Scheme 2. Synthesis of Compounds 3a–m, 6a–c, and 7a–c.

Reagents and conditions: (a) NaOH, H₂O, 90 °C, 48 h, 68–73% or NaOH, TBAB, EtOH, reflux, 24 h, 32–61%; (b) 1a, K₂CO₃, MeCN, reflux, 12 h, 44–72%; (c) HO(CH₂)₂NH₂, K₂CO₃, CuI, l-proline, DMSO, 60 °C, 12 h, 78–90%; (d) TBAB, PPh₃, DDQ, DCM, rt, 30 min, 44–82%; (e) 1a, K₂CO₃, MeCN, reflux, 12 h, 55–70%; (f) 1a, MeOH, rt; (g) NaBH(CH₃COO)₃, AcOH, DCM, rt, 12 h, 50–65% (for steps f and g). X, n, and R are as defined in Table 2.