ethanol;hydrazine hydrateFABRITIUS, Charles-Henry, WO2011/77098, A1, (2 011)Diethyl oxalate (5g, 0.042 mol) and hydrazine monohydrate (2.8g, 0.057 mol) in ethanol (3ml) were heated to reflux for 15 hour. The reaction mixture was concentrated under reduced pressure and the res idue was treated with toluene (100ml x 3) to azeotrope hydrazine in excess. The crude residue was used for the next step without further purification.