Syntheses of Isoflavones and Isoflavone Glycosides, and Their Inhibitory Activity against Bovine Liverβ-Galactosidase

Synthesis of Talosin A and B, Two Bioactive Isoflavonoid Glycosides

“…Treatment of genistein with TMSCl and hexamethyldisilazane afforded 4',5,7-tri-O-trimethylsilyl genistein (10), which was then subjected to glycosylation with 2,3,4-tri-O-benzoyl-6-deoxy-L-talopyranosyl fluoride 11 (Scheme 3). 8 Fluoride 11 was readily prepared by treatment of lactol 7 with DAST in CH 2 Cl 2 at 0 ℃ (100%, α/β＝7∶1). 8 Under the promotion of BF 3 •Et 2 O (4 equiv.…”

“…8 Fluoride 11 was readily prepared by treatment of lactol 7 with DAST in CH 2 Cl 2 at 0 ℃ (100%, α/β＝7∶1). 8 Under the promotion of BF 3 •Et 2 O (4 equiv. ), coupling of the genistein trimethylsilyl ether 10 with glycosyl fluoride 11 afforded three coupled glycosides, which were characterized to the 7-O-,4'-O-, and 7,4'-di-O-glycosyl genistein (12-14), respectively.…”

Preparation and Taste of Certain Glycosides of Flavanones and of Dihydrochalcones

“…A hydroxyflavanone (naringenin, hesperetin, 7 -hydroxyflavanone or 7 -hydroxy-4'-methoxyflavanone, each I mmol) was treated with a mixture of chlorotrimethylsilane (15 ml) and hexamethyldisilazane (15 ml) in pyridine (60 ml) as previously described 7 ) to give a trimethylsilylated (TMS)-flavanone. While stirring, a solution of boron trifluoride etherate (2.5 mmol) in anhyd.…”

“…Accordingly, it was assumed that the sugar components were introduced to the 4' or 3' hydroxyl groups of flavanone. The anomeric configuration of the glycopyranosidic bond directly attached to the hydroxyl groups of the aglycones in [5][6][7][8][9][10][11][12][13][14][15][16] was determined by applying the Klyne rule 12 ) as shown in the experimental section.…”