Acetic acid 10-acetoxymethyl-anthracen-9-ylmethyl ester → Benzyl 4-[3-acetyl-2-(4-fluorophenyl)imidazo[1,2-a]pyridin-7-yl]piperidine-1-carboxylate

Imidazopyridine 34 (290 mg, 0.675 mmol) was dissolved in acetic (50 mL) in a 250 mL round bottom flask. Three drops of sulfuric acid were then added, and the reaction was heated to 140° C. for 24 hours. The reaction was then concentrated under reduced pressure, then diluted with both ethyl acetate and saturated sodium bicarbonate solution, and extracted repeatedly into ethyl acetate. Organic fractions were pooled, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was then dissolved in 5 mL methylene chloride, then loaded onto a 40 g Isco RediSep normal phase silica cartridge, and purified on an Isco OptiX10 CombiFlash instrument using a gradient that started at 100% heptane and ended at 100% ethyl acetate. Fractions containing desired product were pooled and concentrated under reduced pressure. Yield of 35: 180 mg (56%). 1H NMR (400 MHz, CDCl3) δ 1.67 (m, 2H), 1.92 (m, 2H), 2.17 (s, 3H), 2.81 (m, 1H), 2.93 (bs, 2H), 4.38 (bs, 2H), 5.16 (s, 2H), 6.48 (d, J=7.2 Hz, 1H), 6.96 (t, J=8.8 Hz, 2H), 7.24 (m, 5H), 7.57 (s, 1H), 7.76 (m, 2H), 7.86 (d, J=7.2 Hz, 1H). MS (ESI+) 472.2.