Synthesis of derivatives of 4-acetamido-4-deoxy-D- and L-arabinose

1968 ◽  
Vol 46 (3) ◽  
pp. 425-434 ◽  
Author(s):  
A. J. Dick ◽  
J. K. N. Jones
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Exchange Resin ◽  
Cation Exchange Resin ◽  
Acetyl Derivative ◽  
Tautomeric Equilibrium ◽  
Methanol Solution ◽  
Furanose Form ◽  
Derivatives Of

4-Acetamido-4-deoxy-D- and L-arabinose have been synthesized from methyl 4-azido-4-deoxy-D- and L-arabinopyranoside, respectively. In contrast to other 4-acetamido-4-deoxypentoses, the arabinose derivatives in aqueous solution at tautomeric equilibrium exist both in the pyranose and in the furanose forms. The presence of the furanose form (containing nitrogen as the hetero atom in the ring) has been demonstrated by paper chromatography and infrared and nuclear magnetic resonance (n.m.r.) spectroscopy. Acetolysis of methyl 4-amino-4-deoxy-α-D-arabinopyranoside hydrochloride and of the N-acetyl derivative gave 4-acetamido-4-deoxy-D-arabinofuranose tetraacetates whose anomeric configurations were assigned by n.m.r. spectroscopy. Treatment of the 4-acetamido-4-deoxy-D-arabinofuranose tetraacetates with a cation exchange resin in methanol solution and subsequent de-O-acetylation, gave the anomeric methyl 4-acetamido-4-deoxy-D-arabinofuranosides, whose n.m.r. spectra in D2O exhibited the phenomenon of hindered internal rotation.

NUCLEAR MAGNETIC RESONANCE SPECTRAL OBSERVATIONS ON THE GLYCOL-SCISSION OF DEUTERATED D-GLUCOSE

1965 ◽  
Vol 43 (10) ◽  
pp. 2645-2651 ◽  
Author(s):  
W. Mackie ◽  
A. S. Perlin
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Methyl Ether ◽  
Periodate Oxidation ◽  
Lead Tetraacetate ◽  
Resonance Signal ◽  
Pyranose Form ◽  
Furanose Form ◽  
Derivatives Of ◽  
Nuclear Magnetic

The positions of formyl ester groups in products obtained on oxidative glycol-scission of specifically deuterated D-glucose and its 3-O-methyl ether have been determined by n.m.r. spectroscopy. These structural assignments are based on the effect of deuteration on the signal given by the proton located α to the formyloxy group in the undeuterated compound. Thus, mono-O-formyl-2-O-methyl-D-arabinose-4-d (IV) produced by lead tetraacetate oxidation of 3-O-methyl-D-glucose-5-d (I) shows a modified resonance signal for this proton, whereas the signal is absent from the spectrum of the monoformate (III) obtained by periodate oxidation of I. Therefore, IV is a 3-formate and III a 4-formate. According to these findings a furanose form (II) of I is involved in the lead tetraacetate reaction, whereas periodate degrades the pyranose form of the sugar directly.Oxidation of D-glucose-6,6′-d2 with lead tetraacetate is shown in similar fashion to yield 2,3-di-O-formyl-D-erythrose-4,4′-d2, evidence that this degradation involves two successive pyranose-to-furanose interconversions.The preparation of I, and of some other derivatives of D-glucose-5-d, is described.

Nuclear magnetic resonance characterization of the ring conformations of monosubstituted derivatives of 1,3-dioxa-5,6-benzocycloheptene

1983 ◽  
Vol 61 (1) ◽  
pp. 109-115 ◽  
Author(s):  
R. St-Amour ◽  
M. St-Jacques
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Substituent Effects ◽  
Steric Effects ◽  
Slow Exchange ◽  
Conformational Properties ◽  
Derivatives Of ◽  
Ring Conformations ◽  
Twist Boat

The conformational properties of 2-alkyl (Me, Et, i-Pr, and t-Bu) and 2-phenyl derivatives of 1,3-dioxa-5,6-benzocycloheptene (1) were studied by 13C dnmr. Analysis of slow exchange spectra at 100.6 MHz indicates that all derivatives except tert-butyl exist in an equilibrium of chair (major) and twist-boat (minor) conformations. Substituent effects on the position of the equilibrium are rationalized in terms of steric effects.

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