Electron impact ion fragmentation pathways of peracetylated C-glycoside ketones derived from cyclic 1,3-diketones.
Monosaccharide C-glycoside ketones have been synthesized by aqueous-based Knoevenagel condensation of isotopically labeled and unlabeled aldoses with cyclic diketones, 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and 1,3-cyclohexanedione (1,3-CHD). The reaction products and their corresponding acetylated analogs produce characteristic molecular adduct ions by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS). Analysis of the peracetylated C-glycosides by electron ionization (EI) gas chromatography/mass spectrometry (GC/MS) revealed diagnostic fragment ions that have been used to deduce the EI fragmentation pathways and the structure of each C-glycoside ketone. Characteristic gluco- and ribo-specific ions were observed at m/z 350 and 278, respectively. Ions common to both carbohydrate fragmentation pathways were observed at m/z 193 and 169 for the dimedone-C-glycosides, and m/z 165 and 141 for the 1,3-CHD-C-glycosides. Ions with m/z 169 and 141 retain the anomeric carbon (carbon-1) of the original sugar, while m/z 193 and 165 are shown to retain carbons-1, 2, and 3.
Adeuya
Anthony
A
Bioproducts and Biocatalysis Research Unit, NCAUR-ARS-USDA, 1815 N. University Street, Peoria, IL 61604, USA.
Price
Neil P J
NP
D003512:Cyclohexanones; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006027:Glycosides; D007477:Ions / Q000737:chemistry; D007659:Ketones / Q000737:chemistry*; D009005:Monosaccharides / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
C438934:C-glycoside; D003512:Cyclohexanones; D006027:Glycosides; D007477:Ions; D007659:Ketones; D009005:Monosaccharides; C004636:1,3-cyclohexanedione