Scheme 1.

Synthesis of (S)-9 to (S)-14 and (R)-9. Reagents and conditions: (a) BOP, Et₃N, DCM, room temperature (rt), 20 h, 64%; (b) 1,1,1-triethoxy ethane, AcOH, reflux, 3 h, >90%; (c) Cs₂CO₃, corresponding phenol, DMF, 90 °C, 18 h, 95%; (d) TFA/DCM, 1:2, rt, 2 h, quantitative; (e) corresponding alkylating agent, K₂CO₃, CH₃CN, 70 °C. BOP, benzotriazole-1-yl-oxy-tris-(dimethylamino)-phosphonium hexafluorophosphate; Et₃N, triethylamine; DCM, dichloromethane; AcOH, acetic acid; DMF, N,N-dimethylformamide; TFA, trifluoroacetic acid; DCM, dichloromethane.