of peptide cysteine. Through the identification of its t-Bu ester 1 as a more competent form
under ligation conditions, facile N-terminal and side-chain caging for the model peptide and
protein were accomplished. Building upon this, a one-pot ligation and photolysis strategy
was applied in the synthesis of the mini-protein chlorotoxin. More importantly, we extended
the utility of 2 as a bifunctional linker for traceless solid-phase chemical ligation.