Scheme 3.

Synthesis of N-substituted analogues 12, 13a–c, 14a–b, 15, 16a–c.

Reagents and conditions:

a) NaH, CH₃l, DMF, 0°C, overnight; b) H₂, Pd-C (10%), 90 psi, ambient temperature, overnight, c) CH₃l, Na₂CO₃, MeCN, ambient temperature, overnight; d) CH₃COCl, DCM, ambient temperature, overnight; e) BBr₃/DCM (1M), DCM, −78°C, overnight. f) 1-bromo-2-fluroethane, 3-bromopropyne or 3-bromo-1-iodopropene, Na₂CO₃, MeCN; g) HCl (3 M), H₂O, reflux, 5h;