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23.14.1.2.8 Method 8: β-Lactams by [2+2] Cycloaddition of Monoalkylketenes with Imines

DOI: 10.1055/sos-SD-023-00535

Tidwell, T. T.Science of Synthesis, (200623608.

The [2+2] cycloaddition of ketenes with imines to form β-lactams (the Staudinger reaction) was discovered in 1907.[‌119‌] Because of the importance of the products in medicinal chemistry, this subject has been extensively examined, and previously published information regarding this product class can be found in HoubenWeyl, Vol. E 16b, pp 31942, and in a number of reviews.[‌152‌‌160‌] As with other ketene [2+2] cycloadditions, these reactions are often highly stereoselective (see Section 23.14.1.2.7), with a strong tendency to give a cis-stereochemistry of the substituents on the newly formed bond between the terminal carbon of the ketene and the carbon of the imine. However, imines have a higher tendency than alkenes to react by stepwise pathways to form zwitterionic intermediates, and so may show a lack of stereoselectivity in product formation.

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References


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