Polystyrylsulfonyl-3-nitro-1H-1,2,4-triazolide-resin: a new solid-supported reagent for the esterification of amino acids

We describe the application of the polystyrylsulfonyl-3-nitro-1H-1,2,4-triazolide-resin, readily available from the corresponding commercially available polystyryl sulfonyl chloride resin, to the solution-phase synthesis of esters from protected α-amino acids and alcohols in high yields and purity with a low level of racemisation of the amino acids. All by-products can be removed by filtration and extraction.