Sulfoxides of Cys (Sp-methoxybenzyl) and Cys (S-benzyl) were prepared by oxidation with sodium perborate. Hydrogen fluoride and methanesulfonic acid converted the former sulfoxide to Sp-methoxyphenylcysteine or Sp-hydroxyphenylcysteine in the presence of anisole or phenol, respectively, while the latter sulfoxide resisted the actions of these deprotecting reagents. Thiophenol appears to be useful as a powerful reducing reagent ...
![2-amino-3-[(4-methoxyphenyl)methylsulfinyl]propanoic acid Structure](https://image.chemsrc.com/caspic/037/73243-09-1.png)
