Scheme 1.

Synthesis of 7-alkoxytetrahydroisoquinoline derivatives

Reagents and Conditions: (a) (i) 3,4-Dimethoxyphenylacetic acid, BOP, iPr2EtN, DMF; (ii) R-I or R-Br, K₂CO₃, DMF; (b) (i) POCl₃, toluene; (ii) NaBH₄, MeOH; (c) (i) MeOCOCl, iPr₂EtN, CH₂Cl₂; (ii) R-I or R-Br, K₂CO₃, DMF; (d) 3,4-dimethoxyphenylacetaldehyde, TFA; (e) KOH, NH₂NH₂.H₂O, (CH₂OH)₂; (f) BrCH₂CONHBn, iPr₂EtN, Bu₄NI, DMF.