From methyl mannosides to methyl octosides by a stepwise homologation with Grignard C(1) reagents.
A four-step procedure for homologation of methyl alpha-D-mannofuranoside and alpha-D-mannopyranoside was examined. The reactions consisted in (i) oxidation of the terminal hydroxymethyl group in a protected sugar derivative to an aldehyde; (ii) reaction with allyloxymethylmagnesium chloride (or (phenyldimethyl)silylmethyl-magnesium chloride); (iii) protection of the newly formed secondary alcohol group; (iv) deprotection of the terminal CH(2)OR (or oxidation of the CH(2)SiMe(2)Ph) group. From methyl alpha-D-mannosides, stereoisomeric DalphaD and LalphaD methyl heptosides and from them, methyl octosides of D-threo- and L-erythro-alpha-D-manno configuration were obtained.
Stepowska
H
H
Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44, PL-01224, Warsaw, Poland.
Zamojski
A
A
D002236:Carbohydrate Conformation; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008766:Methylmannosides / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009904:Optical Rotation
D007202:Indicators and Reagents; D008766:Methylmannosides