Synthesis of Enantioenriched γ‑Amino-α,β-unsaturated Esters Utilizing Palladium-Catalyzed Rearrangement of Allylic Carbamates for Direct Application to Formal [3 + 2] Cycloaddition

An
efficient synthesis of enantioenriched γ-amino-α,β-unsaturated
esters was developed by utilizing the palladium-catalyzed decarboxylative
rearrangement of enantioenriched allylic carbamates possessing an
ester moiety at the allylic position. The reaction proceeded in good
yield with a high degree of chirality transfer by making use of Xantphos
as a superior ligand for the catalyst. The products directly participated
in the formal [3 + 2] cycloaddition reaction with tosyl isocyanate
under Brønsted base catalysis to afford enantioenriched β,γ-diamino
acid derived imidazolidin-2-ones as versatile chiral building blocks.