Syntheses of Macrocyclic Bis(bibenzyl) Compounds Derived from Perrottetin E

Macrocyclic bis(bibenzyl) compounds are natural products from liverworts and are of growing interest due to recent reports on new isolated compounds and on their remarkable biological activities. We report here on a flexible and general approach to the total set of nine bis(bibenzyl) compounds of the riccardin and plagiochin type derived from perrottetin E. The structures were confirmed through their spectroscopic data, which were compared carefully with those for the isolated products to exclude any errors in arene connection and substitution pattern. Nine isomeric macrocyclic bis(bibenzyl) compounds of the plagiochin/riccardin type, some of which have been found in liverworts, derive biochemically from perrottetin E. Growing interest due to recent reports on new isolated compounds and their remarkable biological activities prompted us to synthesize these bryophyte constituents. We report a flexible general approach to the total set of nine bis(bibenzyl) compounds.