Graft polymerization of various vinyl monomers onto a polystyrene resin (6) containing azo groups having the ability to initiate the radical polymerization was performed. The graft efficiency of vinyl monomers onto 6 increases with time of polymerization and achieves more than 85%. The swelling of 6 affects remarkably the graft efficiency. Scanning electron microscopy (SEM) shows that considerable amounts of graft copolymers are located at the surface of 6. The graft copolymer of chloromethylstyrene onto 6 was treated with (8-( -)-2-amin0-3-@-hydroxyphenyl)-l,l -diphenyl-1 -propano1 to yield a resin (9) carrying chiral amino alcohol functions. Resin 9/borane was used for asymmetric reductions of acetophenone oxime O-methyl and 0-benzyl ethers, leading to 1 -phenylethylamine with 43% and 46% enantiomeric excess (e. e.), respectively. These values are higher than those obtained with the generally used polystyrene resin, suggesting that the enantioselectivity can be improved by modification of the support resin.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.