Synthesis of Novel Pyrazolo[3,4-b]pyridines with Affinity for β-Amyloid Plaques

Three novel pyrazolo[3,4-b]pyridines were synthesized via the cyclization of 5-amino-1-phenylpyrazole with corresponding unsaturated ketone in catalytic presence ZrCl4. The ketones afforded by modifying a stabilized ylide facilitated Wittig reaction fairly high yields. compounds exhibited exciting photophysical properties dimethylamine phenyl-bearing pyrazolopyridine showing exceptionally large Stoke’s shifts. Finally, both dimethylamino- and pyrene-substituted demonstrated selective binding to amyloid plaques Alzheimer’s disease (AD) patient brain slices upon fluorescent confocal microscopy observation. These results reveal potential application development AD plaque probes various modalities for diagnosis.