Synthesis of C-glycosides related to glycero-β-d-manno-heptoses

A Carbohydrate-Based Approach for the Total Synthesis of (−)-Dinemasone B, (+)-4a-epi-Dinemasone B, (−)-7-epi-Dinemasone B, and (+)-4a,7-Di-epi-dinemasone B

“…With ketone 5 in hand, a careful survey of conditions for the stereoselective reduction was conducted (Table ). Reduction of 5 with sodium borohydride in the presence of AcOH yielded a mixture of alcohols 9 and 10 with poor selectivity (Table , entries 1 and 2), which were similar to the results reported in the literature. − Later, it was found that the major product 10 ( S -isomer) could be obtained by the Corey–Bakshi–Shibata reduction − with ( R )-Me-CBS as the catalyst (Table , entries 3 and 4), especially when catecholborane was used as the reductant (ratio 9 / 10 = 06:94) (Table , entry 4). According to the literature, the selectivity for the S -isomer should be better when ( R )-Bu-CBS is used .…”

Chemically-modified polysaccharide extract derived from Leucaena leucocephala alters Raw 264.7 murine macrophage functions

“…Knoevenagel-type condensation involves the reaction of the glycosyl residue with β-dicarbonyl compounds in the presence of NaHCO 3 . Therefore, the reaction of L. leucocephala polysaccharides with pentane-2, 4-dione in the presence of NaHCO 3 gave rise into C-glycosidic 2-propanone of the polysaccharide chain [18,35,36], which afforded C-glycosidic 2-propanol of corresponding polymer by NaBH 4 as a reducing agent.…”

“…According to a previously reported methodology [18], 200 mg of the lyophilized extract (E), NaHCO 3 (200 mg) and pentane-2, 4-dione (300 μl) were stirred in 20 ml water at 100°C for 20 h. The solution was diluted and neutralized with Dowex 50 resin (H + form). The resin was filtered off, and the retentate was mixed with 100 mg NaBH 4 .…”

Occurrence, Synthesis and Biosynthesis of Bacterial Heptoses

“…Similar to the ADP heptoses 55 and 56, the 2-deoxy-analogue 117 is labile and slowly hydrolyzes to the reducing sugar 111 and ADP. In order to generate stable ADP heptose analogues, Cglycosidic analogues have also been recently prepared [145,146]. Reaction of unprotected L-glycero D-mannoheptose 1 with pentane-1,3-dione followed by base-induced enrichment of the -anomer and acetylation constitutes a direct approach towards the -anomeric C-glycosidic ketone 118, which was reduced to give a 1:1 mixture of the two diastereoisomeric alcohols 119 and 120.…”