Reactive & Functional Polymers, Vol.68, No.7, 1127-1131, 2008
Spacer-modified crosslinked copolymer beads for the solid phase synthesis of an amide
The goal of this research was to synthesize an amide using the reaction of a polymer-supported active ester with a primary amine. A new type of the polymer support for an active ester was prepared from poly(omega-bromobutylstyrene-co-divinylbenzene) beads (1). Bromine atoms in 1 were replaced by mercapto groups upon treatment with thiourea and subsequent alkaline hydrolysis. Following this, N-hydroxymaleimide was reacted with the polymer (3). This reaction introduced N-hydroxysuccinimide moieties into the polymer beads via Michael addition, yielding a resin (4). Resin 4 was reacted with a model carboxylic acid in the presence of a water-soluble esterification reagent (WSC). This yielded resin (5), which contained polymer-bound active ester groups. Reaction of 5 with a primary amine gave the objective amide. Resulting amides had a higher purity than those prepared by solid phase synthesis using the corresponding polymer support, which was derived with poly(chloromethylstyrene-co-divinylbenzene) beads and a traditional liquid phase synthesis. Resin 5, after use in the amide synthesis, was regenerated into the active ester form for the repeated use. (c) 2008 Elsevier Ltd. All rights reserved.
Keywords:reactive resin;solid phase synthesis;active ester;crosslinked poly(omega-bromobutylstyrene);amide synthesis