Search

We report the development of a sensitive and specific color test for the detection of the presence of resin-bound aldehyde groups using 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (Purpald). Aldehyde resin turns dark-brown to purple after a 5 min reaction followed by a 10 min air oxidation period. Resins that possess other functional groups (i.e., ketone, ester, amide, alcohol, and carboxylic acid) do not change color under the same conditions. The detection limit is 20 μmol/g for polystyrene-based aldehyde resins.

A series of libraries containing the 2,4-diaminoquinazoline ring system were prepared, starting from polymer-bound amines. The key steps included reaction of the support-bound amine with 6,7-dimethoxy-2,4-dichloroquinazoline, followed by displacement of the second chlorine with an amine and subsequent TFA-mediated cleavage of the product from the support. When a symmetrical or unsymmetrical diamine was used in the displacement step, the free amine could be acylated with an activated acid to generate another set of compounds. The optimization of conditions for the reductive amination and displacement steps will be discussed as well as the final choice of resin for library production. In addition, quality control methods for library analysis is also described.