Total synthesis of three natural phenethyl glycosides

Total Syntheses and Anti-inflammatory Evaluations of Pongamosides A–C, Natural Furanoflavonoid Glucosides from Fruit of Pongamia pinnata (L.) Pierre

“…15 Therefore, glycosyl donor 2,3,4,6-tetracetyl-α-D-glucopyranosyl trichloroacetimidate (2′) was prepared from D-glucose following the literature procedure. 16 In the initial attempt, treatment of 5a with 2′ in the presence of a catalytic amount of BF 3 -(C 2 H 5 ) 2 O gave only a trace amount of desired 4a. Further experimental results showed that by changing the number of equivalents of BF 3 -(C 2 H 5 ) 2 O from 0.05 to 1.1, the glycosylation rate was greatly increased (Table 1, entries 3−5) and the glycosylation proceeded rapidly (within 20 min).…”

“…To improve the isolated yield, we next resorted to Schmidt’s trichloroacetimidate procedure . Therefore, glycosyl donor 2,3,4,6-tetracetyl-α- d -glucopyranosyl trichloroacetimidate ( 2′ ) was prepared from d -glucose following the literature procedure . In the initial attempt, treatment of 5a with 2′ in the presence of a catalytic amount of BF 3 -(C 2 H 5 ) 2 O gave only a trace amount of desired 4a .…”