Syntheses of Glycyrrhetic Acid .ALPHA.-Diglycosides and Enol .ALPHA.-Glycosides.

Efficient synthesis of glycyrrhetinic acid glycoside/glucuronide derivatives using silver zeolite as promoter

“…5,6 Furthermore, previously published glycosylation reactions of glycyrrhetinic acid acceptor derivatives have suffered from low yields in both the coupling and deprotection steps. As examples, Koenigs-Knorr and Helferich-type reactions of glycosyl bromide donors have been performed using silver carbonate, 7 silver triflate 8 or Hg(CN) 2 /HgBr 2 9 or by employing TMS-bromide and CoBr 2 as promoters in the coupling step with reducing sugars. 10 Also condensation of sugar peracetates in the presence of SnCl 4 with a glycyrrhetinic acid aglycon has been reported.…”

Simplified stereoselective synthesis of triterpene 3-O-2-deoxy-α-D-glycosides

“…b-Anomers were not observed by TLC and NMR. 13 C NMR spectra of the aglycone fragments of synthesized glycosides were similar to those of the initial triterpenes. In the 13 C NMR spectra of 2-deoxy-glycosides 4±7 signals due to carbinol atoms at C-3 were observed at 81.7±83.0 ppm.…”

“…The glycoside structures were assigned by 1 H and 13 C NMR spectroscopy ( 1 H and 13 C NMR spectra were obtained using a Bruker AM-300 spectrometer at 300 and 75.5 MHz) by comparison with literature data for aglycons 8±10 2-deoxy-aglycosides. 7,11,12 The chromatographic mobility and physicochemical properties of the newly synthesized compounds were also compared with those of glycosides obtained earlier using NIS-and IDCP-methods.…”

Biological Activities and Syntheses of Steroidal Saponins: the Shark‐Repelling Pavoninins

“…We first tried to attach the N-acetylglucosamine to a C-16b hydroxyl steroid by using the commercially available 2-acetamido-2-deoxy-a-D-glucopyranosyl chloride 3,4,6-triacetate (26). Unfortunately, there was no reaction when using silver triflate as an activator [39]. So we tested the reaction conditions on 5-androsten-3b-ol-17-one (DHEA, 25) as a model study.…”

“…Synthesis of 2-Acetamido-3,4,6-Tribenzyl-2-Deoxy-D-Glucopyranosyl Fluoride (39) From the results of model studies on the glycosylation of the hindered alcohols and chemoselective acetylation, we have learned that the best sugar fluoride for the synthesis of pavoninin-4 should be a benzyl-protected N-acetyl sugar fluoride; that is, 2-acetamido-3,4,6-tribenzyl-2-deoxy-D-glucopyranosyl fluoride (39). Since this sugar product is not commercially available, we turned our attention to the synthesis of the desired glycosyl fluoride 39 (Scheme 7).…”