trifluoroacetic acid in water T=0°C; 20 h;

1.1: tri-n-butyl-tin hydride; 2,2'-azo-bisisobutyronitrile / toluene / 2 h / |Reflux 2.1: methanol; ammonia / 16 h / 0 - 60 °C 3.1: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / N,N-dimethyl-formamide / 0.5 h 4.1: trifluoroacetic acid / water; tetrahydrofuran / 0 °C 5.1: (tetrazol-5-yl)benzene / dichloromethane / 1 h 5.2: 0.5 h / 0 °C 6.1: trifluoroacetic acid / water / 20 h / 0 °C View Scheme

1.1: methanol; ammonia / 16 h / 0 - 60 °C 2.1: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / N,N-dimethyl-formamide / 0.5 h 3.1: trifluoroacetic acid / water; tetrahydrofuran / 0 °C 4.1: (tetrazol-5-yl)benzene / dichloromethane / 1 h 4.2: 0.5 h / 0 °C 5.1: trifluoroacetic acid / water / 20 h / 0 °C View Scheme

1.1: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / N,N-dimethyl-formamide / 0.5 h 2.1: trifluoroacetic acid / water; tetrahydrofuran / 0 °C 3.1: (tetrazol-5-yl)benzene / dichloromethane / 1 h 3.2: 0.5 h / 0 °C 4.1: trifluoroacetic acid / water / 20 h / 0 °C View Scheme

1.1: trifluoroacetic acid / water; tetrahydrofuran / 0 °C 2.1: (tetrazol-5-yl)benzene / dichloromethane / 1 h 2.2: 0.5 h / 0 °C 3.1: trifluoroacetic acid / water / 20 h / 0 °C View Scheme

1.1: (tetrazol-5-yl)benzene / dichloromethane / 1 h 1.2: 0.5 h / 0 °C 2.1: trifluoroacetic acid / water / 20 h / 0 °C View Scheme

1.1: toluene-4-sulfonic acid / acetonitrile / 2 h / 20 °C 1.2: 0.25 h / |Reflux 2.1: tri-n-butyl-tin hydride; 2,2'-azo-bisisobutyronitrile / toluene / 2 h / |Reflux 3.1: methanol; ammonia / 16 h / 0 - 60 °C 4.1: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / N,N-dimethyl-formamide / 0.5 h 5.1: trifluoroacetic acid / water; tetrahydrofuran / 0 °C 6.1: (tetrazol-5-yl)benzene / dichloromethane / 1 h 6.2: 0.5 h / 0 °C 7.1: trifluoroacetic acid / water / 20 h / 0 °C View Scheme