Synthesis and X-ray structures of unexpected 2-O-(5-deoxy-1,2-O-isopropylidene-\alpha- D-glucofuranos-5-yloxy)quinoxalines
Résumé
Reaction of 3-methyl-2(1H)-quinoxalinone (4) and 2(1H)-quinoxalinone (5) with 5,6-anhydro-1,2-O-isopropylidene\alpha- D-glucofuranose 6 gives the unexpected O-glucoquinoxalines derivatives by the intermediary novel intramolecular rearrangement of 5,6-anhydro-1,2-O-isopropylidene \alpha-D-glucofuranose to the corresponding 3,6-anhydro form. The obtained O-glucoquinoxalines 7,8 were identified by NMR spectroscopy. The X-ray crystal structures have been determined at room temperature. Moreover, a solid–solid phase transition has been detected at 198.9 K for O-glucoquinoxalines 7 and the structure of the low-temperature phase has been solved at 188 K