Schizandrin - lignan of unusual structure

Neolignans

“…This was recognized to be eight-membered by UV comparison with model biphenyl derivatives (e. g. 45a) containing bridges of varying number of members between the 2,2' -positions. These facts and the existence of 4 benzylic protons eH NMR evidence) pointed to structure 3.1h for schizandrin, a proposal which is consistent with the inertness of the carbinol function towards acetylation and hydrogenolysis (94). Structure 3.2a was assigned to deoxyschizandrin on basis of its UV (identical to the UV of 3.1h) and 1 H NMR spectra, as well as its incapability of racemization.…”

“…[65][66][67][68][69][70][71][72] The coupling of two units originated from an identical precursor is easily rationalized by the radical pairing mechanism (59), and experimental evidence testifies in favour of this postulate (111). The gene-",040"' o 0 (94) sis of propenyl-+ allyl phenol neolignans, however, presents matter for thought. Coupling of units, endowed with different reactivities, suggests: 1. that the reaction is under strict enzymatic control; 2. that the coupling mechanism involves different reactive species such as propenylphenoxonium and allylphenolate ions rather than radicals; 3. that propenyland allylphenol molecules exist in close spacial proximity and, hence, bifurcation of the biosynthetic pathway leading to both occurs at an immediate precursor.…”

Dibenzo[a,c]cyclooctadiene lignans of the genus Schisandra: importance, isolation and determination

“…The plane structure of schizandrin was elucidated by Kochetkov et al [13]. After the separation by means of column chromatography on aluminium oxide and subsequent paper chromatography, the structure was determined, using the UV, a IR spectroscopy.…”

Isolation of lignans from Schisandra chinensis with anti-proliferative activity in human colorectal carcinoma: Structure–activity relationships

“…The first dibenzocylooctadiene lignan isolated from the fruit of S. chinensis dates back to 1961 and was termed schisandrin [5] or gomisin in Japan. Recent advances in analytical techniques have enabled a more comprehensive characterization of the lignans of these two schisandra species.…”