tert-Butoxy bis(dimethylamino)methane → {(E)-2-[2-(2,6-dimethyl-phenyl)-5-nitro-pyridin-4-yl]vinyl}-dimethyl-amine

To a solution of the 2-(2,6-dimethyl-phenyl)-4-methyl-5-nitro-pyridine (8 g, 33.0 mmol) in anhydrous DMF (30 mL), Bredereck's reagent (20 mL, 99.0 mmol) is added, and the mixture is heated for 1 h at 90° C. The mixture is concentrated under reduced pressure, and the residue is dissolved a mixture of EtOAc-hexane-DCM (1:1:1, 200 mL) and filtered over small pad of silica gel. Removal of the solvent under reduced pressure gives the crude {(E)-2-[2-(2,6-dimethyl-phenyl)-5-nitro-pyridin-4-yl]vinyl}-dimethyl-amine which is used in the following step.