Dimers Stilbene

Firstly, we focus on cofacial dimers formed by stilbene molecules in such conformations, the amplitude of interchain interactions is expected to be maximized [57], Table 4-1 collects the INDO/SCl-calculated transition energies and intensities of the lowest two excited states of stilbene dimers for an interchain distance ranging from 30 to 3.5 A. 

Cis- and fro/w-stilbenes have been reported to add to 2,3-dihydropyran upon photolysis to yield adducts (44) and (45) as well as two stilbene dimers(88> ... 

Syah, Y.M. et al., Andalasin A, a new stilbene dimer from Moms macroura, Fitoterapia, 71, 630,... 

According to the model for [2+2] cycloaddition shown in Fig. 2, it should be possible to reach the pericyclic intermediate upon irradiation of the cycloadduct. If a common intermediate is attained from the cycloaddition and cycloreversion processes, then the sum of the quantum yields for the two processes should equal unity. This has, in fact, been observed to be the case for several exciplex and anthracene excimer systems (49b,52). Stereospecific cycloreversion of stilbene dimers 11 and 12 to t-1 has been observed to occur upon 254 nm... 

Waffo-Teguo P, Lee D, Cuendet M, Merillon J, Pezzuto JM, Kinghorn AD. 2001. Two new stilbene dimer glucosides from grape (Vitis vinifera) cell cultures. J Nat Prod 64 136-138. 

A polyrotaxane that contains stilbene dimers was prepared by Wenz et al. [110], They once prepared a polypseudorotaxane which has (3-CD, 7-CD, p,p-dis-... 

Cyclic conjugated earbanions have also been studied and rarely found to give an electron transfer photochemistry in the absence of an electron acceptor. One example was however found in the case of cyclooctadienyl carbanion irradiated in THF and in the presence of chlorobenzene or rrans-stilbene. Dimeric radical products and phenylated cyclooctadiene were formed in the first case while trans-cis isomerization of stilbene was observed in the second one... 

Scheme 1. Formation of viniferins and plausible biosynthetic pathways of some stilbene dimers...

The retrosynthesis of Aara-e-viniferin (445) by Thomas et al. indicated that the y-butyrolactone (823) was a key intermediate, which later converted from the corresponding stilbene by manganese triacetate-mediated oxidative lactonization (Scheme 18) [407]. In subsequent papers, they described the FeCb-promoted tandem pericyclic synthesis of catechol analogs of restrytisol C. 3,4-Dimethoxy-12-acetoxy stilbene (824), which was synthesized by Heck coupling, was treated with FeCb to give the unnatural stilbene dimers 585 and 586 (Scheme 19) [288]. 

Scheme 19. Synthesis of stilbene 824 and transformation of 824 to dihydronaphthalene stilbene dimers...

Recently, two glycosides of stilbene dimer named compound 1 (33) and compound 2 (34) were obtained from an aqueous extract of the roots of Polygonum cuspidatum. Among them, 34 was a new type of resveratrol dimer possessing a four-membered ring [21]. 

Two glycosides of stilbene dimer, 33 and 34 were isolated from Polygonum cuspidatum. Pharmacological studies showed that 34 which has a special skeleton showed moderate inhibition (inhibition rate 36%) in the formation of MDA at a concentration of 2 pM [21]. 

A stilbene dimer (Gn-3) separated from Gnetum parvifolium exhibited potent inhibitory activities on LTC4 and D4 enzymes and their receptors [61, 62]. 

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