A comparative nuclear magnetic resonance study of acetylated D-fructose derivatives and evaluation of enolization of keto- D-fructose pentaacetate

Derivatives of acetylated D-fructose which had been previously synthesized have been characterized by modern NMR techniques. The following derivatives were used in this study; 1,3,4,5,6-penta-O-acetyl- keto-D-fructose, 1,3,4,5-tetra-O-acetyl-beta- D-fructopyranose, 3,4,5,6-tetra-O-acetyl-1-deoxy- keto-D-fructose, 3,4,5,6-tetra-O-acetyl-1-deoxy- keto-D-fructose oxime, 3,4,5,6-tetra-O-acetyl-1- O-methyl-keto-D-fructose, 3,4,5,6-tetra- O-acetyl-1-deoxy-1-diazo-keto-D-fructose, and 3,4,5,6-tetra-O-acetyl-1-O-trityl- D-fructose. 1H, 13C, Correlated Spectroscopy (COSY), and Heteronuclear Multiple Quantum Coherence (HMQC) NMR spectra were obtained for each sample in solution of CDCl3 or C6D 6. Each derivative was further characterized with modern techniques to confirm the structures and to assign conformational formulas. A stock pile of 1,3,4,5,6-penta-O-acetyl-keto -D-fructose was prepared and used for further evaluation of its enolization to 1,2,3,4,5,6-hexa-O-acetyl-D -arabino-hex-enitol. It was prepared following a procedure by Whistler and Doner. The pentaacetate was then used in a 72 hour reaction with pyridine. 13C and 1H NMR spectra were taken.