First preparation of spacer-linked cyclic neooligoaminodeoxysaccharides.
The preparation of novel cyclic 1,4-butanediol-linked oligoaminodeoxysugars 3-5 and 7 is described which are potential binders to polynucleotides. Neooligosaccharides 3-5 are assembled by two consecutive metathesis protocols. In the first phase metathesis-mediated dimerization of an aminodeoxymonosaccharide which was either allylated at the anomeric center or at C4 led to E/Z mixtures of C2-symmetric homodimers which were transformed into the corresponding 1,4-butanediol linked disaccharides by catalytic hydrogenation of the central olefinic double bond. Double Q-allylation of the head-to-head dimer set the stage for macrocyclization by means of ring-closing metathesis. This ring-closing process was highly dependent of the configuration in the carbohydrate moieties. arabino-Configured homodimer 15 directly yielded the macrocycle 32 which contains two sugar units while under the same metathesis conditions the corresponding ribo-configured starting homodimer 19 afforded cyclic neotetra- and neohexasaccharides 34 and 35 after a preceding dimerization and trimerization step, respectively. In addition, homodimer 23 was coupled with silylglycoside 14a under Lewis-acid promoted glycosidation conditions to furnish the doubly glycosylated homodimer 31. Ring-closing metathesis afforded the macrocyclic neoaminodeoxyoligosaccharide 36 with alternating 1,4-butanediol linkage and glycosidic bond. The primary cyclization products were finally transformed into the respective cyclic neoaminodeoxyoligosaccharides 3-5 and 7 by catalytic hydrogenation and standard deprotection conditions.[1]References
- First preparation of spacer-linked cyclic neooligoaminodeoxysaccharides. Chen, G.W., Kirschning, A. Chemistry (Weinheim an der Bergstrasse, Germany) (2002) [Pubmed]
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