,-Dehydroamino acids (dhAAs) exhibit unique reactivity due to their combined electronic contributions of the nitrogen and carbonyl substituents and due to their pronounced somophilicity. Polar and radical additions have been exploited in the latestage-functionalization of dhAA-containing peptides and natural products. While dehydroalanine and dehydrobutyrine derivates are accessible from their respective serine, cysteine and threonine derivatives, 2 the synthesis of other dhAAs remains challenging. Kinoshita reported two methods using N-Cbz-tosyl glycinates and nitro compounds or aldehydes in an alkylation/nitrite elimination-cascade or Wittig-type reaction, respectively (Scheme 1A). These approaches allow access to a variety of substituted dhAAs but are limited in the protective groups on the tosyl glycine derivative and the accessibility of their respective coupling partners. An alternative strategy utilizes the Schmidt reagent in Horner-Wadsworth-Emmons reactions (Scheme 1B). The method was shown to be flexible, using the N-Cbz protected reagent accessible via a multistep synthesis. Other derivatives may be synthesized by modifications of the reagent. Schmidt reported a direct synthesis of dhAAs from the corresponding amino acids using a N-chlorination, dehydrochlorination and rearrangement sequence. Limitations include the use of reactive tBuOCl and challenging N-protection of the sensitive enamines. Nanjo and Takemoto applied a similar N-chlorination protocol to the selective late-stage desaturation of aliphatic peptides (Scheme 1C). However, carbamate protected residues were not desaturated under these conditions.