Stereocontrolled 1,2-trans-arabinofuranosylation in the absence of 2-O-acyl group in glycosyl donor

• Published in: Carbohydrate research 2024-10, Vol.544, p.109252, Article 109252
• Main Authors: Abronina, Polina I., Novikov, Dmitry S., Malysheva, Nelly N., Zinin, Alexander I., Chizhov, Alexander O., Kononov, Leonid O.
• Format: Article
• Language: English
• Subjects: Arabinose - chemistry; Carbohydrate Conformation; D-arabinofuranose; Disaccharides - chemical synthesis; Disaccharides - chemistry; Glycosylation; Janus aglycone; Mycobacterium tuberculosis; Silyl group; Stereoisomerism
• ISSN: 0008-6215; 1873-426X; 1873-426X
• DOI: 10.1016/j.carres.2024.109252

Stereocontrolled 1,2-trans-α-arabinofuranosylation using polysilylated mono- and disaccharide glycosyl donors was investigated. A complete α-stereoselectivity of 1,2-trans-arabinofuranosylation was found for Ara-β-(1 → 2)-Ara disaccharide glycosyl donors containing five triisopropylsilyl (TIPS) groups with arylthiol (1) (as shown in our previous publications) or N-phenyltrifluoroacetimidoyl (2) (this work) leaving groups. Conversely, in case of monosaccharide thioglycosides polysilylated with acyclic silyl groups (TIPS, TBDPS), stereoselectivity of glycosylation was lower (α:β = 7–8:1), although the desired α-isomer still dominated. Disaccharide glycosyl donor 2 was successfully used in the synthesis of linear α-(1 → 5)-, β-(1 → 2)-linked hexaarabinofuranoside useful for further preparation of conjugates thereof as antigens valuable for the diagnosis of mycobacterioses. [Display omitted] •Stereoselective 1,2-trans-arabinofuranosylation was investigated.•The use of polysilylated Ara-β-(1→ 2)-Ara donors led to the α-glycosides.•The use of polysilylated monosaccharide donors led to the loss of stereocontrol.•Benzyl-free synthesis of hexaarabinofuranoside of M. tuberculosis was performed.