A Ring‐Closing Metathesis Approach to Cyclic α,β‐Dehydroamino Acids

A comprehensive study on the synthesis and ring‐closing metathesis (RCM) of α,β‐dehydroamino acids is described. This sequence has led to the formation of a range of biologically relevant functionalized nitrogen heterocycles. The incorporation of chiral building blocks in the RCM precursors eventually resulted in the formation of optically active 4‐substituted cyclic dehydroamino acids. In addition, olefin isomerization under metathesis conditions was observed for a number of compounds, which could be successfully inhibited either by the introduction of allylic substituents or by the addition of a ruthenium hydride scavenger.