[CH:1]([C:3]1[N:8]=[C:7]([CH3:9])[C:6]([N+:10]([O-:12])=[O:11])=[CH:5][CH:4]=1)=[CH2:2].FC(F)(F)C(O)=O.CO[CH2:22][N:23]([CH2:29][C:30]1[CH:35]=[CH:34][CH:33]=[CH:32][CH:31]=1)[CH2:24][Si](C)(C)C.C(=O)(O)[O-].[Na+]>ClCCl>[CH3:9][C:7]1[C:6]([N+:10]([O-:12])=[O:11])=[CH:5][CH:4]=[C:3]([CH:1]2[CH2:2][CH2:24][N:23]([CH2:29][C:30]3[CH:35]=[CH:34][CH:33]=[CH:32][CH:31]=3)[CH2:22]2)[N:8]=1
To a solution of crude 6-ethenyl-2-methyl-3-nitropyridine (440 mg, 2.68 mmol) in dichloromethane (DCM) (5 mL) was added trifluoroacetic acid (0.268 mL, 3.48 mmol). To this stirred solution was added [(methyloxy)methyl](phenylmethyl)[(trimethylsilyl)methyl]amine (2.74 mL, 10.72 mmol) (carefully) and the reaction mixture was stirred under nitrogen for 1.5 hours. The reaction mixture was diluted with DCM and then treated with saturated sodium bicarbonate solution. The organic phase was separated and passed through a hydrophobic frit. The organic solvent was evaporated in vacuo and the residue was dissolved in DCM (5 mL). This was purified by silica (Si) chromatography (0-100% ethyl acetate-cyclohexane with 0-20% methanol gradient). The appropriate fractions were combined and evaporated in vacuo to give the crude product (201 mg) as a brown liquid. Used directly in next step without further purification. LCMS (2 min, formic) Rt 0.71 min, m/z (ES+) 298 (M+H).
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