Reactions of Imines with Ketenes Staudinger Reaction

1 Reactions of Imines with Ketenes (Staudinger Reaction) 

The reaction of ketenes with imines opens up a useful route for the synthesis of P-lactams. The two-step mechanism involving a dipolar intermediate is outlined in the scheme below.  

In the second reaction step the cis/tram stereochemistry of the product is determined. In general, fraw-P-lactams are formed starting from cyclic (Z)-imines by conrotatory ring closure of the zwitterionic intermediate.  

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