Polymer-supported triazenes as smart reagents for the alkylation of carboxylic acids.

Starting from polystyrene, a simple four-step synthesis of polymer-supported alkyltriazenes (alkyl=Me, Et, benzyl) is described. With this synthesis, a loading capacity of 2.2 mmol g(-1) can be reached. The most prominent application of these polymer-supported reagents is the rapid, highly selective and high-yielding esterification of carboxylic acids, which involves a simple "mix and filter off" procedure at room temperature. If stored in a refrigerator, these reagents are stable for many months and they can be recycled several times.