Staudinger Reaction Of Vicinal-diimines With Ketenes And Their Application

As the antibiotics,β-lactams had saved many lives with their good functions of anti-inflammation and anti-bacterium; because of the ring strain of the four-membered ring structure, they can be opened to form amino acids or expanded to heterocyclic compounds, and thus as intermediates they have important applications in both amino acid synthesis and the synthesis of heterocyclic compounds. The current common synthetic method ofβ-lactams is through ketene and imine [2+2] cycloaddition reaction, which is also known as the Staudinger reaction. Although the Staudinger reactions ofα,β-unsaturated ketenes andα,β-unsaturated imines have been studied systematically, the Staudinger reaction involving vicinal-diimines is still incompletely clear. On the other hand, the iminoβ-lactams and bis-β-lactams generated from the reactions have been widely used in organic synthesis.For these reasons, we synthesized a series of vicinal-diimines from methylglyoxal, butanedione, diphenyldiketone and investigated their reactions with several representative acyl chlorides with different electronic effects and steric hindrance and found that acyl chlorides with electron-donating group not only generate bis-β-lactams but also monoβ-lactams; the reaction could only get monoβ-lactams with trans or cis respectively. Configrations, which is controlled by the electronic effects of the substituent of acyl chlorides and steric hindrance of imine N-substituents. On the basis of our conclusions,4-acyl-β-lactams were synthesize regioselectively and stereoselectively.The current results give a more systematic understanding on the Staudinger reaction of vicinal-diimines, and provide more important intermediates, such as bis-β-lactams and iminoβ-lactams for organic synthesis. Most importantly, we provide a new way to obtain these compounds with good stereoselectivity and regioselectivity.