New cascade and multiple cross-coupling reactions for the efficient construction of complex molecules

摘要: Multiple palladium-catalyzed cross-coupling reactions of the Heck, Suzuki and Stille types on oligofunctionalized cycloalkenes arenes can be performed in very high yields. While Heck type 1,2-dibromocycloalkenes or 2-bromocyclohexenyl triflates lead only to twofold coupling products, latter substrates occurs chemoselectively at site triflate leaving group give bromobutadienes which readily undergo subsequent reactions. The thus obtained 1,3,5-hexatrienes thermal 6π-electrocyclizations furnish bicyclic skeletons, among others cyclohexenone-annelated systems after acidic work-up. Cascades carbopalladation, rearrangement [4+2] cycloaddition with bicyclopropylidene, aryl iodides dienophiles constitute a new class three-component remarkable combinatorial potential, especially since they solid phase using triazene linker. With nucleophiles instead yet another domino reaction consisting nucleophilic substitution alkenyl C-, O- N-centered wide variety interesting compounds. Under properly adjusted conditions even sixfold hexabromoarenes achieved. When initially formed intermediates en route hexaalkenylarenes intramolecular ring closures yield multi-component mixtures isomers expected but couplings pure up 73% yield. Crystal structure analyses reveal that depending nature groups six arms are positioned either same side central making it an cup-shaped molecule alternating above below plane.