2, 3‐Disubstituted γ‐Butyrolactams from the Michael‐Additions of Doubly Deprotonated, Optically Active β‐Hydroxycarboxylates to Nitroolefins. Preliminary Communication

The conjugate addition of the chiral, non‐racemic alkoxy‐enolates 5 and 6 to nitroolefins furnishes the hydroxynitroesters 7–13 , which are catalytically hydrogenated to give the lactams 14–18 . The configuration of adduct 7 from nitroethylene was elucidated by NMR. analysis of the acetal 20 derived from 7 . The assignment establishes that the reaction follows the stereochemical rule of attack depicted in 21 and previously deduced for other electrophiles, i.e. formation of erythro ‐products of type 3b and 4b . No stereocontrol was found at the newly formed chiral centers in α‐ and β‐position to the NO 2 group of 8–12 .