Synthesis of aza-β-lactams by photochemical ring contraction
Abstract
Photochemical decomposition of 4-diazopyrazolidine-3,5-diones (3) in the presence of nucleophiles, XH, leads to the aza-β-lactams (4); decarboxylation of (4e) gives the aza-β-lactam (7), which undergoes reductive ring cleavage to (8), and ring expansion to (9) on treatment with base.