During the past century, β-lactams have been identified as the core of penicillin and since then several strategies have been developed for their synthesis. Traditional methods for β-lactam synthesis usually involved amide bond formation and the Staudinger reaction. In recent years, by the advancement of photo- and transition metal-catalysis, several new methods have been reported for β-lactam synthesis. For instance: ligand assisted metal catalyzed C-H activation/intermolecular oxidative amidation draws attention for β-lactam synthesis. In this review we introduce methods for β-lactam synthesis and present newly developed reactions. We approach the synthesis of β-lactams according to different retro synthesis strategies.

We describe herein a gold-catalyzed rearrangement of propargyl esters followed by allene-ene cyclization to afford substituted bicyclic [4.4.0] dihydronaphthalene compounds. This method is also applied to vinylethers and vinylamines of 1,7-enyne esters to form dihydroquinoline and dihydrobenzopyran structures. The basis of this transformation is the ligand-controlled preferential activation of the alkene over the allene, affording the desired aromatic bicyclic structures in moderate to excellent yields.

Using a combination of triazole-gold (TA-Au) and copper catalysts, the substituted furan was achieved in one pot through a three-step reaction cascade. The reaction tolerates a large substrate scope with simple starting materials. The desired di-, tri-, and tetrasubstituted furans were prepared in good to excellent yields.