Asymmetric Electrophilic a-Substitution of Lactones and Lactams

4-addition of the lactams 72 to nitroolefins provided access to the Michael adducts 73 with good stereoselectivities, which could be improved by recrystallization or chromatography. After reduction and protection of the amino group the y-butyrolactams 74 were converted to the corresponding a-substituted lactams 75 in good overall yields (37-65%) and excellent diastereo- and enantio- 

Since the trapping of the lactam enolate with electrophiles should not be limited to nitroolefins, extension to conjugate additions to alkenylsulfones, the ring opening of N-tosylaziridines, alkylation with functionalized halides, and silylation with chlorotrimethylsilane were explored. 

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