Cyclohexylamine (1.98 mL, 17.34 mmol) was added to a solution of Compound 41 (2.3 g, 8.67 mmol) in toluene (50 mL) and refluxed for 4 h. The solution was cooled and the solvent was evaporated under vacuum. The residue obtained was suspended in water, briefly sonicated, and filtered. The crude product was recrystallized by ether to yield 2.38 g (97%) of white solids. M.P. 193° C. 1H NMR (DMSO-d6): δ 1.28 (m, 1H), 1.36 (m, 4H), 1.55 (m, 1H), 1.68 (m, 2H), 1.87 (m, 2H), 3.62 (s, 3H), 3.90 (m, 1H), 7.70 (m, 3H), 7.77 (d, J=8.0 Hz, 1H), 10.41 (s, 1H). EIMS m/z 341 (M+23).
