Lactams ring-opening recyclization

A regiospecific ring-opening recyclization of -lactams gives 3-spirocyclicquinolin-4(lW)-ones (Scheme 72). ... 

The 1,4-thiazepine (310) has been prepared by ring-opening of (308) to the anion (309), followed by alkylation with 3-bromo-l-chloro-propane and recyclization in the presence of sodium hydride. In the field of )8-lactam... 

Action of catalytic amounts of vanadium compounds on oxaziridine (52) yields caprolactam almost quantitatively. Reductive opening of the oxaziridine ring and /3-scission yield radical (118), which recyclizes with elimination of the metal ion to form the lactam (63) (77JPR274). 

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