sodium tetrahydroborate; acetic acid in 1-methyl-pyrrolidin-2-one; acetic acid T=30 - 35°C;

sodium hydroxide in ethylene glycol T=120°C; 4 h;

ammonium buffer; ammonia in water electrolysis;

1: 1.) potassium hydroxide, 2.) hydroxylamine O-sulfonic acid / 1.) DMF, 2.) DMF, RT, 1 h 2: 27 percent / pyridine / toluene / 1.25 h 3: 1.) potassium tert-butoxide / 1.) THF, 1 h, 2.) THF, RT, 5 h 4: 68 percent / aq. sodium hydroxide / ethane-1,2-diol / 4 h / 120 °C View Scheme

1: 27 percent / pyridine / toluene / 1.25 h 2: 1.) potassium tert-butoxide / 1.) THF, 1 h, 2.) THF, RT, 5 h 3: 68 percent / aq. sodium hydroxide / ethane-1,2-diol / 4 h / 120 °C View Scheme