Synthesis of fluorescence polarization assay probe 1 Reagents and conditions: (a) methanol, SOCl2, rt, 5h; (b) 4-Nitrobenzoic acid, isobutyl chloroformate, N-methylmorpholine, THF, 0 C to room temperature; (c) MeOH, Pd/C, H2; (d) propargyl bromide, K2CO3, DMA, 16h, 50C; (d) Cu(MeCN)4PF6, ligand, 3-azidopropyl amine, MeCN; (e) KCN, H2NOH, MeOH, THF; (f) FITC, DMF