1: (i) aq. HCl, MeNO2, (ii) /BRN= 1788521/, KOEt, EtOH, benzene 2: H2 / Pd/C / ethanol 3: polyphosphoric acid 4: (hydrogenolysis) 6: Pd/C / 350 °C View Scheme

1.1: 80 percent / p-toluenesulfonic acid / toluene / 12 h / Heating 2.1: ZnCl2; hydroquinone / tetrahydrofuran / 2 h / 0 °C 2.2: 70 percent / acetic acid; H2O 3.1: 70 percent / LiCl; DBU / tetrahydrofuran / 1 h / -78 °C 4.1: 85 percent / TMSOTf / CH2Cl2 / 20 h / -78 °C 5.1: 65 percent / MeONa / benzene / 12 h / Heating 6.1: 90 percent / MgCl2 hexahydrate / dimethylsulfoxide / 4 h / 130 °C View Scheme

boric acid T=110°C;