Synthesis of per-6-guanidinylated cyclodextrins

Reaction of per(6-amino-6-deoxy-2,3-di-O-methyl)-α-, β- and γ-cyclodextrins with N,N′-bis(tert-butoxycarbonyl)-N″-triflylguanidine and triethylamine in tetrahydrofuran gave per[6-N,N′-bis(tert-butoxycarbonyl)guanidino-6-deoxy-2,3-di-O-methyl]-α-, β- and γ-cyclodextrins, respectively. Subsequent cleavage of the protective groups with trifluoroacetic acid in dichloromethane afforded per(6-deoxy-6-guanidino-2,3-di-O-methyl)-α-, β- and γ-cyclodextrins in very good overall yields.