The Total Synthesis Of Schizandrin A Hormone And Its Analogues And Non-phenolic Oxidative Coupling Reaction Mechanism

Schizandrin and deoxyschizandrin have been isolated from the fruit of schizandra, whose carbon skeletons areAconstructed by the linking of two C₆C3 units The results of pharmacological studies show these compounds possess extensive significant anticonvulsion activities.These compounds have long been recognized as challenging targets for organic synthesis due to the special structures and the important biological properties exhibited by some members of this class.They were regarded as the coupling products of cinnamyl alcohols or allyl phenols by biosynthesis. Schizandrin has been sythesized previously in twenty steps.Taking advantage of the experience,Schizandrin(A) was prepared successfully by us in nine steps from gallic acid has a bright future for industrialization.At the same time,deoxyschizandrin and some new analogues were also synthesized(C).The present study was composed of the following 5 parts:1.The present synthetic plan consistsof reductive coupling and dehydroxylation of the phenylacetone to give the symmetrical olefins(E,Z),followed by hydrogenation and hydroboration(I-4).The schizandrin,deoxyschizandrin and analogues(A,C) were prepared from intramolecular nonphenolic oxidative coupling reactions by different aromatic compounds andl.4-biaryl substituted butane with 2.3-dichloro-5.6-dicyano-1.4-benzoquinone(DDQ) and thallium(III) trifluoroacetate(TTFA) in trifluoroacetic acid(TFA). The structures of these products have been identified by MS, UV, IR and NMR spectra.