Npys‐Mediated Elimination Reactions of Alcohols and Thiols: A Facile Route to Dehydroalanine and Dehydrobutyrine Building Blocks.

We report a new and rapid method for side-chain dehydration/dehydrothiolation of serine, threonine, and cysteine building blocks. The method relies on activation with 3-nitro-2-pyridinesulfenyl chloride (Npys-Cl) followed by treatment with base. It is possible to perform the sequence as a one-pot operation and due to the significant functional-group compatibility of Npys-Cl, this method may be compatible with multifunctional and complex substrates.