Synthesis of the tetrasaccharide glycoside moiety of Solaradixine and rapid NMR-based structure verification using the program CASPER
Number of Authors: 2
2016 (English)In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 72, no 7, 912-927 p.Article in journal (Refereed) Published
The major glycoalkaloid in the roots of Solanum laciniatum is Solaradixine having the branched tetrasaccharide beta-D-Glcp-(1 -> 2)-beta-D-Glcp-(1 -> 3)[alpha-L-Rhap-(1 -> 2)]-beta-D-Galp linked to O3 of the steroidal alkaloid Solasodine. We herein describe the synthesis of the methyl glycoside of the tetrasaccharide using a super-armed disaccharide as a donor molecule. A 2-(naphthyl)methyl protecting group was used in the synthesis of the donor since it was tolerant to a wide range of reaction conditions. The 6-O-benzylated-hexa-O-tert-butyldimethylsilyi-protected beta-D-Glcp-(1 -> 2)-beta-D-Glcp-SEt donor, which avoided 1,6-anydro formation, was successfully glycosylated at O3 of a galactoside acceptor molecule. However, subsequent glycosylation at O2 by a rhamnosyl donor was unsuccessful and instead a suitably protected alpha-L-Rhap(1 -> 2)-beta-D-Galp-OMe disaccharide was used as the acceptor molecule together with a super-armed beta-D-Glcp-(1 -> 2)-beta-D-Glcp-SEt donor in the glycosylation reaction, to give a tetrasaccharide in a yield of 55%, which after deprotection resulted in the target molecule, the structure of which was verified by the NMR chemical shift prediction program CASPER.
Place, publisher, year, edition, pages
2016. Vol. 72, no 7, 912-927 p.
Glycosylation, Oligosaccharide, Saponin, CASPER, Chemical shift prediction
Research subject Organic Chemistry
IdentifiersURN: urn:nbn:se:su:diva-127344DOI: 10.1016/j.tet.2015.12.042ISI: 000369461900004OAI: oai:DiVA.org:su-127344DiVA: diva2:911301