The absolute configuration of (-)-2 was determined by comparing experimental and calculated electronic circular dichroism (ECD) spectra.

tert-Butyldimethylsilyl O-protected chitosan and chitooligosaccharides: useful precursors for N-modifications in common organic solvents.

An efficient and chemoselective procedure for preparing highly organosoluble 3,6-di-O-tert-butyldimethylsilyl (TBDMS)-chitosan and chitooligosaccharides is reported. The selective modification of the chitooligosaccharides with 0.50 degree of N-acetylation was achieved by using TBDMSCl as the reagent in combination with DMF/imidazole.