Molecular iodine-promoted N- and C-glycosylation of 1-C-alkyl (or phenyl)-glycopyranoses

C-Glycopyranosyl Arenes and Hetarenes: Synthetic Methods and Bioactivity Focused on Antidiabetic Potential

“…There are several methods to introduce the aromatic moiety first starting with suitably protected glyconolactones (Scheme ). Thus, lactols 733 – 735 were obtained from ether protected lactones 130 , 511 , and 728 , and the glycosidic OH was substituted by silylated nucleophiles in the presence of Lewis acids to give the bis- C , C -glycosyl compounds with cyano 736 , allyl 737 , 738 , , and phenacyl 739 , 740 , groups in excellent yields. The newly introduced substituent enters from the α-face, so that the phenyl ring occupies the equatorial orientation, as evidenced by NMR analyses.…”

“… a Method A: Me 3 SiCN, 1 equiv of I 2 , CH 2 Cl 2 . Method B: TMSAllyl or H 2 CC­(OTMS)­Ph, 0.2 equiv of TMSOTf, CH 3 CN, −40 °C .…”

Synthesis of C,N-Glycosides via Brønsted Acid-Catalyzed Azidation of exo-Glycals

“…Early methods made use of tertiary glycosyl halides bearing electron-withdrawing groups in the anomeric position, which reacted with sodium azide to afford the tertiary glycosyl azide. ,− Later, activation of tertiary lactols, − esters, and nitro groups were described by the reaction with Lewis acids in the presence of azidotrimethylsilane. Furthermore, molecular iodine was shown to facilitate the reaction between tertiary lactols with azidotrimethylsilane . Many of these reactions are complicated by the use of toxic and explosive sodium azide as well as moisture-sensitive reagents.…”

“…Furthermore, molecular iodine was shown to facilitate the reaction between tertiary lactols with azidotrimethylsilane. 28 Many of these reactions are complicated by the use of toxic and explosive sodium azide as well as moisture-sensitive reagents.…”