Nitroalkylation and nitroalkenylation reactions of gamma-lactone enolates. A facile ring switch from polysubstituted gamma-lactones to polysubstituted gamma-lactams

Michael addition of lithium enolates of g-butyrolactone 1 and a-methyl-g-butyrolactone 10 to (E)-1-nitropropene 2, (E)-bnitrostyrene 3 and (E)-2-nitro-1-phenylpropene 4 is described. Reactions of the lithium enolate of 10 with 2 and 4 occurred with high diasteroselectivity (80 and 92% d.e., respectively). Reactions of the zinc enolate of 10 with two b-nitroenamines and two methylthiosubstituted 1-amino-2-nitro-1,3-dienes were also examined. Catalytic reduction of the nitroalkylated and nitroalkenylated products allowed the achievement of functionalized g-lactams and/or cyclic hydroxamic acids.