title: Sequential directed epoxydation-acidolysis from glycals with MCPBA. A flexible approach to protected glycosyl donors.
abstract: 4,6-Di-O-protected glucal and allal derivatives react with MCPBA to afford manno- and allo-1-O-m-chlorobenzoate derivatives, respectively, as a result of a syn epoxidation directed by the allylic hydroxyl group, and consecutive ring-opening by m-ClBzOH. When glucal and allal derivatives are fully protected, initial epoxidation proceeds mainly anti to the allylic group to give, after ring-opening, the corresponding pyranosyl chlorobenzoates. Stereoselectivity in the reaction of fully protected galactal derivatives was complete, although only a moderate increase in the syn epoxidation product was observed in 4,6- and 3,4-di-O-protected derivatives. 1-O-m-Chlorobenzoate 18 was selectively protected and activated as donor in the synthesis of disaccharide 21.
authors.affiliation: Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Marín
authors.forename: Javier
authors.initials: J
authors.lastname: Castilla
authors.forename: M Isabel
authors.initials: MI
authors.lastname: Matheu
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Díaz
authors.forename: Sergio
authors.initials: S
authors.lastname: Castillón
mesh_terms: D002723:Chlorobenzoates / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry*; D008968:Molecular Conformation; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D002723:Chlorobenzoates; D006027:Glycosides; D013141:Spiro Compounds; C000433:3-chloroperbenzoic acid