Synthesis of a tetra- and a trisaccharide related to an anti-tumor saponin “Julibroside J28” from Albizia julibrissin

Abstract

Simple and convergent synthesis of a tetra- and a trisaccharide portions of an antitumor compound Julibroside J(28), isolated from Albizia julibrissin, that showed significant in vitro antitumor activity against HeLa, Bel-7402 and PC-3M-1E8 cancer cell lines is reported. The tetrasaccharide has been synthesized as its p-methoxyphenyl glycoside starting from commercially available D-glucose, L-rhamnose and L-arabinose. The trisaccharide part has been synthesized from commercially available N-acetyl D-glucosamine, D-fucose and D-xylose using simple protecting group manipulations. Sulfuric acid immobilized on silica has been used successfully as a Brönsted acid catalyst for the crucial glycosylation steps.

Chemical Synthesis of the Linker‐Armed Trisaccharide Repeating Unit of the O‐Antigen from Pseudomonas putida BIM B‐1100

“…The reaction yielded 2,3-di-O-benzoyl, 3-O-benzoyl 24, 2-O-benzoyl and unreacted 23 in a ratio of 1 : 5 : 2 : 1. [25] Finally, chloroacetylation of the 2-OH group using chloroacetic anhydride in CH 2 Cl 2 -pyridine mixture afforded the glucose donor 5 in 90 % yield (Scheme 3).…”

“…We decided to take the 2‐OH inversion approach to introduce the desired β ‐ManNAcA moiety [23] . Thus, in a separate experiment, the known compound 23 [24] was selectively benzoylated at the 3‐OH position using BzCl in CH 2 Cl 2 ‐pyridine [25] at −50 °C. The desired 3‐O‐benzoyl derivative 24 was obtained in 55 % yield.…”

H2SO4-Silica: An Efficient Promoter for Selective Removal of Benzylidene and Isopropylidene Groups in the Presence ofp-Methoxybenzyl Group

“…[10,11] This is primarily due to the acid-labile nature of the p-methoxybenzyl group that results in removal of the group along with the benzylidene and isopropylidene protections. With our experience using H 2 SO 4 -silica [12][13][14][15][16][17][18][19][20][21] as a mild acid source for various carbohydrate transformations, we envisaged that it might provide the adequate acidity for the hydrolysis of the benzylidene and isopropylidene protections without affecting the p-methoxyphenyl group. In fact, we have observed that the isopropylidene protection may be cleaved selectively in the presence of the p-methoxybenzyl group using H 2 SO 4 -silica as an acid source.…”

Concise synthesis of two trisaccharides related to the cytotoxic triterpenoid saponin isolated from Pithecellobium lucidum

“…Subsequently, the chloroacetate group was selectively cleaved using thiourea 34 to furnish the required disaccharide acceptor 11 in 86% yield. Further glycosylation of the known donor, p-tolyl 2,3,4-tri-O-benzoyl-1-thio-a-D-arabinofuranoside (12) 24 with disaccharide acceptor 11 using NIS in conjunction with H 2 SO 4 -silica afforded the protected trisaccharide 13 in 83% yield. Global deprotection of the trisaccharide was accomplished by treating trisaccharide 13 with 80% AcOH at 80°C followed by NaOMe in MeOH to get the target trisaccharide 2 in 78% overall yield (Scheme 2 1.…”