INTRAMOLECULAR ANODIC OLEFIN COUPLING REACTIONS AND THE USE OF ELECTRON-RICH

The utility of intramolecular anodic olefin coupling reactions involvi ng electron-rich aromatic rings for constructing fused, bicyclic ring skeletons has been examined. Reactions involving alkoxy-substituted ph enyl rings were found to benefit strongly from a 3-methoxy substituent on the phenyl ring. Although overoxidation of the bicyclic product wa s observed in these reactions, this problem could be minimized with th e use of controlled potential electrolysis conditions when a monometho xy phenyl ring was used and avoided entirely with the use of a vinyl s ulfide moiety as the initiator when a more electron-rich phenyl ring w as used. Reactions involving 4-alkoxy-substituted phenyl rings as subs trates did not lead to good yields of fused products. Furan rings were found to be excellent coupling partners for the reactions and afforde d products having fused, bicyclic furan ring skeletons. Cyclizations i nvolving furans were shown to be compatible with the formation of both six- and seven-membered rings, the generation of a quaternary carbon, and the use of a variety of electron-rich olefins as the other coupli ng partner. It appears that the furan can serve as either the initiati ng group or the terminating group for the cyclizations. Finally, the r eactions were shown to be compatible with the use of a pyrrole ring as one of the participants.