Polymer-Supported Cation Radicals

Article abstract of DOI:10.1021/jo00265a043

Reaction of chloromethylated polystyrene (3.90 mequiv/g) beads with triphenylamine and diethylchloroalane resulted in a higly cross-linked polymer.The chloromethylated polystyrene was modified by reaction with 2,6-dibromocarbazole (4) and K2CO3 in DMF at 100 deg C to give an excellent yield of polymer-supported 2,6-dibromocarbazole (5) without concomitant cross-linking.The polymer-bound 2,6-dibromocarbazole was nonreactive toward SbCl5, whereas the homogeneous counterpart 9-N-benzyl-2,6-dibromocarbazole (6) was found to readily generate the aminium cation radical upon reaction with SbCl5.Attachment of phenothiazine to a polystyrene support yielded a reagent that would react very rapidly with SbCl5 in dichloromethane.The polymer-bound phenothiazine cation radical was found to readily oxidize the metal-metal bond in 2 and undergo anion exchange with Bu4NPF6 to afford a more synthetically useful reagent.