•Ten novel NAM-thiazoline derivatives have been synthesized for the first time as a new type of inhibition for human O-GlcNAcase.•Several compounds have shown good inhibitory activity for human O-GlcNAcase (IC50 < 15 μM).•One inhibitor exhibited more than 150-fold selectivity for hOGA over hHex.Human O-GlcNAcase (GH 84) and human β-N-acetyl-D-hexosaminidase (GH 20) from Homo sapiens are two therapeutic enzyme targets that share the same catalytic mechanism but play different physiological roles in vivo. Selective inhibition toward one of these enzymes is therefore of importance to regulate the corresponding bioprocess. Here ten new NAM-thiazoline derivatives were synthesized and subsequently characterized by NMR and HRMS. A preliminary bioassay showed that most of the synthesized compounds exhibited obvious selective inhibition against human O-GlcNAcase over human β-N-acetyl-D-hexosaminidase. Among the compounds tested, compound 7d (IC50 = 6.4 µM, hOGA; IC50>1 mM, hHex) and 7f (IC50 = 11.9 µM, hOGA; IC50>1 mM, hHex) proved to be a highly selective and potent inhibitor. Structure–activity relationship analysis indicated a correlation between the inhibitory activity and the size of the groups linked to the thiazoline ring.

•Fourteen NAG-thiazoline derivatives have been synthesized for the first time.•The inhibition activity of β-N-acetyl-d-hexosaminidases was studied.•The activity data show compounds exhibit selective inhibition for GH84 β-N-acetyl-d-hexosaminidase.β-N-Acetyl-d-hexosaminidases are responsible for the metabolism of glycoconjugates in diverse physiological processes that are important targets for medicine and pesticide development. Fourteen new NAG-thiazoline derivatives were synthesized by cyclization and click reaction using d-glucosamine hydrochloride as the starting material. All the compounds created were characterized by NMR and HRMS spectra. A preliminary bioassay, using four enzymes from two β-N-acetyl-d-hexosaminidase families, showed that most of the compounds synthesized exhibit selective inhibition of GH84 β-N-acetyl-d-hexosaminidase. Among the compounds tested, compounds 5a (IC50=12.6 μM, hOGA) and 5e (IC50=12.5 μM, OfOGA) proved to be a highly selective and potent inhibitor.

•A pentasaccharide analog has been synthesized for the first time.•The plant growth regulation activity of this analog was studied.•The activity data shows the analog can stimulate the growth of wheat coleoptile.The synthesis of a pentasaccharide 2 containing acetamido-2-deoxy-d-glucose and acetamido-2-deoxy-d-mannose related to the cell wall polysaccharide of Rhizobium trifolii 4s has been achieved by a [2+3] approach from commercially available l-rhamnose, d-glucose, and d-glucosamine as the starting materials. The target molecule was equipped with a p-methoxylphenyl handle at the reducing terminus to allow for further glycoconjugate formation via selective cleavage of this group. The bioassay suggested that the synthetic pentasaccharide 2 can stimulate the growth of wheat coleoptile similarly to indole-3-acetic acid (IAA), and promote the wheat seedling development before winter by seed treatment at a concentration of 20 mg/L.

A highly efficient strategy for the preparation of a disaccharide-repeating unit of the O-antigenic polysaccharide of Burkholderia pseudomallei strain 304b, and its dimer and trimer, has been developed through a regio- and stereoselective manner using p-methoxylphenyl 2,4,6-tri-O-benzoyl-α-d-glucopyranoside and 3-O-allyloxycarbonyl-2,4-di-O-benzoyl-6-deoxy-α-l-talopyranosyl trichloroacetimidate as the key synthons. The target molecules were equipped with a p-methoxylphenyl handle at the reducing terminus to allow for their further functionalization and attachment to a carrier protein.

The synthesis of a trisaccharide and a hexasaccharide, the monomer and dimer of the repeating unit of O-antigen polysaccharide from Mesorhizobium huakuii IFO15243, has been accomplished through suitable protecting group manipulations and stereoselective glycosylation reactions starting from commercially available l-rhamnose. The target oligosaccharides in the form of their p-methoxyphenyl glycosides are suitable for further glycoconjugate formation via selective cleavage of this group.

Concise synthesis of a 6-deoxy-α-l-talose tetrasaccharide, 6-deoxy-α-l-Talp-(1→3)-6-deoxy-α-l-Talp-(1→2)-6-deoxy-α-l-Talp-(1→3)-6-deoxy-α-l-Talp, the dimer of the disaccharide repeating unit of the OPS from Aggregatibacter actinomycetemcomitans serotype c, has been accomplished through suitable protecting group manipulations and stereoselective glycosylation starting from commercially available l-rhamnose. The target oligosaccharide in the form of its p-methoxyphenyl glycoside is suitable for further glycoconjugate formation via selective cleavage of this group.

Highly efficient removal of allyloxycarbonyl (Alloc) group was achieved in the presence of CH3COONH4, Pd[P(C6H5)3]4, and NaBH4 in MeOH-THF, within 5 min in almost quantitative yields (>90%, isolated yield) without affecting acetyl, benzoyl, isopropylidene, benzylidene, allyl, benzyl, benzyl carbonate, or azido groups.

Synthesis of the disaccharide β-d-Glup-(1→3)-6-deoxy-α-l-TalpII, and its dimer III from the O-antigenic polysaccharide of Burkholderia pseudomallei strain 304b, were achieved through assembly of suitably synthesized building blocks, 4-methoxylphenyl 6-deoxy-2,4-di-O-benzoyl-α-l-talopyranoside (7), 3-O-allyl-2,4,6-tri-O-benzoyl-α,β-d-glucopyranosyl trichloroacetimidate (8) and 2,3,4,6-tetra-O-benzoyl-α,β-d-glucopyranosyl trichloroacetimidate (11). The total yield of III from 4-methoxylphenyl 2,3-O-isopropylidene-α-l-rhamnopyranoside (1) was 18%.

An efficient synthesis of 4-methoxyphenyl α-l-Rhap-(1→3)-α-l-Rhap-(1→3)-α-l-Rhap-(1→2)-6-deoxy-α-l-Talp, the tetrasaccharide related to the GPLs of Mycobacterium intracellare serotype 7, was achieved with 4-methoxyphenyl 3,4-di-O-benzoyl-6-deoxy-α-l-talopyranoside (6c) as the key intermediate which was obtained through selective 3-O-benzoylation of 4-O-benzoyl-6-deoxy-α-l-taloside. Coupling of 6c with 3-O-allyloxycarbonyl-2,4-di-O-benzoyl-α-l-rhamnopyranosyl trichloroacetimidate followed by removal of the allyloxycarbonyl protecting group afforded the disaccharide acceptor 11. Condensation of 11 with 2,3,4-tri-O-benzoyl-α-l-rhamnopyranosyl-(1→3)-2,4-di-O-benzoyl-α-l-rhamnopyranosyl trichloroacetimidate and subsequent deprotection gave the target tetrasaccharide.