1: Zn, CuSO4, aq. KOH, Py 2: ZnCl2, AcOH View Scheme

acetic acid; zinc(II) chloride

hydrogen iodide; hypophosphorous acid in acetic acid T=100°C;

1: 91 percent / HI, H3PO2 / acetic acid / 100 °C 2: 93 percent / HBr / acetic acid / Heating 3: 87 percent / Adogen 464, Fremy's salt, KH2PO4 / benzene; CH2Cl2; H2O View Scheme

1: 91 percent / HI, H3PO2 / acetic acid / 100 °C 2: 93 percent / HBr / acetic acid / Heating 3: 87 percent / Adogen 464, Fremy's salt, KH2PO4 / benzene; CH2Cl2; H2O 4: 96 percent / NaBH4, O2 / ethanol View Scheme