Pyridine → Toluene-4-sulfonic acid 3-[8-amino-1-(3-benzyloxyphenyl)-imidazo[1,5-a]pyrazin-3-yl]cyclobutylmethyl ester

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Reaction Steps

A solution of {3-[8-amino-1-(3-benzyloxyphenyl)-imidazo[1,5-a]pyrazin-3-yl]cyclobutyl}methanol (23 mg, 0.057 mmol) in dry methylene chloride (3 mL) was charged with pyridine (0.1 mL) and Ts2O (21 mg, 0.063 mmol) at −20° C. under N2 atmosphere. The mixture was slowly warmed to rt overnight. The reaction was quenched with water (1 mL), diluted with ethyl acetate (20 mL), washed with sat. aq. NaHCO3 (10 mL) and brine (2×10 mL), and dried over anhydrous sodium sulfate. The filtrate was concentrated under reduced pressure, and the crude material was purified by silica gel column chromatography (eluting with EtOAc:MeOH=98:2→96:4), yielding the title compound as a white solid. Partial trans isomer was removed by chromatography and the ratio of cis and trans isomers raised to 8:1; MS (ES, Pos.): m/z 555 [MH+]. 1H NMR (CDCl3, 400 MHz) δ 2.27-2.35 (m, 2H), 2.41 (s, 3H), 2.55-2.62 (m, 2H), 2.80 (m, 1H), 3.66 (m, 1H), 4.07 (d, J=6.7 Hz, 2H), 5.01 (br s, 2H, NH2), 5.15 (s, 2H), 7.02-7.85 (m, 15H). Anal. Calcd for C31H30N4O4S.1/3H2O: C, 66.41; H, 5.51; N, 9.99. Found: C, 66.43; H, 5.44; N, 10.07.

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