Synthesis of Bradyrhizose Oligosaccharides Relevant to the Bradyrhizobium O‐Antigen

Abstract

The unique α-(1→7)-bradyrhizoside linkages are constructed for the first time via judicious choice of the glycosylation partners and conditions, thus tetra- and penta-bradyrhizosides relevant to the peculiar O-antigen of Bradyrhizobium are synthesized, which are shown to adopt the defined right-handed helical conformations and to be unable to induce innate immune responses in plants.

Synthesis of Forsythenethoside A, a Neuroprotective Macrocyclic Phenylethanoid Glycoside, and NMR Analysis of Conformers

“…Meanwhile, the condensation of thioxyloside-2-ol 6 with ferulic acid derivative 12 underwent smoothly to give 4 in an excellent 97% yield under the conditions of DCC and DMAP in CH 2 Cl 2 at rt (Scheme ). , The aforementioned phenylethanoid glucoside-6-ol 11 was then successfully glycosylated with thioglycoside 4 in the presence of NIS and AgOTf in CH 2 Cl 2 at low temperature (−5 to 0 °C) to provide disaccharide 13 in 78% yield. − Removal of the three allyl groups was realized with (PPh 3 ) 4 Pd in AcOH at 50 °C, affording 14 in 73% yield. , …”

“…Trajectory coordinates were sampled every 2 ps, and a total of 5000 structures were collected for every simulation. Ensemble average-interproton distances were calculated using the NOEPROM program by applying the isolated spin pair approximation as described in refs and . Solvent-accessible surfaces were calculated with the Surface utility of Maestro and with Molecular Surface displays of ViewerPro Version 4.2.…”

Synthesis of Sialyl LewisX Glycomimetics Bearing a Bicyclic 3-O,4-C-Fused Galactopyranoside Scaffold

“…The synthesis of functionalized trans -bicyclo­[4.4.0]­galactopyranoside 5 (Scheme ), to our knowledge, has not been reported. Annulated pyranosides have been recently described, however, relying mainly on ring closing metathesis (RCM) reactions. − A series of gluco- and galacto- cis - and trans -oxabicyclo­[4.4.0]­decane derivatives, featuring a 4- C , 6- O -fused ring scaffold, were elegantly described by Crich et al , Taking these strategies into consideration, formation of the bicyclic galactopyranoside 6 was planned from the RCM of diene 7 .…”

Synthesis of Bradyrhizose from d-Glucose

“…Bradyrhizose, a rare bicyclic sugar, is an important component of the lipopolysaccharide O-antigen side chain of Bradyrhizobium species (BTAil and ORS278 strains). As a molecular signal, it is thought to be involved in facilitating the fixation of nitrogen in tropical leguminous Aeschynomene s species especially Aeschynomene indica and Aeschynomene sensitiva through a symbiotic process. − Isolation and characterization of this sugar revealed that the monomeric unit consists of an inositol-type backbone that is trans -fused to a pyranose ring resulting in a bicyclic compound, whose α-(1→7)-linked oligomer adopts a compact 2-fold right-handed helicoidal structure …”