triphenylphosphine; diethylazodicarboxylate in tetrahydrofuran T=25°C; 2.5 h;

1: 76 percent / KO-t-Bu / diethyl ether; 2-methyl-propan-2-ol / 3 h / 25 °C 2: 83 percent / Diethyl azodicarboxylate, Ph3P / tetrahydrofuran / 2.5 h / 25 °C View Scheme

1: 95 percent / DCC, DMAP / CH2Cl2 / 17 h / 25 °C 2: 76 percent / KO-t-Bu / diethyl ether; 2-methyl-propan-2-ol / 3 h / 25 °C 3: 83 percent / Diethyl azodicarboxylate, Ph3P / tetrahydrofuran / 2.5 h / 25 °C View Scheme

formic acid T=25°C; 2 h;