Reaction Steps
Pd(PPh3)2Cl2 (20 mg) in a 10 mL of flask under Ar was treated sequentially with 2′-amino-6-bromo-1′-methyl-2-(thiophen-2-yl)spiro[chroman-4,4′-imidazol]-5′(1′H)-one (46 mg, 0.117 mmol) in 1,4-dioxane (5 mL), Cs2CO3 (2 N, 0.5 mL) and 4-cyanophenylboronic acid (34.5 mg, 0.23 mmol). The mixture was refluxed under Ar for 2 h. The reaction mixture was concentrated in vacuo to give the residue, which was purified by preparative TLC followed by preparative HPLC to give pure 3-((2S,4S)-2′-amino-1′-methyl-5′-oxo-2-(thiophen-2-yl)-1′,5′-dihydrospiro[chroman-4,4′-imidazole]-6-yl)benzonitrile (Compound 8a, 1.35 mg, 1%), 1H-NMR (CDCl3): 442-069-3B: 2.30 (d, 1H), 2.49 (d, 1H), 3.01 (d, 3H), 5.81 (dd, 1H), 6.95 (t, 1H), 7.00 (m, 2H), 7.05 (s, 1H), 7.30 (d, 1H), 7.40 (d, 1H), 7.49 (d, 1H), 7.51 (t, 1H), 7.61 (t, 2H), and 3-((2R,4S)-2′-Amino-1′-methyl-5′-oxo-2-(thiophen-2-yl)-1′,5′-dihydrospiro[chroman-4,4′-imidazole]-6-yl)-benzonitrile (Compound 8b, 1.10 mg, 1%). 1H-NMR (CDCl3): 2.40 (d, 1H), 2.63 (t, 1H), 3.31 (s, 3H), 6.12 (d, 1H), 6.95 (t, 1H), 7.00 (d, 1H), 7.05 (m, 2H), 7.30 (d, 1H), 7.48 (m, 2H), 7.54 (d, 1H), 7.68 (t, 2H).
