1: 92 percent / NaHCO3 / dioxane; H2O 2: tetrazole / CH2Cl2; acetonitrile / 0.5 h 3: iodine, pyridine, water / CH2Cl2 4: 95 percent / 33percent HNMe2 / ethanol / 72 h / 45 °C 5: 75 percent / tetrabutylammonium fluoride / tetrahydrofuran / 72 h / 45 °C View Scheme

1: 92 percent / N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline / ethanol / 14 h / 50 °C 2: Et3N, DMAP / benzene / 6 h / Ambient temperature 3: benzene; acetonitrile / 48 h / 65 - 70 °C 4: 92 percent / tetra-butylammonium fluoride / tetrahydrofuran / 20 h / Ambient temperature View Scheme

With  pyridine; water; triphenylphosphine T=55 - 60°C; 11 h;   

Multi-step reaction with 6 steps 1: 88 percent / NEt3 / tetrahydrofuran2: iPr2NH*tetrazole / CH2Cl2; acetonitrile / 0.5 h3: tetrazole4: I2 / H2O; pyridine; CH2Cl2 5: 33percent HNMe2 / ethanol / Ambient temperature6: 86 percent / 1.) tetrabutylammonium fluoride (TBAF); 2.) ion exchange resin (H+, OH-) / 1.) THF, 35 deg C