Improved reproducibility of chemical reactions on purified polystyrene resins monitored by 31P MAS NMR

The use of polystyrene beads from different origins in solid-phase organic synthesis was investigated after a simple cleaning procedure of the starting material. The swelling and thermogravimetric properties and the reproducibility of a five-step reaction cascade were investigated. The resin loadings of polystyrene bound phosphines were quantitatively determined by 31P MAS NMR via addition of triphenyl phosphate as reference compound and the loadings of intermediate products were evaluated by Fmoc cleavage.