Hydrazine hydrate (1:1) → 2-Oxo-1-(2-trimethylsilanyl-ethoxymethyl)-1,2-dihydro-pyridine-4-carboxylic acid hydrazide

The title compound of example 19.1 (9.5 g, 32 mmol) was stirred in ethanol (100 mL) at 78° C. Hydrazine hydrate (7.8 mL, 159.7 mmol) was added and the reaction mixture was stirred at 78° C. for 3 hours. The reaction mixture was cooled to room temperature and concentrated to dryness. The residue was stirred in diethyl ether and filtered to give a yellow solid (8.5 g, 94%).