Scheme 2. Synthesis of γ-lactams bearing different lactam nitrogen substituents. Reagents and conditions: (a) N-bromosuccinimide, THF, 0 °C to rt, 80%; (b) amine, K₂CO₃, ^tBuOH, CuI (10 mol%), N,N′-dimethylethylenediamine, 100 °C; or: amine, K₂CO₃, Cu(0), pyridine, 120 °C, 5–44%; (c) HATU,⁵⁸ⁱPr₂NEt,⁵⁹ MeCN : CH₂Cl₂ (1 : 1), rt, 22–67%. See Table 3 for structures of 23a and 23c–f.