Stereoselective synthesis of trans β-lactams via palladium/N-heterocyclic carbene-catalyzed carbonylative [2+2] cycloaddition

Xie, Pan; Qian, Bo; Huang, Hanmin; Xia, Chungu

Stereoselective synthesis of trans β-lactams via palladium/N-heterocyclic carbene-catalyzed carbonylative [2+2] cycloaddition

2012

Xie, Pan | Qian, Bo | Huang, Hanmin | Xia, Chungu

The carbonylative [2+2] cycloaddition of benzyl chlorides and allyl derivatives with imines and CO for synthesis of β-lactam is effectively catalyzed by palladium/N-heterocyclic carbene complex. The desired β-lactam could be obtained in good to excellent yields (61–96%) with excellent regioselectivities (trans/cis>95:5) and chiral lactams could be obtained with moderate diastereoselectivities. The KIE experimental studies have revealed that the C–H cleavage is most likely to be the rate-limiting step for the carbonylative cycloaddition.

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