STEREOSELECTIVE SYNTHESIS OF FUSED GAMMA-LACTAMS BY INTRAMOLECULAR NITRONE CYCLOADDITION

A series of nitrones 5 joined by amides to olefines were prepared in s itu from the related aldehydes with N-methylhydroxylamine. The nitrone s added intramolecularly to the olefin, and the cycloadditions gave fu sed gamma-lactams 6 stereoselectively. A stereocentre located in posit ion alpha to the nitronic functionality 13 completely controls the ste reochemical course of the intramolecular cycloaddition, which exclusiv ely affords compound 14 with simultaneous introduction of four stereoc entres. The formation of this latter compound was also supported by PM 3 calculations. Furthermore, simple heating of unsaturated oxime 17 le d to compound 19 via intramolecular oxime olefin cycloaddition.