Fig. 3: Chemoselective removal of cyanosulfurylides.

In solution removal of cyanosulfurylide in the presence of oxidation-sensitive residues including tryptophan and StBu protected cysteine. NCS was titrated to the solution until full conversion was indicated by HPLC and mass spectrometry. Reaction went to completion within 5 min at 25 °C without any side-product being observed by HPLC and mass spectroscopy.