MeO2CN=NCO2Me; triphenylphosphine in tetrahydrofuran T=-78 - 20°C; Cyclization;

1: 83 percent / Me4NOH*5H2O / acetonitrile 2: 100 percent / H2 / Pd/C / methanol 3: 86 percent / dimethyl azodicarboxylate; Ph3P / tetrahydrofuran / -78 - 20 °C View Scheme

1.1: LDA / tetrahydrofuran / -78 °C 1.2: tetrahydrofuran / -78 - 20 °C 2.1: 96 percent / aq.HCl / Heating 3.1: 83 percent / Me4NOH*5H2O / acetonitrile 4.1: 100 percent / H2 / Pd/C / methanol 5.1: 86 percent / dimethyl azodicarboxylate; Ph3P / tetrahydrofuran / -78 - 20 °C View Scheme

1.1: TFA / pentane / Heating 2.1: LDA / tetrahydrofuran / -78 °C 2.2: tetrahydrofuran / -78 - 20 °C 3.1: 96 percent / aq.HCl / Heating 4.1: 83 percent / Me4NOH*5H2O / acetonitrile 5.1: 100 percent / H2 / Pd/C / methanol 6.1: 86 percent / dimethyl azodicarboxylate; Ph3P / tetrahydrofuran / -78 - 20 °C View Scheme

1: 96 percent / aq.HCl / Heating 2: 83 percent / Me4NOH*5H2O / acetonitrile 3: 100 percent / H2 / Pd/C / methanol 4: 86 percent / dimethyl azodicarboxylate; Ph3P / tetrahydrofuran / -78 - 20 °C View Scheme

1: 100 percent / H2 / Pd/C / methanol 2: 86 percent / dimethyl azodicarboxylate; Ph3P / tetrahydrofuran / -78 - 20 °C View Scheme