An Efficient Synthesis of Aminomethyl PS-DVB Using FeCl₃-MeNO₂ as a Catalyst

Significance

Aminomethyl polystyrenes cross-linked with divinylbenzene (PS-DVBs) were prepared by the Lewis acid catalyzed Friedel-Crafts reaction and used as polymer supports in the solid-phase synthesis of polypeptides. The Friedel-Crafts reaction of PS-DVB 1 with N-(chloromethyl)phthalimide 2 in the presence of FeCl₃, FeCl₃-nitromethane, or FeCl₃-benzophenone gave N-(phthaloyl)aminomethyl PS-DVBs 3. The dephthaloylation of PS-DVBs 3 with hydrazine gave aminomethyl PS-DVBs 4a-c. Polypeptide 5 was prepared by using the standard Fmoc procedure with the aminomethyl PS-DVBs 4a-d. The reaction using aminomethyl PS-DVB 4b gave the poly­peptide 5 with the highest purity of these polymers.