title: 4,5-dichlorophthaloyl group for amino protection in carbohydrate chemistry.
abstract: Phthaloyl (Phth) is a valuable amino-protecting group for use in synthetic carbohydrate chemistry. Its strong 1,2-trans-directing nature in a glycosylation reaction, when it is introduced to the C-2 position of a glycosyl donor, makes the construction of beta-GlcNAc or beta-GalNAc glycosides quite straightforward. The Phth group can be removed by using an appropriate nucleophile, most typically hydrazine; however, this transformation often requires a long reaction time at elevated temperature when applied to a large oligosaccharide. We studied the 4,5-dichlorophthaloyl (DCPhth) group as an alternative to Phth. A thioglycoside carrying a DCPhth group at the C-2 position was reacted with alcohol by the action of PhSeNPhth-TMSOTf to selectively give the corresponding beta-glycoside. DCPhth could then be removed under mild conditions by using ethylenediamine or hydrazine/MeOH at room temperature.
authors.affiliation: Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Shimizu
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuzaki
authors.forename: H
authors.initials: H
authors.lastname: Iijima
authors.forename: T
authors.initials: T
authors.lastname: Ogawa
mesh_terms: D002241:Carbohydrates / Q000737:chemistry*; D005029:Ethylenediamines / Q000737:chemistry; D006031:Glycosylation; D006834:Hydrazines / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D000432:Methanol / Q000737:chemistry; D009844:Oligosaccharides / Q000138:chemical synthesis; D010795:Phthalic Acids / Q000737:chemistry; D010797:Phthalimides / Q000737:chemistry*
chemical_list: D002241:Carbohydrates; D005029:Ethylenediamines; D006834:Hydrazines; D009844:Oligosaccharides; D010795:Phthalic Acids; D010797:Phthalimides; C029424:hydrazine; C031234:ethylenediamine; C032279:phthalic acid; D000432:Methanol