Stereocontrolled construction of condensed .gamma.-lactam ring systems by cationic cyclizations. Rearrangement of a .gamma.-lactam to a .delta.-lactam
摘要:
A new condensation of 3-alkenamides with benzaldehyde in acidic media, notably polyphosphoric acid, leads to gamma-lactam rings with high regio- and stereocontrol. One such gamma-lactam was shown to undergo a novel and stereocontrolled ring-expansion to a delta-lactam.