Anomeric O-acylation of Kdo using alkyl and aryl isocyanates |
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Authors: | Ichiyanagi Tsuyoshi Yamasaki Ryohei |
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Institution: | Department of Biochemistry and Biotechnology, Tottori University, Tottori 680-8553, Japan. |
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Abstract: | To develop a convenient method for the preparation of an alpha-Kdo derivative carrying a functional spacer at the reducing end, we examined anomeric O-acylation using Kdo and halogenated alkyl/aryl isocyanates as nucleophile and electrophiles, respectively. Reaction of a Kdo derivative with 2-chloroethyl isocyanate in the presence of DMAP gave an alpha-spiro product (82%) and an alpha-Kdo derivative of a dimeric isocyanate adduct (10%). Similar reaction with 4-(chloromethyl)phenyl isocyanate gave only the corresponding alpha-spiro product (81%). The NMR data show that the pyranose rings of both the alkyl and aryl spiro products adopt the 5C2 conformation. Thus, we accomplished alpha-selective anomeric O-acylation by coupling the Kdo derivative with alkyl and aryl isocyanates. |
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Keywords: | Kdo Glycosylation Lipooligosaccharide Lipopolysaccharide |
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