Abstract
The objective of this work is to synthesize the mussel-mimicking ionic polymers bearing electron-rich 1,3,4-triphenoxy motifs of naturally occurring sesamol [3,4-(methylenedioxy)phenol] I. To our knowledge, the work would represent, for the first time, the ring-opening reaction of epoxide built upon the triphenoxy motifs of hydroxyhydroquinone. Sesamol I upon O-alkylation using epibromohydrin has been converted to its epoxy monomer II in 77% yield. Monomer II under ring-opening polymerization using basic Bu4NOH and Bu4NF as well as by Lewis acid initiator/catalyst MePh3PBr/(Bu3Al)-Bu-i led to polyether III in 80-99% yields. Monomer II and allyl glycidyl ether (i.e. allyl 2,3-epoxypropyl ether) IV upon polymerization gave random copolymer V of number average molar mass of 9570 g mol(-1), which upon thiol-ene reaction with HSCH2CH2NH3+Cl- and HSCH2CO2H afforded cationic ((NH3+)-N-boolean AND boolean AND boolean AND) VI and anionic ((CO2-)-C-boolean AND boolean AND boolean AND) VII copolymers, respectively. For facile deprotection, the methylenedioxy (-OCH2O-) motifs in VI was activated by its conversion to labile acetoxymethylenedioxy [-OCH(OAc)O-] unit to obtain VIII in 80% yields. The pendant allyl groups in VIII upon elaboration via thiol-ene reaction using cysteamine hydrochloride and subsequent hydrolysis of [-OCH(OAc)O-] under a mild condition led to a mussel-inspired cationic copolymer IX (78%) having catechol motifs-embedded pendants of 3,4-dihydroxyphenoxy groups.