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.