ß-Selective Glycosylation Using Axial-Rich and 2-O-Rhamnosylated Glucosyl Donors Controlled by the Protecting Pattern of the Second Sugar.
Chem Pharm Bull (Tokyo)
; 69(1): 124-140, 2021.
Article
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| MEDLINE
| ID: mdl-33390514
ABSTRACT
Herein, we describe two counterexamples of the previously reported ß/α-selectivity of 96/4 for glycosylation using ethyl 2-O-[2,3,4-tris-O-tert-butyldimethylsilyl (TBS)-α-L-rhamnopyranosyl]-3,4,6-tris-O-TBS-thio-ß-D-glucopyranoside as the glycosyl donor. Furthermore, we investigated the effects of protecting group on the rhamnose moieties in the glycosylation with cholestanol and revealed that ß-selectivity originated from the two TBS groups at the 3-O and 4-O positions of rhamnose. In contrast, the TBS group at the 2-O position of rhamnose hampered the ß-selectivity. Finally, the ß/α-selectivity during the glycosylation was enhanced to ≥99/1. The results obtained herein suggest that the protecting groups on the sugar connected to the 2-O of a glycosyl donor with axial-rich conformation can control the stereoselectivity of glycosylation.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Ramnosa
/
Sustancias Protectoras
/
Azúcares
Idioma:
En
Revista:
Chem Pharm Bull (Tokyo)
Año:
2021
Tipo del documento:
Article