Scheme. (1) Reagents and conditions: a) bis(pinacolato)diboron, K₂CO₃, Pd(PPh₃)₂Cl₂, PPh₃, dioxane, 50 °C, b) imidazole, K₂CO₃, acetone, rt, 37% for 19; c) bis(tributyltin), Pd(PPh₃)₂Cl₂, DMF, 95 °C, 24 h, 74%; d) 21a, b, Pd(CH₃CN)₂Cl₂, LiCl, DMF, 105 °C, 72 h, 38% for 24a, 36% for 24b; e) LiOH, MeOH-THF-H₂O, rt, 18 h, 92% for 25a, 88% for 25b, 84% for 27; f) 3,4-methylenedioxyphenethylamine, TBTU, iPr₂NEt, CH₃CN, rt, 48 h, 88% for 3, 92% for 6, 70% for 9; g) H₂ (1 atm), Pd/C, rt, 72 h, > 90%; h) DBU, PhH, reflux, 48 h, 90%; i) 2-ethoxycarbonyl-phenylzinc bromide, Pd(PPh₃)₄, THF, 50 °C, 48 h, 87%.