1: 1.) 35percent HCl, acetic acid, 2.) sodium nitrite / 1.) 4 deg C, 20 min, 2.) water, RT, 6 h 2: 90 percent / hydrazine hydrate / 1 h / Heating 3: 1.) 6N HCl, 2.) sodium nitrite / 1.) 0 deg C, 2.) water, 60 min View Scheme

1: 1.) 35percent HCl, acetic acid, 2.) sodium nitrite / 1.) 4 deg C, 20 min, 2.) water, RT, 6 h 2: 53 percent / dimethylsulfoxide / 0.17 h / Ambient temperature View Scheme

sodium dithionite in methanol T=50°C; 3 h;

1: 2.) triethylamine / 1.) DMF, o deg C, 2.) DMF, 10 deg C, 4 h 2: 2.) sodium ditionate / 1.) methanol, 50 deg C, 2 h, 2.) ethanol, water, 50 deg C, 3 h View Scheme

N-ethyl-N,N-diisopropylamine in dichloromethane T=-78 - 20°C;

1: 1.) 35percent HCl, acetic acid, 2.) sodium nitrite / 1.) 4 deg C, 20 min, 2.) water, RT, 6 h 2: 90 percent / hydrazine hydrate / 1 h / Heating View Scheme