Selective Cleavage of 2,2,2-Trichloroethyl Group with Zinc Dust in the Presence of Phthalimido Function

[摘要] In acidic media such as aqueous acetic acid, phthalimide is reduced with zinc dust to give 3-hydroxyphthalimidine while the 2,2,2-trichloroethyl esters or glycosides are reductively cleaved. However, it has been discovered that, by employing a mixture of THF and pH 4.5 buffer solution as a solvent, 2,2,2-trichloroethyl group can be selectively removed with activated zinc dust in the presence of phthalimido function, provided that the reactant or the product does not have any free carboxylic acid function. By applying the above methods, reaction of 2,2,2-trichloroethyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-¥â-D-glucopyranoside (1) with activated zinc dust gave a good yield of 3,4, 6-tri-O-acetyl-2-deoxy-2-phthalimido-¥â-D-glucopyranose (5) in THF-buffer solution, and 3,4,6-tri-O-acetyl-2-deoxy-2-(3-hydroxyphthalimidino)-¥â-D-glucopyranose (6) in aqueous acetic acid.

[学科分类] 化学（综合）