The Barton radical decarboxylation on solid phase. A versatile synthesis of peptides containing modified amino acids

Barton esters were prepared starting from different carboxylic acids loaded on a Wang resin. Light induced fragmentation occurred giving a radical that reacted with CBrCl3 to give the corresponding bromides, whereas conjugate addition to electron-poor alkenes proved to be less synthetically useful. The bromides so formed were further functionalised on the resin with different nucleophiles.