Dimers ampelopsin

Grape related products (red wine etc.) usually contain stilbene monomers, dimers and their glycosides [32]. The relative and absolute structures of (-t-)-ampelopsin F (465) [217], (-l-)-isoampelopsin F (468), (-)-ampelopsin F (469) [218-220], isoampelopsin F (467) [221], and those of the structurally related ones 2b-hydroxyampelopsin F (466) [222], gnemonol... 

The antifungal resveratrol dimers cyphostemmins A and B (481, 482) were isolated from the roots of Cyphostemma crotalarioides planch (Vitaceae). Cyphostemmins A (481) has the proposed cyclohexenic structure [230], while cyphostemmin B has the same structure as that of (-)-quadrangularin A isolated from Cissus quadrangularis [231]. Adesanya et al. considered that the reported structure of (-)-ampelopsin D... 

Ampelopsis brevipedunculata Maxim, ex Trautv. roots ampelopsin A (55a) dimer (C28H2207) + 167° (c 2.12, MeOH) [81]... 

Vitis betulifolia Diels. Gilg. stems ampelopsin A (55) dimer (C28H22O7) NA [90]... 

On the other hand, the group of Yang has disclosed a convenient Tf O-catalyzed FC alkylation protocol to synthesize the dibenzo[a,resveratrol dimers, which is illustrated with the concise synthesis of ( )-ampelopsin B (Scheme 2.16) [18]. Thus, dimerization by oxidative conpling of resveratrol (117) with FeCl gave benzofuran s-viniferin (118), which upon treatment with a catalytic amount (lOmol-%) of Tf O in toluene at 100°C provided ( )-ampelopsin B (119) in 41% yield. The reaction is thought to be initiated by reaction of TfjO with trace water to release a proton that coordinates with the alkene to form a carbocation intermediate. 

---