γ-Lactam derivatives are widespread biologically active compounds, covering a large range of activities. Following our interest in both medicinal and green chemistries, we developed an original, cesium salts-mediated, scalable and solvent-free methodology to transform biosourced pyroglutamic acid and itsderivatives to their N,N′-aminals, N,O,N,S-acetals and C5-substituted γ-lactams in good to excellent