ISSN:
0947-3440
Keywords:
Sucrose
;
Molecular electrostatic potential (MEP)
;
2-O-Modified derivatives
;
Monobenzylation, selective
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Generation of the molecular electrostatic potential (MEP) profiles, in color-coded form, on the solvent-accessible contact surfaces of the two main conformations that sucrose adopts in vacuo as well as in aprotic solvents (e.g. DMF), clearly shows the secondary glucosyl-2-OH to be the most electropositive of the altogether eight hydroxyl groups-conceivably due to the persistence of an intramolecular hydrogen bond of the 2g-O…HO-1f type. The notion that the 2g-OH is accordingly the hydroxyl group most readily deprotonated in aprotic solvents, and that the resulting sucrose 2g-O-alkoxide is the one best stabilized by intramolecular hydrogen bonding, received ample substantiation by smoothly achieving a highly regioselective (〉80%) 2g-O-benzylation in DMF with NaH/benzyl bromide. The resulting 2g-O-benzyl-sucrose (2)- minor products being the 1f-O- (3) and 3f-O-isomers (4)- was converted, by acetylation and hydrogenolysis into the 2g-OH-free sucrose heptaacetate 6, isolable in crystalline form in 42% yield based on sucrose, thus opening up a ready entry to 2g-O-modified derivatives: 2-deoxy-sucrose (12) via radical deoxygenation of a 2g-O-thiocarbamate, 2-keto-sucrose perbenzoate 7 via PDC oxidation, or N-acetyl-sucrosamine 14 and its manno-analog 16 through oximation of 7 and subsequent borane reduction.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.1995199511273
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