Sugars nitrogen-containing, preparation

Aqueous aza-Diels-Alder reactions of chiral aldehydes, prepared from carbohydrates and with benzylamine hydrochloride and cyclopentadiene, were promoted by lanthanide triflates (Eq. 12.65).137 The nitrogen-containing heterocyclic products were further transformed into aza sugars, which are potential inhibitors against glycoprocessing enzymes. 

Following this procedure, several fractions have been prepared from both humic acid and fulvic acid which contain between 97.5 and 98.6% of the total nitrogen as unidentified nitrogen, but only 0.84% as amino acid nitrogen, 0% as amino sugar nitrogen, and 0.53% as ammonia nitrogen. 

Recent advances in the synthesis of imino sugars, comprising the preparation of five- and six-membered heterocycles containing an en-docyclic nitrogen atom, authored by Slawomir Jarosz and coworker (Chapter 9) and amino sugar synthesis, with emphasis on diastereo- and enantioselectivity (Chapter 10) authored by Zbigniew Witczak and Roman... 

In all cases where the chemical properties of these preparations have been studied the active material appears to be predominantly carbohydrate in nature, containing in the case of the A factor 50-70% of reducing sugar, 5.7% nitrogen and giving by colorimetric estimations 25-30% of glucosamine on hydrolysis. 

---