1: 97 percent / triphenylphosphine; hydrazoic acid; diethyl azodicarboxylate / tetrahydrofuran; benzene / 2 h / 20 °C 2: 70 percent / propane-1,3-dithiol; Et3N / methanol / 12 h / 20 °C 3: 82 percent / tetrabutylammonium fluoride / tetrahydrofuran / 1 h / 20 °C View Scheme